Go Back  Bike Forums > Bike Forums > Electric Bikes
Reload this Page >

Uprating battery for bafang Ebike

Notices
Electric Bikes Here's a place to discuss ebikes, from home grown to high-tech.

Uprating battery for bafang Ebike

Old 11-07-19, 08:59 AM
  #1  
ortactoo
Junior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Question 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 !
ortactoo is offline  
Old 11-07-19, 09:58 AM
  #2  
Doc_Wui
Senior Member
 
Doc_Wui's Avatar
 
Join Date: Jul 2015
Location: Chicago Suburbs
Posts: 1,269

Bikes: GT Transeo & a half dozen ebike conversions.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 312 Post(s)
Liked 176 Times in 127 Posts
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.

Last edited by Doc_Wui; 11-07-19 at 10:01 AM.
Doc_Wui is offline  
Old 11-07-19, 11:09 AM
  #3  
2old
Senior Member
 
Join Date: Jul 2014
Location: socal
Posts: 3,421
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 678 Post(s)
Liked 466 Times in 355 Posts
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).
2old is offline  
Old 11-07-19, 12:51 PM
  #4  
chas58
Senior Member
 
chas58's Avatar
 
Join Date: Jul 2010
Location: Michigan
Posts: 4,822

Bikes: too many of all kinds

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1133 Post(s)
Liked 399 Times in 321 Posts
Originally Posted by ortactoo View Post
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 !
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.
chas58 is offline  
Old 11-07-19, 01:41 PM
  #5  
PreacherG
Member
 
Join Date: Oct 2019
Location: West Kentucky
Posts: 41

Bikes: GenZe 102 e bike, 70'S Moosburg 3 sp touring bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 2 Times in 2 Posts
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.
PreacherG is offline  
Old 11-07-19, 04:04 PM
  #6  
Doc_Wui
Senior Member
 
Doc_Wui's Avatar
 
Join Date: Jul 2015
Location: Chicago Suburbs
Posts: 1,269

Bikes: GT Transeo & a half dozen ebike conversions.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 312 Post(s)
Liked 176 Times in 127 Posts
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.
Doc_Wui is offline  
Old 11-10-19, 06:15 AM
  #7  
ortactoo
Junior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Smile 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
ortactoo is offline  
Old 11-10-19, 06:21 AM
  #8  
ortactoo
Junior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 10
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by PreacherG View Post
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.
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.
ortactoo is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.