A useful chart to consider battery and power upgrades.

Power | Range (48V20A Lead)/ | Top-speed
| (48V40A Li-ion)|
500W | 60 km / 125 km | 45km/h
800W | 60 km / 125 km | 48km/h
1000W | 55 km / 115 km | 52km/h
1200W | 50 km / 105 km | 55km/h
1500W | 50 km / 100 km | 58km/h
2000W | 40 km / 85 km | 65km/h
2500W | 35 km / 70 km | 75km/h
3000W | 30 km / 60 km | 80km/h

Sneaky? What am I supposedly trying to do? You obviously aren't a writer, it's a writing style to entice a reader into the subject matter. That's all. It was the question I had for a while until I figured it out, and wanted to share the answer to finding these great rides with the English speaking population in Beijing, since I had to resort to the Chinese-only information and still had trouble figuring it out until I got there.

Petrol version: I've seen this available near Tsinghua University near Wudaokou. They were willing to sell for the same price as the electric version. He was trying to convince me that the cops would ignore me because I'm a foreigner, however, while you may get away with driving without a license, the plate that you need on the back will cost you a little for the Jing-B, letting you drive on and outside of the 4th Ring only. If you try to get a Jing-A so you can drive inside of the 4th Ring and into the city, it will cost you over 10,000 RMB, yes, that's the correct figure I was told.

I ride mine almost everyday to work, I don't do so when it snows and the roads are slick for safety reasons, I don't ride when my schedule for the day has me doing something else that may lead me to not ending the day at the office to pick up my bike. I also like to take the bike out after work and get around town a bit.

Being winter, it has had a more limited range, which has shown improvement already with warmer weather, however, I still feel the desire to just get the upgraded battery and go much farther with less worries, since the Li-ion battery allows driving around without affecting top speed. I also want to increase the speed on mine because I'm a guy, and I want to go faster. Admittedly, you are already going faster than almost everyone else on two wheels in Beijing even at 40~45km/h.

I have carried girls on the back and it doesn't affect top speed much, just the acceleration. With another guy on the back, can be much slower acceleration, but still acceptable since you expect it. Depending on the hills you are thinking about when it comes to slopes, you're unlikely to get much in Beijing, if you park in a garage, which can happen, then those slopes are too much to carry me and the bike up, but I'm a heavy dude. Just push it up and hop on.

500W Power supply
I hope you mean 48V40A Battery, that's fine.
Battery comes out, Dual-disc brakes, etc.
Colors can be ordered in advance, I've seen white, black, silver, maroon, copper (orange), dark blue, dark green, blue camo, green camo, yellow, etc.

The initial bike cost with dual-disc brakes I've mentioned in the original article, and is dependent, as always, on your bargaining skills. Also, if you choose for some reason to have only one or zero disc-brakes and go for padded brakes, it'd be cheaper.

They've told me the battery upgrade cost around 3800 to 4000 as well. It's a hefty price tag considering the bike cost, but then again, you will get what you paid for, especially since electricity (to charge up) is so cheap in China compared to the higher fuel prices.

sorry to say, I haven't done the upgrade yet, but the desire is great. My issue is timing, as I'm often out of town and I haven't seen the time to pull the trigger.

I'm glad you're enjoying the bike, I tried a 60V30A 800W bike at the shop, but more the "modern" style, I can't stand those lack of handle bars. I much prefer these Turtle Kings. And I'm glad you agree you want to do the upgrade too, even if it is more expensive.

A few things I've learned though.
The good first: The chart above is the sell side chart, realistically, 1000W/1500W 60V40A will get you going 65-80 km/h tops, with the range up at 100+km and increase in the "pick-up" in acceleration. Better than what is shown above.

The bad: Turns out there is a term for those speedometers: "欢乐表", ie. "Joy-meter". They are universally designed to show speeds around 7-8 km/h faster than actual. Big bummer. Here's the flip side. These bikes are clones, so you can go to taobao and buy the dashboard from the gas-powered cousins and have actual speed shown, up to 160km/h or something. So for me, this is part of the equation I'm considering, since I want to know exactly how fast I'm going, especially if it's going 65-80km/h.

What I've been told is that all the electric meters are in fact joy-meters, I never liked the yellow backed meters, but mine came in black, much more pleasant to the eyes. But is probably exactly what you're seeing on Taobao.

Might I recommend looking for something like the following, since this is the only good example I've found on taobao thus far: http://shop35653832.taobao.com, more specifically: http://item.taobao.com/auction/item_detail-0db2-1f2f96f5c971a4a5ca0b3ea1...

This is the meter I'm looking at. As you can see, it's a gas-powered speedometer assembly for 55RMB. Battery meter I switched out already, each "pod" can be removed from the capsule and replaced, and mine is now a digital display showing some number indicating thing. 48V20A and the high is 55.* and they say at 46 start going home, and at 42, you're dead. But these numbers would change if/when I switch to 60V.

You can get these digital types fairly cheap too at the shops. I just go to my guys at the store I mentioned in the original post, now there is some competition a few shops down, but I've stuck to my guys, as they remember you and keep up the good work. (FYI: in that section of stores, mine is to the far left).

60V batteries are a 5th cell attached to your 48V-4 cell assembly. But in the Li-ion form, these are all placed into a nice metal container (w/ handles) to slide in and out to bring home to charge. And the weight is lighter than the Lead.

The extra Volts translate into that extra "giddy-up" in acceleration, as I believe, or maybe that's the Amps? Either way, between that and the Amps increase, you get faster speed and longer range, and based on what I've seen advertised online, I'd guess Amps increase range more.

I'm gonna order it all through the shop, they are very helpful i think. They have their own supplier for the batteries, and I think they'll even do the taobao for me.

Yes, the gauge assembly can be mixed and matched, i actually like my blinker/high beam pod, the gas-speedometer, and the digital battery gauge. The shop did this for me once already, now for the gas-speedometer next.

The battery gauge will show those fluctuations you're talking about still, but will give you a much better idea of what's really going on. It's supposed to be much easier to use with the Li-ion battery, since those batteries don't have that crawling top speed as you end a battery cycle. ie. it runs at the full top speed all the way until it dies instantly. So KNOWING the battery amount left becomes EXTREMELY important.

Indeed, I have noticed this, they do seem warmer now with summer. I just figured it is the heat. As this was no where near the case during winter, when everything was cold. This is one reason for why I want to upgrade batteries to the Li-ion as those are placed into a metal container that has a nice handle and is just one block instead of the two duct-taped sets that I have now. I won't be upgrading for a few months, since I'll be out-of-town. Looking forward to upgrading by August!