Installing a 2nd Battery

Enfield

Enfield

Enfield

Soldato
Joined
8 Nov 2003
Posts
7,409
Location
UK
Hi there.

I've got brand new battery in my garage which cost me £40 from Halfords. I bought it for my previous car then removed it after it was written off so it's just sitting in my garage doing nothing.

I can't use it on my current car because it has completely different terminals so i'm wondering if I can have a back-up battery. It would be good just in case the primary battery fails for whatever reason.

I'd likely put it in the boot but have no idea what I need to do in order to wire it up?

Any ideas folks? (I'm a complete novice when it comes to the electrical side of things).

Cheers.
 
Just wire it up in parallel and it will add tot he overall capacity, it will make your car think its only 1 battery.
 
saitrix said:
Just wire it up in parallel and it will add tot he overall capacity, it will make your car think its only 1 battery.
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Or stick the positive in your mouth while touching the earth...... :p

My idea is better tbh ;)
 
saitrix said:
Just wire it up in parallel and it will add tot he overall capacity, it will make your car think its only 1 battery.
Click to expand...

How do I do that mate?

As said, I know jack about electronics.

Ta
 
Seems a bit pointless tbh especially if you cant do the work yourself. Sounds like Rover owners putting in two head gaskets - just incase.

If you have a big ICE system then wire it up to run that could be a good idea, but running it in parallel or series is still a pointless exercise.
 
Enfield said:
How do I do that mate?

As said, I know jack about electronics.

Ta
Click to expand...

Postive of battery 1 goes to positive of battery 2. Negative of battery 1 goes to negative of battery 2.
 
saitrix said:
Postive of battery 1 goes to positive of battery 2. Negative of battery 1 goes to negative of battery 2.
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Woah, it's that easy? :eek:

What type of wire do I need?

Will it put any strain on the alternator?
 
You need thick wiring, 4AWG at least really i would say. Though please dont take my word for it, not sure how many watts starter motors pull.

The alternator will just have to charge up the batteries more often, no extra strain, just charging more often.
 
Where would you put it for a start?! As has been said its completely pointless. Its not as if a battery goes every 6 months.

Its rare for a regularly used battery to just fail. You should get some tell tale slugish turn overs, as long as you don't keep putting off getting it replaced (as I did) then you'll be fine.
 
As I said in the very first post...i'm putting it in the boot.

Shame to waste a good battery. I think the battery the car has at the moment is possibly the original one. It's not going to hurt having two batteries.
 
You will need a battery isolator or one battery will always be discharging into the other. Hooking two batteries in parallel is a bad idea, especially if they are different ampere-hour ratings and even more so if they are different ages.
 
No offence but it is a total waste of a battery, you are better off hooking it up to an old car radio for music in the garage. All you are doing is adding weight to your car for no other reason than its spare?

I have plenty of spare food in the fridge but I don't go round adding weight to myself because it would be a shame not to :p :p
 
Last time I tried using an old battery I blew the electrics on my car, windows, sunroof and the dam window wipers. Dam I missed those when it rained :eek: :o I scrapped it not long after anyway so it was no big deal but was a stupid thing to try.
Get an old cb radio and use it for that
My bro in law has an old Headunit controlling his pc's sound, not sure if he used an old battery but it sounds great.

A battery weighs about 20kilos usually
 
What about those new grounding kits people sometimes fit in search of lost power, is this similar to that idea or even more unlikely to be of any benefit?


I have heard of people relocating the battery to the boot, mainly to make way for a bigger turbo, etc under the bonnet
 
A lot of the time people put the battery in the boot so that they can construct a large heat proof box to put an induction kit in, as in a lot of cars theres not too much space in the engine bay to fit one. And usually the battery is quite far from the engine, so putting a kit in there would avoid heat soak issues.
 
M0T said:
A lot of the time people put the battery in the boot so that they can construct a large heat proof box to put an induction kit in, as in a lot of cars theres not too much space in the engine bay to fit one. And usually the battery is quite far from the engine, so putting a kit in there would avoid heat soak issues.
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Or 50:50 weight distribution ;)
 
Why do you need to wire it up? If you carry a set of jump leads around with you, then you can just connect it directly up if and when the battery fails to jump start it. Also, I think it could cause problems if you did wire it up and one of them failed, as you would have a dead battery there and wouldn't know about it, and the alternator would probably be constantly trying to charge it. Not certain about that though.
 
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