Charging Deep Cycle Batteries

What is the best way to charge deep cycle batteries? I have 4 battery chargers , 4amp, 10amp,15amp & 25 amp. Which is the best? Slowly over a long time with low amps or fast high amp charge? Bill
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Reply By: Member - Balvenie Pastoral - Friday, May 23, 2014 at 15:39

Friday, May 23, 2014 at 15:39
This may help, In 2004 I installed an alternative (and much cheaper) second battery setup which is interchangeable to all our vehicles, mainly to run an Engle. My local Auto electrician put an Optima Gel Deep Cycle Battery in a box with all the gismos to control charging and current flow from its host vehicle and via an Anderson plug it connects directly to the vehicles starting battery. Each vehicle has similar wires to an Anderson plug end connector and the battery pack moves from Vehicle to vehicle on demand, and simply plugs in. When not in use the battery pack is out of the vehicle and on the workshop bench connected into a mains powered Sweedish C Tek 10 watt Battery charger. (Google it ) The C Tek automatically charges and discharges the battery. It is now 10 years old, still the same Optima battery. I can’t fault this setup for my needs and the C tek seems to have been pretty good as far as the battery life is concerned. Good luck.
AnswerID: 533035

Reply By: Motherhen - Friday, May 23, 2014 at 16:02

Friday, May 23, 2014 at 16:02
How many batteries Bill?

Slow is usually better than fast charge but I electrics is not my field of expertise - I am just an end user.

Solar is best through a controller, and no additional charger needed unless you have to top up from mains power in bad weather.

After bulky chargers let us down, we purchased a 25 amp CTEK multi stage charger and it had our bank of batteries topped up to float in an hour when we had spent several days under very shady trees in the Darwin heat. Tiny and lightweight it is far better than the heavy battery sized old chargers.


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AnswerID: 533037

Reply By: Big Woody - Saturday, May 24, 2014 at 06:52

Saturday, May 24, 2014 at 06:52
Hi Bill,
The easiest thing to remember is that different types of batteries respond best to charging the same way they are designed to be discharged.
A deep cycle battery will not like a rapid discharge so therefore a long slow charge will be best.
I would be using the 10amp charger in your situation. 4 will do the job but would generally be used for smaller sized batteries, not a full size deep cycle.

I hope this helps mate.

AnswerID: 533076

Reply By: Dennis Ellery - Saturday, May 24, 2014 at 16:04

Saturday, May 24, 2014 at 16:04
Depends on the battery
Low resistance batteries such as Optima and Lifeline can easily absorb a charge equal to their 1 hour Ah rate - ie 100 amps into a 100ah battery
I have a Lifeline 150Ah battery that I charge at over 100 amps.
Lifeline states that, with repetitive deep cycling, a high charging regime is more beneficial to the cycle life of their battery than low charging rates. That means for my battery I shouldn’t charge it at less than 30 amps for maximum life.
AnswerID: 533094

Follow Up By: Dennis Ellery - Saturday, May 24, 2014 at 18:04

Saturday, May 24, 2014 at 18:04
I should mention, if you don’t know your battery specs – I would limit the charge rate to .2c (20 amps for a 100ah battery).
FollowupID: 816408

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