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fourgonbound
03-13-2017, 07:57 PM
Hi there,

I have a Winnebago View 24J 2017 so with a 2016 Sprinter 3500 chassis (220amp alternator).
I am getting lithium batteries for the coach and am going to place them at the rear of the coach under the bed meaning 10-15' away from where they currently are (they're about 5' max from the solenoid under the passenger seat).
Currently all the wiring for the chassis/coach battery to alternator is done with 2ga wires which works OK for 5' / 60amps of current going thru them to get to the coach batteries (probably max voltage drop of 0.1V).

So I am wondering what is the max voltage of the alternator at the chassis and coach batteries right now during high outputs of the alternator and also what would be the max current being delivered to the batteries.
Adding 10-15' of 2ga wires to get to the LFPs means a potential voltage drop of 0.28V @ 60amps which is huge if the voltage is around 14.1V at chassis: If so, it'd be useless to have the LFPs being charged from the alternator since they need a voltage of at least 14V.

Anyone has data on max voltage/max amps going to chassis battery? (and perhaps average/min)

I also take that because it's computer controlled, there's no way to tweak the voltage huh?

Thanks,
Christophe

mikeme
03-13-2017, 08:08 PM
might want to consider a dc-dc charging device, programmed for the needs of your LI batteries.

do you have a handle on adjustment of the other charging devices?

and it is unlikely you will find a good way to adjust operating parameters of the engine alternator.

sprint2freedom
03-13-2017, 08:20 PM
At some distance (>10-15ft?) running 4/0 or 400 MCM wire to reduce voltage drop at high currents becomes quite heavy, cumbersome and expensive. I assume you've already considered whether your bank really needs to be located in the very back?

In your situation I would think about installing a dedicated ~1000W inverter under the hood, and running a cheap AC extension cord (14 gauge should be enough) to a 3-stage battery charger in the back for the house bank.

The D+ connection on the so-called EK1 terminal under the driver seat provides a +12V signal only when the engine is running. You could use that to actuate a relay to turn on the inverter and automate charging.

fourgonbound
03-13-2017, 08:40 PM
@mikeme : Thanks. The DC-DC charger is a good idea. I might look into that. If it's too expensive, perhaps I just won't wire it and rely on solar entirely?

@sprint2freedom :
Agreed with wire size/weight. This is why I am asking for specifics to make a call on what I'll wire or not.
I keep going back and forth between the placement of the battery and new inverter because the battery is a LFP, it needs to be in a somewhat temperature controlled environment so inside the coach seems like the easiest way to achieve that. Now I do have a storage space under the kitchen, located right next to where the current batteries are but I would have to insulate the whole space I think. This might be the easiest way of dealing with all this, indeed. It will just make them 3 feet further than their current location I believe.
The inverter under the hood option is something I literally just thought about too :P Amp up the voltage to lower the amps going through the wires would help a lot. If I could multiply the voltage by 3, therefore divide the amps by 3, 2ga wires would be ok... And I could run it through my MPPT charge controller since my panels are in series (2S2P 100W panels @ 21Voc so 42Voc)

mikeme
03-13-2017, 09:39 PM
the suggested inverter under the hood would have you run 12 or 14 ga for the 110 volts AC, which you would then have to plug into the shore power charger. not a direct wire, you would need some kind of control/switch/relay to avoid having the engine feed the grid. or plan to only run an inverter/charger from the engine, and not external 110vAC

sprint2freedom
03-13-2017, 10:12 PM
@sprint2freedom :
Agreed with wire size/weight. This is why I am asking for specifics to make a call on what I'll wire or not.
I keep going back and forth between the placement of the battery and new inverter because the battery is a LFP, it needs to be in a somewhat temperature controlled environment so inside the coach seems like the easiest way to achieve that. Now I do have a storage space under the kitchen, located right next to where the current batteries are but I would have to insulate the whole space I think. This might be the easiest way of dealing with all this, indeed. It will just make them 3 feet further than their current location I believe.
The inverter under the hood option is something I literally just thought about too :P Amp up the voltage to lower the amps going through the wires would help a lot. If I could multiply the voltage by 3, therefore divide the amps by 3, 2ga wires would be ok... And I could run it through my MPPT charge controller since my panels are in series (2S2P 100W panels @ 21Voc so 42Voc)

If you somehow were able to generate 42V and connect it to your MPPT controller, you would effectively disable/hinder the MPPT function by forcing the voltage to 42V rather than allowing the controller to vary the voltage to dial in the maximum power. If you're talking about feeding it to a separate, dedicated MPPT controller, then yes that might work. An inverter would be easier, less specialized and more cost effective, though.

