battery tenders & chargers

[euphonius]

OK, it's winter up here in China and the rest of the northern hemisphere, meaning a lot of our bikes are spending most of their time sheltering in cold garages. For other reasons, I'd not ridden my JH600 since August, and had disconnected the battery leads in hopes of preserving the battery through the winter or until I'm ready to ride, whichever came first.

I was surprised that the reconnected battery had enough juice to turn the engine, but almost immediately the battery light came on and it was clear there was not enough current (or is that voltage) to fire the fuel injection system. So I took the battery to a neighborhood scooter garage (aka totally chaotic fright shop with everything from tools to discarded parts to new product to last night's dinner piled in heaps on the floor). The guy said he could charge me in 30 minutes for 5 kuai. An hour later it was back in the bike and she -- shazzam! -- wouldn't you know she fired up right good, first try.

I let her idle for about 10 minutes, thinking I'd be good for another start so I could run out for some gas and other errands on an almost warm Shanghai afternoon. Newbie mistake? When I came back all geared up, there wasn't enough juice to fire the injectors or plug (or both).

So here's my question: Given that there are more months of winter and more months before my shoulder is healthy enough for longer rides, she's likely to be sitting for more long spells before we're back to a battery-friendly healthy riding schedule. What's the best way to coddle a 12v motorcycle battery during long periods of disuse?

Riders in the US all seem to have Battery Tenders or Trickle Chargers that I guess you, what, keep attached to the battery all winter? I've checked eBay and taobao and see there are differences between what's available in China and in the US. US chargers seem to be bigger and fancier, costing $40 or so. China's look like laptop power supplies and cost 40 RMB or less! Both talk about having microcircuitry that calibrates the correct charging voltage, current and duration to optimize battery life.

Are these things worthwhile? Or should I just head back to the local scootery for another 5 kuai charge?

Here's an article saying you should keep your battery connected to a tender all winter.

What's a good strategy here in China, especially if we are limited to local products?

thanks in advance!