Battery frunk relocation

Discussion and technical advice for 84-89 AW10 & AW11 MR2. 3A-LU, 4A-GE, 4A-GZE.

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Pineapplehat
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Battery frunk relocation

Post by Pineapplehat »

Is there a set 'best' way to do this? Plan is to relocate with a fuse on the live and a single earth to the chassis. I've seen threads with people claiming it's better to have a second earth going back to the gearbox but it seems a tad unnecessary if you already have a good earth in the frunk. Also how easy is it to get the wiring through the bulkhead? Am I going to have to get the drill out or is it relatively straightforward? Cheers!
PW@Woodsport
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Re: Battery frunk relocation

Post by PW@Woodsport »

Almost every Mk1 i've engine converted in the last 20 years has had a front battery relocation, so i've done a lot of them!

The battery is best placed on the little "shelf" on the right hand side (as you look at it from the front), a simple angle iron frame with one leg makes the battery tray.

Then feed the live cable through the speedo cable grommet so it is well insulated from the chassis, around 3m of cable needed to do the job, i usually buy 4m and use the rest for earth cabling up front.

My reasons for doing it this way rather than any other is that you can retain a spacersaver spare wheel and it all looks very OEM.

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Pineapplehat
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Re: Battery frunk relocation

Post by Pineapplehat »

PW@Woodsport wrote:Almost every Mk1 i've engine converted in the last 20 years has had a front battery relocation, so i've done a lot of them!

The battery is best placed on the little "shelf" on the right hand side (as you look at it from the front), a simple angle iron frame with one leg makes the battery tray.

Then feed the live cable through the speedo cable grommet so it is well insulated from the chassis, around 3m of cable needed to do the job, i usually buy 4m and use the rest for earth cabling up front.

My reasons for doing it this way rather than any other is that you can retain a spacersaver spare wheel and it all looks very OEM.

Image


Looks nice Paul, very neat! I like the fact it allows you to retain the spare, think this is the way I'll do it. Only other problem is mine's an SC so I'll need to fab up a bracket to support the intercooler
Basirk
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Re: Battery frunk relocation

Post by Basirk »

I did this for my SC.
I used some threaded bar with lock nuts at the top to support the existing battery frame.

If you do this mod then you must put a big, fat fuse near the battery in the frunk (about 150A I think) otherwise a short between the +ve wire and the earthed body between the battery and engine bay will be very nasty. I had a fuse, and it blew for a legitimate reason - without it I'd likely have no car any more.

Personally, I didn't see any benefit doing the mod. It may have improved airflow to the intercooler slightly, but it was a faff to do and limited my frunk space. The weight distribution improvement is pretty negligible, when the total weight of the car and engine is taken into consideration.

Here's some pictures of my mod (I hadn't added the fuse at this point).

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Pineapplehat
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Re: Battery frunk relocation

Post by Pineapplehat »

Thanks for the input, the main benefit for me was never really weight distribution to begin with, moving the battery to the frunk allows more space for a charge-cooler or an uprated intercooler which I'm looking at doing in the future. That and I've seen multiple users claim that the stock battery tray can pose a pretty big fire hazard as standard since the clamp is metal and dangerously close to the live terminal. I'll be sure to use a fuse too, I'd rather not take any risks when messing with the battery!
ulysess1966
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Useful

Post by ulysess1966 »

I've been meaning to do this for 2 years, bought a battery tray, cable, glands. This post has been really useful, I'll finish the job this Spring.
stenky
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Re: Battery frunk relocation

Post by stenky »

I wanted to relocate the the battery as well but due to my car being LHD, Paul's spot is out of question to brake MC being there.
So, later on, instead of adding 3kg of wiring for sake of weight distribution, I decided to go with lightweight battery in the original spot instead.
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ulysess1966
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Daft

Post by ulysess1966 »

I started doing this and to test the set up out I have ended up with a red battery cable running down the outside of the car :)

Anyway, now I know everything works I need to decide do I go through the car or under the car with the cable?

I like the idea of taking Paul's advice and following the speedo cable, any possible problems doing that?

Also, I was looking at 200A marine circuit breakers online that looked like a good alternative to a big fuse, plus they act as a cut-off switch too. Any pitfalls with those?

I'm having a hard time being decisive at the minute, too much work-related stress and not enough fast car :(
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Lauren
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Re: Battery frunk relocation

Post by Lauren »

Go through the car.
2020 GR Yaris - Circuit Pack :lover:
autobody
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Re: Battery frunk relocation

Post by autobody »

1+ on what Lauren said. Got to be safer with the wire inside.
ulysess1966
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Through

Post by ulysess1966 »

Thanks for the advice guys.

Next stupid question, what is the best route through the car?

I had assumed it would be easy enough to go along the centre console, but looking at the front bulkhead there isn't a lot of room. My car had A/C which was removed, but there is a lot of electrical stuff in there in the way.

Does anyone have any advice or photos of where they routed the battery cable?
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Lauren
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Re: Battery frunk relocation

Post by Lauren »

Just got through by the passenger side past the cill. I'm pretty sure that was how I did it.
2020 GR Yaris - Circuit Pack :lover:
davidb
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Re: Battery frunk relocation

Post by davidb »

What advantages are there to battery relocation?
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Lauren
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Re: Battery frunk relocation

Post by Lauren »

davidb wrote:What advantages are there to battery relocation?


I did it purely so I could fabricate a sealed box around my intercooler. So I needed the space. Otherwise there are no advantages.
2020 GR Yaris - Circuit Pack :lover:
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