@mikeme :
I was intending to suggest a dedicated/additional 3-stage charger, not wiring it to the shore power charger.. although that could be made to work, too. A shore power activated relay could switch the charger over to shore power, but normally leaving it connected to the vehicle powered inverter.

mikeme
03-14-2017, 11:58 AM
MPPT devices are designed around the two things they connect, solar panels, and batteries.

any connection between systems with different parameters will be well served by choosing a device which is similarly designed. (considering the different needs of each circuit)

the stock engine alternator is built around the engine battery, and the use profile of a vehicle.

adding a house battery, of any type, is best handled by a specific solution.


If you are putting an extra battery in, it needs dedicated charging equipment matched to the source.

if you are replacing the existing house battery, each source of charging will need to be updated.

mikeme
03-14-2017, 12:00 PM
The first question should have been what kind of Lithium batteries you are installing?

some of them come with extra circuits to allow drop-in replacement of lead acid batteries.

Graphite Dave
03-14-2017, 12:29 PM
Adding a vehicle powered pure sine inverter requires a fuse and a battery disconnect switch. The "shore power" is then sent to a selector switch. The other 120 v source to the selector switch is your real shore power. The selector switch is used to select which shore power you want to use. The shore power charger uses either source.

If you add a second selector switch you can use the vehicle powered inverter for other uses such as heating water or air.

A block diagram of my system:

http://www.ortontransit.info/electric.php

The block diagram has been revised. Instead of the third selector switch I just use a male plug that can be plugged into shore power or power from the house battery inverter. If weather conditions permit I can use the excess solar power to heat the water.

The electrical diagram for my Transit:

fourgonbound
03-14-2017, 04:14 PM
Thanks guys.

I'm thinking of just locating the battery close to the current battery bay -- so ~3' further than current location. It is in the storage box so I'll have to insulate it with probably some foam (http://www.homedepot.com/p/Owens-Corning-FOAMULAR-150-2-in-x-4-ft-x-8-ft-R-10-Scored-Squared-Edge-Insulation-Sheathing-45W/100320352) and a heating pad under it for subfreezing temps. Although the foam might be enough for most occasions since batteries do output a bit of heat which being used so combined with foam, should be ok.

I'd rather not add another piece of electronic.

I'm installing a Lithionics Batteries 300Ah battery. So it has the low/high voltage cutoffs and BMS stuff integrated. Even has a on/off master switch on the battery itself if I ever need to disconnect everything.
I already have all the charging components for it (MPPT charge controller and inverter/charger both programmable). So the only remaining charging piece is the alternator.

@Graphite Dave: Nice diagrams you have there! Looks just like the Winnebago diagrams :)

OrioN
03-14-2017, 05:14 PM
Thanks guys.

I'm thinking of just locating the battery close to the current battery bay -- so ~3' further than current location. It is in the storage box so I'll have to insulate it with probably some foam (http://www.homedepot.com/p/Owens-Corning-FOAMULAR-150-2-in-x-4-ft-x-8-ft-R-10-Scored-Squared-Edge-Insulation-Sheathing-45W/100320352) and a heating pad under it for subfreezing temps. Although the foam might be enough for most occasions since batteries do output a bit of heat which being used so combined with foam, should be ok.

I'd rather not add another piece of electronic.

I'm installing a Lithionics Batteries 300Ah battery. So it has the low/high voltage cutoffs and BMS stuff integrated. Even has a on/off master switch on the battery itself if I ever need to disconnect everything.
I already have all the charging components for it (MPPT charge controller and inverter/charger both programmable). So the only remaining charging piece is the alternator.

@Graphite Dave: Nice diagrams you have there! Looks just like the Winnebago diagrams :)

A few questions for ya...
1) What is the model number of the Lithionics?
2) What make & model battery separator?
3) What make & model is your battery monitor?
4) When you say your current wiring is 2ga, is this from and all wire for the chassis tie-in to the house bank, and if so, what is the longest length of any 'piece'(wire between terminations) of wire?







