Replacement Coach Batteries Group 31
- Thread starter OldWest
- Start date
Five weeks into my summer travels has given me sufficient experience with my lithium battery system to provide a couple of observations:
1) Having two watt hour meters - one for power in and another for power out has proven to be very beneficial. Iv'e found that tracking watt hours in/out is more informative than amp hours. For example - 10 amps at 1 volt = 10 watts and conversely 1 amp at 10 volts = 10 watts. In other words a measurement of amps means nothing without knowing the voltage. Granted - the voltage during charging/discharging only varies by about 1 volt - nevertheless this does skew an amp hour only reading over time.
2) The icharger is highly configurable - which means one can adjust/adapt it to many circumstances - but this also implies a learning curve...
I'm currently in the Redwoods - where I have no solar gain - I really dislike firing up the generator in a campground - but here I only have two choices - start the engine and use the alternator or fire up the generator. In the past - living only with lead acid batteries - the charge current would start off fairly high - around 40 or 50 amps - but within 20 minutes or so it would drop off to 15 amps and gradually fall lower. With the icharger connected to the lithium battery the current draw from either generator or alternator is constant at about 36 amps. Note: I had previously - a few years ago - modified the wiring such that I can use the Mean Well convertors - air conditioner power supplies - to divert power to house batteries.
When I have had solar - whatever they were capable of outputting - the lithium batteries would gladly accept the full output. Whereas with lead acid - once the solar charge controller entered the absorption phase - the current would drop off to 1 or 2 amps regardless of how much was available. And that would go on for hours!
To try and summarize - one of the main advantages of lithium vs lead - as I see it - is that lithium batteries have a much higher acceptance rate than lead acid batteries. In other words - they charge up about twice as fast as lead acid. So whatever the charge source may be - you can leverage it's full output when charging a lithium battery!
The icharger - which is essentially a DC to DC converter - similar to a B2B charger - is an essential part of making the system perform well. It can load down the voltage output of an alternator or other charge source and force it to output more current. It can then step the voltage output up to provide sufficient 'push' for charging the battery to it's full potential. The icharger also monitors each individual cell and can balance the pack as needed and monitor the them to prevent over charging.
Iv'e taken some liberties with the proper terminology in an attempt to express the information in layman's terms.
The more technically savvy folks will no doubt question the quality of my technical writing.
Whereas the less savvy folks will no doubt still be scratching their heads wondering what the heck I'm talking about.
Ah well - such is life
John...
1) Having two watt hour meters - one for power in and another for power out has proven to be very beneficial. Iv'e found that tracking watt hours in/out is more informative than amp hours. For example - 10 amps at 1 volt = 10 watts and conversely 1 amp at 10 volts = 10 watts. In other words a measurement of amps means nothing without knowing the voltage. Granted - the voltage during charging/discharging only varies by about 1 volt - nevertheless this does skew an amp hour only reading over time.
2) The icharger is highly configurable - which means one can adjust/adapt it to many circumstances - but this also implies a learning curve...
I'm currently in the Redwoods - where I have no solar gain - I really dislike firing up the generator in a campground - but here I only have two choices - start the engine and use the alternator or fire up the generator. In the past - living only with lead acid batteries - the charge current would start off fairly high - around 40 or 50 amps - but within 20 minutes or so it would drop off to 15 amps and gradually fall lower. With the icharger connected to the lithium battery the current draw from either generator or alternator is constant at about 36 amps. Note: I had previously - a few years ago - modified the wiring such that I can use the Mean Well convertors - air conditioner power supplies - to divert power to house batteries.
When I have had solar - whatever they were capable of outputting - the lithium batteries would gladly accept the full output. Whereas with lead acid - once the solar charge controller entered the absorption phase - the current would drop off to 1 or 2 amps regardless of how much was available. And that would go on for hours!
To try and summarize - one of the main advantages of lithium vs lead - as I see it - is that lithium batteries have a much higher acceptance rate than lead acid batteries. In other words - they charge up about twice as fast as lead acid. So whatever the charge source may be - you can leverage it's full output when charging a lithium battery!
The icharger - which is essentially a DC to DC converter - similar to a B2B charger - is an essential part of making the system perform well. It can load down the voltage output of an alternator or other charge source and force it to output more current. It can then step the voltage output up to provide sufficient 'push' for charging the battery to it's full potential. The icharger also monitors each individual cell and can balance the pack as needed and monitor the them to prevent over charging.
