For some time, something has been on my mind every so often.
And since you guys are awesome and always give great feedback i thought, lets ask and see what you think.
This is very abstract, just to get the idea, the batteries would all be rechargeable lithium cells:
The drivers would either have an enable input or a switch between the output and the input of the LED.
That means, when the light is off, there is no current flow.
The idea is to avoid cell balancing and enable parallel charging with more current and increased battery capacity.
The LED would be a Cree XP-L V5 running at 3A.
Not sure I understand the purpose/advantages. If cells are in parallel then you don’t really have to worry about cell imbalance. You could just have one more powerful charger rather than four less powerful ones.
Why have multiple drivers?
Edit: or maybe you want to be able to use different cells with different states of charge at the same time?
Mostly just for simpler charging and discharging, the cells will drift apart over time and need to be balanced while charging.
This way, every cell charges individually until at full capacity.
You get simple 1A chargers and protection boards of Ebay, that was the main idea behind it, they only cost a buck per board.
I forgot to mention, build in batteries, not replaceable, maybe then it makes more sense
Cells in parallel will all have the same voltage so will stay balanced when you charge them. This is how large packs like in tesla cars are arranged. Cells in a parallel string are simply connected in parallel. You really don’t have to worry about it especially when all cells are the same make and model (discharge curves and capacity will be near identical). IMO this is more effective and simpler than having a separate charger for each cell.
Li-Ion cells are fine in parallel, you can charge them or discharge them and they stay balanced automatically. It’s series connection you have to watch and make special arrangements for balancing cells.
NiMH cells are more finicky about being in parallel. They don’t like being charged that way and some charging algorithms will have real trouble terminating the charge correctly.
Of course, if you’re doing this to be able to switch between different types of driver - or have multiply redundant backup circuits, for that matter - then nothing I’ve said here is particularly relevant and you should just carry on as you are
One thing to check, though: whether your drivers will tolerate having a voltage applied to their outputs by another driver while they’re turned off.
As the other said with the cells in parallel they are balanced all the time. For all intents and purposes they are 1 large cell.
This is how I charge my cells, I have a big bank of 14 parallel cell holders and charge them all at once. Works great and they always come out perfectly balanced.
Also using separate drivers and charging circuits will leads to far more balance issues. It is very difficult to get parallel power inputs to share the load evenly. There has to be some kind of feedback loop for it to work. Otherwise 1 driver will take all the load until it reaches it’s max and then the next driver will take the load ect.
You are far better off just running the cells in parallel like normal.
Now in series balance problems can be an issue but only in cases where the cells are never separated for charging. In a flashlight where you remove all the cells and charge them all separately, at least every few charges, balance issues are a non-issue.
