Beta Alp 4.0

A collection of information as it arises. There's not a lot out there!

Sunday, February 19, 2012

Flat battery

Wow, a long time since any action on here, I'm very sorry. I can report that our utility room conversion is great, but at a cost of many of my hours.

The last few times I've ridden the Alp that e-start has been rather reluctant although the battery charged readily when I got home and connected the Optimate. Today I decided to do the right thing and estimate the condition of the battery (FTX7L-BS). It had been on the Optimate for weeks and had an open circuit voltage of 13.4V. A good start but not great when directly off charge. I had a 20W bulb on a lead so popped that on - measured 1.75A load. By 1 hour the onload voltage was below 9V, so disconnected it and it rose to 10.1V. The minimum depth of discharge of lead acids seems to be quoted between 10.0V and 11.8V so it was 'empty' by any method, giving a capacity of under 2Ah . The nominal capacity of 6.5Ah is at 10 hours (C/10 ie 650mA) so although I was loading the battery at about C/3 I should have expected a run time of at least 2 hours. It's dead.

I had wondered whether a Hawker high cranking current battery would fit but the specifications suggest not. There is a Lithium battery that should fit but they are silly money currently. So, which conventional AGM battery? Yuasa's offering has a cranking current of 85A whereas the Varta is advertised at 50A; there's a WestCo at 85A too. I feel this is important as the DR350 lump takes some turning over and with the lean jetting a good spin is important. The best price I could find was for a Yuasa was £38 at mds (usual disclaimers).