Dual Battery

Submitted: Sunday, Aug 01, 2004 at 16:51
ThreadID: 15195 Views:2261 Replies:7 FollowUps:9
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Ive got no room under the bonnet of my 4wd to fit a decent 2nd battery and wish to put a sealed one in a custom box in the rear. Does anyone have any opinions and tips for doing this. I will be charging it off a smart solonoid with a wire running from the main battery to the rear.
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Reply By: Mad Dog (Victoria) - Sunday, Aug 01, 2004 at 17:47

Sunday, Aug 01, 2004 at 17:47
I've got a similiar setup with a battery in the tray of my ute and a moderate sized cable running underneath the vehicle inside some kind of armoured conduit that fell off a truck. Fuse both end of the cable.
AnswerID: 70765

Reply By: Member - Jimbo (VIC) - Sunday, Aug 01, 2004 at 18:07

Sunday, Aug 01, 2004 at 18:07
Matt,

I've got a great setup. It was installed by Chris at Battery World, Wantirna, Vic. He put a smart solenoid under the bonnet, ran 140 amp cable along the chassis and popped it back into the car attached to an Anderson plug. He then put a 100 amp Lifeline "AGM" battery into a battery box. The battery box has cable running out of it to another Anderson plug so the battery can be removed when not needed or to be used as a mobile power supply. Inside the box he fitted a circuit breaker and two female waeco plugs to the box. He also added a three way cig socket plug with a male Waeco plug on the end to give me three power outlets if needed. The other female plug on the box is used to power my fridge, an Engel which I got him to fit a Waeco plug to as they clip in and stay in. Total cost $700.

AGM batteries have the advantage that they are completely sealed and will accept an extremely high recharge rate, basically whatever you can throw at them. A normal deep cycle will only take about 5 amps, so takes a lot of driving to get them back to full. AGM's of this size are reported to fully charge from near flay in 2-3 hours.

The other big advantage is the portability. Went away two weeks ago to some unpowered cabins up the bush and was able to take the battery into the cabin to power the fridge, lights and laptop to fiddle with my photography.

I can't speak highly enough of the setup.
AnswerID: 70773

Follow Up By: Member - Jimbo (VIC) - Sunday, Aug 01, 2004 at 18:10

Sunday, Aug 01, 2004 at 18:10
Forgot to mention, a Waeco Thumper 48 amp power supply will set you back aroung $500 and that depends on recharging from a cig socket. I reckon I got twice the capacity for less (when you take into account the solenoid, wiring etc)
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Follow Up By: mattieharding - Sunday, Aug 01, 2004 at 18:18

Sunday, Aug 01, 2004 at 18:18
what did your battery cost alone?
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Follow Up By: Member - Jimbo (VIC) - Sunday, Aug 01, 2004 at 19:59

Sunday, Aug 01, 2004 at 19:59
$350.

That was part of the deal however. You may get quoted up to $450, bargain and see how you do. Lifeline is a USA made battery. There are apparently some very good AGM's such as Fullriver, USA owned and made in China that you can pick up for around $250 for a 100 amp batt.

Be careful if someone suggest Gel batteries, the information is that they are not as good as AGM.

Have a look at this site, great information.

http://www.windsun.com/BATTERIES/Battery_FAQ.htm
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Follow Up By: mattieharding - Sunday, Aug 01, 2004 at 20:50

Sunday, Aug 01, 2004 at 20:50
what size cable has been used in your setup?
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Follow Up By: Member - Jimbo (VIC) - Monday, Aug 02, 2004 at 15:09

Monday, Aug 02, 2004 at 15:09
Not sure of the physical size of the core but it's rated to 140 amp.
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Reply By: mattieharding - Sunday, Aug 01, 2004 at 18:17

Sunday, Aug 01, 2004 at 18:17
thanks for your opinions, any more would be much appreciated
AnswerID: 70775

Reply By: Baz (NSW) - Monday, Aug 02, 2004 at 08:32

Monday, Aug 02, 2004 at 08:32
We have almost the same set up as Jimbo only diff is our second batt is in our camper and it's a 75ah deep cycle, our cable is 6mm to the anderson plug and then to Arrid twin charger dual batt system. We were told that 6mm should be the min gauge you should use due to voltage drop in anything thinner.
AnswerID: 70836

Reply By: Nick - Monday, Aug 02, 2004 at 15:28

Monday, Aug 02, 2004 at 15:28
I also have almost the exact same setup as Jimbo, including a LIfeline AGM (except its an 80 a/hr). I self-installed mine using a Redarc isolator and 10mm2 cable to the rear of my Prado. I can back up all of what Jimbo said, particularly the high charge rate, which in my opinion justifies paying double for the AGM battery. I put an ammeter in my battery box (because I had one hanging around) and can see the battery charging at between 20-40 amps after it has been run down a bit. (so make sure the cable is 6mm2 or more and the circuit breaker or fuse is of sufficient size). When you are travelling only short distances while camped this charge rate is really useful.

Other good things about AGMs (absorbed glass mat batteries) is that they hold charge very well when not in use, and they can crank in an emergency (using jumper leads), as well as deep cycle. Having experienced the performance of mine on a Kimberly trip this year, I wouldn't change to any other system.

Nick
AnswerID: 70908

Follow Up By: mattieharding - Monday, Aug 02, 2004 at 19:31

Monday, Aug 02, 2004 at 19:31
how long does it run a fridge for?

what size breakers/fuses fo u use?
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Follow Up By: Nick - Monday, Aug 02, 2004 at 21:04

Monday, Aug 02, 2004 at 21:04
It depends on the fridge setting and the ambient temperature.
On a normal fridge setting (around zero degrees C) in moderate temperatures it lasts about 48 hours with no running of the engine. In the Kimberley on maximum freeze, providing ice for an icebox it lasted about 24 hours (it awas also powering an 11 watt fluoro for part of that time). However, you don't have to go far sightseeing or run the engine for very long to add a lot of amps back. I was taking the battery down to about 20% capacity (inaccurately measured with a voltmeter - not a good measurement but not much option with a sealed battery). It would be better to drain the battery less but its a trade off between more money for a bigger battery versus shorter battery life. From what I've read though, these batteries cope reasonably well with deep cycling and last longer than standard deep cycles under similar treatment - I haven't had it long enough to judge yet.

I used a 40 amp circuit breaker near the isolator which seems to work OK, however, having seen the amps flowing in, I would use a 50 amp if I were to do it again.

Nick
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Follow Up By: Member - Jimbo (VIC) - Tuesday, Aug 03, 2004 at 14:04

Tuesday, Aug 03, 2004 at 14:04
There are so many variables as Nick said and depends how long you expect out of the battery. If you regularly cycle it down to 20% it will not last as long as if you cycle it to only 50%, but what price convenience?

Lets say you thrash the daylights out of it and only get 3 years it is only $125 per year. I say that's cheap for the convenince, but that's just my thinking.
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Reply By: mattieharding - Tuesday, Aug 03, 2004 at 18:01

Tuesday, Aug 03, 2004 at 18:01
anyone tell me where I can buy anderson plugs for a good price? even online
AnswerID: 71113

Follow Up By: drivesafe - Friday, Aug 13, 2004 at 19:42

Friday, Aug 13, 2004 at 19:42
Hi mattieharding.
Did you manage to get some Anderson plugs. If you didn't send a reply posting and I will be able to help you.
Regards
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Reply By: mattieharding - Friday, Aug 13, 2004 at 19:56

Friday, Aug 13, 2004 at 19:56
Yeah i did get some, have you got some? I might need more soon
What size have you got and how much are they?
AnswerID: 72520

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