Lifeline Battery Review and Equalizing

rollerbearing said:

In beautiful (though sad) agreement with your previous C/5 test.

Click to expand...

Yeah, is what it is. Anyone got a desulfator they want me to test? I will return after a few months if desired.

Have you discounted measurement error, or calculation error? See my earlier post. 57% seems quite low. You also got rid of the surface charge. How much was that?

The inverter load current may oscillate. Mine does (with resistive AC load). When AC voltage crosses zero there's no load current flowing. You say you have an inductor within the inverter that filters the oscillation out. Are you sure? Just looking for possible errors.

Pink plot is current with axis on right. Blue plot is battery voltage.

Midwestdrifter said:

Yeah, is what it is. Anyone got a desulfator they want me to test? I will return after a few months if desired.

Click to expand...

Interestingly, a pwm solar charge controller is not so different.

I keep thinking about the lifeline manual recommendation to bulk charge at rates in the 3C range, and if you cannot do this, to contact them for alternative charge profiles. (for optimal battery life)

3C x 225 amp-hrs x 12 volts is around 8 kW.

Does anyone even make a charger like that?

That is something in the range of 2 x 300 amp alternators.

calbiker said:

Have you discounted measurement error, or calculation error? See my earlier post. 57% seems quite low. You also got rid of the surface charge. How much was that?

The inverter load current may oscillate. Mine does (with resistive AC load). When AC voltage crosses zero there's no load current flowing. You say you have an inductor within the inverter that filters the oscillation out. Are you sure? Just looking for possible errors.

Pink plot is current with axis on right. Blue plot is battery voltage.

Click to expand...

I do get current fluctuations at loads over 1.8kw. Below that the fluctuation is pretty minor. I can get my O-scope out and check today maybe.

The FNDC does average current over a certain period (probably 100-500ms).

The recharge times pretty closely match what I would expect from the measured AH deficit as well.

HarryN said:

Interestingly, a pwm solar charge controller is not so different.

I keep thinking about the lifeline manual recommendation to bulk charge at rates in the 3C range, and if you cannot do this, to contact them for alternative charge profiles. (for optimal battery life)

3C x 225 amp-hrs x 12 volts is around 8 kW.

Does anyone even make a charger like that?

That is something in the range of 2 x 300 amp alternators.

Click to expand...

Makes you wonder about hooking them in series and connecting a couple of really big welders to them!

I was working with some guys once who in a pinch were charging their forklift battery with an old Lincoln Fire Plug welder - 3 phase AC motor driving a DC generator - they were totally surprised when throwing the AC breaker to disconnect - the shop lights stayed on. The forklift battery was driving the whole charging assembly in reverse, the DC generator acting as a DC motor. Ilustrates one of the dangers of unintended backfeed.

Another way to measure battery capacity is:

I = C * dV/dt

C is capacitance, in Farads

My GC2 discharge data:

At 199 min: Vbat = 12.2416 V
At 200 min: Vbat = 12.2396 V

dV/dt = 0.002 V / 60 sec = 33.33 micro

C = I / 33.33 micro = 13.8 A / 33.33 micro = 414 k Farads

210 AH corresponds to 414 k Farads.

You should get 510/210 * 414 k = 10.05 M Farads

Midwestdrifter said:

Basically without solar or shore power you would need to run the gen 4-6 hours per day minimum to get a full charge. Much of that runtime will be at near zero load.

A 220AH bank would be fine for your needs. Using Deka GC2s, you would be looking at around 250-300$ for the bank, pretty cheap. Without solar or shore power a few times a week to get your batteries to a true 100%, they will sulfate and die in as little as 100-150 cycles. If you can tolerate that extra cost, you can treat your batteries are yearly disposables. Otherwise you need around 200W of solar to complete the charge to a true 100% at least twice a week. The rest of the week you can cycle between 95% and 50% SOC. With the GC2s I would recommend a 15V+ equalize charge every 2-4 weeks, for at least 4 hours.


Take note, that regardless of the charging sources voltage, it will never take less than 4-6 hours to recover fully from a 50% discharge. It can take longer (or not at all) with lower voltages though.