.

fourgonbound
03-14-2017, 05:29 PM
A few questions for ya...
1) What is the model number of the Lithionics?
2) What make & model battery separator?
3) What make & model is your battery monitor?
4) When you say your current wiring is 2ga, is this from and all wire for the chassis tie-in to the house bank, and if so, what is the longest length of any 'piece'(wire between terminations) of wire?







.

1) This one (http://lithionicsbattery.com/product/gtr-12v-300-lithium-amp-hours-5d-case-with-internal-neverdie-bms-copy/?) pretty much.
2) Not sure, whatever solenoid Winnebago puts in
3) Magnum BMK (I also have the Magnum MSH3012 and ARC50 remote)
4) I believe the 2ga wiring is from the solenoid / battery disconnect relay to the house battery, about 5' long in the front of the rig. From there to the AC distribution panel is a 8ga wire that is probably around 15' long. I verified that by measuring the voltage drop before and after a load of about 21W and used the voltage drop calculator which ended matching 8ga perfectly. But I also visually verified it (just wanted to be 100% sure since there are like 1,000 wires and it's hard to inspect everything).
I have yet to double check the 2ga wire between battery disconnect relay and battery bank because I saw yesterday a 1ga wire between the solenoid and the battery disconnect relay while installing a trik-l-start.

OrioN
03-14-2017, 05:46 PM
1) This one (http://lithionicsbattery.com/product/gtr-12v-300-lithium-amp-hours-5d-case-with-internal-neverdie-bms-copy/?) pretty much.
2) Not sure, whatever solenoid Winnebago puts in
3) Magnum BMK (I also have the Magnum MSH3012 and ARC50 remote)
4) I believe the 2ga wiring is from the solenoid / battery disconnect relay to the house battery, about 5' long in the front of the rig. From there to the AC distribution panel is a 8ga wire that is probably around 15' long. I verified that by measuring the voltage drop before and after a load of about 21W and used the voltage drop calculator which ended matching 8ga perfectly. But I also visually verified it (just wanted to be 100% sure since there are like 1,000 wires and it's hard to inspect everything).
I have yet to double check the 2ga wire between battery disconnect relay and battery bank because I saw yesterday a 1ga wire between the solenoid and the battery disconnect relay while installing a trik-l-start.

Let's approach this then from a slight angle...

Can I assume the LI's are not installed yet?
Do you have two quality/accurate voltmeters?
Are you able to run a constant 60A load off the house bank? If so, measure the voltages simultaneous from the house bank terminals and the chassis tie-in location. We need to know what the voltage drop is and not for a 21W load.



.

mikeme
03-14-2017, 06:13 PM
Thanks guys.

I'm thinking of just locating the battery close to the current battery bay -- so ~3' further than current location. It is in the storage box so I'll have to insulate it with probably some foam (http://www.homedepot.com/p/Owens-Corning-FOAMULAR-150-2-in-x-4-ft-x-8-ft-R-10-Scored-Squared-Edge-Insulation-Sheathing-45W/100320352) and a heating pad under it for subfreezing temps. Although the foam might be enough for most occasions since batteries do output a bit of heat which being used so combined with foam, should be ok.

I'd rather not add another piece of electronic.

I'm installing a Lithionics Batteries 300Ah battery. So it has the low/high voltage cutoffs and BMS stuff integrated. Even has a on/off master switch on the battery itself if I ever need to disconnect everything.
I already have all the charging components for it (MPPT charge controller and inverter/charger both programmable). So the only remaining charging piece is the alternator.

@Graphite Dave: Nice diagrams you have there! Looks just like the Winnebago diagrams :)

If you do not want to add another piece of electric, disconnect from the engine system. (you should be able to pull a fuse, I would think. if you are thinking of driving in cold, the engine will put out higher voltage than you want, in some conditions.)

also think about at least putting a remote temperature sensor to let you read the battery temperature. You really want to avoid any charging when the battery gets below freezing.

you will have to manage this (cold weather operations) on a manual basis.

fourgonbound
03-14-2017, 10:36 PM
@OrioN:
Correct, LFP isn't installed yet.
I can't pull 60ADC as of now. Nothing really pulls that much. Using the inverter way isn't going to work either because the inverter is next to the battery bank via 1ga wire and the AC goes to outlet right away bypassing the AC panel.
I double checked again and I'm pretty sure it's 8ga from front of rig to AC/DC distribution panel. The way they wired the solar is lame too: 8ga wires in the same conduit as the battery to panel wires but they could've wired it differently eliminating perhaps 5' if not more of 8ga wire. I guess it's still under 3% voltage loss...

