hello , i have right now a 4wd car platform powered by 3 18650 3.7v batteries which are in a battery holder , i want to upgrade the car and add some solar power so i wont have to charge the batteries all the time, i wanted to know since i got confused on how can i charge all 3 batteries with solar panels? the batteries should provide power to 2 l289n motor drivers whilst also being charged by the solar panels ( if not possible at the same time , then i dont really mind that once below a certain point the charging will take place and the car will stop) if its possible i would like to knnow the components i need to order to achieve this, thank you in advanced!
Moved to Project Guidance.... Please don't post in Uncategorized again.
Hi, @tsomech
Welcome to the forum.
Sorry I had to space it out a bit.
It is best to write your posts in point or paragraph form to make it easy to read.
Thanks.. Tom.. 
how much Watt has the panel?
i havent bought the panel yet, i only have the batteries, im a programmer so most of the electronic stuff are unknown to me so im seeking for help , i know the basics mostly
how big a battery capacitance?
how you charge it at usual?
i think around 3350mAh and i usually charge it with 220v ac charger which plugs into the wall
37,2Wh. I think you need 50W panel and perfect sun light to 1 hour charging time.
and proper charger
any advice on what charger to use?
Solar and Li charging does not work very well with each other.
In order to charge my LiPo's, except for LiFePo4's, my solar panels for Li charging charge 2 series connected 2Ah batteries. The batteries run an inverter. Connected to the inverter is a Li battery charger and so on and so forth.
LiPo chargers do not do load sharing. The exception is when using LiFePo4's.
With all that. You can use a TP4056 thingy as a psudo load sharing/charging thingy for the LiPo's. The issue will be that the batteries will last about 3 or 4 months before the need replacing. Also LiPo does not do below freezing very well; exception LiFePo4s.
what about bms?
it depends on panel's characteristics
A BMS works very well with LiFePo4's.
I have 3 banks of 100Ah LiFePo4's. 2 24V banks and one 48V bank that are managed by BMS.
BMS is protection and charging advisor, it need some sort converter due to various voltage from panel
i would using something like DPS3005 or "LM2596 DC-DC Step-down Adjustable CC/CV Power Supply Module"
i've found a pack of 4 3.2v lifePo4 batteries which are the same size as the 18650 , will charging them together be possible? since the other lifePo4 are huge
I do not know. I've not tried to charge 4 3.2V lifepo4's that are the same size as the 18650.
I've tried using the tp4056 method and it does work but it destroyed batteries.
I have spent a lot of money trying to charge LiPo's from solar. Good luck.
then i think ill give up on solar charging, maybe change to wireless charging?
Inefficient, resort to plugging a charger in.
Tom..
