Did anybody think about moving the stock battery to the rear, maybe in the spare wheel molding ? For sure there it has to be fixed a bracket and it´s some work to route the cables inside along the sill to the rear. But it might be well worth the effort to shift 20 kg from front to back. I´ve got an Wagner intercooler and was a bit shocked about + 4 kg weight over the stock part. Then I´ve got the idea with the battery. Of course I could use a Lithium Ion battery to reduce the weight as well, but I couldn´t change my mind till now.The balance might be better with switching the stock battery. Are there any issues with the cables to the alternator / different restistance or any issues with can bus?
Yes did it years ago, mk2 is better to do it to, as you can get 4 wheels across the boot, mk3 i can only get 3 wheels in so one has to go into the wheel well. Thought i had a post on this, will have a look
Looks like i didn't, cables were run though the big rubber gromit in the engine bay, then under the left hand door sill to the wheel well, really need a AGM battery and not a lead acid one.
I think I have no AGM on the MRS3, it´s an acid. Apart from that, I think I will find a way to route the starter cable to the battery, question ist how to deal with the alternator cable ( and there is another as I remember at the battery terminal). No electric specialist who might judge about any issues coming up?
Sorry didn't realise it was a Mk3, where the battery connects to the middle of the three connectors, just run a cable from there, you dont need to worry about the alternator cable as it connected to that fuse block the battery is connected too
You only need to run the Positive cable to the rear. Connect the negative to an earth in the boot. Fit the battery into a well secured box. I also removed battery tray, fitted cut off switch, and fitted cone filter at front , where battery was.
technically you should really run a negative cable to engine as its pretty much rubber mounted there-by offering least resistance to host of sensors that require good earthing
i did that to my mk2, found the very thick +ve cable and a terminal from scrapyard (taken from a bimmer), route it to the spare wheel well, secured the original battery tray/mounting there. i cant remember whether i did drill the firewall hole bigger to accommodate the thick cable. as other said the -ve you just have to bolt it to the chassis. if you worry about the vapour from the acid type battery, there are always a venting hole on the sides, just connect to a hose and vent them out.
