Absorbtion Time for AGMs

[ranger58sb]

Originally Posted by boatbod

I know what the published paperwork says, but I urge you to call Lifeline, describe how you plan on using the boat and then see what they say. Some years ago I followed those written instructions and it nearly cost me 4 batteries in 5 months. Spoke to tech support and they said charge them harder!

Fair enough, they've been very responsive to my questions in the past...

But what I was interested in learning is what conditions exist in your case that cause them to recommend a deviation from their own manual?

-Chris

[belizesailor]

Originally Posted by john61ct

Not saying you should, but open forum discussion are for everyone to learn from, and I'm hoping some other options for current-based charge termination will come out of this one.

I just clarified the type of BM to distinguish from ones like SmartGauge which don't count amps in/out.

BTW I used TDRs every day as a campus data network geek, you can get rough but good-enough ones for just a couple hundred these days. Don't see the need on a boat though 8-)

Didnt mean to imply that you were suggesting I did...and agree its good for discussion.

I used to do network work also and thats when I wanted a TDR, but they were spendy way back then, my boss was cheap, and as a young engineer so was my time...so no TDR for me. 😭

[john61ct]

A related thread where I was hoping to find a dedicated device to cut off any charge source when endCurrent reached

http://www.cruisersforum.com/forums/...d.php?t=181318

[boatbod]

Originally Posted by ranger42c

Fair enough, they've been very responsive to my questions in the past...

But what I was interested in learning is what conditions exist in your case that cause them to recommend a deviation from their own manual?

-Chris

The "manual" is very conservative and works for batteries that are mainly kept on a shore charger. Under cruising conditions (deep discharge, partial recharge) the settings result in premature sulfation and loss of capacity.

[john61ct]

Boosting charge Amps, certainly above .4C, maybe to .6C also helps longevity.

But no substitute for staying above 50% and getting the bank to true "long tail" 100% full, often and asap. A little gennie in the morning helps when solar-only doesn't get you there.

Or move up to Firefly Oasis.

[ranger58sb]

Originally Posted by boatbod

Under cruising conditions (deep discharge, partial recharge) the settings result in premature sulfation and loss of capacity.

Ah. Got it, thanks.

-Chris

[belizesailor]

Originally Posted by boatbod

I know what the published paperwork says, but I urge you to call Lifeline, describe how you plan on using the boat and then see what they say. Some years ago I followed those written instructions and it nearly cost me 4 batteries in 5 months. Spoke to tech support and they said charge them harder!

Odd considering that their market for this battery IS cruising boats. Maybe they designed it more for weekend warriors who spend all week attached to shore power?

[belizesailor]

Well, new bank is installed, tested under normal live aboard loads for several days, ABT is set as good as its gonna get. Now setting ABT = 0 on the BlueSky 3000i and will be gone for at least a month. With that setting, and no load on the house bank, it will just maintain a float charge.

[a64pilot]

Originally Posted by belizesailor

Odd considering that their market for this battery IS cruising boats. Maybe they designed it more for weekend warriors who spend all week attached to shore power?

That would be nearly the ideal for any LA bank, but particularly so for an AGM bank. It's what my boat has been since I bought her, tied in a slip with shorepower.
They are a high dollar bank, and not tolerant of partial SOC cycling, and they do not try to hide that at all, if you cannot get them to a 100% full charge at least once a week and an equalization cycle monthly, then they may not be the bank for you.
I have them as GC's will not fit, not without rebuilding my box, and maybe not even then. (Not sure how much room there is between bottom of box on one side and hull)

[belizesailor]

Originally Posted by a64pilot

That would be nearly the ideal for any LA bank, but particularly so for an AGM bank. It's what my boat has been since I bought her, tied in a slip with shorepower.
They are a high dollar bank, and not tolerant of partial SOC cycling, and they do not try to hide that at all, if you cannot get them to a 100% full charge at least once a week and an equalization cycle monthly, then they may not be the bank for you.
I have them as GC's will not fit, not without rebuilding my box, and maybe not even then. (Not sure how much room there is between bottom of box on one side and hull)

Out cruising I usually give the bank a good bump once a week with alternators. Solar meets our needs but wont really give the big amps bump. Expect that will work OK for AGMs...we shall see.

Have an AGM bank ashore (off grid home) rack mounted telecomm style, lucked into a bunch of them inexpensively. Been running for over 5 years. Similar routine...solar then fire up the generator once a week.

[john61ct]

If you know in advance you won't frequently be getting them up to 100% full, IMO Sam's Club GC2 are the best option unless you can afford Firefly Oasis or LFP.

Only once a week full is still pretty abusive IMO, especially if drawing down below 50% as well.

[belizesailor]

Originally Posted by john61ct

If you know in advance you won't frequently be getting them up to 100% full, IMO Sam's Club GC2 are the best option unless you can afford Firefly Oasis or LFP.

Only once a week full is still pretty abusive IMO, especially if drawing down below 50% as well.

Will keep a closer watch on SOC next season...for now they will be on float for a while.

I can always give them more frequent bumps with alternators. We usually move around every few days anyway.

[a64pilot]

My plan is to get them to 100% twice a week, and equalize once a month.
I figure we will be making water, washing clothes, making ice and whatever else twice a week, so that will be generator run time.
Generator and two chargers can throw 185 amps at the bank, then after about 20 min. It hits absorption and of course amps begins to walk down, so maybe 30 min I can start making ice and a few small loads, and maybe after an hour begin making water, make water for a couple of hours and then shut down gen. By that time Solar ought to be coming on strong and will I hope finish charge to 100%.
If it works out that is 6 hours generator run a week and about two gallons of Diesel.

[belizesailor]

Originally Posted by a64pilot

That would be nearly the ideal for any LA bank, ...

"LA bank"?...as in Lead Acid I assume?

[belizesailor]

Originally Posted by john61ct

If you know in advance you won't frequently be getting them up to 100% full, IMO Sam's Club GC2 are the best option unless you can afford Firefly Oasis or LFP.

Only once a week full is still pretty abusive IMO, especially if drawing down below 50% as well.

Sams Club is LONG way from here...