Iv'e taken some liberties with the proper terminology in an attempt to express the information in layman's terms.
The more technically savvy folks will no doubt question the quality of my technical writing.
Whereas the less savvy folks will no doubt still be scratching their heads wondering what the heck I'm talking about.
Ah well - such is life
John...
OneManVan: Have you been able to live off the 60 amp-hr lithium battery alone (as you can drain it down a lot more)??
(Excludes your microwave use as inverter is hooked up to regular AGM batteries?)
Maybe a 100 amp-hr would give better safety reserve and you could use the original battery compartment as storage.
(Excludes your microwave use as inverter is hooked up to regular AGM batteries?)
Maybe a 100 amp-hr would give better safety reserve and you could use the original battery compartment as storage.
That's a good question - and the short answer is YES - 60ah is more than sufficient.
The long answer is there are different scenarios to consider...
For example - I'm here now in the Redwoods NP ( Jed Smith CG ) for 8 days - where there is basically no possibility for solar gain.
With the exception of the inverter - which as you pointed out - I'm running off the lead acid battery bank - and which I only use a few times each day for 5 or 10 seconds - I have relied entirely on the lithium battery.
This situation has allowed me to make use of the watt hour meters and realize exactly how many watt hours I'm consuming in a 24 hour period. And on the flip side exactly how long I need to run the generator to make up for that loss - typically one hour per day. When I average the numbers out over an eight day period I come up with a total of about 450 watt hours ( roughly 30ah ) per day. Given that the capacity of the lithium battery is about 900 watt hours ( I confirmed this through testing prior to installation ) this implies - under the most demanding scenario - I already have basically 100% more capacity than I need. Granted - over time the capacity will decay - but even after the capacity reaches 50% - typically the end of life for a lithium battery - I will still have enough to meet my minimum daily requirements.
For me - the most typical scenario though - is when I do have solar gain. For example I was previously at Wheeler Peak CG in the Great Basin NP for 8 days. There I had good solar gain from my portable panel from roughly 10 am to 4 pm. When I'm in a campsite like that I switch the loads from lithium to lead once the sun is shining and initiate a charge cycle via the icharger for the lithium battery. During this time - if a load kicks in - for example the fridge - the icharger automatically diverts power from the solar panel to the loads. After the load goes away the icharger automatically diverts the full output of the solar panel to the lithium battery. Once the lithium battery is fully charged I shut down the icharger and leave the lithium battery in standby until I lose the sun. Typically in this scenario - where the lithium battery was only online during the 'dark' hours - the watt hour meter was registering 15 ah consumption per day. So in this case the lithium battery has 200% more capacity than I need.
A third and less frequent scenario are the travel days. When I know that the following day I will be driving for some hours I leave the lithium battery offline during the 'dark' hours and rely solely on the lead batteries. For one thing - I don't want to have to babysit the lithium charge cycle on these hectic travel days. And yes - the icharger does need babysitting when it's in use. But the main thing is I have a surplus of charge capacity on these days - so it does not matter if the lead acid batteries are taking their usual sweet time about achieving a full charge.
As far as eliminating the lead batteries entirely - NO - I never intended to do that and still don't. I need the robust capacity of my two 6 volt AGM's in series and their related wiring to power the inverter. That was all bought and paid for and works fine. I only wanted the lithium battery for the light loads. This allowed me to use light duty relays and wiring - less expense and easier installation.
As anyone with much experience doing extended travels in their Westy already knows - the fridge uses the most power on any given day. I've yet to measure this exactly but I guesstimate it's around 20ah per day - minimum! Depends on what temperature you have it set at ( for me 34 degrees ), what the ambient air temperature is, how much exposure to the sun the passenger side of the van endures, how much warm stuff you add to the fridge each day, and, and, and...
John...
The long answer is there are different scenarios to consider...
For example - I'm here now in the Redwoods NP ( Jed Smith CG ) for 8 days - where there is basically no possibility for solar gain.
With the exception of the inverter - which as you pointed out - I'm running off the lead acid battery bank - and which I only use a few times each day for 5 or 10 seconds - I have relied entirely on the lithium battery.
This situation has allowed me to make use of the watt hour meters and realize exactly how many watt hours I'm consuming in a 24 hour period. And on the flip side exactly how long I need to run the generator to make up for that loss - typically one hour per day. When I average the numbers out over an eight day period I come up with a total of about 450 watt hours ( roughly 30ah ) per day. Given that the capacity of the lithium battery is about 900 watt hours ( I confirmed this through testing prior to installation ) this implies - under the most demanding scenario - I already have basically 100% more capacity than I need. Granted - over time the capacity will decay - but even after the capacity reaches 50% - typically the end of life for a lithium battery - I will still have enough to meet my minimum daily requirements.
