House Battery issues...

[WhereisFranklin]

Ok electrical gurus...
I'm having low voltage issues with my battery bank.

1. 4 x 100amp AGM in series/ parallel to deliver 24v
2. About 4-5 years old

3 . Never discharged under 50% and more likely 60% most times
4.Problem free until this trip...HOWEVER, I did leave them unattended after 2018 trip for about 4-5 months. They finished the trip fully charged. The battery monitor showed good levels of charge but I think it had a glitch from lack of cycling and wasn't reading correctly.

1. Inverter has indicated low voltage alarm twice. Once on this trip (today) and once on a short trip a couple of months ago. After the short trip I bought battery charge up and reset battery meter.
2. Yesterday, batteries went to FLOAT (first time since realising problem a while back) but this morning had low voltage alarm. Battery % at around 65% capacity.
3. The induction cooker we run from the inverter normally draws about 30 amps on the appropriate setting. It was pulling 53 at the lower voltage!

I'm struggling to understand how batteries at 65% can show low voltage and why I wouldn't be able to use more of the remaining capacity without having low voltage issues.

Thanks for any feedback. Neil

 

[kerry]

What is your low voltage alarm set at? 60% charge in a 24v lead acid system would be at 24.48 volts.

 

[Joe917]

That 4-5 months unused may have been the end. With flooded I would say equalize. What does the manufacturer say about equalizing?

 

[MJCake1]

Never equalize agm's.

How long should it take to equalize an AGM battery in a solar system using an MPPT controller?

Answer (1 of 3): Q: How long should it take to equalise an AGM battery in a solar system using an MPPT controller? No. Don’t do it. You could ruin your battery! Equalisation is done for flooded cells only. In flooded cells the process of charging the battery produces sulphuric acid, which is co...

www.quora.com

 

[MJCake1]

Induction cooker does not sound right to me. That's alot of amps. What kind of amps are going in during bulk charge cycle?

 

[DiploStrat]

Questions:

-- Is the low voltage constant, or only when the induction cooktop is running?
-- Is the induction cooktop new?

I have used an induction cooktop on my past and present campers and you may have to set the low voltage shutoff on your inverter down to below 11v. BUT, the voltage should quickly rise to normal as soon as you finish cooking. My cooktop (and microwave) draw about 50A @ 12v and that will make the battery voltage plummet, but it should recover almost instantly.

Suggestion: Post this in the 12v forum. There are a lot of things to discuss, like your charging voltage, charging amps, and, yes, equalization. Lifeline AGM have very detailed instructions on how to do it. Others say to never do it.

Good luck!

 

[Alloy]

Double check all the electric connections. A thermal imaging camera is the best tool to for bad connections.

Amazon.com : FLIR ONE Thermal Imaging Camera for Android USB-C (Gen 3 ) : Camera & Photo

Amazon.com : FLIR ONE Thermal Imaging Camera for Android USB-C (Gen 3 ) : Camera & Photo

www.amazon.com

After that X2. . . .DiploStrat. . . . voltage drop (Peukert's Law) setting the alarm off. . . . . equalization (out of the vehicle) may provide more life.

Peukert's law - Wikipedia

en.wikipedia.org

30amps at 25.4VDC is 762watts. For a draw of 50amps from the same device the battery voltage would need to be 15.24VDC

If possible charge the batteries individually at 12V and leave them sit for 24 hours. Then test the battery voltage. It should not be below 12.6VDC. This can be done at 24V but if there is a bad cell in one battery you won't know which battery is bad.

I've only tried AGM batteries once. They cost 40% more than open cells and lasted 5 years which was less time than any of my open cell batteries lasted.

What I hated most about the AGMs is not being able to remove the caps and test each cells with a hydrometer. I've found bad cells and replaced a bad battery with something cheap. It is the worst thing to do to a new battery but it extends the life of the bank.

 

[WhereisFranklin]

Good q. I checked in manual. Default for inverter is 10v @12v dc or 20v@ 24v dc. I was looking at voltage during operation and it was 22.something so interesting that the alarm went off. Is it a low volt problem I'm thinking now?

