A Bike for Hikes

Looking over the specs for the conhismotor battery you bought, note that it is only spec'd for 20A continuous. To maximize battery lifetime, you might want to limit your max current to 20-25A, not the 30A you have now. I know the battery says it will allow 40A, but if you are doing long uphills at 30A, you could kill your battery in under a year.

I'm extrapolating a little from my experience with NiMH batteries, but batteries really don't like to be discharged continuously at much more than their rated discharge current.
 
Rassy said:
Since it's just extra work to wire up/replug, etc. to measure the amps going into the battery, I would recommend you just keep it simple and measure your usage. Then after a couple of recharge cycles, even if the charger isn't right on 5 amps, you will know the actual output of the charger and can just use that number in the future to estimate the charge time needed. Just my $.02.

I pretty much started out that way when I got a power meter. And I completely understand not wanting to hack into a molded plug/cable to install a connector system on a packaged LiFePO4 battery pack/charger. Particularly, if under warranty.

Lipo usually requires more emphasis on what's going into the cells than what comes out and all of our wiring is pretty much exposed and easy enough to tap into. And in practice, IMO once you've seen a few 20-22A or 30-35A draws from a controller, you've seen 'em all. Nowadays, for my usual trips I only monitor the total charge power (tells me pretty much what I used) and only bother with a meter on my bike if I change something, riding a new or unknown route (best maintain close track of consmption) or sense a problem somewhere.
 
So, I built my wife's bike around a 2807 9C kit from Justin at ebikes.ca(hat tip to methods, who filled my head with incredible knowledge to get me there). I also happened to have a business trip scheduled to Vancouver, so I took an opportunity to visit their store and picked up the kit in person. When I arrived, the receptionist was trying desperately to refer a customer screaming, "GRIN TECHNOLGIES... Y U NO FIX BATTARY?!?!!!" to Endless Sphere for expert advice. :mrgreen:

They eventually assembled the kit and I even got to chat with Justin in the lobby for awhile. I knew who he was even before he introduced himself. He carries himself like a born entrepreneur with a love for his electric bikes, and he picked up where methods left off, filling my poor head with a second bundle of information. It was quite an honor, a lot of fun, and had I known, I'd have readily come down even if I weren't a cheapskate trying to save $50 on shipping. :oops: Their new warehouse is huge and full of bustling excitement. I took pictures for souvenirs.

Had a heck of a time dragging the wheel across Vancouver, to the conference(where a lot of people were curious about it), onto the plane, and home. When I finally cracked it open, it turns out the box 9C had labeled as a rear wheel actually contained a front wheel. :roll: In an act of extraordinary generosity and business sense, Grin offered to sell me the front wheel for a song so we didn't have to ship it back, and to send me the correct rear wheel too. Of course, I still need to buy a cycle analyst, controller, throttle, and so forth to match -- which is where the business sense part comes in. :wink:

Not sure what I'll do with the front wheel in the end, but I'm temporarily using it in my wife's bike, a massive 34 lb black & pink cruiser. I matched it to my old 36V/20AH battery from YXM Zone.

The thing is amazing, considerably better than the Magic Pie(which is now using 48V/20AH). The battery was definitely not the problem; I don't think the motor is either. The wheel size certainly isn't helping, but hers are still 26", not 20" or 24".

The major difference, from what I can tell, is the 35A controller. Her bike will comfortably suck 1200W from the old battery pack while hauling my fat behind up a hill, and there's only nominal voltage sag. She finds it hilarious to glide past me as I'm huffing, puffing, and looking for a house to blow down.

Meanwhile, the 48V battery somewhat improved the 700c Magic Pie's performance on slight hills, and considerably improved it on flats. Steep or long hills are still totally insurmountable, and with the additional wattage, the controller will now occasionally shut down completely if too much is asked of it, even in 30 degree weather with a motor casing cool to the touch. I strongly suspect, as other people have mentioned, that the internal controller in the Pie is not sufficient for our needs in our mountain hamlet. It just can't pull enough sustained amperage to stay efficient on the long hills, and once things start to deteriorate, its speed and thus efficiency drop, causing a positive feedback loop in the wrong direction.

Most likely I'll keep using the Magic Pie until I go nuts, and then buy a 26" hardtail and rig it up with the 48V/20AH battery to my lucky extra Grin wheel, and order another pile of stuff from that magical little shop in Vancouver, and somewhere on my way towards emulating amberwolf, I'll find a way to make a customer of myself for methods too.
 
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