Charging a deep cycle battery

[Greg]

I've got a new deep cycle battery that I use to run my electric trolling motor and I'm having trouble charging it. I've got a 10 amp charger with auto shut-off. Do I need a 2 amp charger that is manual and if so how long do you leave it on for? Any help would be appreciated.

[EAGLE EYES]

Greg, What kind of trouble are you having? The 10 amp charger you currently have should work just fine. An important thing to watch is the amp draw on the amp meter. Some chargers don't have a meter if that's the case junk it. If your charger does have one though, watch the amp draw. If it nearly reaches zero output shut it off and the battery should be fully charged at that point. I once had a charger with auto shut off that didn't have an amp meter and I boiled a few batteries until I decided to get rid of the charger and operate it manually. Never had problems in 10 years unless the battery was shot or needed H20. Good luck ! Oh, almost forgot! The 2 amp trickle charger you were wondering about is probably going to achieve the best charge transfer, But who has the time to watch for that long. I don't have that much patients.

[Dave S]

The 10 amp automatic charger should work fine. For a 110 amp battery which has been discharged to half its charge you need to replace 55 amps. I seem to recall that a battery charger recharges at approximately 70% efficiency. 55 amps / 10 amp per hour / 0.70 = 8 hours

You need to make sure you put the battery charger on as soon as you can after a days fishing and not wait several days before recharging for maximum battery life.

[RiverRat]

The Sears battery charger I have has a 2amp, 10amp switch.
It also has a deep cycle and all others switch.

[Greg]

Thanks for the replies. The problem I was having was that the auto charger was kicking itself off quite a few times when the battery was completely drained. When it finally did start to take a charge the amp meter would only go down to about 5 amps no matter how long I left it on. Battery water level is good. It may just be a faulty charger. I'm going to borrow my brother's and see. Thanks again.

Greg

[mbrandt]

I use to have this same problem when the battery was drained. I don't think it is the charger turning off, but the circuit breaker tripping. At least it was on mine. Not exactly why it did this, something to do with heat I think. After a while it would reset and come back on. But it only happened on very drained batteries. I have since replaced my charger.

Mark

[Gearhead]

Deep cycle batteries discharge slowly and with a flat discharge curve. I've found the best way to recharge them is very slowly. Now, I realize we all don't have that kind of time to put it on a trickle charge or 2amp at most. But, I've found that the batteries last the longest when treated in this fashion. Regular car batteries don't seem to benefit from this slow recharge, but the deep cycles do. We use them on our race cars because we don't run alternators. The flat discharge curve helps maintain peak ignition circuit performance throughout the race. Hope this info helps.

[Steve_IA]

I know that I should recharge my deep-cycle battery as soon as possible after using it... and I know that a rechargeable deep-cycle battery has a longer life if fully dis-charged before recharging. Now my delema is... do I recharge my deep-cycle battery after every use, even if I only drain it partially, or do I fully drain it before recharging even if it takes several days of fishing? Steve (IA)

[vetspet(ind)]

i believe your info is incorrect...deep cycle batteries do not and should not be fully discharged if possible...you are thinking of nickle cadnium batteries....the NiCad batteries have a memory....lead batteries do not...if you take deep cycle batteries and only allow them to discharge approx 50% and then recharge and compare this group to a second group allowed to fully discharge the first group (50% group) will last much longer than 2x the latter group....altho the amount of discharge time will be the same...hope i'm not making this confusing...there are sites on the net which describe this in detail...do not fully discharge a deep cycle battery if possible steve
5

[vetspet(ind)]

i had a similar problem and discovered i had a "dead short"...in my battery...it had developed a dead cell...had to scrap the battery...not sure if thats the only thing which can do this... if you have a sealed battery it is hard to determine this but if you can test each individual cell you may find there is one cell which will not take a charge....auto zone can put your battery on a machine which places a load on it to see if its no good....my battery with the dead cell showed 13+ volts on the meter yet had a bad cell...steve

[Steve_IA]

Thank you for correcting my misconception about fully discharging a deep-cycle battery. I do have another question on this subject as well...Is it neccesary to disconnect the leads from the battery while re-charging? I have two trolling motors attached to this battery and nothing else. I have been disconnecting the leads from both motors at the battery but am wondering if/why this is neccesary. Steve (IA)

[Rockman]

Another thing to consider is that if a battery is left drained for too long, or the charge is gone or near gone, the plates will start to have crystals of sulphur build up on the plates in the battery. The result is a 'sulfated battery', and the only way to correct this is high amp charging so the charge can break this through this 'film' of sulphur crystals, and then reenergize the plates in the battery, provided the plates aren't alrady fried.I did this with a car battery once, and I did follow the directions in the charger's owners manual. I can't say for sure if this would work with a deep cycle battery, or if deep cycles sulfate like regular car batteries.