Lithium vs. AGM

Davydd

Well-known member
My 800ah lithium battery bank is maintained at 41 deg. F. and above with 10 amps total of 12V electrical resistant heating pads sandwiched between batteries that turn on and off automatically to maintain that minimum temperature no matter how cold it gets. The heating pads draw power directly from the batteries. If they were on all the time (which never happens) they would draw 240 amps in 24 hours off the batteries. When it is that cold out you aren't likely to sit around a camp site and will be on the move re-charging batteries in under an hour's driving. The batteries are underneath the floor in a minimally insulated fiberglass box. As far as charging them they charge to 99% via shore power, second alternator or solar. When they reach 99% charging from any of those sources are turned off until battery use drops them down to about 90%. They are 4-1/2 years old and still going strong. It is all managed automatically from a touchscreen Silverleaf controller where I can view real-time status of what goes in and out the batteries, temperature of every cell and voltage of every cell.

I'd never consider anything else again and have no fears or qualms about lithium ion.

PS. I've had the luxury of inside heated storage the last two winters but used to store outside plugged into a 20A 120V plug. Most all houses have them by code on the outside.
 
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elemental

Wherever you go, there you are.
I like the AGM’s simplicity and ability to take some (relative) abuse from someone who isn’t monitoring things super close. [...] So I’m leaning more towards the kind of ‘set it and forget it’ of a robust AGM system.
You can kill AGMs pretty easily, too. Deep discharge them once or twice. Leave them on a constant trickle charge that never gets them to 100% state of charge. Let them sit for long periods of time with no charge input [e.g., your SO unplugs the trickle charger and you don't notice for a while].

But they cost less than Lithium's when you have to replace them!
 

Midwestdrifter

Engineer In Residence
Does your math include the cost for charging?

Some folks can get away with using less PV, or fossil fuels.... or an intangible such as time.
Important considerations. A lithium pack can give an apparent increase in PV capacity of as much as 30%. Assuming the pack is sized correctly. Higher efficiency, and the ability to capture harvest lost during the lead absorb phase.

Such considerations need to be made on a case by case basis. For folks starting from the ground up, where low temperature issues are minor or non-existent, lithium packs are hard to beat except in low utilization scenarios. Lithium packs age out like all batteries, so a installation where the unit is only used 30 days a year would not see any cost savings compared to lead.
 

Boxster1971

2023 Sprinter 2500 144wb AWD
I'm sticking with AGM for now. The ONLY reason has to do with not having to think about dealing with low temperatures during storage. But it is a BIG reason given our usage pattern. If I stored my van someplace with continuous shore power, the calculus might be different. But I don't, and this makes Li a huge hassle, IMO.
That was also my thinking in 2014 when I installed my four 6V AGM battery upgrade. But I now realize my use pattern and availability of shore power where I park the van make Li a good choice for my next van.

I'd like to have the electrical power independence that Davydd discussed above from his Advanced RV setup.
 

Graphite Dave

Dave Orton
I wonder how many conversions actually need lithium battery pack?

I have a single 255 amp-hr AGM located inside the van and have a single 300 watt solar panel.

1. Easily provides all the electrical capacity required for my application.
2. I am still about 1000 lbs under the vehicle capacity.
3. No need to save a single cubic foot of space.
4. No concerns about temperatures.
5. Almost never need to charge from the vehicle electrical system.
6. Same battery lasted 9 years in the sold Sprinter with similar install.

I understand if air conditioning is required or weather conditions in Northern states does not yield enough solar charging. Also could be needed if people must carry and use in their van every electrical appliance that they use at home.

The question is how many conversions need the lighter battery or do not have the space for an AGM.
 

Davydd

Well-known member
This past trip to the southwest we left right when the polar vortex chased us south in late January from Minnesota, it took us three days with no hookups to get out of freezing weather all the way down to -15 deg. F. overnight. On the way home we didn't escape the cold weather again for another three days of boondocking in March. The 800ah of lithium batteries and diesel-fired heat it was easy. It was a crazy winter. It snowed and got below freezing in Las Cruses, New Mexico. I doubt we could have done it with our other two RV Sprinters with lead-acid batteries.
 

Wrinkledpants

2017 144WB 4x4
I wonder how many conversions actually need lithium battery pack?

I have a single 255 amp-hr AGM located inside the van and have a single 300 watt solar panel.

1. Easily provides all the electrical capacity required for my application.
2. I am still about 1000 lbs under the vehicle capacity.
3. No need to save a single cubic foot of space.
4. No concerns about temperatures.
5. Almost never need to charge from the vehicle electrical system.
6. Same battery lasted 9 years in the sold Sprinter with similar install.

I understand if air conditioning is required or weather conditions in Northern states does not yield enough solar charging. Also could be needed if people must carry and use in their van every electrical appliance that they use at home.

