Battery Testing With Maynuo M9812

[MotoDan]

Hello all,

I recently bought a Maynuo M9812 DC load and am trying to do some battery capacity testing - specifically for lithium coin batteries. The manual shows a time limit range of 1 sec to 16 hrs, but I can seem to find a way to change this value. Ideally I would like to go beyond 16 hours since a CR2032 for example has an approximate capacity of 220mAh @ 2mA. This equates to around 110 hours.

So far I really like the M9812. Hoping someone else has done some battery testing and knows of a way to change the cutoff time.

[BillB]

I've got the ITech 8511+ which I thought would be similar enough to help, but looking at the M9812 that does not seem to be the case. (ITech goes to 99999 seconds) 

Maybe they are using a 16 bit number for the seconds timer, which would limit you to a maximum of ~18 hours?

[ovnr]

The Maynuo loads are not very appropriate for the task. My M9712 set to 0.5 mA CC reads 0.2 mA - while actually taking 1.6 mA. Set to 500 mA, it takes 501.2 mA. So there's a mostly fixed offset, and at very low values it'll just completely ruin any hope at an accurate result.

I doubt there's anything that can be done about the time limit.

[MotoDan]

What about setting the time limit? The specs show 1 sec to 16 hrs, but not how to set the timeout.

[Mr. Scram]

I’m interested in one of these units, so don’t mind me taking a seat in the thread.

[georges80]

I think to use the battery test mode in a useful fashion (i.e. to collect the discharge curve data and then export to csv etc) you need to be using their software package and the USB/Serial dongle. I have a home made isolated dongle and their software is pretty reasonable.

In the battery mode you can set time limits and sampling rate etc to log the discharge curve.

cheers,
george.

[Mr. Scram]

I think to use the battery test mode in a useful fashion (i.e. to collect the discharge curve data and then export to csv etc) you need to be using their software package and the USB/Serial dongle. I have a home made isolated dongle and their software is pretty reasonable.

In the battery mode you can set time limits and sampling rate etc to log the discharge curve.

cheers,
george.

Are you referring to using software versus using the device on its own? If so, I gather using the device together with home grown software would be viable too?

[georges80]

^ Maynuo software. It's pretty reasonable for what it is. The battery mode works just fine and I have used it to get Ah ratings of various li-ion cells at differing load currents (10's to 100's of mA draw).

cheers,
george.

[Macbeth]

Maynuo uses the MODBUS protocol vs SCPI. Doesn't matter if you use the OEM software. If you need to DIY then there is https://github.com/MetalPhreak/pyMaynuo to help you out.

The 9 pin D sub is not RS232 but TTL. Not isolated either.

[MotoDan]

Thanks for all the comments. I decided to download the Maynuo M9700 software which allowed me to run my battery test without a time restriction.