@mikeme:
Correct, this is why I want to insulate the storage box and use a heating pad which are used for black/grey tanks and are automatic (start heating if temp goes below 45F and stop once it's at 65F). But I would definitely use a thermostat too to make sure the heating pad isn't messed up. I won't be in extreme cold weather often at all so I don't mind handling it manually.

OrioN
03-15-2017, 12:02 AM
@OrioN:
Correct, LFP isn't installed yet.
I can't pull 60ADC as of now. Nothing really pulls that much. Using the inverter way isn't going to work either because the inverter is next to the battery bank via 1ga wire and the AC goes to outlet right away bypassing the AC panel.
I double checked again and I'm pretty sure it's 8ga from front of rig to AC/DC distribution panel. The way they wired the solar is lame too: 8ga wires in the same conduit as the battery to panel wires but they could've wired it differently eliminating perhaps 5' if not more of 8ga wire. I guess it's still under 3% voltage loss...

.

You will find out soon enough if the wires are adequate!

Alt. V @14.1V with a 3% line lose is 13.67V at the house bank. LiFePO4 100% SOC V's is 13.4V (Lead Acid is 12.6-12.8V). This +0.3V is not adequate to maximize or achieve a high amperage charge the bank.


.

fourgonbound
03-15-2017, 12:33 AM
@OrioN:
I think you misunderstood me: The 8ga wire is from solar panels to battery bank. No more than 25A going through them and the MPPT charge controller will be set to 14.6V if anything. But I might just move the charge controller near the battery since the panels are 2S2P, there's at most 13A coming from the PVs. That's more efficient.

The wires going from the alternator to the current battery bank is 1ga so much better than 8ga and it's like 5' long. Placing the new battery in the storage will lengthen those wires by like 5' max and I guess I could use bigger wires to lessen voltage drop.

mikeme
03-15-2017, 09:52 AM
@mikeme:
Correct, this is why I want to insulate the storage box and use a heating pad which are used for black/grey tanks and are automatic (start heating if temp goes below 45F and stop once it's at 65F). But I would definitely use a thermostat too to make sure the heating pad isn't messed up. I won't be in extreme cold weather often at all so I don't mind handling it manually.

My suggestion was for a thermometer with remote hookup. (should be cheap. a laser pointer IR thermometer would let you do this by hand if you don't get in the cold very often)

it also would be best if all your charging choices had battery voltage sensing (from the battery).





You also might want to send an e-mail or call Lithionics and ask them what they think of putting the LI battery directly on the engine circuit.

fourgonbound
03-15-2017, 03:47 PM
@mikeme:
Yeah that's better, like this one on Amazon (https://www.amazon.com/gp/product/B007FTQUX0/ref=ox_sc_sfl_title_3?ie=UTF8&psc=1&smid=A2ANVX7C75D1I).
I have the Magnum battery monitor kit (BMK) that plugs into the remote ARC50 and into the MSH3012 inverter/charger. So that'll sense the battery voltage.

I contacted Lithionics already about alternator charges to the battery and they say it's fine yeah. Considering the voltage coming from the regulator is never above 14.2V or so, it's safe for charging.

Graphite Dave
03-15-2017, 03:54 PM
@Graphite Dave: Nice diagrams you have there! Looks just like the Winnebago diagrams :)

Never seen a Winnebago diagram. Mine evolved just one line at a time. Still finding errors.

OrioN
03-15-2017, 07:05 PM
Hi there,

I have a Winnebago View 24J 2017 so with a 2016 Sprinter 3500 chassis (220amp alternator).
I am getting lithium batteries for the coach and am going to place them at the rear of the coach under the bed meaning 10-15' away from where they currently are (they're about 5' max from the solenoid under the passenger seat).
Currently all the wiring for the chassis/coach battery to alternator is done with 2ga wires which works OK for 5' / 60amps of current going thru them to get to the coach batteries (probably max voltage drop of 0.1V).

