I am looking for a module to use these 18650 batteries as a power source, 2 or 3 cells. Ideally, I would like to run off the battery voltage, and hook up an external DC 12v power supply to constantly charge the batteries. I seen these "BMS" modules on eBay, but it looks like the power supply charge and load are using the same lines into the battery array. I was looking for separate power-load output, with a separate power-charge input. To me this would seem like a common thing, but I am having trouble finding something for this purpose. Has anyone seen anything like this ?
DocStein99:
I am looking for a module to use these 18650 batteries as a power source, 2 or 3 cells. Ideally, I would like to run off the battery voltage, and hook up an external DC 12v power supply to constantly charge the batteries. I seen these "BMS" modules on eBay, but it looks like the power supply charge and load are using the same lines into the battery array. I was looking for separate power-load output, with a separate power-charge input. To me this would seem like a common thing, but I am having trouble finding something for this purpose. Has anyone seen anything like this ?
No, I haven't seen such a thing and would not buy/use it if I did see it. Battery charging is based on current, not voltage, while your project is based on voltage. No, the two at the same time are not compatible.
Paul
The machine at the shop needs 6v-9v for it's battery back up memory, and company want to charge $125.00 for the device. I am trying to save money here. I can stick (2) cells in there, it will run - except now they have to keep plugging in a charger to recharge the back up batteries. Do you see the issue here ? How can I handle this situation. I would like some rechargeable batteries, in there - on a constant charge so we can close the door and be done without this nuisance requiring any more maintenance.
You could use a voltage regulator on the output to keep the voltage at 6 volts.... I did it for charging lithium batteries with a solar cell... when the cell is charging it outputs 5v, the lithium ion battery charges between 3.7-4.2v.. so i put an LDO 3V regulator to match the output of two AA batteries....
Ok, I know how a voltage regulator works. Your are on the rigtht track with the solar cells. That solar array constantly recharges the batteries right? Are you running off the battery power WHILE it is charging ?
yes. It is for a weather station... during the day the solar panel charges the battery and provides power to the sensor... the weather station doesn’t draw very much though...
I think this will do what you want? (no specific endorsement of that seller - the same item is sold by many vendors)