Hello folks!
I have a simple AA battery USB charger. It can take a vIn from 2.4v-4.5v, and output a vOut of 5v, perfect for charging smartphones and such using NiMH batteries.
But it can only output 1 amp if vIn > 3.5v. This means using 3 NiMH batteries. But you should never discharge a NiMH battery below 1v, or you will damage the battery. With 3 batteries, this means the circuit should stop when vIn reaches 3v. But the circuit keeps on chuggin to well below 2.4v, overdischarging my batteries.
Now I'm no electronics wiz. I'm just a project kiddie. I bought the finished circuit on ebay for $5, soldered a battery and a switch to it, and stuffed it in an Altoids tin. I asked on another message board if there was a simple solution to my problem, and they started talking about comparators and hysteresis and SMT components and getting a PCB prefab'd by a professional PCB manufacturer... all of which are a bit above my skill level (and more effort than I was hoping to put in).
Is there any simple way of stopping my circuit when vIn reaches 3v? Because at the moment, the simplest way I have is checking the batteries with a voltmeter every 30 minutes or so, and then manually flipping the switch when they get too low.
Thanks for any help!
I have a simple AA battery USB charger. It can take a vIn from 2.4v-4.5v, and output a vOut of 5v, perfect for charging smartphones and such using NiMH batteries.
But it can only output 1 amp if vIn > 3.5v. This means using 3 NiMH batteries. But you should never discharge a NiMH battery below 1v, or you will damage the battery. With 3 batteries, this means the circuit should stop when vIn reaches 3v. But the circuit keeps on chuggin to well below 2.4v, overdischarging my batteries.
Now I'm no electronics wiz. I'm just a project kiddie. I bought the finished circuit on ebay for $5, soldered a battery and a switch to it, and stuffed it in an Altoids tin. I asked on another message board if there was a simple solution to my problem, and they started talking about comparators and hysteresis and SMT components and getting a PCB prefab'd by a professional PCB manufacturer... all of which are a bit above my skill level (and more effort than I was hoping to put in).
Is there any simple way of stopping my circuit when vIn reaches 3v? Because at the moment, the simplest way I have is checking the batteries with a voltmeter every 30 minutes or so, and then manually flipping the switch when they get too low.
Thanks for any help!