So I am wondering what is the max voltage of the alternator at the chassis and coach batteries right now during high outputs of the alternator and also what would be the max current being delivered to the batteries.
Adding 10-15' of 2ga wires to get to the LFPs means a potential voltage drop of 0.28V @ 60amps which is huge if the voltage is around 14.1V at chassis: If so, it'd be useless to have the LFPs being charged from the alternator since they need a voltage of at least 14V.

Anyone has data on max voltage/max amps going to chassis battery? (and perhaps average/min)

I also take that because it's computer controlled, there's no way to tweak the voltage huh?

Thanks,
Christophe

Thanks guys.

I'm thinking of just locating the battery close to the current battery bay -- so ~3' further than current location.

I'd rather not add another piece of electronic.

I'm installing a Lithionics Batteries 300Ah battery. So it has the low/high voltage cutoffs and BMS stuff integrated. Even has a on/off master switch on the battery itself if I ever need to disconnect everything.
I already have all the charging components for it (MPPT charge controller and inverter/charger both programmable). So the only remaining charging piece is the alternator.



te ARC50 and into the MSH3012 inverter/charger. So that'll sense the battery voltage.

I contacted Lithionics already about alternator charges to the battery and they say it's fine yeah. Considering the voltage coming from the regulator is never above 14.2V or so, it's safe for charging.

In summary:

You've stated that you do not want to go the 'additional equipment' route (DC-AC-DC).

Charging from the alternator @14.1V is OK for the Lithionics. This doesn't exceed the Max voltage, and if it did the BMS will mediate. 14.1V is the alternator's MAX, and there will times when this is lower when the vehicle is using other equipment/loads or load control.

Your current wiring will mostly achieve sub-par efficiency, and not maximize what the alternator is capable of nor what your new bank could benefit from. The LI can accept a 1C charge at most SOC's, and this could approach ~100A at times and be achieve with a complete wiring upgrade.

To reiterate, LI are more sensitive the your cable losses, than Lead Acid. Their resting volts are 13.35V, lead acid is 12.6-12.8V. Notwithstanding their lower internal resistance, they still require any voltage higher than their resting voltage to accept a charge, but the higher this is the greater the charging amps will be.




.

fourgonbound
03-15-2017, 11:05 PM
You're right, the wires suck right now. I turned on the engine and measured the voltage at house battery and it read 14.23V. Same at chassis. Obviously the current was low since the batteries were somewhat charged.

But if I go back to my original plan to have the new battery in the back of the rig (15' further than now) and use #4/0 wires instead, the voltage drop would be 0.10V at 70amps or 0.15V at 100amps. In both cases, above 14V meaning the battery would be getting a charge. A set of red/black 15' long #4/0 on Amazon is about $100 so I think I'll do that. Then I don't have to worry about insulating the storage compartment and running wires from the AC box to there either.

Another thing I noticed is that when Winnebago wired the solar system from charge controller to battery, they use a 35' 8awg wire. I understand the default setup is 100W panel but man, what a drop when you have 400W! Today my panels could output 250W combined so around 18amps were going through that 8awg wire. I measured a huge voltage drop of 0.73V !!
So if I do have the battery under the bed, in the back of the rig, where the solar wires are actually passing by, I can just wire the solar wires straight to the battery from there. Instead of 35', it'll 10. Plus I can actually just move the charge controller down there so the PV wires will run longer (lower amps, higher voltage) and the charge controller to battery wires will just end up being a couple of feet!

fourgonbound
03-15-2017, 11:10 PM
@OrioN:
To come back to the DC-AC-DC idea, would I need a pure sine inverter or a MS one enough? The rig currently has a Xantrex Pro 1000 which is MS and since I'm going to get rid of it, perhaps that idea could work too...

OrioN
03-15-2017, 11:14 PM
@OrioN:
To come back to the DC-AC-DC idea, would I need a pure sine inverter or a MS one enough? The rig currently has a Xantrex Pro 1000 which is MS and since I'm going to get rid of it, perhaps that idea could work too...

Best (correct & fastest) is to contact the Battery Charger Mfg's for this information.

PS.... the 1000W inverter will limit you to a 60A charger.



.

fourgonbound
03-15-2017, 11:30 PM
Good idea. Just emailed Magnum. Doubt it'd work well though since the MSW are going to go passthrough the whole rig then. Some appliances won't like it.

