Connecting multiple batteries and charging

Hi guys, I have just purchased a second Amptech 105Ah deep cycle battery to increase the power in my Ultimate camper, my original Amptech is approximately 1 year old and has had very little use. My first question is how do I connect both batteries together to run 12volt with 210 Ah capacity. I believe that it is positive to [positive and negative to negative is that right?

My second question is when I use my Ctec charger, do I connect the positive from the charger to the positive of one battery and the negative from the charger to negative of the other battery or doesn't it matter which battery it is connected to as it is running in parrallel.
Thanks, Tim
Back Expand Un-Read 0 Moderator

Reply By: Member - Ed C (QLD) - Friday, Mar 26, 2010 at 10:36

Friday, Mar 26, 2010 at 10:36
(1) yes

(2) makes no difference

:)

Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

Member
My Profile  Send Message

AnswerID: 410450

Reply By: Peter McG (Member, Melbourne) - Friday, Mar 26, 2010 at 10:37

Friday, Mar 26, 2010 at 10:37
Hi Tim,

The quick answers are Yes and Yes. You need the two batteries in Parallel so that they operate as a single battery system and you then connect the Ctek to one positive and one negative terminal.

If you use the Ultimate forum you will also find lots of us who have improved the original battery setup.

You might need to check the capacity of your Ctek charger. With 210 Ah you could be using a charger with decent capacity. I use the 25amp Ctek.

Cheers

Peter
Ultimate No 10
AnswerID: 410451

Follow Up By: usguys07 - Friday, Mar 26, 2010 at 10:44

Friday, Mar 26, 2010 at 10:44
Thanks Peter nad Ed, now I've got something to do on the weekend!
Tim (Ultimate 328)
0
FollowupID: 680359

Follow Up By: usguys07 - Friday, Mar 26, 2010 at 10:44

Friday, Mar 26, 2010 at 10:44
Thanks Peter and Ed, now I've got something to do on the weekend!
Tim (Ultimate 328)
0
FollowupID: 680360

Follow Up By: Member - Ian W1 (QLD) - Friday, Mar 26, 2010 at 15:16

Friday, Mar 26, 2010 at 15:16
I'm glad to see a couple of Ultimate users here!!! I pick mine up next Tuesday and really looking forward to getting away in June for a couple of months. Did you find that just the one battery was not enough to give you a day or two non-driving time?
Im hoping to install some solar panels in the next couple of weeks and have been thinking about a 2nd 105aH battery too as I've got a 25000 CTek charger ready to go.
All the best
0
FollowupID: 680385

Follow Up By: Peter McG (Member, Melbourne) - Friday, Mar 26, 2010 at 15:29

Friday, Mar 26, 2010 at 15:29
Ian,

I'm pretty sure that you will find lots of us Ultimate owners here. Make sure you signup to the Ultimate forum when you get yours as well.

The battery question really depends on what you have done for choice of your fridge. The single battery will be fine if you have the standard gas fridge. You'll need 2 if you have a compressor fridge like some of us have shifted to. I think Ultimate still fit an Exide battery and this really isn't the best choice for the Ultimate. Sealed AGM batteries around 100Ah are good and you can easily fit 2 into the locker.

By the way, some of the Queensland mob are organising an info evening on electrics so you might check this when you join the forum.

Enjoy the camper.

Cheers

Peter
0
FollowupID: 680388

Follow Up By: Member - Ian W1 (QLD) - Friday, Mar 26, 2010 at 15:38

Friday, Mar 26, 2010 at 15:38
Thanks Peter. Yeah, I'd like to go along to the 'electric night' so I'll check out the forum next week. At this stage i've got the standard 3-way Dometic fridge from Ultimate so with a 2nd battery plus solar (2x 75/80watts) and Xantrex regulator , I hope I'll be ok for a few days provided the sun keeps shining in the Kimberley.Thanks again, cheers
Ian
0
FollowupID: 680389

Reply By: Battery Value Pty Ltd - Friday, Mar 26, 2010 at 10:45

Friday, Mar 26, 2010 at 10:45
Tim,

yes, pos to pos and neg to neg, that's correct for a parallel configuration.

Also yes, to your second question.

Be aware that some chargers have problems switching back from the boost to the float voltage if their rated current is smaller than about 10% of the battery capacity.
So in your case the charger should be rated at least 20A.
Even though your charger might be rated high enough, it could miss the switch over condition which could lead to battery overcharging - if there were loads connected during charging and/or the battery temperature was higher than say 35 degrees.
Better chargers have an overriding adjustible timer which limits the boost charging stage, effectively negotiating the affect of load currents, temperature, and battery capacity on the switch over condition.
Read more aboutcharger recommendation

For any other questions, just do a 'follow up' to this, or use the notification form inside the linked page.

Best regards, Peter
AnswerID: 410454

Follow Up By: usguys07 - Friday, Mar 26, 2010 at 17:09

Friday, Mar 26, 2010 at 17:09
Hi Peter, can you tell me what size cable should be used between the two batteries when run in parallel eg 2B+S or 3B+S etc.

The running length between each battery is approximately 400 - 450mm.

My Ctec Multi XS 7000 is only rated around 7.5amp I think, but is capable of maintaining up to a 225Ah battery. Hope that this makes sense!
Thanks, Tim
0
FollowupID: 680405

Follow Up By: Battery Value Pty Ltd - Friday, Mar 26, 2010 at 19:14

Friday, Mar 26, 2010 at 19:14
usguys07,

minimum B&S 8 (copper diameter 3.3 mm) should keep you out of trouble over these short runs.
Don't forget to fuse each wire at the battery positive with 30 amps.

I personally don't like the 7 amp charger of yours.
From memory it doesn't have temperature compensation, although this is just as important as the correct charging voltage, and secondly it's a bit small for the two big batteries.
If it starts charging at its maximum rate and voltage it might not revert back to the float charging voltage after the absorption stage.


Best, Peter
0
FollowupID: 680415

Sponsored Links