How many Amp-Hours do you want in LiFePO4?

[Grunchy]

Here's the scoop, I only live about 5 km from work.

I should be cycling anyway, if not walking, the trouble is the main road is extremely busy with a posted limit of 80 km/hr and no bike path nor sidewalk.  Plus, I have to cross the train tracks adjacent to an irrigation canal and there is only one crossing for MILES.
(I'm talking Glenmore Trail in Calgary Alberta Canada, going the short distance from Riverbend to Foothills industrial park).

However, I can cut through the community of Ogden and avoid Glenmore Trail, and ride along the 50 km/hr neighborhood roads there for half the trip, and then up a short, steep hill to Glenmore Inn, cross the tracks and the canal using the sidewalk, then cut through the industrial park for the second half of the trip.

It seems like a perfect thing for an e-bike so I am motivated.  I figure that 10 Ah would be perfect for a daily trip like that, however, I would also like to pull a tag-a-long kiddy bike & do more pathway riding on the weekends.  Anybody who knows Calgary knows there are about a thousand kilometres of pathways here.

Should I settle for 10 Ah?  Go for 15 Ah?  Not settle for less than 20 Ah?  For instance, I estimate it is about 15 km to downtown from here along fairly level pathways.   

[biohazardman]

You will probly always wish you had a little more.  I am running 36V 10AH Lifepo4 batts and get about 20 miles (32 km) per charge.  Running mostly at full power and pedaling at stops to get moving and also on hills.  Would guestimate no more than 10 percent of the time are my legs helping out. I would have liked the 15AH also but the cost was prohibitive at the time. I would like to take some side trips now and then but the lack of more battery does not allow it.  Get a bit more than you think you need.

[vince_t1]

Here's the scoop, I only live about 5 km from work.

Grunchy,

I posted on the yard works batteries from Canadian Tire. I have upgraded my pack to four batteries. I can easily go 30KM with really no peddling expect for starts and some assistance going up hill. The batteries appear to be very rugged and I have been running the 500 watt 36 volt motor on 40 volts with no problem, well over a couple hundred kilometers. The weight of the batteries is minimal and I can also use them with the CT lawn tools.

The only draw back is that I used them in their packaged form, thus I have to charge them seperately. I have two chargers and have not had a single problem.

My next step is probably to upgrade my tires to something with less rolling resistance, I am using the stock tires that came with the 99 dollar bike.