Determining AH rating of aging batteries

Fisherguy wrote:

So Barry, leaving the trailer plugged in all winter is ok? I used to remove the batteries, put them in my garage and charge them once a monthbut got lazy last year.

Yes, you want to do this for longer battery life. Batteries like to be charged. To Mex, I don't know of any temp compensated float chargers.

Have to change C to F here...

A temperature sensitive battery float charger is the answer to maintain flooded batteries in the off season. There's quite a variance in ambient temperature conditions, so compensatory sag and bulge is much more desirable. The question is do any of the maintainers do this?

Letting a battery just "sit" is not good for it. If I had let my parrot sit without him having company he would like so many others, plucked all his feathers out and gone nuts.

Voltage was 12.1 this morning, 51% SOC so I guess I'm ok.

Ordering a Freas #1 hydrometer, actually I'm ordering 3 cuz they have a min order. of 40 bucks.

So Barry, leaving the trailer plugged in all winter is ok? I used to remove the batteries, put them in my garage and charge them once a monthbut got lazy last year.

Fisherguy wrote:
Ya, I need to do it more often.

Past years I took the batteries out over the winter and charged them once a month, this past winter I left them on the trailer and plugged the trailer in once a month for a day, wonder what's best over the winter?

Best is leave the batteries on Float all the time, don't just run them up every so often, although that will get you by. One version is to wait until they get down to 12.4v and then recharge to 100% then let them go again. IMO if you have shore power use it full time.

If you don't like your trailer converter's float voltage you can get a special float charger. I like that Can Tire 2a one that sits at 13.4 once the batts are charged. (goes on sale about every three or four months for half price--20 vs 40 last I saw.)

On the weak cell now, it does recover with E but how long does it stay there with the batts on a 13.x float? Anyway the test did show plenty of capacity even with that weak cell. The unknown is how much longer can you keep getting what you want from that bank.

At least you know about it and can start saving up for replacements. Mex might know if they will die slowly or if you should worry about a sudden collapse while camping. (if so, I suppose you could swap in a 12v boat battery to replace those two batts and get by so it won't ruin that trip)

PS, off topic but while you are here, can you confirm you run your PD9280 off a 2000W Honda at 80a? Been some dispute whether that is possible. If you do please give some detail such as whether the converter's amps are tapering down anyway and how rapidly at the time so the Honda keeps running or if it can keep running the load at above 74ish amps for quite a while or what. Thanks.

connect the manual charger. Set to 12volts "Hi" disconnect ground cable so you don;t bake your rig's electrical. Let charge until all the cells are bubbling very vigorously. Sometimes this takes 15 hours or even longer. Stop the charge at 16.0 volts.

Honorable battery is like honorable chain. not good when towing car, weak link breaks and angry chain comes through back window.

What's the deal with "Don't wanna equalize manually?"

Timer modules have a purpose in life. Set timer for four hours, come back and check with a volt meter and a dip of the weak-sister cell. Been doing it that way for more than 50 years. I refuse to sit in a heated, vibrator LaZboy and do it click-click-click with a remote.

The lowest cell -must- rise. If it doesn't rise turn out the lights the party's over. Sometimes with true deep cycle batteries you have to threshold "boil the electrolyte" to slap the drone cell awake.

RV'ers spend thousands of dollars on meters and gauges that likely have appalling accuracy. I won't get into the subject of 55 minute or hour and 7 minute storage "monitors". But some balk at the idea of actually "purchasing" a hydrometer that is MUCH EASIER TO READ than a dime store toy.

Saying in the commercial fishing industry "It works right, or it's 'over the side'"

Ok, so after 9.5 hours, the weak one was down to 1.172 or so, the rest were all 1.21, trimetric shows 52% and 12 volts no load. So I imagine by morning that voltage will creep up a little? (Bed time, work in the morning)
That voltage seems low to me for 50%, what should I be seeing no load voltage wise and 50% SOC? I thought it should be 12.2-12.3?


EDIT

OK, Google tells me 50% should be 12.1 volts

Fisherguy wrote:
Mex, none of the old transformer type chargers I had had any way to crank up charging voltage to 15 volts.

Barry, do I measure the weakest cell till it's at the half SG? It's almost there after drawing 102 amps for 9 hours, voltage on the trimetric is still showing 11.9 volts (with the load on). Maybe equalizing it before starting the test bumped things up to where they should be?

I'm really not feeling like this test is doing me much good. (probly cuz I'm not really sure what I'm doing.) I might just try setting the trimeteric to show I'm starting at 200 Ah and see how that goes our next trip.

Trojan spec for 50% is 12.1v and 1.172 SG

I haven't done it with a weak cell in the bunch. IMO ignore that one and go with the rest for their SG and that loaded voltage should be lower before you are near 50%.

What you are trying to find out is what is the capacity of the bank in spite of the weak cell, to see if that weak cell matters very much.

There is a guy here all summer with a pair of older 6s where one has all three cells in the green (just barely) and the other has the middle cell like that but the outer two cells are deep in the red. Looks bad. But he is getting by ok, even runs a 3000w inverter and his MW on that pair. He does have 130w solar on them which is what is saving him. He plans to get new batts next year, doesn't camp till then after this summer.

Just goes to show you don't have to rush out and do anything this minute if your bank still does the job.

Mex, none of the old transformer type chargers I had had any way to crank up charging voltage to 15 volts.

Barry, do I measure the weakest cell till it's at the half SG? It's almost there after drawing 12 amps for 9 hours, voltage on the trimetric is still showing 11.9 volts (with the load on). Maybe equalizing it before starting the test bumped things up to where they should be? Doesn't seem to last though..?

I'm really not feeling like this test is doing me much good. (probly cuz I'm not really sure what I'm doing.) I might just try setting the trimeteric to show I'm starting at 200 Ah and see how that goes our next trip.
What should my trimeteric voltage be at 50%, 12.2V?

I have no problem getting my 6s and also the T-1275s to baseline SG using the VEC1093DBD Equalize feature. Sometimes it takes two runs of E one right after the other, but it gets done. And being automatic, you don't have to babysit the Equalize episode.

On hydrometers, I find the standard $6 glass tube with bobber works fine (pun!) The idea is to use the same hydrometer so even if it is out a bit on calibration you can see if it is still getting to the same numbers. No doubt the expensive fancy ones work better. Like the dog is the only one who can hear the difference when you get a better stereo :)

Stubborn batteries laugh at newer "gizmo" chargers that have lights, buzzers and power windows.

"Eight equalize cycles and the cell partially recovered?"

The original Harbor Fright 10-amp manual charger was unique. No longer available. People want a plug and play life these days. Too bad reality sticks it foot out and sends the dreamers sprawling. Customer demand. "I won't buy it unless it's automatic - even if it doesn't work! It's still automatic"

The best type of manual charger that may or may not be available on the market would be a fifteen amp, heavier than hell, transformer powered box with a wind up timer and voltage selection click-click-click knob. This one is a candidate to maintain something like 5 amps charge rate at 15.5 volts. An ideal charger terminates the charge with 5 amps at 16.00 volts for a hundred amp hour battery.

Automatic chargers are as pitiable as automatic disherwashers. Wait a minute I can't say that...my automatic dishwasher shows up Monday, Thursday and Saturday.