So, huge thanks to Tom, he put me in touch with Rechie from Unit Pack Power (http://www.unitpackpower.com
), and I ordered a 36V 25AH silver fish pack, with Sanyo 3500 GA batteries, 4A charger, 496 bucks out the door, with shipping, no customs fee to Europe. I will let you know how it performs when it comes. They are a big company, and have a warehouse in the UK in case there are any issues. I am American by the way, moved to Czech Republic 13 years ago, love it here. Great cycling culture. Glad to meet up if any of you get over here, beers on me
OK, so, I got the battery pack today, 36V 25AH. Charger is 4 Amp. Charged it up, took a good six hours or so from empty to full, and took it for a spin.
I don't know the shape of the battery that I bought with the used Guewer bike a few weeks ago, thinking maybe 8.8 or 10AH, about 4 or 5 years old, about 4000 km on the bike.
Results - Holy cow, I mean, for a little 250w motor, what a difference it made. With the old battery I would easily have to feather the throttle and pedal harder up a hill because the assist would run out, with this one, really solid, full assist all the way up. You do have to put in some effort with a small motor, but it really was not much more than normal pedaling even up some decent sized slopes in Prague. So, Thanks much Tom for your advice, Rechie the sales manager was a pleasure to deal with, and it did get from China to Czechia in 9 days, UPS delivery. For what it's worth, I am running a Silverfish battery, and it was plug and play 100 percent. Really delighted at this point, not the cheapest but well worth it.