Proper use of 2nd battery

Submitted: Monday, Jul 28, 2014 at 21:28
ThreadID: 108919 Views:1457 Replies:3 FollowUps:1
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Hi All
I currently have a secondary battery in my van which is connected and charged with an AC/DC charger when I am on-grid. I also have my fusebox connected directly to the battery which runs all my devices like laptop.

I'm just wondering if this is the correct way to connect my devices straight from the 2nd battery, when I have the charger connected.

Where should I be connecting my load (fusebox) when the battery is being charged?
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Reply By: kevmac....(WA) - Monday, Jul 28, 2014 at 23:21

Monday, Jul 28, 2014 at 23:21
Been floating/charging my 120a/h battery whilst using devices at same time for some 12 mths or so without any damage to charger or 12 volt items. I am using a Projecta 6 stage 21amp charger, connected anytime am on the grid or rare occasions the gennie is running.The music centre for caravan is only 12 volts so is always running when van ij use or am working on it. Unlike the present where everything is direct wired, down the lline will be installing a fuse box purely for isolation purposes.

AnswerID: 536758

Follow Up By: Van T - Monday, Jul 28, 2014 at 23:34

Monday, Jul 28, 2014 at 23:34
Well whist its bulk charging it is at 14.7v, which is well above '12v'.

Im only plugging in my laptop adaptor which is 10-15v but depending on what you plug into the battery (while charging) it could cause damage.

Doing some research I believe I need a 12v regulator...
FollowupID: 820973

Reply By: Member - John and Val - Tuesday, Jul 29, 2014 at 08:11

Tuesday, Jul 29, 2014 at 08:11
Your "12 volt" lead acid battery actually has a no-load voltage of about 12.6 due to its electrochemistry. When charging, the charger (or the alternator) will be called on to deliver up to about 14.5 volts, or for some (eg calcium doped) batteries up to about 15 volts.

Any gear intended to run from a "12 volt" battery should handle this full voltage range.


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AnswerID: 536765

Reply By: olcoolone - Tuesday, Jul 29, 2014 at 08:54

Tuesday, Jul 29, 2014 at 08:54
I'll answer you question none technically.......

You have connected your devices correctly and it's OK to charge the battery with your 240v charger at the same time whilst using them.

The fuse for your gear like laptop, lights, fridge and what ever else should be as close as possible to the power source (in your case your secondary battery).

Your fuse box should come straight of the positive (+) terminals on your battery and the negative (- or earth) of the negative terminal of your battery.

The 240v charger should be connected directly to the positive and negative terminals.
AnswerID: 536769

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