Fantastic Small Programmable Electronic Load and Battery Discharger

I posted this on the RCGroups Battery forum and think it might be useful here, too.

I just had my ebike batteries, LiFeP04 16S/12Ah each, upgraded to LiIon 14S/22.4 Ah each or about 1,800 usable Watt Hours. With my style of always peddling with a medium load on my legs, I can get a theoretical 125 miles on a charge using an 80% DOD with both batteries in Parallel. I frequently ride from 35 to 50 miles so I needed a way to discharge the packs down to storage when I return from a weekend day ride. I don't usually ride during the week. I have Transistor Devices Incorporated 1,500 Watt and 4,000 electronic loads. However, they are very heavy and bulky and are kept in a garage cabinet. It takes a lot of effort to use them. I toyed with going the hair drier, resistor bank route but thought there must be something more precise and fun to use. I did a lot of investigating and finally, came across this fantastic, tiny up to 150 Volts DC, up to 40 Amps current and a 400 Watts maximum , very versatile programmable load and battery discharger. In battery mode, you can program Low Voltage Cutoff (LVC) and the load will be disconnected when that Voltage is reached. It also has an available option upon reaching LVC, to reduce current to half and then resume discharging until LVC is reached again, at which time, the load is cut permanently. It does standard CC, CV, CR and CW/Power mode discharges and shows capacity out in Ah or Watt hrs. It's fan is PWM controlled and is pretty quiet up to the 250 Watts that I have discharged at so far. This thing is tiny! There are two quite good videos on operation, tear down and accuracy out there to watch. All the reviewers are impressed with the quality of the build including PC boards and accuracy. For about $210 delivered from Chino, CA, this gem is very hard to beat. You could storage discharge four, 4S packs in parallel at up to 25 Amps total assuming a starting Voltage of about 4 VPC.

I can't seem to embed or link the short video I have of the unit in battery discharge mode reaching LVC and then dialing back current to half. I have no idea why, but I'm thinking of buying another one just to have. For me, it sure beats the light bulb, hair drier, resistor bank method. Just having the automatic disconnection of the load at LVC makes it worth the price. And it saves wear and tear on your charger not doing the high heat discharges.

The unit is software controllable and has two different interfaces on the back panel for this purpose. They are all over Ebay pretty much from one seller. Be sure to choose the one that ships from Chino, CA and not china if you're in the U.S. They have a warehouse there.

The manual: https://www.scribd.com/document/516768354/KP182-KP184-Manual

https://www.ebay.com/itm/265198724437

Excellent report, thank you

The manual says that it has "Voltage far end measuring function (remote sense)".
Unfortunately it says nothing else about it (as far as I can see).

I can see a V sense port on the front - have you tried it?
It looks like a co-ax connector - if you have tried it a picture of the cable end and how it is wired would be really useful.

Thanks

..... I frequently ride from 35 to 50 miles so I needed a way to discharge the packs down to storage when I return from a weekend day ride......

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.. :? Right there. ^^...i am interested to know what cell voltage you are at after a 50 mile ride ?
...and what cell voltage you feel is necessary for storage until the next weekend ride .
Have you considered using just one battery ?
But yes, ..good find on the discharger....but is it just a 400W max ?

The center port is for remote Voltage sense. I don't use it but the guy in one of the videos shows it being used. Just convert from the coax-looking port (a mating connector is included in the box) to two wires with alligator clips or your preferred connector and measure remotely at your source. You choose remote sense in the menu system otherwise, it's at the input. My personal method was to use my Keysight 34465A 6.5 digit meter in-calibration to take a one time measurement at the source while the load (same every time) was being drawn and compared it to the KP184 readout. I noted the difference and adjusted LVC accordingly. I shoot for about 3.8 to 3.82 VPC resting after about 1 hr after termination. I discharge the packs in Parallel at 2 Amps each for a total of 4 amps or about 215 Watts. That's about .22C. The low rate keeps Voltage bounce back low. IIRC, after my first 44 mile ride (packs were charged to 4.17 Volt termination with a 4 Amp cutoff), my resting Voltage was 54.5. My Watt Hours per mile were 14.4. There is no point for me personally, to use one pack at a time. I plan fairly accurately to have plenty of capacity upon return home so I don't need the protection of a second battery to engage to get me home. Pulling from both reduces Voltage sag and makes it far nicer to both packs. I can pull 1600 Watts and only be pulling each pack at .7C - the cells are coasting. I will also regularly charge to about 4.1 VPC to again, increase my life-cycle charge cycles and I won't pull capacity beyond 3.7 VPC resting. I can afford to do all this because of my very large overall capacity and my "relatively" short rides.

Here is a link to the first of a three part video review:

https://www.youtube.com/watch?v=Ln8ZWX7TXE0

....after my first 44 mile ride (packs were charged to 4.17 Volt termination with a 4 Amp cutoff), my resting Voltage was 54.5. My Watt Hours per mile were 14.4. There is no point for me personally, to use one pack at a time. I plan fairly accurately to have plenty of capacity upon return home so I don't need the protection of a second battery to engage to get me home. Pulling from both reduces Voltage sag and makes it far nicer to both packs. I can pull 1600 Watts and only be pulling each pack at .7C - .....

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Help me understand here...
You run 2 , 56v packs i parallel totaling 2500Wh..( 1250 Wh each)
Your typical ride consumes 650-700Wh, and a peak load would be 1600W
To me, removing one of those packs drops your ride weight by 5 kg, still gives you 2X the capacity you need, and the peak load on the cells is only 1.3C....Unlikely to reduce the life compared to 0.7C, for any reasonable cell !
Also , with your dual pack set up, with a finishing voltage of 54.5v, (3.89v per cell) .....why do you feel it is so critical to reduce that to 3.8-3.82 v for storage ? .. Between weekend rides !
Is there data to show that 0.1v difference make a detectable improvement in cycle life ?

https://www.youtube.com/watch?v=NGrWOk47wAA

A video showing a fault in one of these supplies, and the cause. Conclusion is a shipping event (drop or bang).

A good illustration on why inspecting and testing electronic equipment on receipt is a good idea. Even basic ground testing is a lot better than nothing.