Bimota Forum

[welshlamb]

Its a slow burn for sure but not totally inactive (that could be me or the project I'm not sure)

Anyway......
I wanted to use a LiFePo battery on this build but with the correct specs the Magnetti Marrelli item wouldnt fit in the OE battery box (too wide but lower and less deep)

As the OE case is quite heavy anyway I thought I might have a go at fabricating a new battery case from alloy sheet.





One thing I noted when looking at the OE box was although the front support stay is central on the box the main stay/support at the back (that attaches to the cyl head) isn't as it has to allow for the offset of the rear cyl from the frame c/l. With the battery having to fit up into the underside of the fuel tank I would certainly have to get the positioing of that bracket spot on!

Step 1 Wrap new battery in card to make a template (not forgetting templates for all the brackets .


Step 2 transfer template dims and markings to alloy sheet. (remembering to add allowances for foam lining)


Step 3 Make up a wooden 'buck' the same size as the battery to form the alloy around


Step 4 Cut out all the pieces and start forming around the wooden buck


I did several trial fits with the back support in place (double sided tape!) to be confident that everything would line up with the space in the fuel tank bottom

Step 5 Take the bits to someone with a TIG welder and ask them to please weld it all together!




Step 6 Add some foam to ensure a nice tight fit and install on the bike; cursing only slightly (!) when you notice that your welder mate has picked up the wrong positioning mark for the front stay!


Step 7 (Take a break and a walk around the garden)


Step 8 Return to garage and find that with slight bending of bracket that it can do its job (not the ideal solution but its functional and its under the tank anyway)




Step 9 Install battery and check that the tank fits on OK! (It does!!)




Result:
Before OE Box 610g and battery 5300g total 5.91kg
Now New Box 230g and battery 1100g total 1.33 kg
Saving 4.5kg or just under 3% of bike's total original weight.

What would I do differently?
-use thinner alloy sheet but maybe slightly harder grade (the thicker sheet is harder to bend to exact small radius turns without proper equipment) I used 2mm 1.5 (poss 1.2mm) would be fine as battery weighs so little
- get a good welder (to be fair this was a friend doing it at mates rates)for the full Bimota Beauty treatment it deserves better. But for now its fine and there are still many other issues to deal with before the bike hits the road
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Not as many bikes as I would like and already too many to keep up with!

[brian]

Nice work Ralph!

That's a really good weight saving for little cost (other than the battery).

I worry about lithium ion batteries on these old bikes with dodgy charging systems. I've had a bad experience with 2 x lithium batteries on different bikes where they overcharged and almost caught fire. One of them actually blew the side out of the battery.
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[hindsight]

Very nice Ralph -

Looking at the design, I wonder whether it could be formed out of a single sheet, with the attachment brackets being cutouts that are folded out, rather than welded on?

Also - I'll have a closer look at mine, next time I have the bodywork off. I know I've got the original heavy holder, but there's a Marelli battery in there - is that a different spec of battery from what you're looking at?

Regards,
Mike

[welshlamb]

[welshlamb]

[hindsight]

[welshlamb]

[2bims]

Looking good there Ralph...and I dont often give praise as you know....yeh...the old plate steel one is really not "Bimota" standards...although all the nice welded on tabs for the fuse box...Starter solenoid etc are what bimota do best....always everything has its place....although using another "Oil cooler" valve cover on the rear cylinder to hold the base of the box threw me....a long while ago....making it more difficult for valve and shim servicing...of course...as the ruddy battery, the box, and everything connected to it has to come out to get the valve cover off...but then thats what makes these bikes so beautiful....the effort and fore thought to save weight and space...fully engineered right through and through...nice to see some progress also

[Ahab]

Ahoy!
What type of Shido battery did you buy?

Regards,
Ahab