NewStats: 3,262,427 , 8,177,132 topics. Date: Monday, 02 June 2025 at 09:26 AM 38674a

ewizard1:

Brand new Samsung 18650 cell for N1800?

Why you con turn am to question na
I know it worth it bro.

Cells don hard to find.

dollarnaira:


Brand new?

Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

AdexAyanfe:


Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

Issue with bms.

AdexAyanfe:


Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

Definitely it's a charge controller issue.

I have an issue like this on ground.
I am thinking of a way out( I think it happens mostly on this pwm controller reason is you can't set it) if you find solutions let us know

AdexAyanfe:


Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

what setting did you set as your maximum charge voltage on your controller? The bms over voltage protection is coming up thereby causing voltage fluctuations

AdexAyanfe:


Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

nothing to worry about my setup has been like that for almost two years now, since bms cut it off at 12.6..

AdexAyanfe:


Please what's wrong with my setup. I've presently assembled 3S3P li-ion battery( while waiting for more batteries) with 3S 40A bms, with the cell all balanced. But anytime its fully charged to 12.6v (I'm only charging solar for now), the voltage then start fluctuating at 13.8v, 13.9v, 14.1v.
But when I checked the actual battery voltage (bying the bms) I noticed charging has been cut off and it was around 12.55v then.

But anytime it starts fluctuating due to charging disconnect, once I put a reasonable load on it, it adjust itself and displays 12.6v.

Please what could be the issue, I've tested 2 3S 40A bms, it's the same.

Could it be my solar charge controller

@dollarnaira @penuelseun @officialfestus @everyone

Your system is working as it should based on parameters of both the charge controller and the BMS, you didn't (can't) adjust the parameters on Ur CC as it is set for lead acid battery at 14.4v, while Ur BMS is locked at 12.6v (which is the verified safe working voltage for 3s lithium ion battery packs).
So while the CC tries to get to 14.4v the BMS clips it at 12.6v the reason the reading after the BMS is 12.55v which is less than 12.6v.
The increase in voltage when load is applied is that the inverter is pulling direct from the CC and since it can do higher than 12.6v, it would naturally increase, and the fluctuations are due to the solar fluctuation due to cloud covers.
For optimal use, get a CC with adjustable settings so you can set Ur voltage at 12.6v max and stop clipping on Ur BMS or else you might fry Ur BMS and in turn Ur CC. Cheers

dollarnaira:


Issue with bms.

Oooh...I'll check it again boss. Thanks

Obnoxious2001:

Definitely it's a charge controller issue.

I have an issue like this on ground.
I am thinking of a way out( I think it happens mostly on this pwm controller reason is you can't set it) if you find solutions let us know

I guess as much, cus the lowest float voltage is 12.7v on the pmw and it will rather keep pumping up the voltage unless bms cut it off. Probably some other different pmw does better at that.

Penuelseun:
what setting did you set as your maximum charge voltage on your controller? The bms over voltage protection is coming up thereby causing voltage fluctuations

12.7v. That is the lowest the pmw could be set to.

taiwooguns33:
nothing to worry about my setup has been like that for almost two years now, since bms cut it off at 12.6..

ooooh...wow. Alright boss. Thanks 👍

saint2ace:


Your system is working as it should based on parameters of both the charge controller and the BMS, you didn't (can't) adjust the parameters on Ur CC as it is set for lead acid battery at 14.4v, while Ur BMS is locked at 12.6v (which is the verified safe working voltage for 3s lithium ion battery packs).
So while the CC tries to get to 14.4v the BMS clips it at 12.6v the reason the reading after the BMS is 12.55v which is less than 12.6v.
The increase in voltage when load is applied is that the inverter is pulling direct from the CC and since it can do higher than 12.6v, it would naturally increase, and the fluctuations are due to the solar fluctuation due to cloud covers.
For optimal use, get a CC with adjustable settings so you can set Ur voltage at 12.6v max and stop clipping on Ur BMS or else you might fry Ur BMS and in turn Ur CC. Cheers

Thanks for your response boss. I have a question though.
Going by your response, the CC will peg the max voltage at 12.6 right? If so where will I hook the CC.
For the part of "Stop clipping on ur BMS", is it at the solar input or battery input on the pmw the CC will be?

AdexAyanfe:

Thanks for your response boss. I have a question though.
Going by your response, the CC will peg the max voltage at 12.6 right? If so where will I hook the CC.
For the part of "Stop clipping on ur BMS", is it at the solar input or battery input on the pmw the CC will be?

By "CC", I think he meant your PWM charge controller.

The CC is simply your charge controller (PWM type) in the picture you ed. That device is your CC

He's advising you to get an MPPT charge controller so you could replace your current CC (which is a PWM). The reason for replacing is so you could set your max charging voltage to 12.6v on the new MPPT charge controller

Wizyoung:


By "CC", I think he meant your PWM charge controller.

The CC is simply your charge controller (PWM type) in the picture you ed. That device is your CC

He's advising you to get an MPPT charge controller so you could replace your current CC (which is a PWM). The reason for replacing is so you could set your max charging voltage to 12.6v on the new MPPT charge controller

oooh...thanks boss. Now I get it 👍
I thought he was referring to buck converter. To peg the voltage at 12.6v
CC- Charge Controller 👍...Understood. thanks

AdexAyanfe:
oooh...thanks boss. Now I get it 👍
I thought he was referring to buck converter. To peg the voltage at 12.6v
CC- Charge Controller 👍...Understood. thanks

Will suggest you DON'T OVER LABOUR your cc. Get an edible pwm or a 5A buck converter if on a tight budget. Protect your battery via these b4 u it via bms. Protect! Protect!! Protect!!!

dollarnaira:


Will suggest you DON'T OVER LABOUR your cc. Get an edible pwm or a 5A buck converter if on a tight budget. Protect your battery via these b4 u it via bms. Protect! Protect!! Protect!!!

