CB350K draining battery

[florence]

When I leave my bike overnight it drains the battery unless I disconnect it.   It's so annoying, I was thinking of putting a switch in but that's not ideal.  Any ideas?

[Bryanj]

Rectifier fault is all i can think of, try disconnecting that instead of battery

[florence]

is that the orange thing under the seat?

[AshimotoK0]

is that the orange thing under the seat?

Yes and it's a selenium type (if its the orange painted type)  and they do suffer from age and go leaky electrically. The last bikes used a silicon one which doesn't really suffer with age other than corrosion and is in the form of an aluminium finned heatshink assembly painted black. You can also replace with a silicon bridge rectifier off eBay which are dirt cheap but you would need to mount on some form of heatsink.

https://www.ebay.co.uk/itm/KBPC3504-Silicone-Bridge-Rectifier-Diode-35A-400V/254064460742?epid=652989830&hash=item3b276c03c6:g:jBMAAOSwPK1ZVivi

Or this type which is a bit dearer but pre-wired with heatsink integral.

https://www.ebay.co.uk/itm/184114042152


It could also be the 'crowbar' type regulator, which is mounted underneath the battery box and has three wires. Just disconnect it and see if the leakage goes away. As long as you have a decent battery connected, you can run temporarily without the regulator, in fact the earlier bikes like the CB450 Bomber and CB72/77 etc never had any form of voltage regulator fitted, they relied solely on the battery to clamp the alternator voltage. having said this, the regulators are totally solid-state and are very reliable.

[florence]

Thanks Ash, that is excellent.  I do remember that this bike used to burn through batteries when I used it regularly in the nineties, they just didn't last long.  If I disconnect the voltage regulator do I need to bypass wire it or just remove it from the circuit?

[AshimotoK0]

Thanks Ash, that is excellent.  I do remember that this bike used to burn through batteries when I used it regularly in the nineties, they just didn't last long.  If I disconnect the voltage regulator do I need to bypass wire it or just remove it from the circuit?

Just disconnect it ... it's has basically the same function as the Zener diode used on Triumphs in the late 1960's but it much better as it has a more precise voltage activation ... at that activation point it conducts any excess charge away to earth to prevent the battery from overcharging.

[florence]

thanks, now I understand, perfect.  thanks again.  BTW, do you still need carb bodies?