Questions re lithium batteries

[William_H]

I have ordered 2 of these batteries from China Pardon our interruption...
I have a Shoprider mobility scooter I use to tow my ali dinghy down to the water for access to swing mooring. It was designed to use 2x 40AH deep cycle LA batteries. They have died again 3rd set over some years. I propose to fit these Li batteries in series for 24v operation. I have always charged the LA batteries with 2x 20v 10w solar panels in series. Less than half an amp. So my questions are along the lines of am I going to get in trouble just chargiong the li batteries the same way. I have also available 170 w 40 v panel which could also be used for charging at like 4 amps max.
The batteries have a charge control built in. I thinkl that means that on reaching full charge it will cut off all charge. I wonder then if 40 v appplied to the batterie swill be too much. 20v each hopefully.
I have a possibility of arranging a 20v and a 10 v panel in series to give 30 v no load which might seem safer but obviously less charge at marginal sun shine. Recharge time is not a real concern.
I can't see any indication of max voltage for the batteries when not taking charge
Have I got the right idea. Should I buy an MPPT controller that can be set for Li battries? I hope some of our experts can advise. ol'will

 

[PaulRainbow]

You cannot connect the solar panels directly to the batteries and if you did that with the LA batteries that's likely why they keep dying. Lithium batteries are typically 3.2V per cell and charge voltage should be 14.4V, for a 12V pack, absolute max, preferably a little less. You also should not float charge Lithium batteries.

If you did connect the panels directly to the battery the BMS should block the charging, as the voltage will be too high. Finally, the BMS is there to protect the battery, it is not a charge controller, it's the last line of defence.