Using fuse on a dual battery system

Submitted: Monday, Apr 18, 2011 at 20:12
ThreadID: 85724 Views:8245 Replies:4 FollowUps:7
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I am going to set up a dual battery system in our van and am not sure if and/ or where I should use a fuse to protect my gadgets and battery.
I will be using a 100 ah AGM battery, a 1500w Sine wave power inverter and a watson 140a dual battery kit.
Should I use fuses? How many, where and what amount of Ah?
And do you just use anderson plugs to be able to disconnect your second battery or does it have other functions?

Ty.

Auke
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Reply By: Roachie.kadina.sa.au - Monday, Apr 18, 2011 at 21:29

Monday, Apr 18, 2011 at 21:29
Auke wrote: I am going to set up a dual battery system in our van and am not sure if and/ or where I should use a fuse to protect my gadgets and battery.
I will be using a 100 ah AGM battery, a 1500w Sine wave power inverter and a watson 140a dual battery kit.
Should I use fuses? How many, where and what amount of Ah?
And do you just use anderson plugs to be able to disconnect your second battery or does it have other functions?


Auke,

I'm not familiar with the Watson dual battery kit, so can't assist much with that one specifically. However, in general terms, if this dual battery system is mounted in the engine bay, there should be a suitable circuit breaker close to it's output. The cable from the dual battery set-up then needs to the routed to the rear of the vehicle and terminated using a 50amp Anderson Plug. Note that an Anderson Plug is just a neat, positive and convenient method of joining two cables together which need to carry more amps than what a normal trailer connecting plug can handle.

On the caravan, you need to install another Anderson Plug with cables leading to your battery, via another circuit breaker, mounted close to that battery.

The c/van battery should be earthed to the chassis as well as using the earth/black cable from the Anderson Plug.

So, you now have the first half of the equation done......you have power coming from the vehicle, via a dual battery system and circuit breaker, Anderson Plug, another circuit breaker, then to the c/van battery. This will keep the battery charged when the system is in operation.

Back to the caravan battery......

You now need to set-up a system of fuses for the items you wish to operate using this battery. I suggest something like this:
http://www.narva.com.au/products/browse/boxes

So, you would run one heavy cable to the pins on one side of the fuse block. I find that it is best to solder the cable on to the tabs, but you may also choose to use the "daisy-chain" method. The pins on the opposite side are used individually....run a separate cable from a fuse to each item you want to provide power to (eg: water pump, radio/cd player, 12 volt lights etc). The size of the fuse you use will differ for each accessory you are powering.

As for the inverter, I believe it is best to take the 12v input cables for this, directly off the battery, via a fuse (which I'd imagine is provided with the inverter as an "in-line" type)..

Hope this helps. If in doubt, best to seek professional assistance.

Roachie
AnswerID: 451724

Follow Up By: Roachie.kadina.sa.au - Monday, Apr 18, 2011 at 21:43

Monday, Apr 18, 2011 at 21:43
Just found this: http://cgi.ebay.com.au/FUSE-BOX-CARAVAN-MARINE-4X4-DUAL-BATTERY-12-VOLT-6-WAY-/300547378697?pt=AU_Car_Parts_Accessories&hash=item45fa050e09#ht_1218wt_754

It would be a better option than the other one I showed, as you only need to add one simple feeder wire....no soldering or daisy-chaining!!!

Hmmm, might get one of those myself!!
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FollowupID: 724346

Reply By: Faulic_McVitte - Monday, Apr 18, 2011 at 23:30

Monday, Apr 18, 2011 at 23:30
dont know if you realise you will never get the battery in the van charged with that setup. To get the battery in the van charged you will need a DC to DC charger. Use your battery isolator in conjunction with the DC to DC charger. Mount the DC to DC charger near the battery in the van.
Use a 5AG fuse holder and 50A fuse and make sure your wiring is minimum 8B&S
AnswerID: 451735

Follow Up By: Aukedb - Tuesday, Apr 19, 2011 at 09:10

Tuesday, Apr 19, 2011 at 09:10
I am hooking the 100ah AGM up to the matson DB kit and that in turn to my starter battery.
That should be good to charge it...shouldn't it?
obviously my starter battery is wirde to my alternator. which I allready checked for the correct voltage.

Why would I still need te charger?
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FollowupID: 724380

Follow Up By: Aukedb - Tuesday, Apr 19, 2011 at 09:19

Tuesday, Apr 19, 2011 at 09:19
ohh and my starter battery is under the driver seat and the aux battery is going to sit like a meter away...so not of distance to allow for voltage drop.
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FollowupID: 724383

Follow Up By: Faulic_McVitte - Tuesday, Apr 19, 2011 at 10:09

Tuesday, Apr 19, 2011 at 10:09
Aukedb so you are fitting your van battery in the vehicle and going to run power by cable to your van?
To get 12.7V to the van will mean you will need minimum 6B&S cable.
The issue is your main start battery never charges more than 70% and you will be lucky to have 12.3V at the van. If you only want to power a fluro light or a LED light overnight that will be fine, but if you want to power a TV or laptop or anything else it is useless. If you want to stop 2 days and have a bit of TV or use your laptop you need to do the job properly once.
If you want to do the job properly and have a fully charged battery at the end of the day you need to use a DC to DC charger and preferably fit the battery in the van or run 6B&S cable to the van, but that still means you need to use a DC to DC charger to get the aux battery 100% charged.
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FollowupID: 724390

Follow Up By: Aukedb - Tuesday, Apr 19, 2011 at 10:45

Tuesday, Apr 19, 2011 at 10:45
obviously I am not a mechanic :0 and I am going to let a mechanic do it, but the idea was to let the alternator charge my starter battery to a certain voltage and then the matson will automatically switch to the aux battery to charge that afterwards. and it will switch of as soon as it is also full
All the cables I ordered are at least 6B&S.

My van does not have a bonnet....the whole engine is under the front seat :).
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FollowupID: 724392

Reply By: Member - Boo Boo (NSW) - Tuesday, Apr 19, 2011 at 11:06

Tuesday, Apr 19, 2011 at 11:06
Auke

Up until your last reply I think most repliers thought you were talking about a caravan not a motorhome of some sort.
AnswerID: 451773

Follow Up By: Aukedb - Tuesday, Apr 19, 2011 at 11:15

Tuesday, Apr 19, 2011 at 11:15
yeah I kinda thought that as well :)
But if I do it like this in my "campervan" would that be ok?

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FollowupID: 724395

Reply By: Member - Boo Boo (NSW) - Tuesday, Apr 19, 2011 at 11:30

Tuesday, Apr 19, 2011 at 11:30
Roachie was spot on. Just leave out the anderson plug and wiring to the caravan.

AnswerID: 451775

Follow Up By: Aukedb - Tuesday, Apr 19, 2011 at 11:46

Tuesday, Apr 19, 2011 at 11:46
ah ok that's easy.

now would it be possible to add a small solar panel to charge the aux batt a bit when the engine is not running? I am using a 100ah deep cycle AGM battery.....or is that bad for the battery?
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FollowupID: 724396

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