Batteries wired parallel ???
Submitted: Thursday, Apr 30, 2009 at 23:50
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Member - Kroozer (WA)
Right, i think this is a pretty easy question for the gurus out there. Am i right in thinking that if i wired 2 12v 18 a/hr batteries together in parallel i would still get 12v and 36amp/hr.
Reason being is i have one battery already (thinking of buying another instead of Thumper or waeco power pack) and just want a back up device to run my Waeco CF35 ACverb for a few hours. Will only be used as a fridge set at around 2-3 degrees c, and it has the cover and will be in back of car in good shade. Will only ever be used at night actually for around 8-10 hours and it wont be getting opened at all during these hours, and would cooled down to its temeprature. Im guessing the ambient temps to be anywhere from 5c - 20c, so not hot at all.
Does this sound alright, i was thinking if it used a max of 2 amp/hours for around 10 hours = 20 amp/hrs, which leaves me at least 1/3 of my
battery power to save batteries.
Only thing is charging the batteries, i currently have a SLA 1 amp battery charger that i charge my current battery with. It does a good job. But if i have it wired in parallel can i charge both at the same time through same charger. i know it will take longer, but is it safe or possible. Just looking for a cheap and easy way to get me by for the time being until i can get my dual battery system. Could be a while away so i really want something to fill
the gap thats not overpriced like the Thumpers and stuff.
Cheers
Reply By: trainslux - Friday, May 01, 2009 at 00:12
Friday, May 01, 2009 at 00:12
Short answer is yes.
but
with deep cycle batts, you dont want to pull them down past 50%, or you shorten the cycle life avaliable to you by a large amount.
so by putting 2 in parralell, your getting 1 18ah battery, with some cycle life if that makes sence.
yes you can charge them in parrallel.
Head off to a battery place, and get a price on a sla 50 75 or 100+ ah battery, and fit it inside a cheap battery box with the fittings you require.
much cheaper than the thumper, and better performing too.
Yes you can do what your suggesting, but with money, and time, there are better options available to you if you know what I mean ;)
Trains
AnswerID:
362531
Follow Up By: Sand Man (SA) - Friday, May 01, 2009 at 07:23
Friday, May 01, 2009 at 07:23
Better performing???
If the Ah rating is the same how can it be better performing?
The Thumper actually has a group of smaller Ah batteries inside the box, connected in parallel to give the total Ah capacity of the unit.
I use both a Thumper (75Ah+) and an auxiliary Deep Cycle battery under the bonnet and I'm buggered if I can state categorically that the auxiliary battery is better performing than the Thumper.
As for cheap battery boxes, ever tried lifting one that has a 75Ah or 100Ah AGM battery inside?
The lid is secured with a strap and the handle is on the lid. Duh!
Bill
FollowupID:
630254
Follow Up By: trainslux - Friday, May 01, 2009 at 18:15
Friday, May 01, 2009 at 18:15
If you take what I said in context, you will see that a larger amp hr battery will give better performance, or results, or better than what he currently has with 18ah.
And cheaper than a thumper setup.
is that more clear now??
I agree, both of the same ah would be the same, only the price could be different thumper vs battery and batt box setup.
cheers
T
FollowupID:
630353
Follow Up By: RV Powerstream P/L - Saturday, May 02, 2009 at 09:12
Saturday, May 02, 2009 at 09:12
Two x12V18AH batteries in parallel will stay 12V but increase in amp Hour capacity.
Two x12V 18AH batteries in series will give 24V and stay at 18AH
Dont forget that it is theoretical AH as you never get the full benefit of the stated capacity.
Ian
FollowupID:
630423