Click to expand...

Thanks. That's kinda what I was thinking, based upon what I've read here. I can either pony up for solar, or I can just accept that I'm gonna have to be replacing the two batteries periodically.

How much solar do you think I'd need for a set up like what I'm talking about here, with just two GC2 type batteries?

I would suggest 300w, but 200w would work. Some is better than none though.

Midwestdrifter said:

I would suggest 300w, but 200w would work. Some is better than none though.

Click to expand...

Thanks. That doesn't sound insurmountable.

Next question:

If I were to substitute LiFePO4 for flooded cell or AGM, that would obviously eliminate any sulfation concerns.

But how does the charging "profile" needs of a LiFePO4 battery compare to what we've been talking about with lead-acid batteries? Can they take a charge faster, and thus maybe not require running the generator as long? Do they still require an extended period of charging as 100% SoC is approached? Would the benefits of solar still be needed with LiFePO4? How deep can/should LiFePO4 batteries actually be discharged on a regular basis- some people say you can take them all the way to 0% SoC without hurting them, but a lot of people say 20% SoC. Some people even say no more than 50% SoC, just like regular lead-acid batteries.

I'm wondering if I could get away with a much smaller LiFePO4 set-up that would last longer (more cycles), and at that point, LiFePO4 might actually make financial sense.

I have no weight or space concerns driving these questions. Just the financial and practical aspects.

The Grand Tour said:

Thanks. That doesn't sound insurmountable.

Next question:

If I were to substitute LiFePO4 for flooded cell or AGM, that would obviously eliminate any sulfation concerns.

But how does the charging "profile" needs of a LiFePO4 battery compare to what we've been talking about with lead-acid batteries? Can they take a charge faster, and thus maybe not require running the generator as long? Do they still require an extended period of charging as 100% SoC is approached? Would the benefits of solar still be needed with LiFePO4? How deep can/should LiFePO4 batteries actually be discharged on a regular basis- some people say you can take them all the way to 0% SoC without hurting them, but a lot of people say 20% SoC. Some people even say no more than 50% SoC, just like regular lead-acid batteries.

I'm wondering if I could get away with a much smaller LiFePO4 set-up that would last longer (more cycles), and at that point, LiFePO4 might actually make financial sense.

I have no weight or space concerns driving these questions. Just the financial and practical aspects.

Click to expand...

There are several threads discussing the needs and characteristics of LFP packs. I won't go into detail here.

Yes, with alternator and gen charging (a beefy charger is needed), you could likely forgo the solar install with lithium. Instead cycle indefinitely between 5 and 95% SOC. A 150AH lithium pack would serve your needs quite well. It would not be cheap, probably costing around 8-10$ per AH. The savings come with higher cycle life, but that can take a long time for a lightly used van to reach (if ever).

Midwestdrifter said:

There are several threads discussing the needs and characteristics of LFP packs. I won't go into detail here.

Yes, with alternator and gen charging (a beefy charger is needed), you could likely forgo the solar install with lithium. Instead cycle indefinitely between 5 and 95% SOC. A 150AH lithium pack would serve your needs quite well. It would not be cheap, probably costing around 8-10$ per AH. The savings come with higher cycle life, but that can take a long time for a lightly used van to reach (if ever).

Click to expand...

Yeah, I'm sorry if I'm taking this a little off topic. I've been poring over various FAQs, links, and threads, and just wanted to benefit from the knowledge base that's currently being exercised here.

How beefy a charger? Something like the PMBC-100 100-amp smart charger from Powermax Converters driven by a 2,500 watt propane generator?

I'm seeing LiFePO4 options as low as the $10/Ah range, but I'm not seeing them priced any lower than that.

This would not be a lightly-used van- it would be for full-time boondocking, so if the ROI is driven by use, we're there.

Are you saying that I could safely take LiFePO4 down to 5% SoC on a regular basis without hurting it? And are you also saying that I could live with only charging to 95% SoC without causing a problem?

