Saving two Optima batteries...

[IRGuy]

Some of you might remember that about a year ago I posted some info on the Optima AGM storage battery products. I had purchased a total of 6 of these to be installed as part of my upgrading the main 12 volt battery/power distribution system in my ’83 B33 FBC. I installed them in three banks of two batteries each, one bank for each engine starting and one bank for house power and generator starting.

Each battery bank also feeds a single bilge pump.. I have three bilge pumps, (forward, midships and aft), each drawing power from it’s own battery bank. I am not using the boat these days, because I am involved in a general rebuild and upgrading of almost every system, so the only load on these batteries are the bilge pumps. I had an older three bank battery charger online to keep the batteries fully charged. The charger is installed in the space forward on the engine room, where the holding tank and water tanks are located. “”Out of sight.. out of mind!”.

Last week I noticed there was a little more than normal amount of rainwater in the center bilge compartment. I also heard that the bilge pump for this area was running, but saw there was no water exiting the thru hull fitting. Strange. I also noticed that the light in the manual-off-auto switch panel for this pump was on, but dimmer than usual. Also strange. I suspected corroded wiring or a bad ground connection.

To make a long story short.. I found the online battery charger had died… probably weeks before, and apparently the midships bilge pump, in response to the heavy rains we had been having over the past several weeks had drawn so much power from it’s battery bank that the voltage from this bank had dropped so much that the pump had enough power to run, but at a reduced speed, which was not fast enough to lift the discharge water high enough to get over the high point in the discharge hose. This kept the pump running constantly, and drew the battery bank down even further.

After I figured this all out I took a voltmeter reading on the affected battery bank, and found 6.2 volts! Here I was with two almost new batteries so far discharged my portable battery charger would not recharge them.. instead it kept beeping a warning that the batteries were “faulty”, and would not accept a charge. The prospect of having to buy two new Optima AGM batteries for about $175 each was not pleasant, especially since these were essentially new. My local battery sales guy assured me the batteries were junk, and would not ever accept a charge. I was more than a little upset!

Out of despiration I called Optima, and spoke with one of their customer service people. He told me that there was a good chance to save the two batteries. What he suggested was to take one 6.2 volt Optima battery, and connect it in parallel to a good battery with normal 12+ volt output.. then attach the charger to the two batteries, and set the charger at 10 amps (the max for my portable charger) for a couple of hours. I did this and bingo.. the Optima read 11.9 volts. I reattached the portable charger for another couple of hours and reached 12.3 volts by the end of the day. I know that I might have shortened the life of these two batteries, and at present due to other things I can’t start the engine they serve to see how they respond to a load, but at least I feel I might have saved these batteries from premature death. I used the money I “saved” to buy a new charger and battery monitoring panel.

I post this with the expectation that someone else here might have a similar situation one day, and might recall and benefit from this trick.

[RAWicklund]

I too have paralleled a good battary with one that my charger condemed, to make it take a charge.

I hate my electronic charger when it claims 'open cell' 'faulty connection' or some other error code and refuses to even try......

At least it could try :-D

[Rawleigh]

I have had good luck with the 120 volt charger from Batteryminder rescuing deeply discharged batteries. It supposedly desulphates them. It has saved several that my Schumacher faulted out on. It has an AGM mode that charges to the higher level needed by these batteries. It is a portable charger.

[scot]

As normal, I'm confused. I was under the impression that the glass wrap dry cell batteries could handle a complete discharge better than a conventional battery?

[Rawleigh]

I don't think so. More charge/discharge cycles, vibration proof, spill proof, etc, but they must have the proper charger and charging cycle or they will die prematurely. I have a pair of Exide Orbitals on my boat the are going on 8 years old and are still performing properly. They are near the end I am sure, but I want to see what I can get out of them. i use a Xantrex Trucharger.

[Carl]

When I wind up with a dead battery that won't take a charge... I find leaving a trickle charge with a small portable charger will give it enough juice to eventually start charging again.

I think these computerized ones just see no charge taking place and default to a fault.

[IRGuy]

The new charger I have on order is a Xantrex TrueCharge 2, 40 amp model. (The old one that died is an earlier version of the same charger). The mfgr's literature says it will "recharge dead batteries". I hope I never again have to find out if this feature works!

The main reason I made this post is I never heard before of combining a discharged and a good battery to trick the charger into thinking it was dealing with a moderately discharged good battery. Apparently my 10+ year old portable charger had some logic built into it which did not allow it to try to charge what it considered a battery that was too far discharged to be salvageable.

[bob lico]

IR GUY my battery bank like yours with 6 odassey agm batterys are in there 9th year. battery moniter of all three banks shows new . i use a true charge 40 with settings for agm and keep battery temperature heat on medium.what can i say engine fire in one half turn as i demostated to numerous brothers on this board . just gave frank a demo cannot detect engines turning over they fire up in haft turn of crank for all these years.i will demo at greenport.

[scenarioL113]

just gave frank a demo cannot detect engines turning over they fire up in haft turn of crank for all these years.i will demo at greenport.

I do attest to this!

[dougl33]

Frank,

I just re-read this thread. What's wrong with your engine that it can't be started?

[IRGuy]

Doug...

Not sure what you mean about me not being able to start an engine.. one starting battery bank was discharged to 6.2 volts.. but I brought them back with the procedure I mentioned. No engine problems here.

[AndreF]

I think Scot is right about glass mats being able to take alot if discharges, at least that's what I've read.......if I wasn't so lazy I'd look it up.......but the charger has to be up to it.

[dougl33]

at present due to other things I can’t start the engine they serve to see how they respond to a load,

This is the line that gave me the impression you had engine issues. Glad to hear that's not the case.

[IRGuy]

Doug...

OK.. I see now what you were referring to! I meant because of other things I can't start the engine so I could see how the battery bank responded to a (starting) load.