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Fan/Heater capacity tester problem - can't go beyond ~7 amps?

blutow

Solar Enthusiast
Joined
Dec 20, 2020
Messages
344
I am trying to run my first individual cell capacity test. I've got one of the cheap fan-based capacity testers.

On an individual 3.2v cell, I can't push more than ~6.8 amps (~22 watts). I'm running 10awg silicon wire with ring terminals and have basically zero voltage drop in the leads. If I hook up a 12v battery, there is no problem pushing more amps and watts.

Also, the voltage is reading about .1 low compared to my multi meter, but I guess I can live with that.

I have the amp limit set to 50 and wattage limit set to 130, so I'm not sure what is going on. I'm hoping I'm just doing something dumb and I don't have a bad tester.
Any thoughts? Thanks.

IMG_0480.jpg
 
How many watts do you get at 12V?

My guess is that the power rating is based on whatever the highest voltage the unit is rated at .... and you won't get that at a lower voltage. Maybe current limited?

I had one of these ordered and it never arrived .... maybe someone else who has used on will check in.
 
I had no issue going up to 130watts at 12v (the cuttoff I have set). I can't get it over 22 watts at 3.5v.
 
So, at 12V you are getting over 10 amps and only a little over 6 amps at 3.5V.

I have no idea how the devices applies the load but the 3.5 V would require a VERY low resistance and would have do over 37 amps to get you to 130 W.

I have no idea what is typical for these, but I know quite a few have used them and still hoping someone who has will check in.
 
I've used that device and some very similar designs.


 
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