For me - the most typical scenario though - is when I do have solar gain. For example I was previously at Wheeler Peak CG in the Great Basin NP for 8 days. There I had good solar gain from my portable panel from roughly 10 am to 4 pm. When I'm in a campsite like that I switch the loads from lithium to lead once the sun is shining and initiate a charge cycle via the icharger for the lithium battery. During this time - if a load kicks in - for example the fridge - the icharger automatically diverts power from the solar panel
A third and less frequent scenario are the travel days. When I know that the following day I will be driving for some hours I leave the lithium battery offline during the 'dark' hours and rely solely on the lead batteries. For one thing - I don't want to have to babysit the lithium charge cycle on these hectic travel days. And yes - the icharger does need babysitting when it's in use. But the main thing is I have a surplus of charge capacity on these days - so it does not matter if the lead acid batteries are taking their usual sweet time about achieving a full charge.
As far as eliminating the lead batteries entirely - NO - I never intended to do that and still don't. I need the robust capacity of my two 6 volt AGM's in series and their related wiring to power the inverter. That was all bought and paid for and works fine. I only wanted the lithium battery for the light loads. This allowed me to use light duty relays and wiring - less expense and easier installation.
As anyone with much experience doing extended travels in their Westy already knows - the fridge uses the most power on any given day. I've yet to measure this exactly but I guesstimate it's around 20ah per day - minimum! Depends on what temperature you have it set at ( for me 34 degrees ), what the ambient air temperature is, how much exposure to the sun the passenger side of the van endures, how much warm stuff you add to the fridge each day, and, and, and...
John...
Attachments
If you set the fridge to a higher temperature, you will use much less energy. You also have the benefit of slightly less condensation on the cooling panel and resultant water in the bottom. Dometic probably publishes a graph of T vs W, and I suspect it has a wicked curve.
Yes, the FDA recommends 33-34F and while there's no doubt that food safety is greater the closer you are to freezing, the benefit of much less battery use may well outweigh the risk.
We keep a pretty much vegetarian van, and if we have meat we consume it on the same day. Our fridge is at 46F = 8C, which is what our German milk carton recommends as the maximum storage temperature. It's also the top temperature our home fridge (which we keep at 2C) will go to. Never had a problem with milk, and of course cheese, vegetables, fruit, jams, etc all do fine at the warmer temperature. And they just leave eggs out on the supermarket shelves here -- go figure!
Ted
Yes, the FDA recommends 33-34F and while there's no doubt that food safety is greater the closer you are to freezing, the benefit of much less battery use may well outweigh the risk.
We keep a pretty much vegetarian van, and if we have meat we consume it on the same day. Our fridge is at 46F = 8C, which is what our German milk carton recommends as the maximum storage temperature. It's also the top temperature our home fridge (which we keep at 2C) will go to. Never had a problem with milk, and of course cheese, vegetables, fruit, jams, etc all do fine at the warmer temperature. And they just leave eggs out on the supermarket shelves here -- go figure!
Ted
5,000 miles, 4 months & 40 campgrounds - dry camping. Reflections on living with lithium
In previous posts Iv'e described how I integrated a lithium battery into my existing DC electrical system and how it performed under various scenarios.
Now for the bad news:
Really the only part of the system that has failed to live up to my expectations is the icharger 3010. The full explanation is probably more complicated than most folks would be interested in so this is just a high level description. Basically the problem is - the icharger requires too much 'babysitting' when the charge source is solar. The way it's designed - if the input voltage drops below a certain threshold the charger generates an error and stops charging - it has to be manually restarted. The threshold can be lowered but doing so leads to other problems. The error can occur when solar panel are putting out less power than the loads demand - for example the refrigerator kicks on, the inverter is turned on, etc... So it's impossible to go off and leave the charger unattended when there is a possibility that demands might exceed supply...
The icharger is basically a DC to DC converter - or B2B charger designed primarily for charging lithium batteries. It has many features - among them the ability to balance individual cells in a battery pack. For me - that was the main selling point.
At the time I configured my lithium battery system I was under the impression that cell balancing was a necessary part of a well designed system. To some extent I still believe that's true. But perhaps only under certain circumstances...
