Battery, controller and motor selections

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Joined: 09/11/2008
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Points: 2

Hello All,

I am putting together an e-bike that will be a commuter bike that will carry some cargo (a few bags of groceries) for at least 20 miles of range at 20 mph with some pedal assist from me. There will be a few hills along my regular routes. I am wondering if the kit that I have selected below will work for my needs.

I am considering the BMC hub motor with a 36v-25a controller: http://www.comcycle-usa.com/ProductInfo.aspx?id=4855834

I am considering a Ping Battery 36v-20ah Lifepo4: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=320297101216&Category=11332&_trksid=p3907.m29

Specifications
Fit 36V Motor Wattage: 400 Watts to 800 Watts, 500 Watts suggested
Voltage: 36 Volts
Capacity: 20 Amp Hours
Dimension: 150x110x280 mm ( 6x4 1/2x11 inch )
Weight: 6.80 kg ( 15.00 lb.)
Charging Voltage: <46 Volts
Charging Current: <5 Amps
Rated Discharging Amperage: 20 Amps
Max Continuous Discharging Amperage: 40 Amps
Maximum Discharging Current (Peak): 60 Amps
Lifecycle of the whole pack: >85% capacity after 1000 cycles.
Lifecycle of single cell: >85% capacity after 1500 cycles, >70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate)

I want to make sure that the controller (36v-25a) will work well with the 36v-20ah Lifepo4 battery. I thought I read somewhere that the controllers can have a higher peak amperage and I want to make sure that it wouldn't harm the battery.

Thanks for your help!

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Offline
Joined: 08/05/2008
Posts:
Points: 2
Re: Battery, controller and motor selections

I think you are in good shape. I don't know as I have seen a similar comment about controllers pulling more than their rated current. Even if it did pull 40A for a few seconds, it would not be beyond your battery's max continuous rating. IIRC the 40A(max continuous) is rated for a 12 second burst.

If you want to be kind to your battery, don't nail the throttle at a dead stop. Ease it in while you peddle up to speed. In general, low speed: low throttle.

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Joined: 12/25/2007
Posts:
Points: 342
Re: Battery, controller and motor selections

I have run my Giant LaFree pedelec for 28 miles on a Ping 24V 20Ah pack, and I still had juice left, how much, I do not know. Average speed was probably like 10 MPH counting in the hills and cursing on the beach boardwalk, top speed was 22 MPH. The motor probably did half the work. My total weight including the bike is 250 Lbs. I had 480 watts to use, you have 720 watts.

Deron.

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