Serial to usb on Kunkin KP184 electronic load

[interflexo]

Yes. The KP184 Modbus Software is compatible with Windows 11.

Please check the drivers of your USB to Serial Adapter for any issues regarding Windows 11.

[rallyhard]

Thank you to the forum admins for maintaining this excellent resource.

I bought Interflexo’s software and find it useful, but have a bit of an issue that I was wondering if anyone else has. I tried asking Interflexo/Manuel, but haven’t heard back yet.

We use the KP184 along with the PC software to perform discharge tests on deep cycle lead-acid batteries. It works well except that during the test, the voltage will occasionally dip severely for a very brief moment and then continue normally. The test bench is not being disturbed when this happens. I’ve tried wiggling the wires between the unit and battery during the test to see if there is a bad connection, but the voltage doesn’t change at all when I do that. It happens randomly during tests whether using remote or local sense. The dip in voltage will eventually cause the test to end early as it dips below the test end voltage, so I have to keep restarting it.


Thanks for any input. 

EDIT: Here are the test reports showing the voltage dips:

https://i.postimg.cc/JtC8kjR3/kp184-Report1.png

https://i.postimg.cc/6qvwqMx5/kp184-Report5.png

[interflexo]

Hi,
No other customer complains about this. It must be hardware specific.
Does this happen with only one specific lead-acid battery or with other ones as well?
Does this happen with a Li-ion battery / LFP battery  / DC Power supply discharge tests as well? Please do some similar basic tests with your system to rule out the device being tested.
What USB to Serial adapter are you using?

Sometimes lead-acid battery internal serial busbar connections get corroded, break and show a similar behaviour.

On one of your test reports the reason for the end test was Kunkin KP184 shut the load OFF (not the software).
On these long tests the Windows system power settings should be configured to not interfere with the on going test.
Can you use an oscilloscope and do a trigger test with a low voltage (Ex: 11V) to make sure the quick voltage dips are not real?

[korjaa]

Hello,


I recently bought one of these KP184s and I've been using it to test Ryobi drill batteries. I have also noticed that occasionally I get spikes, usually downwards, but there have been few upwards also.

Example of downward spike (0A...10A toggling, 15 period):


Example of upward spike (0A...15A toggling, 15s period:


0A...5A toggling causes periodic spikes?



The message checksum is checked, so the data should be OK. I know the checksum is calculated as I spent a while debugging it. The source is available in https://github.com/korjaa/kunkin-kp184, in case anyone is interested. I have not inspected the waveform with a scope to verify if the spike is real.

Does this happen with a Li-ion battery / LFP battery  / DC Power supply discharge tests as well?

Mine are Li-ion batteries, 5s2p

Does this happen with only one specific lead-acid battery or with other ones as well?

Multiple batteries for me.

Update:
Tried scoping the waveform, wasn't able to catch the spike during test. I did however noticed that if the load is small 100mA/10mA/0A, there is actual ~2V..3V dip in the voltage occasionally, maybe every 30s. The spike period matches with my earlier 0A...5A toggling test.


It does not happen if I disconnect the battery from KP184. The downward slope of the spike is related to the current.

Below are some spike lengths measured with different load values:
Output OFF -- 200ms (happens even with the output off)
8mA -- 1ms...6ms
30mA -- 200us...300us
100mA -- 60us...80us
500mA -- 40us...60us
700mA -- 40us
1A -- couldn't get it to trigger in few minutes.