The question is how many conversions need the lighter battery or do not have the space for an AGM.
1. You must have a light electrical load if 125AH is all you need. That would not work for us.
2. Most of us are under gross, but saving 100 lbs and gaining 35AH has a lot of value to us.
3. That battery would not fit where we have our 200AH lithium. It would need to be mounted under the van.
4. Lifeline's manual shows a pretty substantial reduction in capacity around 32 degrees F battery temp. You lose nearly 50% of your rated capacity at cold temps (below freezing).
5. Lifeline's manual shows it would take 4 hours to recharge a 255AH battery from 50% SOC using a 60a charger (125A usable). We can recharge 160 amps usable in 1 hour of driving or high-idle, which is feasible to us since we frequently have a short commute from our camping spot to the ski resort parking lots. When you combine the reduction in capacity due to cold battery temps with the slow recharge rate - lithium was the only viable solution to exist in areas where solar wasn't available.
6. I'll be honest and say I don't really care about this. I know lithiums are supposed to last longer than AGM, but it's unlikely we'll have the battery this long.

For us, lithium was not just money well-spent, but it allow us to exist off-grid, basically perpetually. No generators or solar needed. But, we do have 160w of solar to maintain the fridge in the summer, but we do not have space on the roof for 300w of solar as we store gear up there.
 

Graphite Dave

Dave Orton
1. You must have a light electrical load if 125AH is all you need.
A conversion electrical system can have a wide range of power requirements. Depends on what needs to be powered and the time period the power is used. Some people use a lot of power and others do not. So the requirements can be met in three ways. Either limit your power usage, provide a large battery capacity or move the van to better weather conditions.

I do some things to eliminate the need for a large battery pack:

1. All LED lights.
2. Live and travel in a moderate climate that has sunshine.
3. Do not partake in winter sports.
4. Eliminate the need to keep van interior warm at night in winter. Use heating pad to stay warm which reduces run time of the refrigerator.
5. Bought a gas engine so I can idle to charge from the vehicle without driving.
6. Have 12 volt DC/120v AC refrigerator so I can power it on 120v AC while driving with vehicle powered inverter instead of using house battery capacity.
7. Can use 120 volt AC air heater while driving.
8. If excess solar power is available I can heat shower water with the excess.
9. I can decide to or not to use the microwave based on battery SOC.
10. Use propane stove for cooking. Do not have induction burner.
11. Have large solar panel with MPPT controller.

IMO the major advantage of lithium is the charge rate. Lots of amps can be used for charging until full. AGM requires reduced amperage as you near 100% SOC. In my case I almost never am able to bulk charge the battery because battery is not discharged enough. The size and weight savings are usually not important. Most conversions are not at the maximum weight limit and batteries can be located under the vehicle if necessary.

A lithium battery with a second alternator on a gas engine looks to be a good combination if high capacity electrical system is required. High charge rate with engine that can be idled. The new 2020 Transit will have a second alternator option with the gas engine which I suspect will reduce the second alternator cost.
 

Wrinkledpants

2017 144WB 4x4
A conversion electrical system can have a wide range of power requirements. Depends on what needs to be powered and the time period the power is used. Some people use a lot of power and others do not. So the requirements can be met in three ways. Either limit your power usage, provide a large battery capacity or move the van to better weather conditions.

I do some things to eliminate the need for a large battery pack:

1. All LED lights.
Same
2. Live and travel in a moderate climate that has sunshine.
Not willing to sacrifice on that. Lithium allows us to live comfortably 4-seasons. And that could be brutal winters, too, not just light winter weather.
3. Do not partake in winter sports.
Makes sense for your moderate climate needs
4. Eliminate the need to keep van interior warm at night in winter. Use heating pad to stay warm which reduces run time of the refrigerator.
We run the D2 a lot. We'll put 2k hours on it a year. We like being in shorts and t-shirt when it's 5 degrees outside :)
5. Bought a gas engine so I can idle to charge from the vehicle without driving.
That's one benefit of gas over diesel, but with high-idle, we've had no issues. And, it's rare we need to idle to recharge given how fast it happens when we drive
6. Have 12 volt DC/120v AC refrigerator so I can power it on 120v AC while driving with vehicle powered inverter instead of using house battery capacity.
7. Can use 120 volt AC air heater while driving.
8. If excess solar power is available I can heat shower water with the excess.
Our coolant powers the hot water, but we'll run the 750w electric element without worry if needed.
9. I can decide to or not to use the microwave based on battery SOC.
We use electricity like a kid in a free candy store. If we're spending 6-figures on the van and build, we want comforts. Our electrical usage *feels* free since we spend very little xtra fuel to recoup it
10. Use propane stove for cooking. Do not have induction burner.
We purposely did not want to deal with propane. Induction feels dirt simple to us.
11. Have large solar panel with MPPT controller.