Okay boss. Thanks for your response.
Yeah, I have a 5A buck converter.
Please is the wiring illustration to connect the buck converter correct boss?

AdexAyanfe:

Okay boss. Thanks for your response.
Yeah, I have a 5A buck converter.
Please is the wiring illustration to connect the buck converter correct boss?

It is correct.
How big is your battery?
If not very big and 's voltage not higher than the converter's max, the buck converter can work without the cc after editing to 12.6v. Try both out to make the best choice.
What is the wattage of your pv ()?

A very small heat sink is missing in the converter.

AdexAyanfe:

Okay boss. Thanks for your response.
Yeah, I have a 5A buck converter.
Please is the wiring illustration to connect the buck converter correct boss?

not correct, you place the buck converter between the s and the charge controller not between battery and charge controller

AdexAyanfe:

Okay boss. Thanks for your response.
Yeah, I have a 5A buck converter.
Please is the wiring illustration to connect the buck converter correct boss?

what is the size of your solar s as a 5a buck converter is small for sizes over 80w

Penuelseun:
not correct, you place the buck converter between the s and the charge controller not between battery and charge controller

We are here to learn. If the buck of 5a is in between the pv and cc the the purpose of the cc is defeated esp if the cc is of greater amp than the converter which it is in this case.

The converter here prevent the battery from hitting above 12.6v.

dollarnaira:


We are here to learn. If the buck of 5a is in between the pv and cc the the purpose of the cc is defeated esp if the cc is of greater amp than the converter which it is in this case.

The converter here prevent the battery from hitting above 12.6v.

Have you connected it this way before? Buck converter between and cc was how I connected mine and it worked perfectly

dollarnaira:


It is correct.
How big is your battery?
If not very big and 's voltage not higher than the converter's max, the buck converter can work without the cc after editing to 12.6v. Try both out to make the best choice.
What is the wattage of your pv ()?

A very small heat sink is missing in the converter.

Thanks boss.
50w .
Do you mean as illustrated in my diagram below? Like I should totally by charge controller?

Penuelseun:
what is the size of your solar s as a 5a buck converter is small for sizes over 80w

My is 50w boss

Penuelseun:
not correct, you place the buck converter between the s and the charge controller not between battery and charge controller

Something like this?

dollarnaira:


We are here to learn. If the buck of 5a is in between the pv and cc the the purpose of the cc is defeated esp if the cc is of greater amp than the converter which it is in this case.

The converter here prevent the battery from hitting above 12.6v.

You mean this connection will successfully prevent the battery from hitting above 12.6v when connected as illustrated below?

But with the PV going into the buck converter input, will the out still remain pegged at 12.6v even when the PV input voltage fluctuates due to different intensity of the sun at different times? Or will the output remains unchanged at 12.6v nevertheless?

Penuelseun:
Have you connected it this way before? Buck converter between and cc was how I connected mine and it worked perfectly

You mean this connection will successfully prevent the battery from hitting above 12.6v like this?

But with the PV going into the buck converter input, will the out still remain pegged at 12.6v even when the PV input voltage fluctuates due to different intensity of the sun at different times? Or will the output remains unchanged at 12.6v nevertheless?

AdexAyanfe:

Thanks boss.
50w .
Do you mean as illustrated in my diagram below? Like I should totally by charge controller?

Yes!
What is the voltage of your pv?
This is for small set up say 30ah or less.

Note that a good pwm will win.

AdexAyanfe:

You mean this connection will successfully prevent the battery from hitting above 12.6v like this?

But with the PV going into the buck converter input, will the out still remain pegged at 12.6v even when the PV input voltage fluctuates due to different intensity of the sun at different times? Or will the output remains unchanged at 12.6v nevertheless?

Yes!
12.6v is the full charge voltage. It will stop charging at this voltage. Didn't look at your diagram well before I pushed in my thoughts.

Buck 5a
Cc 20a

Do the Math

AdexAyanfe:

You mean this connection will successfully prevent the battery from hitting above 12.6v like this?

But with the PV going into the buck converter input, will the out still remain pegged at 12.6v even when the PV input voltage fluctuates due to different intensity of the sun at different times? Or will the output remains unchanged at 12.6v nevertheless?

Yes, you just have to set your buck converter output voltage to around 12.7v, using a pwm charge controller that can go as low as 12.6v is still your best option, any of these controllers s 3s lithium charging

AdexAyanfe:

You mean this connection will successfully prevent the battery from hitting above 12.6v like this?

But with the PV going into the buck converter input, will the out still remain pegged at 12.6v even when the PV input voltage fluctuates due to different intensity of the sun at different times? Or will the output remains unchanged at 12.6v nevertheless?

Did this some years ago

dollarnaira:


Yes!
12.6v is the full charge voltage. It will stop charging at this voltage. Didn't look at your diagram well before I pushed in my thoughts.

Buck 5a
Cc 20a

Do the Math

Get these charger controller and rest.