Uprating battery for bafang Ebike
 

I currently have a 48v x 17.4a downtube cylinder type battery for my 750w mid drive Bafang which is currenly 3yrs old. It is still capable of 30+ mph but the range which is more important to me than top speed has fallen from 30 miles to about 24 so I want to replace it with a more powerful battery but can I do this using the same controller set up that came with the kit ? I'm currently thinking 20a x 50 or 52v .Iwould be grateful for any help you can give me but please bear in mind that I'm clueless about electrics - hencet his post !

Batteries are rated by AH, and also by their maximum current capability. You can get as many AH as you want, but make sure the battery is rated to supply the same max current as the old one, which was probably 30A.

My BBS02 is from 2016. It will run on 52V, and I have a 52V pack, but it's really not a good match. The motor controller thinks it is a 48V pack and will run it down too low for a 52V pack. Not good for battery life.

My 52V, 10 ah four-year old Luna battery still powers a similarly aged BBS02 fine qualitatively, that is for a maximum off road excursion of 20 miles and 3,000' of climbing. Guess I've never "exhausted" it. That said, probably I will procure only 48V batteries in the future, but have a couple of 52V that need to be "worn out" first. Luna has a display for the BBS02 that shows voltage, so one could conceivably shut down when the 52V system is at cut-off (which my table of voltage vs SOC is 44 - 45V).

Amp-hours gives you range
Voltage gives you speed.

So, you want a battery with lots of amp hours to get your range.

You'll get a little more power at 52v, but not more range (maybe less, since you are using more power). 52 is close enough to 48 that it is in the range of most controllers - but that is a good point above of possibly getting in too deep a discharge state with a 48v controller. Li-ion batteries don't like that too much.

Yep, bike range often does go down in a battery much over 3 years.

(as for the education part here is a tidbit. most batteries are 18650 batteries, and those are configured in series (voltage) and parallel (amps) to make your battery. they are rated at 3.7 volts, so all batteries are a multiple of that. Put 10 groups of those in in series and you get 37 volts (so we'll call it 36 volts, cause we like multiples of 12). multiply the 3.7 by 13 (series groups) and you get 48 volts. 14 in series gives ~52v. That is a long way of saying you can't get a 50volt battery pack with this type of battery.

I saw a youtube video recently suggesting low tire pressure can cause lost range. This time of year, the cooler temps will lower pressure. It may be worth checking.

Cooler temperatures lower the battery efficiency faster than low tire pressure kills mileage. At 42F, it just feels like I've lost half the range vs 77F.

Uprating battery
 

Thanks for that tip. I know the importance of tyre pressures on performance and how batteries are less efficient in the cold but wasnt aware that tyres are too. I'll check them more often in the winter. Cheers

Thanks Preacher G. I hadn't allowed for that I shall check them more often in the winter but the range is down in the summer too so after being charged up approx 600 times over 3years I think the batteries have started to detiorate.