OrioN
03-15-2017, 11:36 PM
Good idea. Just emailed Magnum. Doubt it'd work well though since the MSW are going to go passthrough the whole rig then. Some appliances won't like it.

The DC-AC-DC system would be dedicated and only use this inverter to power a DC-AC charger (assuming Modified Sine-wave compatible) or any other non-sensitive equipment.



.

calbiker
03-16-2017, 10:58 PM
You will need a pure sine inverter, a MS will not work. The MS inverter outputs 150V peak, while the pure sine outputs 170V peak. They both output the same rms voltage (120V) but not peak voltage. A converter requires 170V peak for operation.


To come back to the DC-AC-DC idea, would I need a pure sine inverter or a MS one enough? The rig currently has a Xantrex Pro 1000 which is MS and since I'm going to get rid of it, perhaps that idea could work too...

HarryN
03-17-2017, 04:53 PM
Hi there,

I have a Winnebago View 24J 2017 so with a 2016 Sprinter 3500 chassis (220amp alternator).
I am getting lithium batteries for the coach and am going to place them at the rear of the coach under the bed meaning 10-15' away from where they currently are (they're about 5' max from the solenoid under the passenger seat).

Thanks,
Christophe

Interesting project. Do you have room for a box that is 18 H x 20 W x 29 L ? If so, there are some alternatives that might make your life a lot easier.

fourgonbound
03-17-2017, 07:10 PM
The storage area near the battery bank (current one) is 44x20x18.5.

fourgonbound
03-18-2017, 05:04 AM
I contacted Magnum and I'm not sure they really know the answer. They said it should work but like calbiker said it probably won't.

@calbiker:
I understand and agree with your statement.

HarryN
03-18-2017, 04:43 PM
The storage area near the battery bank (current one) is 44x20x18.5.

Thanks for the off line discussion. Your component choices look pretty solid.

Sacramento can get pretty warm in the summer, so perhaps don't get into too much of a hurry on charge rate. Even with the low internal electrical impedance, you won't have all that much margin on that pack in July and August. Nothing wrong with it that battery, just starting to butt heads with summer temps in the central valley.

fourgonbound
03-18-2017, 08:04 PM
Even with the low internal electrical impedance, you won't have all that much margin on that pack in July and August. Nothing wrong with it that battery, just starting to butt heads with summer temps in the central valley.

What do you mean?

HarryN
03-19-2017, 01:54 AM
What do you mean?

Every battery system has upper and lower temperature limits, sometimes these are warning, protective shut downs, or actual damage points.

In the case of Li based ones, it is slightly more complicated because:
- Somewhere around 32 F you aren't suppose to charge them, but you can discharge them at a lower temperature. Still, not as low as for instance a conventional lead acid or AGM. That is why some setups are insulated and / or heated.
- Somewhere around 113 F exterior battery temperature, some LiFe batteries will exhibit reduced cycle life if charged and discharged.

I didn't write the information down, but I think that the Lithionics has an upper temperature limit close to 113 F on their web site for the battery that you linked to.

On some chemistries, such as LiCo, which are very sensitive to getting too hot, it is a big deal because they can run away. On LiFe, typically they won't run away, but can be internally damaged if the cell temperature gets too hot. My understanding is that this is a combination of the factors, such as how hot the actual battery case is and the heat generated by charging / discharging.

105 - 108 F is a common summer occurrence in Sacramento. The interior of the van can easily hit 120 F if parked in the sun. If you were to now add to this by a high current charge or discharge, there is a reasonable chance that the battery would be close to or perhaps out of the temperature spec and trigger a shut down.

The batteries that I use have different temperature ranges like that as well. The manual shows somewhat higher temperature ratings than the Lithionics, but sometimes it is hard to tell what is a recommendation vs problem vs loosing 10% of cycle life vs loosing 50% of cycle life.

To give a somewhat related example, Tesla liquid cools their battery pack and on really hot days, actively cools this liquid (like a chiller) and actively heats it when it is too cold. That is a key aspect of the performance.

Nissan Leaf batteries at least used to be air cooled and there were some cycle life challenges in the south west on early models.

fourgonbound
03-19-2017, 02:09 AM
I see. The Lithionics batteries are rated 32F - 113F for charge and -4F - 140F for discharge. So you're right that I'll have to find something for summer temps. My rig is parked in the sun and I could leave the Maxxair fan on and all windows down but even then it may still get above 113F on very hot days. I will ask them what they do since they're based in Florida, they have to run into issues like that.

