ebike refurb

[lxgoldsmith]

hi guys.

I referenced this site years ago to build a battery to match a 1kW Chinese hub kit on a cheap steel frame mountain bike. It hits a comfortable 30mph. I'm in a new area (hilly, cold, rough roads). I am considering upgrading to a more powerful setup to deal with steeper hills and higher speeds, but the bike has to be fixed either way.

The old battery is long since dead and I tossed the crappy "waterproof" bag along with it. I'm keeping the bike frame at a minimum since it's in great shape and has decent suspension. I've yet to replace the tubing and tires.

I'm trying to find sources for a regenerative controller, 30ah+ LiFePO4 battery, battery casing, and battery gauge. Which sites are the most relevant lately?

 

[flat tire]

Don't use lifepo4 unless you want twice the weight and tons of sag. For a good controller with variable regen you need to pay to play. I like ASI others use sevcon. For a battery gauge, you would use a cycle analyst or your phone, since many controllers now have bluetooth and a app you can use.

 

[Sunder]

If you're looking for parts to assemble your own, Aliexpress and only use sellers that have a high volume, and near perfect ratings. I'm talking 99.5%+. Read the reviews carefully. Any complaints that are consistent across 2 or more buyers, you should ignore that seller. I learned that the hard way.

If you are looking for quality, ready to go equipment, go to ebikes.ca

Agree with Flat Tire, LiFePo4 is old tech now. Advances in Li-Ion and LiPo means that the risk of fire is lowered compared to 5 years ago, and the density difference is much bigger now.

The other alternative is that LTO is now a much cheaper technology. Same fire resistance as LiFePo4, comparable energy density, but power density blows LiFePo4 out of the water, as does cycle and shelf life. (10,000 to 30,000 cycles, 30 years plus).

 

[lxgoldsmith]

The other alternative is that LTO is now a much cheaper technology. Same fire resistance as LiFePo4, comparable energy density, but power density blows LiFePo4 out of the water, as does cycle and shelf life. (10,000 to 30,000 cycles, 30 years plus).

I'm intrigued. Early research with specs listed by different manufacturers shows that a 48V 20AH battery would be ~16kg. It isn't as light as an 8kg lipo for going up and down the 4 steps outside my door, but it would avoid degradation issues and handle high enough loads.

Technically, I only need to travel 8 miles between charges, if I were to disconnect the battery at my destination. A 3kW setup would go ~10 miles at full throttle on a 20ah battery (worst case).

 

[Sunder]

That might be true for a hard cased cell like this:

or this:

But I've used Prismatic pouches. This baby here is 48V @ 28AH and weighs in at 15.5kg:

I have also noticed that sellers often use shipping weight, rather than actual cell weight. According to the buyer I got that from, it should have been 20.2kg, but I've weighed it on an accurate scale.