@etienne how did you power the fans on your battery? I’d like to install one on my bms as the temp is close to 60 when I fly. Most computer fans are only 12v max that I can find.
Hi @dzubot,
I googled for 48V fans (didn’t know whether they would exist), but found them at RS.com
I also found a small electronics board that can convert 48 to 12V, but decided to go directly with the 48V fans.
I have the feeling I don’t need them though, usually they’re not running.
I’d like to add that both surfaces of the BMS are aluminum sheets. onto one of them the MOSFETS are directly connected for heat dissipation (the MOSFETS are the pieces that connect and disconnect the current, so they are the pieces that get the hottest).
When building my case, I stuck the aluminum plate with the MOSFETS together with heat-transmissible pads (those that are used to stick coolers to CPUs) directly to the aluminum case.
So the heat is dissipated fairly well onto the whole case.
Interesting. Thanks for fan link and info. That wouldn’t work in my battery as it’s lexan case. What temp do you see your bms get to?
My battery stays at healthy 30° but bms gets very close to 60°, I have to ease off on throttle for it to cool down.
Had a good flight today on third attempt. First two tries I climbed up for couple min and the BMS hit 60° and cut off power. One landing was in nice yellow canola field. Lucky no damage and good landing. I had chase cam on so will share that video. After setting bms high temp cuttoff to 80° I had excellent 30 min flight. Temp is only an issue on take off. During cruise temp was 45°c. Only light lift so mainly on power the entire flight. Start voltage 56v end 44v. One parallel group of batteries dropped to 2.5v cutt off with power on and the bms shut power off so that’s why I didn’t fly longer. All other groups were around 3.15v and the one was 2.8v. Glad I have the bms to save the cells.
My friend and I were both flying (he had scout) at a friends privately registered airstrip. Airstrip owner called and said his neighbor to the east made noise complaint against us to the rcmp. This was mid day flight, and we did not fly over this persons property nor were we flying low. Canada is terrible for this lots of people are against anything that flies. Our towing operations got shut down after neighbors complained and cops threatened to ticket us for distracted driving if we tow in that county again. But yeah I just can’t stress enough how the sound is an issue on this machine. The quieter we can make it the better for everyone including people on the ground.
1 Like
@dzubot your Vruzend Battery thread has now officially become the “noise” thread.
I have completed another flight yesterday evening. A nice 25 minutes up in the air (I know, not very long)
but the funny thing happend after landing.
two weeks ago I have flown with my combustion engine, same spot as most of the time, very near to my house. When I landed, I had to be careful, as in the center of the greenfield somebody was playing with his dog (the dog barked like hell, because he was scared by that oversized eagle coming down near him).
So back to yesterday, I landed after that 25min flight on the same greenfield, packed up my glider, and the same guy with the same dog walked by noticing “wow, what I giant drone”
So we started talking, and I told him that we’ve seen each other two weeks ago, that that was a combustion engine whereas this serves the same purpose but is electric, bla bla bla…
And here comes the funny thing: He said: yeah, I noticed that. It’s much quieter.
not that the theory needed any confirmation (the theory that low frequency noise travels much farther than high frequency noise), but his personal perception is as the theory expects.
Note: my wife at staying at our house, watching me fly a few thousand feet away confirmed the same.
Ya, the X4 is definitely more annoying for the pilot but better for the people on the ground if they’re not super close.
That’s really interesting, makes sense the higher pitch doesn’t travel as far. So maybe the noise complaint was actually because of my friend flying his Scout paramotor at the same time as me! He obviously had longer flight, could have been the combination of both us flying as well, definitely louder then just one. Would be interesting to have a DB meter recording sound of the opening and gas at take off to compare noise at various distances.
9 Likes
Not really to do with paramotor but moreso our mission with electric. Mapped the Columbian icefields today in my Pipistrel virus. Using minimal fuel, 100litres, flying 15,000’ for 7 hours. We are tracking the depletion of the glacier I can’t get any more fuel efficient aircraft other then electric. Once they arrive I’ll be sure to switch. Thanks to the developers of openppg for bringing us an awesome electric flying machine! @Pdwhite
4 Likes
So I’ve flown quite a few times with this battery now. Couple things ill want to change? I think I should put the bms on the bottom instead of the top of the pack so that it stays cooler, I’m also wondering if I should go with a thick copper bus bar to take the power from the pack. Reason, I’m not getting to utilize the full power available from pack, the last group of parallel cells drop much lower vs the centre cells. I’m not sure if it’s the positive or negative group of cells that are low but it’s either one of them. They will hit 2.8v while the rest of the parallel groups are still at 3.1v. Does anyone have any other suggestions as to how to combat this variation in voltage?
1 Like
I’ve had some issues where the end parallel groups that I take the power leads from are lower volts vs the centre cells when i’m flying and they hit the 2.8V cut off much sooner then the rest of the pack. I talked with Vruzend, they recommended to
take power from each cell to reduce loads on the cells as well as decrease the high temps i’m seeing with my BMS. So here’s the modification i’m doing to the pack.
1 Like
Flew today, the mod to the battery definitely helped keep things cooler, the BMS was only 25ºc during cruise, got to 55 on max throttle, before this was about 75ºc on climb and 40-50 in cruise. But still ran into issue with one group of battery dropping lower then the rest, this time closer to the middle of the pack. Any ideas why this is happening? I still have plenty of power left in the pack after 30 minutes but can’t use it due to the one group of cells getting lower then the rest…maybe it’s bms setting but I didn’t think it would be capable of balance controlling the voltage during discharge.
This screenshot is after landing. When I had a load on the pack the voltages where 3.1-3.2 except the one lower one that says 3.231, this was 2.9v under load.
Can you probe each cell in that row to see if you have a bad cell?
I don’t think this is the case. This is first time this group of cells has been low. Before this it was the outside cells that dropped lower. If there was a trend of these cells always being low then that would indicate a bad cell. I can probe them if I take the case apart. But will fly couple more times first and see what it does.
1 Like
Today I had two very bad failed take off attempts after a great evening flight yesterday. First attempt today after taking off the paramotor pitched back on me drastically, almost seemed like a top motor stopped spinning. I landed fine and checked everything out and could not identify what pitched me back so drastically. One very odd thing is as soon as I landed from this first flight the system went into safe mode on its own.
Second flight I took off and I lost all power shortly after take off. Only a bloody nose, no damage to the paramotor. The battery bms log said overcurrent protection went off. But there is no way that I hit the 320amp max bms cutoff setting. It is set to shut down after 5 seconds at 320 amps, and I don’t take off with max throttle. I’ve since taken it home and run it hard at max throttle with zero issue.
Any ideas?
How do you know this? Are you measuring your amps? If I remember correctly you are running KV160 with 14S
There is a possibility that your ESC’s are shutting down at 90% throttle. But on the other side etienne
has no problems (don’t remember if he runs 13S)
Hope you are well…
Now I’m debating if I possibly hit the discharge overcurrent protection setting. It’s set to 320amps 5 second cut off and from watching the video again it seems like I had power on for 5 seconds and then it cut so it’s possible I was going full throttle and didn’t realize. Before this flight the cap/spring for the throttle came off so I didn’t have that resistance I normally have in the throttle. I have a phone display showing me the battery stats but during take off there’s too much going on to monitor it
Does your phone log the battery data? If not maybe you can do a screen record.
It only logs when the bms hits certain settings to shut the power off. So it had a log saying it hit the over current discharge.
I’d like to get screen recording app for when things like this happen.
1 Like