yeah I looked at the alternator when trying to find the slow drain as I'd read that a dodgy diode in the rectifier circuit can allow current to flow the wrong way. By bridging the disconnected -ve battery lead and the -ve terminal with the engine off I picked up a 1 second fluctuating current draw of 5 to 25 mA . By a process of elimination, disconnecting the alternator, pulling fuses and relays etc I narrowed it down to the flasher unit. When I pulled that out it dropped to a steady 3mA draw that went down to 2mA when I disconnected the clock. I'm assuming that residual draw is the DME. 3mA would be fine but 25mA will add up really quickly on a little 16Ahr battery. I've since picked up a replacement second hand flasher on ebay only to be unable to recreate the problem which is a bit frustrating. In the meantime I'm pretty sure that is what has knackered my battery as the manual specifically says that slow long term draw will kill it.
My alternator belt is squealing a lot anyway, I think due to a small misalignment and poor manual tensioning. I've ordered a replacement mini 40A Daihatsu Charade alternator in pursuit of the holy grail of M50 engined Sportster owners - having the Alternator on the correct side of the engine. That may improve battery charging performance too.
Last edited by morris; 4th April 2016 at 20:02..
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