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Another 12V battery conversion!

Kai Knickmann (Damask 0945) from Germany looked at the options for replacing his old 6 volt batteries and an offer from a local trader produced another 12 volt battery conversion. (Jun 06)


Twin BOSCH 4FNs wired in parallel provide improved starting performance and a near original look. (Photo: Kai Knickman)

Finally my good old 6V batteries died this winter despite being hooked to a trickle charger all through the winter months and some thorough power load tries last week. Maybe ten years were enough for those lead acid batteries. Initially I was inclined to leave the car as original as possible, but when a local motor trader offered replacement 6 volt batteries at something in the range of 140 € (each! - that is £) for new 6 volts, I reconsidered my options.

After browsing the V8 Register archives on the web, especially V8 Workshop Note 329, I declined to go for one "big" 12 volt battery like an "063" or "065" (although the idea of a spares box in the redundant battery box was tempting!) because I didn't like the idea of flattening the base stand with the big mallet.

Another V8BB thread started by Mike Price last October mentioned using a small 12 volt battery from a Japanese car which was a similar size to the 6 volts in the V8 and this route seemed interesting for me, although there seemed to be a potential clearance problem in height. In the meantime, V8 Workshop Note 330 goes quite a long way in showing the merits and feasibility of such a single 12 volt battery solution.

BOSCH offered a good choice for me with a battery called 4FN which is geometrically identical in footprint with the old standard 6 volt ones (they are just a fraction lower than the original 6 volts which are 175 mm high), using silver technology for a longer lifetime,

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being service free and sealed for life and as an additional plus, having a nice black case as well. Of course, the electrical values due to the reduced size are less impressive with 360 amp cold start and 40Ah capacity. But after the first test with just one unit (I was in quite a hurry!), the starter cranks the engine far better than ever in the last four years!

In the meantime, V8 Workshop Note 330 goes quite a long way in showing the merits and feasibility of a twin 12 volt battery solution. This leaves me with plenty of power under all circumstances, keeps the appearance nearly original and still saves me half the cost, as one of these small 12 volt batteries is just 70€ here in Germany. This all in all seems to mimic a setup that Anthony DeBella in the US uses on Damask 1317 with good results according to his latest information on the V8BB.

There are just minor modifications to change the electrical connections so the two 12 volt batteries are connected in "parallel". A second earth lead strap was fabricated for the second battery similar to the original one and attached to an earthing point already included by MG in the offside battery box side member. Then you need another cable to link the two positive points. You might think of using the original cable passing over the differential through the rubber hose, but it seemed to be pretty short to me, so I routed a new longer one the same way. At the right hand side, there are now two cables attached there to the positive terminal - the original hot wire from the car's wiring loom and the new link cable.

Finally I need to add that I turned the J pegs which clamp the batteries down from looking frontward to rearward as the new batteries have a stepped upper side being pretty low on the terminal side. As the threads on the J pegs are a little bit short now, I used 15 mm spacers to get the nuts "higher up". Alternatively, you could either shorten and rethread the old J pegs or use new shorter ones straightaway.

So all in all I'm quite happy with the new layout which you can see finished on the attached picture. You just need to be able to live with the fact that the batteries in the back were designed to fit a FIAT Panda!