 

[WhereisFranklin]

That 4-5 months unused may have been the end. With flooded I would say equalize. What does the manufacturer say about equalizing?

Not sure, recent problem. Fusion Batteries. Have read AGMs not suited to equalization.

 

[WhereisFranklin]

Induction cooker does not sound right to me. That's alot of amps. What kind of amps are going in during bulk charge cycle?

Hmm, we operate at a setting of 4 on a 10 setting scale for cooker. I measured it at around 900w from memory. The inverter is 1000w. So 900/24= 37.5 amps. That's why when I saw 53amps this morning I was concerned. Either the voltage was low or cooker is drawing more than it should??
Not sure about charging, Solar panels (flat mounted on roof)750w but never full wack so maybe 20amps. When travelling, alternator via VSR rated at 80 amps but not exactly sure input.

 

[WhereisFranklin]

Questions:

-- Is the low voltage constant, or only when the induction cooktop is running?
-- Is the induction cooktop new?

I have used an induction cooktop on my past and present campers and you may have to set the low voltage shutoff on your inverter down to below 11v. BUT, the voltage should quickly rise to normal as soon as you finish cooking. My cooktop (and microwave) draw about 50A @ 12v and that will make the battery voltage plummet, but it should recover almost instantly.

Suggestion: Post this in the 12v forum. There are a lot of things to discuss, like your charging voltage, charging amps, and, yes, equalization. Lifeline AGM have very detailed instructions on how to do it. Others say to never do it.

Good luck!

Low voltage triggers when using cooktop, but not all the time. Cooked last night, boiled water for cuppa , all good. Got up this am to boil more water and low voltage alarm occurred. Has not been a problem for two weeks then , after floating yesterday, went weird.

We have been using exact system for 4 years, nothing has changed, all good. Cooker has been bounced around a fair bit but still operational but could be worth investigating. I will seek out the 12v forum. Thanks for input.

 

[WhereisFranklin]

Double check all the electric connections. A thermal imaging camera is the best tool to for bad connections.

Amazon.com : FLIR ONE Thermal Imaging Camera for Android USB-C (Gen 3 ) : Camera & Photo

Amazon.com : FLIR ONE Thermal Imaging Camera for Android USB-C (Gen 3 ) : Camera & Photo

www.amazon.com

After that X2. . . .DiploStrat. . . . voltage drop (Peukert's Law) setting the alarm off. . . . . equalization (out of the vehicle) may provide more life.

Peukert's law - Wikipedia

en.wikipedia.org

30amps at 25.4VDC is 762watts. For a draw of 50amps from the same device the battery voltage would need to be 15.24VDC

If possible charge the batteries individually at 12V and leave them sit for 24 hours. Then test the battery voltage. It should not be below 12.6VDC. This can be done at 24V but if there is a bad cell in one battery you won't know which battery is bad.

I've only tried AGM batteries once. They cost 40% more than open cells and lasted 5 years which was less time than any of my open cell batteries lasted.

What I hated most about the AGMs is not being able to remove the caps and test each cells with a hydrometer. I've found bad cells and replaced a bad battery with something cheap. It is the worst thing to do to a new battery but it extends the life of the bank.

Thanks for response. Yeah, travelling atm but when we stop for a bit I'll do some investigating. AGMs suit the rough and tumble of travel I suppose and venting problems are reduced. Hopefully it's one rogue battery but mixing old and new is problematic too.

 

[dreadlocks]

they are dead jim, I too distain AGM's.. they are fragile lil snow flakes and if you ever look at em wrong and they are done for.

IMHO go pickup 4x 6v GC Batteries.. money better spent, the'll hold up much better to what you throw at em, the cheapest GC battery is far more robust than the best AGM.

 

[WhereisFranklin]

Appreciate all the responses. Thanks.

 

[WhereisFranklin]

they are dead jim, I too distain AGM's.. they are fragile lil snow flakes and if you ever look at em wrong and they are done for.

IMHO go pickup 4x 6v GC Batteries.. money better spent, the'll hold up much better to what you throw at em, the cheapest GC battery is far more robust than the best AGM.

Ta. GC? I'm in Oz.? Golf Cart?