While testing some 18650 cell short circuit current capability I encountered a big problem with my multimeter, the Aneng AN8008. It has not enough resolution, maxing out at about 10A. So I scoured the web for a solution. Didn’t find anything, unfortunately, besides “current warning threshold”, and a self-proposed hardware change – halving the current sensing resistor. Both methods have downsides – one still doesn’t allow my meter to measure over 10A, only shifts the buzzer threshold and second one leads to worse sensing at lower currents, as well as having the displayed value halved, which will be confusing in the long run.
Solution? Use my older multimeter, it’s capable of 20A.
BUT, I encountered this tutorial: https://www.jackenhack.com/aneng-an8008-modify-for-better-accuracy-faster-readings/ and had to modify my unit.
I started a bit backwards – from replacing the reference voltage decoupling capacitor. I stole all the necessary capacitors from a donor Xbox 360 motherboard, this way I know that they are of good quality and I didn’t have to order any parts.
At this point I had replaced all but one ceramic capacitors. Also, side note, the author of that tutorial had a Rubycon 100uF capacitor, while I had a crappy Capxon one. One more reason to replace it with a known good Nichicon part.
Yeah, I’m also not a big fan of the way the last capacitor is mounted, but as long as it does its job I’m happy. The electrolytic capcitor is the one I had left from recapping the Gigabyte motherboard.
So, did all that work did anything? Yes, the multimeter now autoranges in less than 1 second, compared to about 3-5 before this mod was performed.
How about Vcc noise? I sadly forgot to make my own measurement before the mod, but here’s a picture after the mod.
The oscilloscope shows almost no noise – ~4.4mV, that’s pretty much the level of random signals picked up by the probe wire.
Would I overall recommend this modification?
YES!
There is one more thing I found – enabling the temperature measurement, but for my needs I don’t reallistically need that function.
Thanks for reading!