Hi! Can I use two 2450mAh NiMH AA and one 2200mAh NiMH AA together in a circuit that calls for 3 AAs? I have a multicell charger, so I can charge them all back to 100% individually no problem.
<csb>
So I bought one of these premade DC-DC boost converters specifically made for charging high-drain USB devices like iPads and tablets and such. Here's the specs:
So I'm aware that one will die before the other two. That's fine. But is it safe? Is it bad for the batteries, or the circuit? What about when that third battery dies, but the other two are still running, and the device tries to draw high current, will it damage the battery some how?
Also, quick second question: The 3 batteries only got warm, but the boost converter IC got pretty darn hot. Finger started to hurt after pressing on the IC for about 10 seconds, which I think means ~50-60°c. Do you think I should put a heatsink on it? I dont have any special IC heatsinks, but I do have old copper CPU heatsinks and a dremel to cut them down, how would I go about attaching a piece of copper to it? Just thermal paste?
<csb>
So I bought one of these premade DC-DC boost converters specifically made for charging high-drain USB devices like iPads and tablets and such. Here's the specs:
Well it only supplied 200mA with two fully charged NiMH AAs (2.4-2.8v), but with 3 NiMH AAs, I get the maximum current my device can draw! (850mA). So obviously I need 3 for this to be a decent charger. Unfortunately, I don't have any matching sets of 3 AA NiMHs, because I always bought them in pairs. I have a matching set of 4 AAAs, but they are only 1000mAh, not really ideal for a mobile charger, despite the incredibly high efficiency rating (and its accurate, my batteries barely even got warm when charging at 850mA).Description:
1. Input 2V~5V DC voltage arbitrarily, can stable output 5V DC voltage, the input with two AA batteries can output current of 1000mA, single lithium battery power supply can output current of 1200mA, for mobile phone, camera, single chip microcomputer, digital power supply products.
2. high conversion efficiency, up to 90%, on average about 85%, 3.7V up to 5V/1A typical application efficiency reached 87%, below measurement chart for your reference
3. with indicator light
Electrical specification:
The input voltage: 2.0V ~ 5.0V
No load output voltage: 5.1V +/-0.1V
Conversion efficiency up to 90%, average 85%
Maximum output current: (can work for a long time):
Vin>=2.0V):600ma
(Vin>=2.5V):800ma
(Vin>=3.0V):1000ma
(Vin>=3.5V):1200ma
So I'm aware that one will die before the other two. That's fine. But is it safe? Is it bad for the batteries, or the circuit? What about when that third battery dies, but the other two are still running, and the device tries to draw high current, will it damage the battery some how?
Also, quick second question: The 3 batteries only got warm, but the boost converter IC got pretty darn hot. Finger started to hurt after pressing on the IC for about 10 seconds, which I think means ~50-60°c. Do you think I should put a heatsink on it? I dont have any special IC heatsinks, but I do have old copper CPU heatsinks and a dremel to cut them down, how would I go about attaching a piece of copper to it? Just thermal paste?