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I have a brand new PJ LFPSWSP-8000 inverter, the main board is V11.1, and the fan never turns on. I have had large loads on it that eventually cause the inverter to shutdown, but the fan never turns on. I have checked the fan itself and it will power up when power is directly applied to it. also this is a 2021 model with the fan plugged directly in to the main board. Does Anybody have any ideas as to what might be wrong with this unit, this is actually the third one i have bought that behaves this way, i have returned the other two.
Thanks,
Kyle
Does yours have the fan toggle switch?
FWIW, if you know how to power it manually, you can probably buy a cheap thermistor switch for the appropriate temperature and just put that in series with it, touch it against the hottest part of the transformer. Sometimes it's better just to improvise... -_-
I have a brand new PJ LFPSWSP-8000 inverter, the main board is V11.1, and the fan never turns on. I have had large loads on it that eventually cause the inverter to shutdown, but the fan never turns on. I have checked the fan itself and it will power up when power is directly applied to it. also this is a 2021 model with the fan plugged directly in to the main board. Does Anybody have any ideas as to what might be wrong with this unit, this is actually the third one i have bought that behaves this way, i have returned the other two.
What's the rated fan voltage? EDIT: and the inverter battery voltage?
also...what's the part number on the CPU? PIC18F87K22....or is it an 87K90...or is it an 86K90...??
I updated code for PJ last year to control the fan from BOTH thermistors (as their original code would ONLY switch the fan from ONE thermistor), but if they're using the original 87K22 processor, it will still only control the fan from ONE thermistor. Any of the later processors (i.e. anything except the 87K22) SHOULD be able to control the fan from both.
The inverter voltage is 24V, the cpu number is the 87k90. Thank you for the quick response.
Kyle
The inverter voltage is 24V, the cpu number is the 87k90. Thank you for the quick response.
Rated fan voltage?
It says 24V on the fan.
It says 24V on the fan.
That might be a bit of a problem, as the control board is only going to give it +12v. However, it still should run...just not very fast.
If you can test the fan on 12v and it doesn't run, then that's likely the problem. Fortunately, there's a pretty easy workaround: the FET on the board only connects the fan negative wire to battery negative. This means that you technically can cut the fan positive wire off of the connector (leave the negative wire intact!), and splice the fan positive wire to battery positive (= +24v).
Test the fan on 12v first (before cutting the fan positive wire!)
I see what your saying. If i cut the positive wire and put it to battery positive, is there a chance of damaging anything, such as the FET you mentioned?
When i apply 12v to the fan it spins up, but not very fast. But when the inverter is hooked to 24v batteries and a load is applied i dont get anything out of the fan.
I see what your saying. If i cut the positive wire and put it to battery positive, is there a chance of damaging anything, such as the FET you mentioned?
What's the part number on the FET near the two 2-pin fan connectors?
On the 11.1 board I have here, it's NCE80H15, which is an 80v, 150A FET--if that's what you have, running fan positive to battery positive won't hurt it at all.
Worth noting that the 80H15 is a terrible choice for the provided control signal, as that FET barely turns on at 4.5v--and the CPU runs at 5.0v. At best, that FET will BARELY be turning on. They should have used a logic-level FET for the fan control.
When i apply 12v to the fan it spins up, but not very fast. But when the inverter is hooked to 24v batteries and a load is applied i dont get anything out of the fan.
Fan control is based on measured temperature, not load. But if the inverter is shutting down due to overheat, then it most definitely should be running the fan(s). If the inverter shuts down due to overload, that won't cause the fan(s) to run.
The FET nearest the fan connector is a RU7088R, looking at its data sheet, it should be fine to run the fan+ to 24V battery? but i still have the issue that it does not seem to turn on at all. I understand what you are saying about overheat vs overload, i believe that the problem is overheat. I have had the exact same model inverter bake cookies in an electric oven with out issue, but this one cant even get it preheated before it shuts down.
The FET nearest the fan connector is a RU7088R, looking at its data sheet, it should be fine to run the fan+ to 24V battery? but i still have the issue that it does not seem to turn on at all. I understand what you are saying about overheat vs overload, i believe that the problem is overheat. I have had the exact same model inverter bake cookies in an electric oven with out issue, but this one cant even get it preheated before it shuts down.
Yes, the RU7088R is a 60v FET--so a 24v potential across it (when it's off) will be just fine.
However, it also has a relatively high gate threshold voltage...which means it'll BARELY turn on with the 5.0V the CPU can provide.
Note that the ideal gate drive voltage for a standard MOSFET is 10-15v. I put a red line @ 5v on the above graph--note that based on temp, it MIGHT be partially turned on with a 5v gate drive.
If the FET is barely turning on, that will cause the PCB's default 12v to be even lower (which could cause the fan not to run). PJ really should have used a logic-level FET for this one...
There are several tests you can do to figure out the cause of the problem if you're game to feel like a technical electronics detective 😉.
I have had the exact same model inverter bake cookies in an electric oven with out issue, but this one cant even get it preheated before it shuts down.
Remember, you bought a PJ..........
That means that the model number means basically nothing. Published specs pretty well mean absolutely nothing.
If it works for your needs, great. If it doesn't...well...you bought a PJ 😉. I've heard a lot of reports from customers saying that the PJs with the v11 board all alarm/shut down at far lower loads than prior models did (and of course many times less than the "rated" load). That's an overload shutdown, not necessarily an overheat shutdown.
If it's overheat shutdown, the main MOSFET heatsinks and/or the transformer will be extremely hot to the touch afterwards. These type of shutdowns usually take 5 minutes for the heat to build up.
An overload shutdown usually happens in 30 seconds or so--and there will be little if any significant heat inside.
So far i am pretty happy with PJs, especially considering the price. I have had a couple of them and when they died it was my fault. I had one of the stainless steel 8000W models that had a significantly larger transformer and it worked great until i let the smoke out.
As far as this model goes, i am pretty sure it is a thermal shutdown, it takes about 5min with a heavy load, water heater or oven. i have not done this with the top cover off, so i cant speak to the internal heat. I would love to feel like a technical electronics detective, let me know what to test please.
Thank you so much for all the help!