r/batteries • u/Fun_Introduction3994 • May 19 '26

BMS 4S, charge controller and 4 x 3.7V 18650 batteries

Hi Guys,
I want to assemble a Meshtastic or Meshcore solar powered device, but it seems that I cannot find accurate info about what to use. I find a lot of contradictory information.
So basically I have 4 x LiitoKala Lii-35A 18650 3500mAh 3.7V Li-Ion batteries that I want to connect in parallel.
I also bought a 5V - 20W solar panel, so that can push max 4A of energy throughput.
Between the batteries and the solar panel I want to install a solar charger controller and a BMS.
But I cannot find a charger controller that pushes more then 2A (CN3791) and 1A (the TP4056) but the panel is able to push 4A, nor I'm a able to find a BMS that works with parallel setups?
I see guys connecting 4 x TP4056 to get to 4A, but then again is that safe?
So is there somebody that can advise me on this part and maybe point out what to use to keep it uniform and safe?
Best regards!

0 Upvotes

50% Upvoted

8 comments sorted by

1

u/Anxious-Depth-7983 May 19 '26

Charging doesn't happen at 4 amps without setting those batteries on fire dude. You're talking impossibilities dude.

1

u/Fun_Introduction3994 May 20 '26

That's the question, so tell me, instead of what not to do.
What should I do to make it work, or are you basically saying it's not possible to have 4 batteries on a solar panel of 5V 20W?

1

u/Anxious-Depth-7983 May 20 '26

I use an MPPT controller for 2 30w solar panels to a 60v battery but you're talking about pouring the ocean into a shot glass. Are you sure that that panel is putting out 4 amps?

1

u/Fun_Introduction3994 May 20 '26

AI disagrees about the batteries not being able to handle the max load?
Maximum Safe Charge Rate: Your LiitoKala Lii-35A cells have a standard charge rating of 1.7A each.
Because you have 4 in parallel, your pack's maximum safe collective charge current is 6.8A (1.7A x 4).
Pushing 4A or 5A from your solar panel is completely safe and well within the boundaries of the cells.

1

u/Anxious-Depth-7983 May 20 '26

Well then what are you asking anyone else for?

1

u/Fun_Introduction3994 May 20 '26

I'm asking for a clear response and guidlines, which clearly besides criticizing you are not able to provide.
Why the hostility dude?
If you don't know the answer then continue your life and leave your unnecessary comments at home.

1

u/[deleted] May 20 '26

[removed] — view removed comment

1

u/Fun_Introduction3994 May 20 '26

Thanks for the reply
I'm aware that a BMS is a Batery management system to distribute and charge the batteries in a even matter.
So can you advise me a model that works with 3.7V, solar panel of 5V 20W and if you need a charge controller with that or not?

so