system volt meter vs batt. sudden death

[TinkerToy]

The question is...would a volt meter monitoring the system voltage be of value in detecting the onset of the sudden death of the battery? A volt meter placed across the battery terminals?...or ...your suggestions as to the optimum meter placement would be appreciated With the long distant rides ahead there is nothing worse than being stranded, trying to get a battery ect... [ my thought is a lower than 11.8 volts on the crank means no go, key on voltage indicated before engagement of the starter] Your thoughts and technical expertise will be appreciated !

[hjsbmw]

My experience, not really expertise, is that a voltmeter *sometimes* tells you when the battery is already bad. It is not much use for predicting that. A voltmeter will more reliably allow you to tell if there is a problem in the charging circuit: wiring, alternator, regulator,...

[Liam]

TInkerToy,

I think you're on the right track as far as measurement is concerned. I'd expect a failing battery to have an increased internal resistance, so measuring the voltage across the terminals under the startup load might be a useful measure. I'd also expect the rate of voltage drop as the engine started, to be useful, but harder to measure.

In the end, the question is what do you do with the info that your battery is failing? BMW replaces on failure not on suspect voltage drop measured by the customer. I got stranded with less than 900 miles on the bike. I got a jump start and road to my dealer. They put the battery on their tester and it tested good. Then they put it back in the bike and the bike wouldn't start. They replaced the battery.

After that, I couldn't trust the battery. For me, the solution to the trust problem was an Odyssey PC535.

IMHO this bike is as good as motorcycles get. I love it. But you gotta fix three critical things: the horn, the battery and the seat. Fortunately, they're all easy fixes.

Liam

[goo]

on the obc display

[ka5ysy]

i'd rather have a voltage number than average speed on the obc display

I have VDC set up as data displayed on my Garmin GPS. Works great !!.


However, from experience, I can tell you that by definition the sudden battery death syndrome give absolutely NO warning. I rode around all morning the day mine crapped out, and had no indication anything was wrong. Until lunch. Then it would not restart at all, and when jumped, it would not maintain enough to even move the bike if placed in gear. PITA !