To help explain what I mean Iv'e attached a charge curve graph/plot for a battery similar to mine. For an LFP battery such as the one I installed it is recommended to limit charge current to .5C - so for a 60AH such as mine that means no more than 30 amps ie: half it's rated Capacity. So whenever I'm referencing the chart it's with regard to the .5C curve - the RED one.
As you can see 80% of the curve is relatively flat. The beginning and end of the charge cycle rises and falls very quickly - these are referred to as the 'knees' of the curve. Manufacturers understand that most consumers are only interested in AH/dollar. So when they publish their glossy sales brochures they include the first and last 20% of capacity. And when they're selling 'drop in' replacement batteries they set the under and over voltage protection thresholds very near the absolute minimum and maximum allowable voltage. So they're essentially 'red lining' the battery to boost their sales figures! Unfortunately most battery management systems ( BMS ) do not allow the end user to adjust the thresholds.
That is the main reason I built my system from scratch. I want to be able to keep the battery operating in the flat part of the curve.
When I received my battery I performed a number of tests. I carefully monitored the individual cell voltages and current from 0% state of charge up to 100%. Two things jumped out at me during these tests.
1) cell #2 always seemed to be a non conformist in the knee regions.
2) the safe part of the curve was smaller than I thought it would be - less than 80%.
I entered this 'experiment' believing that with properly administered 'behavioral modification therapy' the individual cells could be 'taught' to conform. IE: rise and fall at the same rate - plus or minus a few millivolts ( .003 volts ). I believed that cell balancing would achieve this.
Unfortunately that turned out to be NOT entirely true...
Perhaps a brief explanation of what cell balancing is would be in order. Typically the way this works is once the battery gets into the upper part of the knee there is a tendency for the individual cell voltages to go their separate ways. Invariably there will be winners and losers in the race to the top. Unfortunately in the case of a lithium battery pack the prize for being the winner is DEATH. So to prevent any cell from 'redlining' a resistor is placed across the cell that are getting too far ahead. In essence this allows the 'laggard' to catch up. The goal is for all cells to cross the finish line together. In essence this is what I now believe is the only purpose of cell balancing. I had previously imagined that this would 'teach' all cells to stay in sync. But from my experience this does NOT seem to be true. Once a 'laggard' always a 'laggard'... Not all cells are created equal...
So when charging - if the upper threshold - finish line - is set to a conservative value - then it's no longer necessary for all cells to cross the finish line in unison. Initiating a typical cell balancing routine in the flat part of the curve just wastes time and energy.
For my 60AH battery pack redline is defined as 14.4 volts IE: 3.6 volts at the cell level. So - in theory if I define the 'finish line' to be 13.9 volts IE 3.475 volts at the cell level then the cells can be up to 125 millivolts ( .125 volts ) out of sync before there is a risk of any individual cell 'redlining'.
I have been operating my icharger 3010 with the 'finish line' set to 13.68 volts ie: 3.42 volts at the cell level. At this level the cells are typically never more than 20 millivolts ( .020 volts ) out of sync with one another as they approach the 'finish line'. Across the flat part of the curve they're typically only a few millivolts out of sync ie: well balanced.
So you may be wondering what setting the upper and lower thresholds to such conservative values does to the storage capacity of the battery. Well - again - I performed a number of different tests on the battery pack when I first received it. The flat part of the curve was indeed smaller than some sources indicated they should be. But I did not have any curves from the manufacturer for the 60AH battery. So it was a bit like comparing apples and oranges. The tests I performed yielded enough information to determine where best to set the upper and lower thresholds. The goal being to watch the individual cells during charge and discharge cycles and note where the cells started to get really out of sync - ie: > 20 millivolts. Then I performed several charge/discharge cycles within those boundaries ie: 12.6 (3.15) ~ 13.6 (3.4) - and measured watt hours in and watt hours out. Operating within these very conservative limits I was measuring 900 watt hours of capacity. Which is basically what the battery is rated at.
So - where do I go from here...
I purchased a different battery charger:
https://www.invertersupply.com/inde...sult&search_in_description=1&keyword=dmt-1230
You can read specifications and user manuals till you're blue in the face. But until you actually get it installed and live with it for some months you won't know if it satisfies your needs.
