Deep Cycle battery output?

Submitted: Wednesday, Feb 09, 2011 at 17:38
ThreadID: 84231 Views:2587 Replies:1 FollowUps:2
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Hi all,
I currently have a Rotronics dual battery set up in my GU Patrol.
The Deep cycle battery in the Patrol is a Century 80 amp hour wet battery.
I have recently installed a Ctek Dual DC to DC charger in my camper trailer which has an output of 20 amps. This charges my 2 x 100 amp hour Remco AGM batteries. I also have a Dometic 2350 3 way fridge in my camper trailer which I run on 12 volts while driving.
I would like to know if the wet deep cycle battery in the car is able to continuously output 35 amps approx?
Would an AGM battery be a better choice?
I am pretty sure that my cable size is ok.
Any thoughts or advise would be greatly appreciated.

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Reply By: Rod - Wednesday, Feb 09, 2011 at 17:57

Wednesday, Feb 09, 2011 at 17:57
I also have a rotronics DB system and a 3rd battery in my CT. Is your rotronics system an isolating one ( usually above $500 to buy) or the cheaper parallel one ?

I'd recommend an AGM as the second battery in the vehicle as I had found that deep cycle flooded batteries do not accept the charging current available from the alternator as well as AGMs. You can have a 80W alternator and find that the DC flooded battery will only accept say 10A after say 30 minutes of driving (despite being relatively discharged). An AGM battery will accept a higher charge current and take less time to charge.

Presumably your question about the 35A from the wet DC battery is only relevant to when the car is running ? If so, I can't see an issue with 35A. My isolating rotronics system sems to spend 90% of it's time charging the 2nd battery, in which case, you should have plenty of current spare to also run the CTEK.

I don't think it is feasible to suck 35A from a flooded DC battery with the alternator off for any period of time.

AnswerID: 444790

Follow Up By: cobes - Wednesday, Feb 09, 2011 at 18:11

Wednesday, Feb 09, 2011 at 18:11
Hi Rod,
Thankyou for your reply.
Yes my Rotronics is the isolating one.
If the system appears to struggle I may change the wet cell to an AGM.

Thanks again.

FollowupID: 716925

Follow Up By: Peter_n_Margaret - Thursday, Feb 10, 2011 at 09:37

Thursday, Feb 10, 2011 at 09:37
Couple of considerations.....
1. If you are drawing that 35A while the charger/alternator is running it won't actually go into and then out of the battery, it will be supplied direct. The battery will simply provide a 'buffer' effect.

2. Be careful about putting an AGM under the bonnet. I understand that they don't like getting too hot, but have no links to that advise.

OKA196 Motorhome
FollowupID: 717039

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