How long should it take to charge deep cycle

[rndn]

I just bought a new deep cycle group 27 battery for my trolling motor. It has 105 amp hr capacity label. I also just installed a new onboard 3 bank charger for this one deep cycle as well as my 2 starting batteries. I am wondering how long it should take to charge the deep cycle battery. The charger is a 5-5-5 charger from Bass Pro and is supposed to be able to give up to 15 amps for any of the three legs if the other batteries are already charged. It's a three stage charger and should go into a maintenance mode once the batteries are fully charged. It has now been on there for 6 hours and the lights still indicate it is still charging. Thank you in advance for any help!!

 

[crw1957]

Re: How long should it take to charge deep cycle

I have never had any luck with those lights on the chargers. I too have seen lights indicating the batteries were still charging and i knew they should have been charged. I use a timed charger, 10 amp, set it for 10 hrs. and let it go. Have I ever overcharged a battery? Probably. It seems as though no matter what i do, my batteries last about 3 years max. The only thing I have not tried is the more expensive "Smart Charger". This charger is suppose to sense the condition of the battery and decrease the charge as time goes by. The greatest thing I have found is the Low Battery alarm on my GPS. If the voltage drops below 11.5 volts, the alarm sounds. I then know to charge the battery. 10 hrs and she is up and running. If the charging system is working right, the battery stays charged except during dry dock. Then i turn on the GPS, check voltage and presto, 10 hrs. if needed. Pretty basic however, it has worked for me for 35 years.

 

[bruceb58]

Re: How long should it take to charge deep cycle

Just because you have a 10 amp charger does not mean you are putting 10 amps into the battery. A lot depends on the charger and many chargers are not constant current. This will cause the charge to taper a bit as the battery charges. If your 100 amp hour battery is 50% discharged and you charged it with a 5 amp charger, it would take 10 hours to charge it back up if you really put out a constant 5 amps. More likely it will be around 15 hours. The good thing about modern 3 stage chargers is that it will finish the charge without overcharging and...yes...the lights actually do mean something on a 3 stage charger.

Another thing, if you let your battery get down to 11.5V, you are severely discharging the battery and limiting its life in a big way. I would never let it get much below 12V before I would charge. That is your 50% point.

 

[rndn]

Re: How long should it take to charge deep cycle

The lights are now at the maintain and ready to use level. I guess I was just a little nervous it was taking so long, but it looks like I'm all set. Thanks for the information and hopefully this 3 stage on-board smart charger will be a good investment for me and work as it is advertised.