Breaking in Lifeline AGM batteries (about how long?)

Skyko

I have been cycling my Lifeline GPL31XT 125 AH 12V AGM batteries for about 7 cycles and am still not quite seeing what I think should be full capacity.

I may not be doing things correctly as I have only been discharging them about 20% to 30% (so 70% or 80% SoC). My Magnum is set to AGM1 and bulk charges for a minute or two then flips over to absorption charging at 30 down to 4 amps for about an hour, then float charge at 3 amps down to 1 amp over 4 hours.

When they come off float they are at 13.19V but the next morning they are at 12.85V (inverter off, no other DC loads). I hooked up a 120V heater which drew 25 amps at 24.4V and let it run for an hour. Initially voltage dropped to 12.4V then after 30 minutes the voltage went down to 12.2V per battery which on Lifeline's chart means 30% DoD. After another 30 minutes it was 12.05V per battery (while loaded) which exactly matched 40% DoD at the 4 hour rate line. I bulk charged at this point with 52 amps for a few minutes, then it went to absorption at 30 amps for awhile (didn't measure the exact time). Off of float, each battery is reading right at 13.18V but it will likely drop.

So, from what I can tell, right now my batteries only have about 80% capacity (starting off at 80%, dropping to 70% after 30 min and 60% after another 30 min). According to Lifeline specs I should see 230 reserve minutes at 25 amps which I would guess means I should be able to get 2 hours at 25 amps without taking them below 50%. I don't think I am seeing that capacity yet.

Should I change the Magnum settings from AGM1 to something else or should I just continue cycle and charge to try and "break in" the batteries as some have said is required?

Blackcherry04

Re: Breaking in Lifeline AGM batteries (about how long?)

I don't know if this fits your exact your batteries or not, it did my Surrettes.


Attachment not found.

Skyko

Re: Breaking in Lifeline AGM batteries (about how long?)

Ah, so that explains things. Sounds like I should just live with the 80% to 85% capacity and not try to rush the break in.

Blackcherry04

Re: Breaking in Lifeline AGM batteries (about how long?)

Skyko wrote: »

Ah, so that explains things. Sounds like I should just live with the 80% to 85% capacity and not try to rush the break in.

I don't think that some people know that the process happens, I didn't. My past experience was with many, many GC-2's. It only took 6-10 cycles and they would to 100% capacity. The Surrettes Deep Cycle were totally different and it took at least 50 cycles to 50% dod and I kept on doing EQ's to get them back up. That was not the track I should have taken, I should have just extended the absorb time to get them to 2 % of capacity and watched the amps going in and stopped the charge and they would have taken care of themselves.

I also compounded my problem by putting them in float service for 5 months and they sulfated and stratified over the winter. They are doing fine now.

Alaska Man

Re: Breaking in Lifeline AGM batteries (about how long?)

I'm just now starting to see my AGM's work as specified and I've been using them hard for about a year. Going down into the 70% range daily before recharging. I make sure to float them at least once a week.

I've found the system works best if I charge with my generator in the morning to 85%-90% which I can normally do within an hour of run time. I then let my array top them off. At least that's what works best for now with the array I have. We do plan to add another 1kw next year.

Photowhit

Re: Breaking in Lifeline AGM batteries (about how long?)

Skyko wrote: »

When they come off float they are at 13.19V but the next morning they are at 12.85V (inverter off, no other DC loads). I hooked up a 120V heater which drew 25 amps at 24.4V and let it run for an hour. Initially voltage dropped to 12.4V then after 30 minutes the voltage went down to 12.2V per battery which on Lifeline's chart means 30% DoD. After another 30 minutes it was 12.05V per battery (while loaded) which exactly matched 40% DoD at the 4 hour rate line. I bulk charged at this point with 52 amps for a few minutes, then it went to absorption at 30 amps for awhile (didn't measure the exact time). Off of float, each battery is reading right at 13.18V but it will likely drop.

I believe even AGM batteries need to be at rest for a significant amount of time to determine the state of charge by voltage. Did you allow the batteries to rest after the load?

Also, "...I bulk charged at this point with 52 amps for a few minutes..."

What size is your battery bank? 2 - 12V or 6 - 12V? Very confusing switching back and forth from 12 to 24v info, What rate of charge can your batteries handle? what percent of charge is 52 amp? Is this with in the batteries charging specs?

Marc Kurth

Re: Breaking in Lifeline AGM batteries (about how long?)

As your batteries cycle a few more times, you will see closer to a 13.0v (26.0v) static measurement the next morning in your example, after a full charge. I am intimately familiar with the 31XT's and I would expect to see 13.0v (26v) for at least 3-4 weeks after fully charging these batteries. If you don't get 13.0v (26v) after breaking them in, you aren't fully charged.

Once you get them broken in, be sure to charge them as hard as you can from a current perspective, while maintaining the standard voltage limits. In a continuous deep cycle application, those batteries need to see at least a 25-30 amp charge rate as a minimum. Of course in a normal PV system with a more shallow average DOD, a lower charge rate is acceptable. Your 52 amp charge rate is only 42% of the 125 ah C/20 rating - which is great for this particular battery.

Once your batteries have been cycled around 12-15 times, the definition of a full charge is:
A current draw of under 0.5% of the C/20 rating, at the full absorption voltage. So in your case, something under 0.6 amps amp will tell you that they are fully charged when you are feeding them 28.4v to 28.8v at 77 degrees.

Until they have been used a bit, the current draw may not drop to the low levels that you will see later and you won't have full capacity. That is why I teach my customers to cycle these batteries before thinking about testing capacity!

Marc

PNjunction

Re: Breaking in Lifeline AGM batteries (about how long?)

Marc - thank you for that!

I have had friends bring home Lifelines / Concordes, and immediately start doing EQ (one of the few that allow for it, under specific conditions) when they haven't even been cycled more than twice, just hammering them right out of the gate. Egads!

A little patience with high-quality batteries goes a long way!

serenity0357

Re: Breaking in Lifeline AGM batteries (about how long?)

I asked about my Lifeline GPL-L16 Deep Cycle AGM Batteries from Powerstride Battery and the need to break-them-in, condition them and received this response.


"Just use them as normal and they will naturally hit their sweet spot after
50-100 cycles."

Ty Hoad
eCommerce Manager
Powerstride Battery
122 Enterprise Ct
Corona, CA 92882
951.808.3748 Direct
951.273.7198 Fax
www.powerstridebattery.com