Lithium iron Battery connection

pmmali

10 mW
Joined
Aug 11, 2022
Messages
27
Dear all,

I have a small question.

my bike having 12V 12ah 5 gel batteries, all are expired now. and I have built 5 12V 30Ah battery packs with 18050 batteries. each pack is 12V and each pack have separate BMS too. i can charge it with12V charger each battery.
Now can I series all batteries to get 60V and can I charge it with a 60V charger? because each 12V battery pack has a separate BMS.
this is why I am asking this question.

kindly help me to solve this issue.
 
Hi Guys,

Kindly let me know it is possible to convert ordinary e-bike charger (48V/60V/72V) can be convert to Lithium iron batteries? if yes kindly let me know how to do it or provide me any simple diagram to test my self.

Regards.
 
Hi Guys,

Kindly let me know it is possible to convert ordinary e-bike charger (48V/60V/72V) can be convert to Lithium iron batteries? if yes kindly let me know how to do it or provide me any simple diagram to test my self.

Regards.
 
you built 5 packs from 18650 cells and now you have 5 batterys with 12v and 30AH with bms each and you want to connect it in series?
there is no 12v lithium pack possible with 18650 cells. 3s is 10.8V and 4s is 14,4V. what did you built there?
you can not connect batterys with bms in series. bms is rated for specific voltage. connecting in series will increase voltage and there will be a big bms mess. you also can not charge and discharge this way.
for 60V you need a 16s battery made of 18650 cells or 21700. for 30Ah you need 10-12 paralell cells. so your battery should be 16S11P and have one 16S BMS rated for the right current you want to draw.
an ebike charger is usually for lithium cells. if it have the right voltage you can use it. for 16S it should be 67.2V

edit:
i see you were talking about LiFe cells. never heard about 18050. if you are using LiFe then you need a charger for it. normal ebike charger can be adjusted in voltage but there is a profile for liion and i wouldnt use it for LiFe.
 
pmmali said:
Hi Guys,

Kindly let me know it is possible to convert ordinary e-bike charger (48V/60V/72V) can be convert to Lithium iron batteries? if yes kindly let me know how to do it or provide me any simple diagram to test my self.

Regards.

which charger do you have? the only e-bike charger that i know of that covers a voltage range that wide is Grin's Cycle Satiator, that can charge anything between 36V-84V nominal. It can also charge virtually any battery type/chemistry (including LiFePO4), so no conversion needed.
 
Hi Zablock,

Thanks for your detailed reply and i have build 4s is 14,4V battery packs.
 
pmmali said:
Hi Zablock,

Thanks for your detailed reply and i have build 4s is 14,4V battery packs.

Well, you still haven't clarified what kind of cells you are using. 4S of Lithium Iron (phosphate per your posts), would be 3.2Vx4 nominal, or 12.8V, or 14.6V fully charged. If you were using Lithium Ion cells, then 4S would be 3.7Vx4 nominal, or 14.8V, or 16.8V fully charged. You need to be clear on what chemistry you are using, since one is more dangerous than the other, so make sure you know before you hook them up to a charger.

That said, what you are proposing with have issues if your packs, let alone the cells in them, get out of balance. If they do, the BMS for the pack with the highest voltage will stop the charging for the full series of packs. At the pack level, the cell with the highest voltage with stop the charging for that pack. So, none of the packs or cells will ever balance.

For the charger, most cheap chargers, at least the non-brick style, have a potentiometer in them to adjust the voltage, although I'm not sure what you mean by "ordinary e-bike charger". So, if all the packs in series, when fully charged are 58.4V fully charged (14.6 x 4), then the charger should be adjusted to 58.4V for charging. If the batteries are Lithium Iron Phosphate (LiFePO4), then you would mainly have the balancing issue above to deal with, but you won't burn the house down. If the batteries are Lithium Ion I would scrap the idea, or forget the BMSs since they can't do the job that one BMS for the pack would do, and actually do the opposite.
 
I have used good condition Toyota Prius Hybrid Batteries. this battery is having 7.2V I don’t how many amperes on it.
anyway, I want to make a 60V battery pack from these batteries for an electric scooter.
since this battery is 7.2V so I don’t know which BMS has to connect with it,
I just wish to know if it is possible to series Lithium or hybrid batteries without any BMS.

Originally almost all electric scooters had 12Vx6 lead acid batteries (60V) connected on series. no BMS on it we are using the charger directly.

In the same way, it is possible to series lithium or Hybrid batteries without any BMS and charges them directly?

I am expecting a clear and detailed answer from experienced members on this forum.
 

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Not a good idea - you need a BMS. The purpose being to keep the cell voltages the same, and stop one or more from getting too high. or low. (Look up what happens when you overcharge a Lithium cell.)

Ok, you CAN do it without a BMS. Maybe you charge each cell separately. Or you're there with a volt meter monitoring the cells. Or you like risks. But in general, you want to use a BMS.

Which BMS depends on the cells and your planned usage. I don't know much, but my thought is the BMS must be rated lower than what you want to draw from your cells (to effectively protect your cells), but high enough to meet your battery goals. (ie. Full throttle on your bike doesn't cause the BMS to shut off the battery to protect it.)

Lots of info to read and to know. Good luck!
 
@ColinB,
Thank you. and please let me know what kind of BMS i i can use for this type battery.
 
Those are not "Lithium Iron". Those are NiMH. Good thing you posted a picture.
There's a forum sticky on those
https://www.endless-sphere.com/forums/viewtopic.php?t=6726

You should go to the battery forum if you need more info, so you don't burn your house down, and share pics right away, so they know what you're talking about.
 
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