On paper - it would appear that this charger can be configured to integrate with my lithium battery system. It is not capable of performing cell balancing or terminating the charge cycle if any individual cell 'redlines'. But as Iv'e tried to explain - I no longer feel that is a requirement if the thresholds are kept in the 'safe' zone. 13.9 volts is the lowest value the 'finish line' can be set to for battery type lithium. That's about .1 volts higher than I would like. IE: not as conservative as I would like. With battery type defined as program ( custom settings ) the lowest value is 13.8 but it's doubtful that setting would work well for lithium batteries as it never terminates the charge, instead it goes to float after the 'finish line' is crossed.
One additional comment regarding the finish line - ie: termination voltage. The chargers I've mentioned don't terminate the charge cycle as soon as the battery voltage reaches the upper threshold. Instead they hold the charge voltage at the upper threshold until the acceptance rate - ie charge current - falls below a given set point. With respect to the DMT-1230 the set point can be set to 1.5, 3 or 6 amps. As with lead acid batteries the acceptance rate of lithium batteries tapers off as the battery approaches 100% SOC. So the charge cycle will terminate sooner if the set point is 6 amps and later if the set point is 1.5 amps. You can squeeze a bit more juice into the battery with a lower set point but it takes longer to finish the charge cycle - and it increases the risk of one or more cells 'redlining' when there is no BMS ie: cell balancing in place.
Once I receive the DMT-1230 I'll hook it up to my 60AH battery and a solar panel - adjust the lithium charge profile - 13.9 volts with a 3 amp termination current - perform a couple of charge/discharge cycles - and see what happens...
So - the journey/experiment continues.
John...
In previous posts Iv'e described how I integrated a lithium battery into my existing DC electrical system and how it performed under various scenarios.
Now for the bad news:
Really the only part of the system that has failed to live up to my expectations is the icharger 3010. The full explanation is probably more complicated than most folks would be interested in so this is just a high level description. Basically the problem is - the icharger requires too much 'babysitting' when the charge source is solar. The way it's designed - if the input voltage drops below a certain threshold the charger generates an error and stops charging - it has to be manually restarted. The threshold can be lowered but doing so leads to other problems. The error can occur when solar panel
The icharger is basically a DC to DC converter - or B2B charger designed primarily for charging lithium batteries. It has many features - among them the ability to balance individual cells in a battery pack. For me - that was the main selling point.
At the time I configured my lithium battery system I was under the impression that cell balancing was a necessary part of a well designed system. To some extent I still believe that's true. But perhaps only under certain circumstances...
To help explain what I mean Iv'e attached a charge curve graph/plot for a battery similar to mine. For an LFP battery such as the one I installed it is recommended to limit charge current to .5C - so for a 60AH such as mine that means no more than 30 amps ie: half it's rated Capacity. So whenever I'm referencing the chart it's with regard to the .5C curve - the RED one.
As you can see 80% of the curve is relatively flat. The beginning and end of the charge cycle rises and falls very quickly - these are referred to as the 'knees' of the curve. Manufacturers understand that most consumers are only interested in AH/dollar. So when they publish their glossy sales brochures they include the first and last 20% of capacity. And when they're selling 'drop in' replacement batteries they set the under and over voltage protection thresholds very near the absolute minimum and maximum allowable voltage. So they're essentially 'red lining' the battery to boost their sales figures! Unfortunately most battery management systems ( BMS ) do not allow the end user to adjust the thresholds.
That is the main reason I built my system from scratch. I want to be able to keep the battery operating in the flat part of the curve.
When I received my battery I performed a number of tests. I carefully monitored the individual cell voltages and current from 0% state of charge up to 100%. Two things jumped out at me during these tests.
1) cell #2 always seemed to be a non conformist in the knee regions.
2) the safe part of the curve was smaller than I thought it would be - less than 80%.
I entered this 'experiment' believing that with properly administered 'behavioral modification therapy' the individual cells could be 'taught' to conform. IE: rise and fall at the same rate - plus or minus a few millivolts ( .003 volts ). I believed that cell balancing would achieve this.
Unfortunately that turned out to be NOT entirely true...
Perhaps a brief explanation of what cell balancing is would be in order. Typically the way this works is once the battery gets into the upper part of the knee there is a tendency for the individual cell voltages to go their separate ways. Invariably there will be winners and losers in the race to the top. Unfortunately in the case of a lithium battery pack the prize for being the winner is DEATH. So to prevent any cell
So when charging - if the upper threshold - finish line - is set to a conservative value - then it's no longer necessary for all cells to cross the finish line in unison. Initiating a typical cell balancing routine in the flat part of the curve just wastes time and energy.