IMO the major advantage of lithium is the charge rate. Lots of amps can be used for charging until full. AGM requires reduced amperage as you near 100% SOC. In my case I almost never am able to bulk charge the battery because battery is not discharged enough. The size and weight savings are usually not important. Most conversions are not at the maximum weight limit and batteries can be located under the vehicle if necessary.

A lithium battery with a second alternator on a gas engine looks to be a good combination if high capacity electrical system is required. High charge rate with engine that can be idled. The new 2020 Transit will have a second alternator option with the gas engine which I suspect will reduce the second alternator cost.
See above in bold.

You asked how many people need lithium - well nobody really. But, the convenience we gain from it is huge. I rarely ever look at SOC or think about power usage. A big requirement was 4-season comfort without hassles. 10 years ago, this would have been a challenge, but with today's tech, we can do that. The freedom of choosing where we want to camp regardless of weather, access to shore power, or concern about solar is immensely liberating. At least for us. For your situation, looks like AGM is a perfect fit.
 

Graphite Dave

Dave Orton
You asked how many people need lithium - well nobody really. But, the convenience we gain from it is huge. I rarely ever look at SOC or think about power usage. A big requirement was 4-season comfort without hassles. 10 years ago, this would have been a challenge, but with today's tech, we can do that. The freedom of choosing where we want to camp regardless of weather, access to shore power, or concern about solar is immensely liberating. At least for us. For your situation, looks like AGM is a perfect fit.

Different systems for different requirements. I also seldom look at the SOC or think about power usage. System just works. I also do not use shore power or concerned about where I camp. We both have systems that work for our requirements. Not being negative about lithium when it is required.

The one thing that works very well for me is the vehicle powered inverter. Nice to have 120 volt power available with engine running. Now that I just bought an electric bike I can charge it while I drive or charge the house battery or heat shower water or run the electric air heater in back of the van. Seldom need to charge the house battery from the vehicle powered inverter backup.
 

GSWatson

2013 144
I just spent a good half hour on the phone with Roni at BattleBorn discussing the suitability of my replacing my AGM’s with lithium’s. I have the CTEK Dual w/smartpass system; my two Lifeline’s are 8 years old; they were purchased from my local battery shop when they were 4 years old, not sure of history. But, they were $180 for the pair, so, I think I got my money’s worth.

Long story short is that, although the BB’s and other lithium’s are described as ‘drop-in’s,’ the charging profile of the CTEK isn’t compatible with their BMS - specifically, Roni was worried about the “Desulfation Charge” of 15.7 at startup. There’s no real indication of how long this lasts; I’ve never seen in on my Victron, and there’s no good info from CTEK online about this.

FWIW, when I bought the batteries and was looking at the CTEK system, I called Lifeline and the engineer I spoke with was a fan of the CTEK line, so it was a good pairing.

I’m going to stick with AGM’s for now; the extra $$ for the batteries and charging system is a bit much for the value I’d get back.

It will be interesting to see where we are in a couple years...


Cheers,
Greg
 

autostaretx

Erratic Member
...- specifically, Roni was worried about the “Desulfation Charge” of 15.7 at startup. There’s no real indication of how long this lasts; I’ve never seen in on my Victron, and there’s no good info from CTEK online about this
Most of the various chargers and solar controllers i've seen speak of either a one hour or a 4 hour desulfation equalization operation. Solar controllers tend to do equalization at the end of a period (up to 30 days), and some shore-power chargers do desufation at the beginning (if they sense that the battery needs it (logic unspecified)... the CTEK D250S takes this path)

added: i was confusing "desulfation" (pulses) with "equalizing" (higher than float)
Above paragraph has been edited to specify which state i was babbling about.

--dick
(i'll try to provide links to the documents)
The Blue Sea "Solar Boost SB1524iX" doesn't speak of doing desulfation at all, just 3-stage. (so it does equalize)
 
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Midwestdrifter

Engineer In Residence
If I remember most Ctek chargers do a desulfation only if configured, and the batteries resistance matches a certain profile? When they do, some of them pulse the 16V for a couple seconds, at a 20% duty cycle or so.
 

GSWatson

2013 144
Yeah, it’s unclear in the CTEK literature about the duration. It is an automatic feature, not configurable. The brochure sites a timer cut-off of four hours, but no rhyme nor reason. I’ve reached out to them but have heard nothing.

In the end, I’m going with Lifeline gpl-4 AGM’s. The batteries and CTEK will run under a grand for 220ah of the highest quality AGM. They’re going to be perfectly adequate for the purpose, and in ten years, the van will be sold to someone else no doubt.


Greg
 

autostaretx

Erratic Member
I (tried to) clarified my previous post (due to me confusing desulfation and equalization)

Here's what my $40 HQST PWM solar controller does ... it doesn't desulfate (the manual says that equalization helps avoid the need) ... and it doesn't equalize for gel or Lithium.

HQSTvolts.png

--dick
 

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