AGM batteries for Battery Pack

[cjc_td5]

I have an old Waeco (Blue Apple) Outback Battery Pack inside which the batteries have long since died. Actually I think the batteries were cooked a while ago by a previous attempt by me to charge them up (can’t remember exact scenario any more). The pack has two CP12120 12v 12Ah AGM batteries inside it. I am looking to repack the battery pack with the same type of batteries again. I intend to remove the jump start poles from the unit as I never intend to use the pack as a starting battery. The pack is used in the camper to run fluoro lights and/or a camp shower etc.

Is there a maximum amperage that these AGM batteries can be recharged at? Can I wire them so that they direct charge off the main vehicle battery (2 CP12120s in parallel inside the battery pack) or will they draw too much current when drained and cook themselves again? If so, I presume I would have to fit a current limiting device to limit the max current delivery to the battery pack? Are current limiting devices like this available “off the shelf”?

I can fit a single LC-XC1228AP AGM battery into the existing Waeco casing which has the advantage of being a 28Ah battery, but it will only fit on its side. Is this an issue with AGM batteries?

Apologies for being slightly off Land Rover topic, but it does usually reside in my D2a!

Cheers,
Chris

[dswatts]

You would have to have some sort of current limiting, otherwise they will cook. not sure of the maximun current rate for these batteries. Would guess around 7 amps per battery. yes you can mount them on their side.

[steveG]

Only 4.8A max charging current according to this spec sheet:
http://www.vision-batt.com/newpdf/CP/CP12120.pdf

Steve

[simonmelb]

Hi Chris,

Some AGM batteries can take the full inrush current directly from your alternator - see Drivesafe's post here:

http://www.aulro.com/afvb/technical-chatter/99461-anyone-used-gel-batteries.html#post1193863

Hope this helps.

[cjc_td5]

Thanks all for your replies.

Assuming that I use two CP12120s in the battery pack with an individual max current draw of 4.5A (and that they are wired in parallel), could it be assumed that I could put say 9A max into the battery pack and they will split the current evenly? Would I be better off say limiting the max current supply to say 5A so as to not potentially overload one battery (with a longer charge time of course)?

Following from this, it appears that it may be actually cheaper to put 3 7Ah batteries into the pack for about the same total Ah capacity. The 7Ah AGM batteries appear to have a max charge current of about 2A, so would I be best limiting the max charge current to the battery pack of 2A or 6A?

I have "googled" current limiting devices etc but only get a myriade of circuit diagrams. Does anyone know of any "off the shelf" current limiters??

Thanks
Chris