It's funny how different battery manufacturers have different temp specs (except for 32F for charging) but it's the same chemistry so I don't understand how they can differ in terms of temp specs.

I could insulate the battery just like for cold but I'm not sure it'll help that much... But perhaps? What do you do in your boxes?

OrioN
03-19-2017, 02:57 AM
I see. The Lithionics batteries are rated 32F - 113F for charge and -4F - 140F for discharge. So you're right that I'll have to find something for summer temps. My rig is parked in the sun and I could leave the Maxxair fan on and all windows down but even then it may still get above 113F on very hot days. I will ask them what they do since they're based in Florida, they have to run into issues like that.

It's funny how different battery manufacturers have different temp specs (except for 32F for charging) but it's the same chemistry so I don't understand how they can differ in terms of temp specs.

I could insulate the battery just like for cold but I'm not sure it'll help that much... But perhaps? What do you do in your boxes?

FYI... all batteries are effected and will degrade increasingly with high temperature charging, don't sweat this (pun not intended). READ: Charge within the mfg. specifications. Chalk it up to the overall cost of over usership.

If you want to reduce the rate of degradation, then charge(bulk) them during the cooler times of the day.

Enjoy life....




.

HarryN
03-20-2017, 03:52 AM
. I will ask them what they do since they're based in Florida, they have to run into issues like that.

It's funny how different battery manufacturers have different temp specs (except for 32F for charging) but it's the same chemistry so I don't understand how they can differ in terms of temp specs.

I could insulate the battery just like for cold but I'm not sure it'll help that much... But perhaps? What do you do in your boxes?

Florida tends to be in the 90s and high humidity. It definitely feels hot to us, but the actual temperature is lower. Also, the humidity helps block a fair amount of the spectrum, which is one reason we tend to get high UV / sun burns in CA relative to FL.

As far as differences between brands, there are hundreds of differences between batteries, most are only known to the internal experts, as there is no benefit to provide information to their competition. Minor differences in cathode and anode construction and composition make huge differences. LiFe is sort of a "family" of battery types, which is a sub type of a number of Li based battery chemistries.

Insulation of your compartment is a good idea. I do that, and more.

To some extent you sort of make a decision on a battery based on what you can afford, and what people are willing to sell to you. After that, you read the documentation as often as you can stand, and implement as much as you can.

As an example, a lot of companies have approached Tesla to purchase cells and packs from them, but mostly they won't do it, as it is a strategic advantage for them. That is why I don't think that LiFe battery prices are going to drop like other people do. If you aren't buying at least 20K battery packs per year, there are only a limited number of good quality suppliers willing to sell to you.

I've had to make some commitments on my side with my battery supplier as well - not 20K, but definitely a commitment.
Harry

fourgonbound
03-20-2017, 04:00 AM
I don't think that LiFe battery prices are going to drop like other people do.

I totally agree with you. All the blogs keep saying prices are going to go down but they've been the same for the last 5 years AFAIK.

Technomadia had issues with heat in AZ and moved their battery bank in another, bigger compartment where the water tank is located: Large body creating a buffer for temps. The coach under the bed has the water tank right there too. So I'm hoping it'll help as well.

Also, the RV will be getting most of its charge from solar in the AM when it's less hot (never 113F) and will switch to float mid day to end of day when warmer. I don't think it'll really ever charge at 113F while in storage. I'll just have to make sure I ventilate the whole thing before driving it when hot then.

fourgonbound
03-25-2017, 03:52 AM
When the engine is running, the solenoid connects the engine battery and the coach batteries together, right?

Then how is it that when one of them is fully charged but not the other, the voltage reading is different on them?

The fully charged one will read something like 13.6V whereas the one charging 14.2V.

mikeme
03-25-2017, 12:27 PM
When the engine is running, the solenoid connects the engine battery and the coach batteries together, right?

Then how is it that when one of them is fully charged but not the other, the voltage reading is different on them?

