Loss of volts on AGM battery?

[russp]

Wondering if anyone has ideas except buy some new ones. I have a couple of 220 AH 6V Lifelines in series as the house battery, hence one large 220 AH 12V battery, and they are quite old, maybe 8 years. Every indication that they are identical in condition, always same voltage across either battery.

They charge up fine, but once disconnected from charger initially show 12.6V but this sinks with no load down to 12.3V over next 24 hours. I have been load testing them and with a steady 200 W (17A) load they are outputting 100AH before the unloaded voltage falls to 11.7V, so they still have reasonable capacity but certainly not like new as should be around 12.0V at 50 percent discharge. So they start 0.3V low, finish 0.3V low, but otherwise appear normal. Any ideas? I am cycling them a few times from full to 50percent (of rated capacity) to see if can improve them.

And should note, no question about voltage readings, Xantrex and multimeter are identical.

Regards
Russ Peel
Avalon #150

[wolfe10]

Russ,

Couple of points:

If you do replace them, you might consider the Lifeline 4D's: http://www.lifelinebatteries.com/marinedeepcycle.php

At least on our 2004 they fit, and offer 210 amp-hrs @ 12 VDC each for 420 amp-hrs @ 12 VDC total. Measure carefully, it IS a tight fit, but would almost double your battery bank size.

You might also try equalizing them (Lifeline calls it "Conditioning"). Details are found on page 20 if you go to:

From any page on the Lifeline Website:
"Lifeline documentation" (upper right tab).
Click and download "Lifeline Technical Manual". Go to page 20.

Brett
2004 Catalina 350

[nybor]

Hi. I replaced my two 4DL that were 4 years old with new ones. However, I wondered about the old ones and useful life left. I found the neatest battery charger that does all the diagnostics and then automatically de-sulfications the plates. The charge is only for AGM batteries, is ok for Lifeline, et. al., and doesn't have any buttons to push - all microprocessor controlled. I just attached it to one of the old batteries and after it did some tests (took several minutes), it started de-sulficating (?)

here is the link. Another sailor said it was the best $99 he ever spent.

http://www.amazon.com/BatteryMINDer-Cha ... 656&sr=1-3


if the above is not hyperlinked, the item is the model 2012-agm from BatteryMINDer.

dave

[russp]

Thanks for the reply Brett, I did have 4 x Lifeline 4Cs originally, equivalent to 2 x 4Ds, but the solar charger didn't have an AGM setting and cooked two of them (learning experience) which I then replaced with a GPL-31T as nothing else was available where I was at the time.

The 4Cs are definitely improving with heavy cycling, -50 percent of C, + 50 percent of C, etc and I have downloaded Lifeline Technical Manual as you suggest and will explore conditioning.

And Dave, what happened to your old batteries after you started desulphating them? Were you able to restore their capacity, do you now have 800 AH available with your new and old batteries? I have been reading up on desulphating on web/YouTube, lots of opinions on!

Regards
Russ Peel
Avalon #150

[russp]

Was about to send a specific note to Brett re batteries, but thought I should take the opportunity to thank Ken and Bruce and all those who spend their time making the Forum and Daily Digest work. It is a fantastic "subset" of the Internet where you are likely to find much more specific information than wandering at large in the universe.

In relation to batteries, because I asked the question, and because Brett directed me to a document on the Lifeline batteries site, and because it suggested I check out my (Xantrex 40i) charger, and because this charger (unbeknown to me) has an equalisation function which the Lifeline manual says is equivalent to AGM "conditioning", my battery is currently being "conditioned". 15.37V for 8 hours after being fully charged.

I have been wandering the Internet for the past 3 weeks and finding a vast array of information, much of it contradictory or weird, the information that Brett directed me to is exactly what I was looking for but didn't know it.

I very much hope this forum continues and grows for as long as people are sailing C350s (or at least for as long as I will be!).

Regards
Russ Peel
Avalon #150

[nybor]

Ah, batteries...
I checked with the tester this morning and it was STILL de-sulfating (conditioning)!!! The charger also has a built in thermistor so it temporarily interupts the process if the battery gets too warm (they say the temp monitoring is approximate, since you don't directly hook up a sensor to the battery).

I remember the these batteries were left completely discharged for maybe a year, before it was sold (to me). However, if this works, I will have two additional ones.

But, responding to Russ, I added a third 4DL in the port locker. It fits perfectly up against the battery container bulkhead. So, with a my solar and wind generators, I am trying to sell the excess power to the Marina. (they don't seem to interested). Oh well. The only issue is with all the weight on the port side (outboard and batteries), the boat lists to port about 45 degrees at the dock. I had to get a concrete contractor pour 6 cubic yards (around 1,000 lbs.) into the starboard locker to right the boat. However, now the waterline is about 6 inches from the deck. I hope this will be ok in rough seas.

dave

ps, Russ, as I mentioned, Ken gets a ton of kickbacks whenever we mention a product! I know for a fact that Lifeline paid for him and 20 friends to fly (1st class) to Tahiti for a two week stay at the Tahiti Hilton. FYI