For my 60AH battery pack redline is defined as 14.4 volts IE: 3.6 volts at the cell level. So - in theory if I define the 'finish line' to be 13.9 volts IE 3.475 volts at the cell level then the cells can be up to 125 millivolts ( .125 volts ) out of sync before there is a risk of any individual cell 'redlining'.
I have been operating my icharger 3010 with the 'finish line' set to 13.68 volts ie: 3.42 volts at the cell level. At this level the cells are typically never more than 20 millivolts ( .020 volts ) out of sync with one another as they approach the 'finish line'. Across the flat part of the curve they're typically only a few millivolts out of sync ie: well balanced.
So you may be wondering what setting the upper and lower thresholds to such conservative values does to the storage capacity of the battery. Well - again - I performed a number of different tests on the battery pack when I first received it. The flat part of the curve was indeed smaller than some sources indicated they should be. But I did not have any curves from the manufacturer for the 60AH battery. So it was a bit like comparing apples and oranges. The tests I performed yielded enough information to determine where best to set the upper and lower thresholds. The goal being to watch the individual cells during charge and discharge cycles and note where the cells started to get really out of sync - ie: > 20 millivolts. Then I performed several charge/discharge cycles within those boundaries ie: 12.6 (3.15) ~ 13.6 (3.4) - and measured watt hours in and watt hours out. Operating within these very conservative limits I was measuring 900 watt hours of capacity. Which is basically what the battery is rated at.
So - where do I go from here...
I purchased a different battery charger:
https://www.invertersupply.com/inde...sult&search_in_description=1&keyword=dmt-1230
You can read specifications and user manuals till you're blue in the face. But until you actually get it installed and live with it for some months you won't know if it satisfies your needs.
On paper - it would appear that this charger can be configured to integrate with my lithium battery system. It is not capable of performing cell balancing or terminating the charge cycle if any individual cell 'redlines'. But as Iv'e tried to explain - I no longer feel that is a requirement if the thresholds are kept in the 'safe' zone. 13.9 volts is the lowest value the 'finish line' can be set to for battery type lithium. That's about .1 volts higher than I would like. IE: not as conservative as I would like. With battery type defined as program ( custom settings ) the lowest value is 13.8 but it's doubtful that setting would work well for lithium batteries as it never terminates the charge, instead it goes to float after the 'finish line' is crossed.
One additional comment regarding the finish line - ie: termination voltage. The chargers I've mentioned don't terminate the charge cycle as soon as the battery voltage reaches the upper threshold. Instead they hold the charge voltage at the upper threshold until the acceptance rate - ie charge current - falls below a given set point. With respect to the DMT-1230 the set point can be set to 1.5, 3 or 6 amps. As with lead acid batteries the acceptance rate of lithium batteries tapers off as the battery approaches 100% SOC. So the charge cycle will terminate sooner if the set point is 6 amps and later if the set point is 1.5 amps. You can squeeze a bit more juice into the battery with a lower set point but it takes longer to finish the charge cycle - and it increases the risk of one or more cells 'redlining' when there is no BMS ie: cell balancing in place.
Once I receive the DMT-1230 I'll hook it up to my 60AH battery and a solar panel - adjust the lithium charge profile - 13.9 volts with a 3 amp termination current - perform a couple of charge/discharge cycles - and see what happens...
So - the journey/experiment continues.
John...
Attachments
Last edited:
I received the Kisae/Abso DMT-1230 DC to DC charger and performed a number of different tests. It seems to be a pretty good charger and mostly works as advertised. Anyone considering purchasing one of these should be aware that as the manufacturer recommends cable size is critical to good performance. IE: very heavy gauge cables are a necessary! It's especially critical in the cables between the output of the charger and the input to battery. I was testing with 10 gauge wires - only 12 inches between the charger and the battery - seeing a .3 volt drop at 30 amps. With a lithium battery .3 volts can be the difference between life and death...
However - for me - 13.9 volts is too high a voltage for my lithium batteries. The cells got more than 100 millivolts ie: .1 volt out of sync. I don't think I redlined any cells but it was scary how quickly and drastically things began to get out of hand. So I'll probably return this charger and fall back to the original setup - IE: icharger 3010. Given a choice between having to babysit the charger and possibly killing the battery I have to choose babysitting. Live and learn...
However - for me - 13.9 volts is too high a voltage for my lithium batteries. The cells got more than 100 millivolts ie: .1 volt out of sync. I don't think I redlined any cells but it was scary how quickly and drastically things began to get out of hand. So I'll probably return this charger and fall back to the original setup - IE: icharger 3010. Given a choice between having to babysit the charger and possibly killing the battery I have to choose babysitting. Live and learn...
