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battery relocation mc1


kyekye09
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Find a rear engined car with the battery in the front- then fit in reverse! :lol:

I think you need to add cutoff switch to your list. If you just go for a gel battery in the original position to start with you would get a lot of the effect for less hassle, then wait for better weather before pulling out the carpets and trim to do the full job.

so im looking for a 911 then WACK11111:lol:

think what i will do is get the battery and get the tray welded into position and tackle it in the coming months

the mx5 is about 3 foot to short what bmw's can i hack up...???? i think i remember my old e30 having a battery in the boot

325i definitely did not sure about the rest

;) yeah mine was a 325i but im sure it had the battery box built into the body work or was part of the boot floor but surely i could use the wiring

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At least with E46 BMWs it was that 6-cyl and diesel versions had battery in the boot and 4 cyl gasoline versions had smaller battery in front. E46 at least had quite deep box ready made for battery, there would be space in deck also, same space that is used by rear muffled, but on the other side of the car, but it would need sheet metal work.

With the wiring of course it would need to be thicker than original, because wire is much longer, voltage drop in cabling is the key here. I did some measurements with my MB3 just for fun when replacing the battery:

with 2 years old Exide X-tra 45Ah battery, there was huge voltage drop at the battery, voltage at start was just 10,5 Volts (under load) and because of that low voltage, current was somewhere like 120 Amps peak when turning the key, it was a bit lazy sounding start but not anything serious.

With Optima Yellow top 38Ah (Civic-size of course), it hold the voltage at 12,2 volts under load, and because of that also start current was over 200 Amps peak. It made huge difference with starter speed, quick and easy start.

Those current were peak currents, so when engine started rotating current went down quite quickly and of course engine started soon. But if you have to crank longer for some reason, current is more like 80 Amps than 200 Amps when engine is accelerated to speed that starter has the power to rotate constantly. At cold weather currents are of course higher when oil is like pudding. Even 5W-40 is almost like pudding when temp is -30C..

I'm not really sure what was the point, maybe that AWG 0 is almost a overshoot, it's thick and has (Calculated with AWG 0, 20C temp, 5 meters long CU cable) 0,32 Volts of voltage drop with 200 Amps, with 100 A it's then only 0,16 Volts of drop, AWG 2 would have drop of 0,52 Volts and it's much easier to pass through cabin, with that, voltage drop is close to original cabling at engine bay. And yes, AWG 2 handles 200 Amps for short perioids easily and 160 Amps forever without heating too hot.

But don't use these for guide with audio equipment, then use thickest wire you can, it's always better for amp to have more constant voltage. :) I'm just speaking about starting / charging cable here. But if you wan't relocate battery for performance, you don't want that extra weight coming from overshooting cable thicknesses, copper is really heavy. Of course at least one AWG unit thicker cable if using some cheap "hifi" cables which are mostly aluminium.

Copper cables can be identified with markings OFC, pure copper etc markings.. Mostly when markings have some A (CAA etc..) somewhere, it's mostly aluminium. Don't be fooled, there is also copper covered aluminium cables so be careful. And marketing that says "current flows on outer parts of cable" is somewhat misunderstanding, with low frequencies current flow throughout the cable and electricity flow is getting closer to surface only when frequencies are getting higher. Skin-effect is really effecting closer to radio frequencies than normal power distribution frequencies. And in car environment, power is DC and with power densities in cars, that effect is basically nonexisting.

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Optima are deep cycle batteries- great but very expensive and not needed unless you have a lot of accessories draining power, iirc not that light either.

On the 0awg, probably overkill but better safe than sorry is what they're saying I think.

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optima yellow tops are not very good anymore, nothing like what they used to be like.

Remember you MUST have a sealed battery. GEL/AGM will be your best bet.

Oddessy are very good along with Shuriken. XS Power are fantastic but expensive.

I'd certainly go for 0awg. Its not heavy and wont slow you down. It will fit no problems and if its overkill then thats good.

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