A few weeks back it looked like my battery was kaput – no longer able to hold a charge. For instance that 10.20v charge of mid Sept dropped way back to 9.6 within two days. Not a good sign.
Eirbyte suggested taking the battery to a garage and have them charge it for a few days. Because maybe some high amp input might help. So I figured well why not see if I can produce a few high amp bursts myself and see what happens (and if it didn’t then I’d take it to the garage)?
So in recent weeks I’ve found a few spare half hours and done a few 5km spins.*
The first one was the easiest – thanks to the resistance being low. During it I managed to hit a peak of 17.5 volts while pedalling 23-25km/h (for maybe 10-15 seconds). The end of that run saw the battery charged up to 11.2v before gradually dropping back to 10.7 over a week.
Another 5km cycle ten days ago (during which I managed a couple of 16.5v bursts – 17.5 was just not possible) topped it up to 11.75 – and the perhaps reassuring news is that this morning the voltmeter shows the battery still have 11.15v in it. That seems better.
Of course I may be engaging in some futile cycling here. This might not work. But at least I’m getting a bit fitter while learning what sort of voltage can be put out at a given speed.
I’ll give it a few more 5km cycles and see if the charge can be brought back up to – and stays – anywhere near the original 12.3v it had when I bought it. If not, then I’ll try the garage.
But two things I’ve learned from this.
- Don’t drain the battery down to levels that make the inverter alarm go off.
- Don’t leave a battery at a low-charge level for any length of time.
Oh… and now that I’m getting into the numbers… it’d be handy to have the gadgets to measure my amp / watt output. So I can compare my pedaling with that David Butcher (interesting project and, yes, I’ll probably build one of them too!).* Before you pour ridicule on that rate of pedaling, bear in mind that a) I am dreadfully unfit and b) there is amazing resistance in this yoke! Getting anywhere near 25km/h is quite a feat. Far more realistic to keep around 12-13km/h and work up to short sprints every so often to hit those higher voltages.