1. I'd guess for the average camper, this is too much work and too easy to forget what you're supposed to be watching.
Like your linked article said, consumers will destroy the new lithium batteries so the whole industry will get a bad rap. Not a drop in and ignore.
Maybe will just have to wait for Tesla--if they can save Puerto Rico, maybe they'll have an RV house version with smart charger/monitoring/etc.
2. Given the capability of your 60 amp-hr lithium battery, I wonder if one can live off a 100 amp-hr lithium with an inverter and microwave (assuming proper care and feeding). I think some folks have only one 100 amp-hr lithium battery--would sure help the expense side.
3. Load Diversion
Wonder if your original icharger battery charger load diversion feature would be sufficient to use excess solar to heat a small hot water heater. Otherwise, extra solar energy is wasted once batteries are charged.
Like your linked article said, consumers will destroy the new lithium batteries so the whole industry will get a bad rap. Not a drop in and ignore.
Maybe will just have to wait for Tesla--if they can save Puerto Rico, maybe they'll have an RV house version with smart charger/monitoring/etc.
2. Given the capability of your 60 amp-hr lithium battery, I wonder if one can live off a 100 amp-hr lithium with an inverter and microwave (assuming proper care and feeding). I think some folks have only one 100 amp-hr lithium battery--would sure help the expense side.
3. Load Diversion
Wonder if your original icharger battery charger load diversion feature would be sufficient to use excess solar to heat a small hot water heater. Otherwise, extra solar energy is wasted once batteries are charged.
Paul_E_D
Member
I'm not so sure this isn't a lot of over thinking. I drop in replace motorcycle batteries with LiFPO4 all the time. They out perform lead acid and charge on the alternator, I use regular trickle chargers at times to maintain them. So far no fires, and I haven't killed one yet.
Sometimes just do it if it works?
Sometimes just do it if it works?
Lithium batteries in an RV is still a relatively new alternative to conventional lead acid batteries.
I have been trained and worked as both an Electronic Technician and RV Repair Technician. Although I'm now retired I still have an interest in both fields. It's now a hobby, pastime, pain in the ass, all of the above
I became increasingly curious over the past few years how I might be able to transition from lead acid to lithium. Last year I finally got serious about it and embarked on an 'experiment'. Iv'e learned quite a bit along the way but I still have a lot to learn. I could have simply purchased a 'drop in' solution. But I wouldn't have learned very much with that approach. I chose an approach that has more or less 'forced' me to learn along the way.
I thought it might be helpful/useful to other Westy owners to share my 'technical notes' as the 'experiment' progresses in case they might also be considering switching from lead acid to lithium.
John...
I have been trained and worked as both an Electronic Technician and RV Repair Technician. Although I'm now retired I still have an interest in both fields. It's now a hobby, pastime, pain in the ass, all of the above
I became increasingly curious over the past few years how I might be able to transition from lead acid to lithium. Last year I finally got serious about it and embarked on an 'experiment'. Iv'e learned quite a bit along the way but I still have a lot to learn. I could have simply purchased a 'drop in' solution. But I wouldn't have learned very much with that approach. I chose an approach that has more or less 'forced' me to learn along the way.
I thought it might be helpful/useful to other Westy owners to share my 'technical notes' as the 'experiment' progresses in case they might also be considering switching from lead acid to lithium.
John...
Talking to
“Being in New Mexico, I would first try Fisheries Supply in Washington state, as they are probably the nearest distributor to you. See our distributor map on our website - https://oceanplanetenergy.com/advan...our-firefly-battery-dealers-in-north-america/
IF that doesn't work out, we have stock here in Maine and can ship you two via UPS.
From your description, it sounds as though your battery charger is rather small - (10 amps?). The Firefly like a higher charge amperage from time to time - nearer to .4C. (This means 40% of total capacity - if you had two GP 31 in a parallel bank for 232 amp hrs, it would be better to have an 80 - 100a charger). Remember too, that your charge sources - solar, and shore power - need to be programmable for the Firefly charge parameters of 14.4v Bulk/Absorption and 13.4v float. This is critical to the life cycles of the Firefly.
I am also wondering if your van's main alternator also has a charge relay connected to your house bank?
We can help you with these other questions if you need - just reply to this email, or give us a call @ (207) 370-9112.
