Battery voltage?

[mestrezat]

Over the last few day, my batteries don't seem to be getting up to a full charge(12.6 or so)after running my generator or from the alternators on my engine. My meter shows lots of amps and volts going in(gauge shows a charge of 14.3 or more)after the chargers have been run for a while. Once turned off, the volt meter shows them dropping to about 12.35 to 12.4 almost immediately. Then what is left appears to discharge at a normal rate.
I'm guessing my Trojan t105s are slowly going bad(have 6). Bought in 2013. Suggestions on how to check to see if only one or two have gone bad. Hate to replace all six if not necessary.

[fallingeggs]

Well that is because it doesn't sound like you have been fully charging your batteries! Full charge , for flooded lead acid, is when your bank is accepting around 1% of their capacity. New, for 6 T105s, this would be less than 10 amps. This is really only completed with shore power or solar. It takes a few hours of charging on the generator/alternator for the acceptance current to drop to this level, which is why a full charge under a generator hardly ever happens unless you really pay attention to it.

After three years of not fully charging the bank, it is very possible they are shot.

Also, T105s want to be charged at 14.8 volts. Low voltage charging is not going to help the matter.

My suggestion is to read up on this forum on how to correctly charge the batteries. All the answers are here if you spend sometime looking. Then buy a new bank and correctly charged them and they will last much longer. May also require a new charger and controller for the alternator. Or you put up with replacing the bank every two or three years.

[Maine Sail]

Originally Posted by mestrezat

Over the last few day, my batteries don't seem to be getting up to a full charge(12.6 or so)after running my generator or from the alternators on my engine. My meter shows lots of amps and volts going in(gauge shows a charge of 14.3 or more)after the chargers have been run for a while. Once turned off, the volt meter shows them dropping to about 12.35 to 12.4 almost immediately. Then what is left appears to discharge at a normal rate.
I'm guessing my Trojan t105s are slowly going bad(have 6). Bought in 2013. Suggestions on how to check to see if only one or two have gone bad. Hate to replace all six if not necessary.

#1 You can't fully charge Trojan T105's, even when brand new, unless you are running the charge sources well in excess of six plus hours. As they age charging to full/100% takes even longer due to sulfation.

#2 Sounds like you are chronically undercharging your T105's, especially if charge voltage is only getting to 14.3V, unless the batteries are very warm and that is a temp compensation @ a 77F reference. Trojan T105's will do significantly better at a temp compensated 14.7V to 14.8V for absorption.

#3 Once the batteries have risen to 14.8V you then need to hold them at that voltage for several hours, 3.5 - 5+ hours, in order to attain a full 100% SOC charge. The less often you get to 100% the more rapidly your batteries will fail.

#4 If that has been your charging practice since 2013, the capacity loss will not be reversible, but the bank may still be "usable". You should do a complete 100% SOC recharge then perform a temp compensated equalization. See if that helps.

[mestrezat]

I've been charging them using either my generator or my alternator when motoring since we installed them in August of 2013. Spent some time in. A marina in Grenada and on the hard in Trinidad where I was on shore power.
After I run the generator, the volt meter has shown the voltage to be 12.6 or higher steadily decreasing as load is put on them. Now, suddenly once the generator is turned off, it goes to 12.35 or 12.4, skipping the 12.6. I run the generator till my meter goes into "accept mode from "charge" mode and the generator output drops since the meter shows the batteries(as far as it is concerned)close to full. I know that unless I'm on shore power ther is no way to get them "full" but the sudden drop in voltage concerns me.
I can take readings at each of the cells to see which may have gone bad and replace as necessary.

[Stu Jackson]

Originally Posted by mestrezat

I can take readings at each of the cells to see which may have gone bad and replace as necessary.

That's the answer. You could also do it in groups of two since you have a 12V system and one bad 6V cell makes the one attached to it useless anyway, then find out which of the two 6V ones is bad and only buy one new 6V. Good luck, good detective work.

[StuM]

Originally Posted by Maine Sail

#4 If that has been your charging practice since 2013, the capacity loss will not be reversible, but the bank may still be "usable". You should do a complete 100% SOC recharge then perform a temp compensated equalization. See if that helps.

Is that a typo? Shouldn't it be "NOW" ?

[StuM]

Originally Posted by Stu Jackson

That's the answer. You could also do it in groups of two since you have a 12V system and one bad 6V cell makes the one attached to it useless anyway, then find out which of the two 6V ones is bad and only buy one new 6V. Good luck, good detective work.

Given the treatment that they've had, they will almost certainly all be affected to some extent. Sticking one or two new batteries in a bunch of old ones is not a good idea. Unfortunately, it looks like time for replacement of the complete bank.

[Cheechako]

Originally Posted by mestrezat

Over the last few day, my batteries don't seem to be getting up to a full charge(12.6 or so)after running my generator or from the alternators on my engine. My meter shows lots of amps and volts going in(gauge shows a charge of 14.3 or more)after the chargers have been run for a while. Once turned off, the volt meter shows them dropping to about 12.35 to 12.4 almost immediately. Then what is left appears to discharge at a normal rate.
I'm guessing my Trojan t105s are slowly going bad(have 6). Bought in 2013. Suggestions on how to check to see if only one or two have gone bad. Hate to replace all six if not necessary.

Seems a bit early for them to go bad, I think the lowest I've had them go bad is 5+ years. (other than shorts) New batteries at rest often read about 12.45 though. So you are down a tad. Have they sat a lot not cycled? Do you have a good voltmeter to check the accuracy of your instrument?

[newhaul]

Originally Posted by StuM

Is that a typo? Shouldn't it be "NOW" ?

Actually stu I do believe not is corect in this case the dammage is done there is no recovery .

[a64pilot]

Before burying them though I'd try a deep discharge with an immediate recharge and equalization. It seems sometimes you can get some capacity back by "cooking" them a little. But I agree tossing in one or two new batteries is a waste. It seems a new battery or two in a string of old ones, rapidly ages, I mean rapidly

[StuM]

Originally Posted by newhaul

Actually stu I do believe not is corect in this case the dammage is done there is no recovery .

Doh! I read that as "not irreversible" for some reason.

[newhaul]

Originally Posted by StuM

Doh! I read that as "not irreversible" for some reason.

Not your fault you are.from the wrong half of the world.

[smac999]

Get to a dock. Plug in for 24 hours to fully charge. Then Equalize them. Do a 20 hour discharge test (google it). Get your capacity actually anwsered instead of everyone guessing. Then charge again for 24 hours. Or replace if less then 75% or so.

You are either replacing all or none

[mestrezat]

I'd love to be at a dock in a marina BUT with them costing $200 or more(lots more) per night. It's just not going to happen. I charged my batteries for about 90 minutes this AM and once shut off, the voltage dropped to 12.45 and stayed there for a while before usage made it drop. The Trojan T105 run $192 per here in the USVI. I may have to limp along with batteries that don't fully charge till I can get back the the real USA and better prices. Been gone 8 years so maybe it's time.

[a64pilot]

Buy a generator then.
To fully recharge batteries of just about any lead acid type takes 5+ hours. The plus comes from that maybe you can recharge brand new excellent condition batteries in 5 hours, but the older and more sulfated they get, that time gets longer.
By partial charging them, your in a losing loop, the more you partial charge them, the longer it will take to fully charge them, it's a spiraling cycle.
But if you got 8 years out of them partially charging them, then I'd continue what I was doing and buy a new bank every 8 yrs. that is actually a great record for batteries in my opinion.