If so, I'm wondering if I'd actually need 150 Ah of capacity- we'd be able to recharge every single day with the generator, and possibly even letting the alternator make it's contribution of electrons almost as often- it's not like we'd need to go 2/3/4 days of being silent in the woods without running the generator. If I could safety get 24 hours of usable capacity from a smaller (less expensive) LiFePO4, I'd think I'd be good. But I'd like to get your input on that idea as well. The single biggest power hog we'd have, would be the refrigerator, which at 1.3 Ah/h, would theoretically use about 31.2 Ah in 24 hours. I would think that the LED interior lighting, the roof fan(s), and the two laptops would be incidental to that.

Thank you so much for taking time to help me to get up to speed on this stuff. I really appreciate it.

The Grand Tour said:

Are you saying that I could safely take LiFePO4 down to 5% SoC on a regular basis without hurting it? And are you also saying that I could live with only charging to 95% SoC without causing a problem?

Click to expand...

Yes. For max life staying between 15% and 90% is ideal, but with the kind of cycles you will be seeing its not a big value lost. The ROI is definitely there for full time applications. You would want a shore power charger (on gen) in the 100A range. That would allow you to run the gen for an hour or two a day to recovery all the AH you need. The alternator can also supply 50A when the engine is running, so a few hours of driving may supply all the charging you need for a given day.

In our case we often have the engine running for 10 or more hours a week. With a lithium pack that would mean around 1000AH per week from the alternator, likely more.

If you would like to start your own thread (unless you already have one) and post some detailed usage case info, and questions, you would likely get feedback from a number of folks with good advice.

What I am finding interesting is the financial question:
- Is it worth spending the extra money to keep the batteries always charged correctly, vs
- Swapping them every 2 years.

Other then perhaps a sterling Battery to Battery Charger - or the Orton method, most other solutions would cost much more than swapping batteries.

Rough numbers I am estimating $1K parts and labor to implement either of those solutions.

Perhaps incorrectly, I am viewing this thread as not so much a lifeline battery review, as a "should I have used a better charging method than an ACR plus some solar?".

Midwestdrifter said:

Yes. For max life staying between 15% and 90% is ideal, but with the kind of cycles you will be seeing its not a big value lost. The ROI is definitely there for full time applications. You would want a shore power charger (on gen) in the 100A range. That would allow you to run the gen for an hour or two a day to recovery all the AH you need. The alternator can also supply 50A when the engine is running, so a few hours of driving may supply all the charging you need for a given day.

In our case we often have the engine running for 10 or more hours a week. With a lithium pack that would mean around 1000AH per week from the alternator, likely more.

If you would like to start your own thread (unless you already have one) and post some detailed usage case info, and questions, you would likely get feedback from a number of folks with good advice.

Click to expand...

Yeah, I'll start another thread. Thanks.

HarryN said:

Perhaps incorrectly, I am viewing this thread as not so much a lifeline battery review, as a "should I have used a better charging method than an ACR plus some solar?".

Click to expand...

You are incorrect. Adding a DC-DC charger would have had minimal effect on the battery life. Only a generator with significant runtime, or shore power would have had a major effect.


This thread illustrates the challenges, of working with mobile off-grid lead acid systems. As well as the relative capacity loss that can be experienced with partial charge cycles.

Midwestdrifter said:

You are incorrect. Adding a DC-DC charger would have had minimal effect on the battery life. Only a generator with significant runtime, or shore power would have had a major effect.


This thread illustrates the challenges, of working with mobile off-grid lead acid systems. As well as the relative capacity loss that can be experienced with partial charge cycles.

Click to expand...

Makes sense. I guess it just reinforces that all of our tricks to "reduce" the need for a generator isn't the same as "eliminating" the need for a generator.

Would an auxiliary alternator solved this or would you still have been short?

HarryN said:

Makes sense. I guess it just reinforces that all of our tricks to "reduce" the need for a generator isn't the same as "eliminating" the need for a generator.

Would an auxiliary alternator solved this or would you still have been short?

Click to expand...

I started an auxiliary alternator thread...