Regards, Tom and the OPE Crew”
“Being in New Mexico, I would first try Fisheries Supply in Washington state, as they are probably the nearest distributor to you. See our distributor map on our website - https://oceanplanetenergy.com/advan...our-firefly-battery-dealers-in-north-america/
IF that doesn't work out, we have stock here in Maine and can ship you two via UPS.
From your description, it sounds as though your battery charger is rather small - (10 amps?). The Firefly like a higher charge amperage from time to time - nearer to .4C. (This means 40% of total capacity - if you had two GP 31 in a parallel bank for 232 amp hrs, it would be better to have an 80 - 100a charger). Remember too, that your charge sources - solar, and shore power - need to be programmable for the Firefly charge parameters of 14.4v Bulk/Absorption and 13.4v float. This is critical to the life cycles of the Firefly.
I am also wondering if your van's main alternator also has a charge relay connected to your house bank?
We can help you with these other questions if you need - just reply to this email, or give us a call @ (207) 370-9112.
Regards, Tom and the OPE Crew”
I believe my mistake which might have damaged the battery was to come back from a trip and connect the van to solar at home in a not very good location rather than bulk charging first.
Then I tried shore power after 1 week without success but realized it wasn’t working. On week 3 I started pulling the voltmeter.
Then I tried shore power after 1 week without success but realized it wasn’t working. On week 3 I started pulling the voltmeter.
westyventures
In the Oregon Outback
I just installed a pair of 125Ah Victron 'SuperCycle' batteries in mine. They are tested to suffer no damage from deep discharge as much as 90% in over 300 cycles. Heavy!
Ipedalfaster
New member
Are you using the original charger unit and wiring with the SuperCycles? Curious to know how they have performed for you as I am interested in purchasing a pair.
westyventures
In the Oregon Outback
I had planned to update to a more modern charger but so far it seems to be fine. I tend to use the Iota brand often in builds.
I recently became aware of some lithium batteries that seem to offer a lot of bang for the buck...
These two video series are worth watching if you're interested.
They both involve DIY installations of four 3.2 volt 280 AH batteries in series.
The cost plus shipping is less than $500 - so you're basically getting the equivalent three Battle Born batteries for half the cost of a single BB battery.
The four batteries together would measure (L,W,H) 11.33, 6.81, 7.87 & the weight would be about 46 lbs
Typically Group 31 batteries measure about 13 x 6.8 x 9.44 inches & weigh 50~60 lbs
FWIW:
I've been working on my lithium upgrade for several years now.
The 'custom' BMS I built is designed specifically for the Kisae DMT1250
My BMS configuration will work with any lithium battery bank.
Link to photos of my most recent/current install:
https://photos.app.goo.gl/Q6p5ypjTy215ejDw6
Blog I did a few years ago - some info still relevant:
https://1manvan.blogspot.com/2018/06/diy-lithium-battery-system-disclaimer_30.html
FWIW: Thornwave introduced a new product since I did my most recent installation - it combines the shunt and the power monitor into a single product.
https://www.thornwave.com/collectio...tor-dc-power-meter-with-integrated-500a-shunt
These two video series are worth watching if you're interested.
They both involve DIY installations of four 3.2 volt 280 AH batteries in series.
The cost plus shipping is less than $500 - so you're basically getting the equivalent three Battle Born batteries for half the cost of a single BB battery.
The four batteries together would measure (L,W,H) 11.33, 6.81, 7.87 & the weight would be about 46 lbs
Typically Group 31 batteries measure about 13 x 6.8 x 9.44 inches & weigh 50~60 lbs
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FWIW:
I've been working on my lithium upgrade for several years now.
The 'custom' BMS I built is designed specifically for the Kisae DMT1250
My BMS configuration will work with any lithium battery bank.
Link to photos of my most recent/current install:
https://photos.app.goo.gl/Q6p5ypjTy215ejDw6
Blog I did a few years ago - some info still relevant:
https://1manvan.blogspot.com/2018/06/diy-lithium-battery-system-disclaimer_30.html
FWIW: Thornwave introduced a new product since I did my most recent installation - it combines the shunt and the power monitor into a single product.
https://www.thornwave.com/collectio...tor-dc-power-meter-with-integrated-500a-shunt
piyush123
Member
hi there is a lot of brain power and knowledge here so sorry if my question seems too simple . I believe my old house batteries are damaged it was my fault i left the bathroom fan on they got low voltage. My batteries started off gassing , so disconnected them. If i want a drop in replacement what should i get ? ,
