… the real learning!

The battery in my old Apple PowerBook (PowerPC) doesn’t hold a charge for longer than maybe 10 or 15mins. So I’m pretty much reliant on an external source of electricity. It’s not the biggest power drain in my office but at 65w (max), and running for hours at a time, it is definitely the biggest consumer.

So how long can I feed it from the turbike-charged battery?

Well, today I ran the computer almost non-stop for 11 hours. For perhaps 5 hours of that time I was also running my 11w daylight-mimicking desklamp. After 11 hours the inverter alarm sounded meaning it was time to pull the plugs to prevent over-draining the battery. The voltmeter showed 11.3v left in it.

So I took the battery out to the garage, hooked it up and started pedaling. The going was tough (the resistance is heavy!) and after 40mins of on-and-0ff pedaling the battery voltage now seems to be hovering about 12.05 – 12.10v.

At no point during that pedaling did I get the volts beyond 13.3v. So all the signs suggest there’s a good bit of pedaling left to do yet! It will be interesting to see how much longer before I hit 14.5v (the suggested point to stop pedaling in order to prevent over-charging).

It’s not my plan to ever discharge the battery this much again. So maybe 4-5 hours would be the max I’d draw out of it on any one day (less when I get a new laptop that charges its own battery while drawing juice). Hopefully that means it could be recharged with 15-20mins of cycling. But only time and experience will tell.

I’m still very new to all this volt-monitoring and stationary-bike exercising, so all I can be sure of right now is that

• mountain bikes are ridiculous machines to try to cycle efficiently on
• the sooner I get my racer installed, the better
• long-term I think I’ll augment this system with photo-voltaic panels
• the pedaling in one position, for extended periods, with a constant pedal rate against a steady resistance could make me very good at time trials (watch out Fabian Cancellara!)

The Turbike is finally up and running in my home (well, my garage actually!). Early days yet and there’s still lots to be done with it… but it is producing power and I’ve successfully run my computer and desk lamp from the battery for at least 6 hours in one go.

Not sure how long the battery will be able to run my office for in one go… but over the coming weeks I hope to test it out and let you know about it. As part of that testing I’ll also keep an eye on how much pedaling is needed to get the battery charged up again.

But initial impressions (after that 6 hour draining, and running 2 laptops for 3:30 one evening) suggest that maybe 20 to 30mins pedaling at a steady and sustainable rate does that recharging quite nicely.  This means a daily stint of pedaling might be needed.

Of course if my laptop battery would actually keep a charge… well, things would be much easier. But maybe I’ll be able to afford one soon 🙂