Battery voltages.

Feliz

Well-Known Member
For a 48 volt battery what does 20% and 80% equate to in volts? Thanks.
I don't think it's simple math which I can do.
 
Feliz - this is from Juiced's FAQ on their website:

What is the voltage value for 20% and 80% on my battery pack?
For 48V 20% is about 42V and 80% is about 51V
For 52V 20% is about 45V and 80% is bout 55V
 
@Feliz

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Thanks, I looked everywhere for that but couldn't find it, I've seen it all kinds of times but never saved it. Thank you.
 
That chart is wrong. This is a correct chart for lipo percentage. A 48 volt battery is a 13s and 52 volt is a 14s. This chart was put out by a lipo manufacturer and not an ebike company. Stay in the white zone for best performance.
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Mark, you seem absolutely confident that your chart is accurate for the boat and plane model batteries you sell. You are also adamant that the chart published by Juiced is highly inaccurate for the purpose of understanding battery voltage at various percentages. I don't fully understand the significance of (s)tack numbers, except that a greater number equates to more cells in series and a higher voltage battery. I would like to see the mathematical equation used in arriving at the voltages listed in the chart you've been blogging.

With the understanding that partial charge and discharge cycles of Li-ion battery packs remain the best use for longevity, my only iron in the fire is the investment I have in my Juiced bike battery. There remains a desire to utilize best, as much of the power in the pack, without undue stress on the cells. I need accurate information that is usable in my specific application (a 14s battery which s 52 volts with 19.2Amp hours). Specifically, I want to know what is the real voltage of the battery pack at 20% capacity.
 
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Feliz - this is from Juiced's FAQ on their website:

What is the voltage value for 20% and 80% on my battery pack?
For 48V 20% is about 42V and 80% is about 51V
For 52V 20% is about 45V and 80% is bout 55V
This is the information I have been going by -with regard to best utilization of my CCX battery. I am alarmed and confused by the chart posted by Mark, and his adamant assertion that his graph shows more accurate capacity voltages. I have been looking for clarification of the different values and a mathematical equation for arriving at those values. All chart information offered needs to be verifiable or assertions of a chart's accuracy (or inaccuracy) is just a bunch of rhetoric.
 
So confused I'm trying to figure out if my 48v 21ah battery is good enough to run a 750watt 48v bafang rear hub motor with a 22a KT controller,or would I smoke my battery any advice much much appreciated.
 
So confused I'm trying to figure out if my 48v 21ah battery is good enough to run a 750watt 48v bafang rear hub motor with a 22a KT controller,or would I smoke my battery any advice much much appreciated.
You should be good. Seems like most 750 watt motors come with a 22A controller. Are you replacing an existing controller? That'd be the best way to know. Your battery has 21 AH, probably at least a 30A BMS. Just a guess though. Do you have more info on the battery? cell type? BMS?
 
You should be good. Seems like most 750 watt motors come with a 22A controller. Are you replacing an existing controller? That'd be the best way to know. Your battery has 21 AH, probably at least a 30A BMS. Just a guess though. Do you have more info on the battery? cell type? BMS?
Must be good vado to resurrect this 5+ year old thread with a totally irrelevant question 🙃
 
You should be good. Seems like most 750 watt motors come with a 22A controller. Are you replacing an existing controller? That'd be the best way to know. Your battery has 21 AH, probably at least a 30A BMS. Just a guess though. Do you have more info on the battery? cell type? BMS?
 

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So confused I'm trying to figure out if my 48v 21ah battery is good enough to run a 750watt 48v bafang rear hub motor with a 22a KT controller,or would I smoke my battery any advice much much appreciated.
The 21AH rating on the battery refers to it's capacity, not how much current it will supply. The 22A rating on the controller is the maximum current it will supply to the motor. 22A should be fine for a 750W motor.

Some batteries and controllers have fuses which are usually rated between 30 and 40A. If you have fuses, make sure they are 30A or greater, and you should be good to go.
 
Without the detailed battery specs it's hard to say for certain.
But I would say it would be very rare to have a 21ah battery (that's on the large size) that wasn't built robust enough to supply a 750w motor.

Mount the battery securely... that type of connection is prone to failure from vibration. Perhaps add straps around the battery if it doest seat tightly to the base.
 
Hi thanks to you all for the speedy reply,fuses no I don't think I could honestly say this battery has them .
The battery is sealed of course but if you look at the photos I posted,I was wondering why does my battery have a white sticker with 750 on it.
I also have the same battery with a sticker on it but that is 250 any one no why that is.
So have no Idea about specification of my battery I'm guessing that a 48v 21ah battery can handle a 750w 48v motor, connected to KT 22a controller.
 
Hi thanks to you all for the speedy reply,fuses no I don't think I could honestly say this battery has them .
The battery is sealed of course but if you look at the photos I posted,I was wondering why does my battery have a white sticker with 750 on it.
I also have the same battery with a sticker on it but that is 250 any one no why that is.
So have no Idea about specification of my battery I'm guessing that a 48v 21ah battery can handle a 750w 48v motor, connected to KT 22a controller.
No idea what the 2 stickers mean.
There's also no manufacturer identification sticker?
But yes I believe it is relatively safe to assume that the 21ah is OK to use with the motor as described.
If the battery is of any quality it should shut itself off if over worked.
 
Ok thank you so much for your help believe me it's very much appreciated,I was really nervous about the upgrade I didn't want to suddenly explode while riding.
So finally this will be my set up,750watt bafang rear hub motor 48v with KT 22A 36V/48V Controller,48v 21ah battery.
 
Stickers don’t usually mean much. A 750 watt sticker is just an identifier for the bike to enter the country. Other countries you could see a 250 watt sticker.

My controller can provide 1200 watts. I could get a 48v 750 sticker on eBay and be compliant for the officer. If they were interested in looking. Just searching eBay, I can purchase these.

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Also, with slightly higher current than the original controller, more heat can be produced. If the controller is inside the bike frame, then more heat will build up there. It won’t be an issue unless you 100% throttle and going 6mph for more than 10 minutes. If you can’t touch the controller for longer than 5 seconds then it’s getting too hot.
 
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