Electronics > Repair
ZKETech EBC-A10H blown MOSFET - Help Confirm Part Number
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tifkat:
I picked up a used ZKETech EBC-A10H battery capacity tester recently, which was from a deceased estate. The seller knew nothing about it, but it powered in and came with all the standard cables.
When I set it up and powered it on, it was reading a continual ~8A at 0v with nothing connected.
I did some tests and of the two MOSFETs, one had a forward voltage of 2.93v and the other had about 0.05v (testing in diode mode)
I dismantled the unit and I found the under-board MOSFET to be in good physical state. It's an IRFP250M. This is the guy with the 2.93v forward voltage.
The one with the 0.05v looked a little worse for wear.
As it's missing a big chunk, I can't readily identify it. I am assuming that the 2 would be identical, but it would be awesome if someone with one of these testers can confirm the MOSFET which is protruding from the board, next to the temperature component (KSD-01).
What else should I check? Would it be sensible to change both MOSFETs together? Should I look at an alternative MOSFET?
tifkat:
Those voltage levels were when testing G to D. Red lead on G, black lead on D.
whatboy:
L9oks like they are in parallel... if so they are equal.
sam_sam_sam:
I would like to add something to this post as I have had the same issue with this battery tester
The issue with this battery testing machine is that under no circumstances should you ever try to charge battery packs with any kind of BMS protection boards because some BMS boards do not like to be over voltage or over current and this battery testing machine has the following issues with the way this battery testing machine is designed and setup
The issue is that if the BMS board does not like either situation it spikes the voltage to 24 volts or higher and drops down 0 volts and if you keep trying to charge the battery pack and keep trying it destroys some components on the controller board and I personally have not found the problem with what gets destroyed by this situation
When you set the voltage and current what you are really doing is setting the current only based on the voltage at the time you start the charging cycle this not an issue when you are charging battery cells that are naked meaning no BMS board of any kind or any other type of device that disconnects the battery from the current or voltage
One other issue that you need to be aware of is if you have a lead acid battery that is not taking a charge is just as bad because it spikes the voltage and there is no current being taken by the battery under being tested
The mosfets are for the discharge mode only and controlled by the controller
The XL4015 5A DC Buck Step Down Voltage Converter Constant Current ic chip controls the charging system but not in the way this ic chip is normally controlled it is in the current mode only but I have not found any data sheets showing how to use this chip in the current mode only because it is controlled by the controller and there is no information about how this is controlled
One note you can modify this testing machine to only monitor the voltage/current function but you have to remove the mosfets and the XL4015 ic chip and add a jumper wire on the ic chip
The charging relay to the output pin on the XL4015 ic chip footprint and then you can use it as a monitor you also have to add a set of wire to the mosfets board where the are to have this device in parallel with the battery and power supply and the loading of the battery for this to work properly
One other note you can change the switching power supply from 24 volts to 12 volt switching power to the same footprint also you can us a XL4015 module that has a adjustable voltage/current pots with a voltage meter module boards both of them can be bought from EBay or any other seller that carries them if someone is interested in finding one just post it in this post and I will post a link to where you can find one
What I going to build is a BMS protection board system that can test them using the XL4015 module board that I referred to earlier and you manually adjust the voltage and current to suit the battery pack that you want to use
I have tested this configuration and concept and does work very good I just not had time to put this together in an enclosure and make it interface with the battery testing machine when I have this project completed I will post some pictures of the completed project
sam_sam_sam:
Very important update on this issue about the mosfets going bad on this battery testing machine I have been working on this issue some more recently and have more information about it
The issue with not being able to battery test BMS boards with this device has bothered me ever since it happened to me but I want an answer to the question to WHY ??? you can not test BMS protection boards
So a couple of days ago while I was at work I was brainstorming ( not having a brain fart ) about this issue and decided to run this test on my battery testing machine to get some answers how I ran this test is as follows
The the parameters are as follows
Set the battery testing machine to CC 4.20 volts @ 1.00 amps
But here is the twist of this test
Hook up the voltage leads to a 18650 battery cell
Hook up the output power leads to two 28 volt incandescent light bulbs in series
Then hit start on the testing machine what results do you think you will get
The the incandescent light bulbs light up at 24 volts and the screen shows the following
Battery voltage is 3.994 volts
Battery current is 840 milliamperes
Conclusion is that this battery testing machine only controls the current but to make sure that my hunch is correct I ran the following test several times with different amperage as follows
Set to as follows
100 milliamperes light bulbs did not light but the amp screen shows 100 milliamperes
200 milliamperes light bulbs did not light but the amp screen shows 200 milliamperes
500 milliamperes light bulbs are lighting dimly and the amp screen shows 500 milliamperes
Final conclusion is that this battery testing machine only adjusts the current output
But I have a very important question to ask how is this battery testing machine controller controlling the buck converter circuit I can not find any information about how to control this buck converter in current mode only
The data sheet only has how to use it in voltage mode or in cv cc modes together but not only the current mode
I did read some where that you use the feedback pin to control the current mode but no one has elaborated about how it functions in detail and better yet with a microcontroller how you would control it
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