The order arrived super fast. The unit feels and looks to be well thought out in design and constructed of good materials. Also, it appears to be assembled with good quality controls in place. It's bigger looking than I expected. Here are a couple pics with a couple popular lights to give a sense of size.
Appears to have thermal grease nicely squeezed. I didn't take notes on the temp readings, but it alternates the reading during the load runs.
Connecting wires to it is pretty easy. Uses standard powers supply jack for it's 12v. The turn pot is for the display contrast.
The UI is pretty intuitive. You do need to remember to clear memory when changing cells or it will accumulate the Ah measurement. I clear memory by holding the bottom right button for about 2 seconds. It does not clear your current or voltage cutoff settings. Those setting also persist if the power is disconnected from the Load Unit.
I didn't have much time to test it much, but I ran it through enough paces to feel comfortable that it performs as advertised. I discharged a few cells and results seemed reasonable. I did have one run stop prematurely with the display saying "Error 1". I had the cut off voltage set to 2.5v, but the cell was at 3.63v (under no load).
and connected it to a DPS5015 and ran various voltages and current levels through it. The max voltage I took it to was 30v and the max current I took it to was 10a. I ran at 150w (30v at 5a) for a few minutes. It seemed to run fine and show no signs of stress.. At each voltage and current, the current measured matched the DPS5015 reading less .01 amps. Voltage readings on the load were lower. I believe this was due to the leads and connection I had running from the DPS5015 to the Load Unit.
The fan is nice and quiet. It appears to turn on and off automatically based on temperature. It may have only one speed, but I didn't do a prolonged run at 150w. So maybe it speeds up. The air movement keeps the heatsink fins cool to the touch and probably helps cool the Shunt that is under the heat sink. Her it is discharging a cell at 10a. The fan didn't turn on until a few minutes into the run.
Discharging cells, I measured current usage by the load. It pulls about .6w when the fan is off (first pic) and 2.75w when the fan is running (second pic). It also uses .6w when no load is running.
I'm very satisfied with the unit. It is going to be very handy in stress testing cells and measuring/verifying the accuracy of powers supply and such. I would like to know what caused the error message on the INR18650-13Q cell. The cell was from a recent used power pack pull. So I suspect the cell has some type of issue. If I figure it out, I will report back. I'll try to add some more info in a few days or as soon as I get a chance.
I have that 20w USB powered one finally. Just waiting on a USB - TTL cable so it can connect to PC for data. Runs great.
However I got the 60w version of this and it is flakey. I think it has a short. Fan doesn’t work right and the cells voltage drops massively under load.
Kind of neat. These have really got me back into electronics.
I’m going to be building my own variable power supply soon. Shame things take so long to get here
I take it you mean the unit you mentioned in this post? Good to hear it's working well. Please let us know what you think about the data feed after you get that part running. You have me thinking about buying one of those now.
Sorry to hear about your 60w problems. Is it the same unit that HKJ reviewed? Sometimes back lighting the pcb can reveal issues. Close up macro shots blown up on a computer screen can sometimes reveal shorts and cold solder joints. Maybe share the picture in HKJ's review. It may reveal a failure point that others should be aware of.
I think that time waiting for the orders to arrive contributes to the addition.
Here are a couple shots from a discharge test I ran this morning at 10amps (cut off 2v):
I'm so digging this 150w load unit. I recently had to repair a shunt that I was using to measure current in a light. I had to repair it because one of the leads broke off. Anyone that makes these (see this thread on how to make them), knows the lead positioning and even how solder deposits are key to getting an accurate reading. Temperature is also important. At the time I performed the repair, I was in a big rush and just ball parked the repair based on the where the solder broke. I decided to measure it today using 4 ways to measure current flowing through it. I used the 150w Load unit to control the current flow and the DPS5015 to provide and verify the 10 amps (Set it to 12v and 15a). They all show that I need to move the lead a little further way from other lead. So cool to have another reference point.
I have been wanting one of these for some time, just have not had the funds to invest in one yet.
I do wish there was one that could do say 20A loads but oh well, 10A is plenty to get a good understanding.
Popping various cells into it at a fixed current and then seeing what the voltage drops too is a good way to figure out the “real world” internal resistance.
Great idea. One of the biggest reasons I bought this unit was to periodically stress test cells that I rely on in high current series arrangements. I didn't think to about getting IR measurements while I'm at it. Got to look up how to do that. Thanks for the suggestion.
While you can use it to get “technical” IR measurements there are so many different methods of doing this I find the results to be useless unless comparing them from the same testing setup (aka, you can only compare your own cells).
Since you can only compare your own cells I find a much simpler and more effective benchmark to simply hit the cells with a known load (in my case an old dust buster that pulls a lot of current) and then watch the cell voltage under load.
I then sort them by how much voltage they are able to maintain under load. Takes about 5 second per cell to test and is very applicable to real world use in a flashlight.
For example in my setup a 30Q might maintain 3.5V, an HE2 3.6V and a GA around 3.3V with most usable salvaged / laptop cells between 2.6-3V. Under 2.6V and I keep them around for really low drain applications as long as they do not self discharge unreasonably.
This is not all that “technical” but very quick and practical. My Imax B6 with firmware upgrade measures the IR and it works well but I find the voltage test to be more useful.
