Flooded Cell bank discharged to nearly zero volts

[MichaelStacy]

The last time I was at my boat (3 weeks ago) I inadvertantly left a light on in the aft cabin - which after 3 weeks discharged my 1 year old house bank (two golf cart batteries)to about zero volts. Normally I leave the charger on (3 stage), but didn't this time. The batteries had never been discharged more than 35% before.So, the question is, have much has this affected the performance of the batteries? I know that flooded cell batteries like to remain charged, and do not like deep discharges (anything below 12 volts is considered deep)Anyone experience this with relatively new well maintained batteries to know how the batteries performed subsequently.Thanks,Michael

 

[BobW]

You probably knocked some life off them

and even some A/H capacity, but as long as you charge them up fully, and then go on to an equalize charge, you likely won't notice any change in performance.Of course, you may also have just plain KILLED them There's no way to know without charging them up - when they are charged, you might want to take them to an auto shop for testing.The problem with deep (or complete) discharge is that the inner, hard-to-reach plate surfaces get discharged along with the outer ones. When it comes time to charge, if the charge is not applied long enough for the electrolyte to circulate completely, the nooks and crannies won't get re-charged very well. This will cause the sulfation on them to crystalize, which takes them out of action permanently (there are some 'super-zap' charging processes that claim to cure this problem). The longer the battery is kept discharged, the worse the problem gets.On a cruising boat, where 80 or 90% charge level is all that is regularly achieved, you'd be in for a spell of engine/gen set noise, since the last 10 to 20% of charging takes a LONG time. Since you're on shore power, just let your 3-stage charger do its thing for a few days to a week. Then switch it to equalize and be sure to monitor the water levels.Gee, I thought all you yachties up in Santa Barbara had captains and crews and young deck-hands to polish your brightwork ;D Dang, there goes another fantasy Good luck!Cheers,Bob

 

[Fred Ficarra]

After all that

I'll just say relax Michael. They're golf carts. They can take it. And leave that charger on.

 

[ruedi ross]

dead batteries

It definately sulfates batteries to sit discharged for any length of time. If your batteries are one year old and well maintained, you probably didn't damage them too much. Sounds like they were completely discharged for 2 weeks+. You may have lost 15- 20% of your capacity. You can test them by fully charging them and then discharging them at 10% of their total AH capacity and timing how long it takes to discharge them down to 11.8 or so volts. You may also want to consider trying an electronic pulse desulfinator. This will help recover any lost capacity in your batteries, and it is also an excellent device that will extend your battery life. I have used these and the do work, how well will depend on the quality and age of your batteries. here's a link.www.batterylifesaver.com/index.html

 

[Benny]

They should be fine.

You may need a high AMP charger to get the charge started. Go ahead and get them fully charged. Some chargers have a Desulfate and Recondition Mode and it would be helpfull to run the batteries through it. "Vector" makes a 2/10/20/35 AMP charger with a Recondition Cycle which is portable and rather inexpensive. Batteries can be run through this cycle once a month.Our shore power battery charger is hard wired to one of the outlets and will automatically come on when the main 120V AC breaker is switched on. This helps prevent forgetting to flip a switch. The downside is that a short on the charger will disable the whole 120V system instead of just a dedicated circuit.

 

[MichaelStacy]

Thanks for responses

Bob, Fred, Ruedi, & Benny - thanks for your input. I'll relax, and see how the battery charger does for the next couple of weeks.Michael