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

How fast can I charge a 36v10.4Ah battery?

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

How fast can I charge a 36v10.4Ah battery?

Old 09-06-21, 04:36 PM
homeless in ca.
Full Member
Thread Starter
Join Date: Dec 2020
Location: Longueuil, Quebec
Posts: 204
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked 47 Times in 37 Posts
How fast can I charge a 36v10.4Ah battery?

I just got an e-bike. It's fun to ride but range is not yet sufficient to make this a daily driver.

I purchased an additional battery identical to the one that came with the bike. And I'll probably get another one asap. Links are below. The batteries are 36V10.4Ah. The charger that came with the bike is 2A.

I work as a tech and do service calls that sometimes take 30 minutes to an hour. I'd like to get a couple of "fast" chargers to bulk charge my batteries during those stops.I'd still use the 2A charger at home.

If there is a "smart charger" that could lower the output as battery voltage increases that would be even better. But I saw some 4A chargers for $20. I'm tempted to go ahead and order 3 of them and do the bulk charging manuallly.

I'd also like to know if it's possible to charge two or three batteries with one charger. Since in my case the batteries are identical.


homeless in ca. is offline  
Old 09-06-21, 05:14 PM
Senior Member
Join Date: Jul 2014
Location: socal
Posts: 3,725
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 746 Post(s)
Liked 582 Times in 441 Posts
Most "experts" state that batteries are stressed by fast charging. Accordingly, charging at 2 amps probably is optimal, and higher rates probably will decrease battery life. Check the literature to determine how much.
2old is offline  
Likes For 2old:
Old 09-06-21, 08:48 PM
Senior Member
Doc_Wui's Avatar
Join Date: Jul 2015
Location: Chicago Suburbs
Posts: 1,327

Bikes: GT Transeo & a half dozen ebike conversions.

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 327 Post(s)
Liked 221 Times in 157 Posts
Your 36V10,2AH battery probably has 40 cells, arranged in a 10x4 array. In battery talk, that's 10S-4P for 10 series groups and 4 parallel cells per group.

With a 2A charger, each cell gets 0.5A in charge current. You would have to look at the spec sheet for the max charge current, but I "think" most commercial cells would be fine at 1.0A. My biggest charger though is 3A, and that's actually 2.7A actual current. I chose it over a 4A or 5A charger because my experience is that the 5.5mm connector will overheat at 4A,

Some of my batteries use RCA XLR microphone plugs for charger connectors, These won't melt.
Doc_Wui is offline  
Likes For Doc_Wui:
Old 09-06-21, 09:48 PM
Senior Member
Join Date: Jun 2008
Location: Vancouver, BC
Posts: 9,201
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 1186 Post(s)
Liked 289 Times in 177 Posts
Originally Posted by homeless in ca. View Post
If there is a "smart charger" that could lower the output as battery voltage increases that would be even better.
They don't really have to be 'smart' to do that. All lithium chargers will start with a constant current until the battery voltage reaches about 4.2V/cell. After that the voltage will be held constant and the charge current will gradually taper down. The charger should shut off when the charge current drops below a fixed threshold, typically around 5% or so of the capacity - in your case around .5A.
gregf83 is offline  
Likes For gregf83:
Old 09-07-21, 01:59 PM
homeless in ca.
Full Member
Thread Starter
Join Date: Dec 2020
Location: Longueuil, Quebec
Posts: 204
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked 47 Times in 37 Posts
I've always heard that fast charging is fine as long as you don't go over 80% of the battery's full capacity. The Luna charger puts out 5A but switches off when the battery reaches 80%. Or they can switch to a lower amp setting if you want a full charge.

In my case I don't want to spend hundreds of dollars on smart chargers if I can do the same thing manually with a timer. I'll just check the voltage and if the battery is 50% then I can safely add 3 amps and set the timer for 45 minutes.
homeless in ca. is offline  
Old 09-10-21, 11:01 AM
Join Date: Dec 2020
Posts: 45
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked 28 Times in 20 Posts
I think using a timer with basic chargers is a good simple solution, but you do need to "know" your particular batteries. Even with a timer I would also keep a close eye on the charge state of the batteries using a multimeter or more preferably an inexpensive inline voltage and amperage monitor.

The Luna advanced charger simply gives you the choice of 80, 90, or 100% charges (there's no default) at various amperage rates (1-5amps). While many question the build quality of the Luna units I've been pleased with mine for about a year now. My 52v battery is rated to be able to be charged at up to 8 amps so the occasional fast charge at 5 amps is fine ... but I normally just charge my battery to 90% at 2 amps.
mclewis1 is offline  
Likes For mclewis1:
Old 09-10-21, 12:03 PM
Full Member
Join Date: Jul 2018
Location: MN
Posts: 235
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Liked 149 Times in 80 Posts
Her is a link I found on the Luna web site regarding battery charging that may help:

MNebiker is offline  
Likes For MNebiker:
Old 09-15-21, 11:40 AM
Senior Member
Join Date: Mar 2021
Posts: 680
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 307 Post(s)
Liked 156 Times in 119 Posts
The faster a battery is charged the fewer charge cycles it is likely to accept. Best bet is to get a second battery if you really need more range or perhaps consider using your legs to pedal so the motor is drawing less from the battery. Every e-bike I have looked at had a range variance of 100%, or 50 miles little pedaling but 100 miles if the rider's legs did most of the work.

Lithium battery chargers will usually provide maximum charge rates until the battery has a SOC of around 50% and then taper off. I don't know if the brick type transformers are that sophisticated and this is probably why they tend to be low output 2 amp ones. You will also shorten the useful life of a lithium battery if you draw it down to 50% or higher SOC and then recharge it. Batteries are rated for a given number of charge cycles and not amount of recharge per cycle. A battery that is recharged when it is at 20% SOC is likely to last longer than one recharged when it is at 60% SOC as the latter will be recharged more times per mile traveled.
Calsun is offline  
Likes For Calsun:
Old 09-16-21, 06:20 AM
Full Member
Join Date: Feb 2021
Location: Wadsworth, Ohio
Posts: 343

Bikes: 2008 S Works Stumpjumper FSR Carbon, 2016 E Fat Titanium Bike Custom built by me.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 121 Post(s)
Liked 180 Times in 107 Posts
I regularly fast charge at 5 amps even to a 100% state. I have about 300 cycles so far. If the battery does not get hot no problem Once in a while I slow charge. I have two 2 amp chargers. a 5 amp charger and a 15 amp charger.

My 5 amp charger is the Luna charger. I have charged both 52 Volt and 48 volt with the same charger on a trip. I just open the case and use a small screw driver to change the pot voltage between 58.8 volts and 54.6 volts. .
KPREN 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 or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.