The fully charged one will read something like 13.6V whereas the one charging 14.2V.

if they are hooked together, the voltage will be the same, minus the current times the resistance of the wire /solenoid between them.

are you measuring the voltage with a digital meter at the actual battery?

it is not unusual for other points in the system to have different voltages due to wire losses and other loads on the system.

fourgonbound
03-25-2017, 04:40 PM
From the other thread (https://sprinter-source.com/forum/showthread.php?t=54919&page=2):

Regardless of my readings though, if there are two banks getting charged by one charger but nothing to balance the load/voltage to the different banks, how can that be good for the one that is fully charged?

You said the voltage should be the same, which is my understanding as well. Then how can it be good for let say the chassis battery to keep getting a 14.2V current if it's fully charged?

In the RV case: If you are plugged in to the shore for a few days, then the chassis battery will be definitely not as charged as the house battery. And then you start driving around, the alternator/regulator will still output 14.2V and high currents to charge the chassis, no? In this case, it'll be bad for the house battery which is going to expect float charge.
I understand that little current will go to the house battery in this case because of its internal resistance, so it'll be more like in absorption phase instead of bulk or float. But still not great for a fully charged battery, right?

HarryN
03-25-2017, 11:38 PM
When the engine is running, the solenoid connects the engine battery and the coach batteries together, right?

Then how is it that when one of them is fully charged but not the other, the voltage reading is different on them?

The fully charged one will read something like 13.6V whereas the one charging 14.2V.

Your question is an excellent insight of what can happen.

Consider the slightly more complex case of:
- Multiple battery chemistries
- Multiple battery banks (in your case - two of them - house and engine, but the number can be higher.
- Charging from solar, AC grid plug in, alternator, perhaps a generator through a charger. There is nothing that stops multiple charging methods to be in use simultaneously.

And in some of my projects - multiple battery pack voltages.

Combine this with the somewhat complex electrical systems in a sprinter van and it isn't very long before predicting what will actually happen in a completely connected setup is "challenging".

Since I could not confidently predict what would happen in this "completely connected approach" and didn't want to fry anyone's sprinter, I set them up as two "semi - isolated" electrical systems. They can share a common ground, but the (+) is isolated.

For the (+) connection points, I use electronics to isolate / convert as necessary. It is a bit brute force but works. I didn't invent the method, the military does this all of the time.

fourgonbound
03-26-2017, 05:06 PM
For the (+) connection points, I use electronics to isolate / convert as necessary. It is a bit brute force but works. I didn't invent the method, the military does this all of the time.

I will add a small switch that will override the solenoid ignition switch so I can separate the two systems most of the times and only combine them when the house battery is low and needs bulk charging from the engine or when the chassis battery is dead.

I have a trik-l-start around the solenoid so that will still work and keep the chassis battery charged when solar/shore charges the house battery regardless of that switch.

mikeme
03-26-2017, 11:52 PM
From the other thread (https://sprinter-source.com/forum/showthread.php?t=54919&page=2):

Regardless of my readings though, if there are two banks getting charged by one charger but nothing to balance the load/voltage to the different banks, how can that be good for the one that is fully charged?

You said the voltage should be the same, which is my understanding as well. Then how can it be good for let say the chassis battery to keep getting a 14.2V current if it's fully charged?

In the RV case: If you are plugged in to the shore for a few days, then the chassis battery will be definitely not as charged as the house battery. And then you start driving around, the alternator/regulator will still output 14.2V and high currents to charge the chassis, no? In this case, it'll be bad for the house battery which is going to expect float charge.
I understand that little current will go to the house battery in this case because of its internal resistance, so it'll be more like in absorption phase instead of bulk or float. But still not great for a fully charged battery, right?

Look at this figure

http://www.mpoweruk.com/chargers.htm

if the two battery states of charge are such that the charge voltage of one is higher than the discharge voltage of the other, you are ok.

if, on the other hand, the discharge voltage at that charge level is higher than the resting charge voltage of the other, a current spike would happen until the condition is eliminated

but unless the battery is almost out of charge, this will not happen.


if this was the case, the engine would not start.

while the engine is running, the voltage is maintained high enough that neither battery will be discharged, and the current provided by the alternator will be provided to the lower charge battery, and the electric loads of whatever is hooked up to the circuits.


but you have a point that ideal treatment of the battery will not be achieved. but during the extra time when the more charged battery would normally be in float level, not a huge amount of extra charge will be applied.

in the case you suggested, the imbalance is only while the alternator is providing current to restore charge lost from rest and starting the engine.

always better to keep any lead acid battery charged, or as close to it as possible.