Charging NIMH AA batteries.

I have a question about charging with solar. I know they need to be charged to a certain voltage and when they peak they go back down by a certain amount. But is there a better way to estimate how high you can charge the voltage to as well I mean I see nothing mentioning voltage only current. And I know the voltage does go up as well but what’s the limit for it ?

Thanks

With batteries you charge them at the “target voltage” or what they’re rated for, for instance a 3.7V LiPo. Batteries are rated for “charge rates” and “discharge rates”. Like for some RC battery packs they could say “1C” which is 1 Coulomb per Second. Here for what a coulomb is: https://www.physicsclassroom.com/class/ … lomb-s-Law. Big picture, this regulates that a pack for “1C” can be charged at 1A current flow, well technically most packs are labled 1C for discharge rates but I hope this helps a little.

What you have to make sure of is checking and double checking the datasheet for the individual batteries. They will tell you how at what voltage to charge the batteries and the maximum amount of current that can flow while charging.

What happens with batteries is that while charging it becomes harder and harder to pump in more electrons so the current will lower. The electric potential, voltage, will equalize to the charging target voltage and current will go down. Ideally, a perfect 3.7V battery will charge to 3.7V and once it is done charging the current will be 0. This is why we have battery management systems to regulate these variables and create an optimum charge experience. It’s possible to over heat, over charge/discharge, and other catastrophes.

Solar is no exception as far as the battery’s charging experience is concerned. The problem is that solar isn’t constant and can fluctuate depending on the sunlight. All the more reason to have a solar battery management system (BMS).