Voltage Sag causing blx100 issues lvc?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

N0isyknuckles

Member
Messages
51
Reaction score
30
Arrma RC's
  1. Granite
I needed to drain a 3s battery so that I could place it into storage mode so I cracked out the granite. This granite is on it’s 3rd ESC in the past month...currently has a 120blx on it.

i decided to run a Voltage alarm on it. The batteries were around 4.05 volts when I started and I set the alarm to 3.6. A few warm up passes and then gave it about 90% throttle on a straightaway. It didn’t take long and my alarm went off. I checked the voltage on the batteries and they were around 3.9.
I kept setting the alarm lower and lower and would consistently get alarms at .3-.4 volts at rest above the set voltage on the alarm

Is this normal for batteries to sag this much when under load? and how long do esc’s average volts to determine LVC? I’m assuming some of this was my problems with the blx100.
 
You're probably confusing LVC with thermal, check your bearings. Another cause can be improper radio calibration, when the ESC (I've seen this on a blx185) sees a radio signal past 100% it will shut down for a bit and then restart. But my guess since you had to "dust it off" your bearings need rebuilt. ?
 
That lipo you were trying to bring down to storage was unbalanced. That triggered the alarm. Common. Use your charger in storage mode. The best way. Then balance mode it manually to make sure it stores well. That's what I do.
 
You're probably confusing LVC with thermal, check your bearings. Another cause can be improper radio calibration, when the ESC (I've seen this on a blx185) sees a radio signal past 100% it will shut down for a bit and then restart. But my guess since you had to "dust it off" your bearings need rebuilt. ?
My granite is only about a month old. The prior two blx100 esc’s would go into “slowpoke” mode and then no throttle. Batteries would be resting at 3.8-3.9 when this would occur. Servo would still turn wheels. That’s LVC correct?
My alarm was set for 3.6 and resting battery voltage was 3.95. I duplicated this about 5-6 times.
That lipo you were trying to bring down to storage was unbalanced. That triggered the alarm. Common. Use your charger in storage mode. The best way. Then balance mode it manually to make sure it stores well. That's what I do.
When I was done testing all 3 cells were at 3.78, 3.78, 3.79 at rest. I use balance charge or storage every time. My internal resistance is at about 10 for each cell.
 
Resting voltage is not the best indicator except when fully charged. And lipo alarms are not precise enough IMO. 10 ohm IR's are not bad. But IR reads are most important with fully charged cells. That's why most chargers only give IR stats in Charge mode only.
Storage charge the lipo and let it sit for 24+ hours then check the resting voltage of all cells.. Your lipo alarm should show which cell is sagging. Mine does. Check the sag as soon as you get the alarm triggered. Cells recover quick. You can do this on the bench.
 
Last edited:
Use your charger in storage mode. The best way. Then balance mode it manually to make sure it stores well. That's what I do.
Same, sometimes I break my trucks before I get to run all my packs so even a fully charged pack I place on the charger and run a storage charge and it will discharge it to 3.8v.

I don't have a lipo alarm but I do have a cell voltage checker that I use to check my batteries and when I use it on a running motor voltage actually sags quite a bit. At idle with ESC turned on with no load I read out 3.6v on my cells and when I disconnected from the esc it bumped back up to 3.8v. When I was running it on the bench it would sink down as low as 3.0-3.2 and bounce back when off throttle/no steering. I am not familiar with how the logic of LVC is in the esc but I recall it is based on an average cell voltage over a period of time, so a sag of a few seconds of acceleration doesn't trigger it, but I can see how a lipo alarm would just pop off as soon as it would sag below threshold.
 
Lipo alarms will monitor and trigger for each cell. They are not perfectly accurate but gives a baseline comparison for each cell. A cell checker works like a lipo alarm just without the alarm. ESC LVC circuits cant read cells individually. (Except for the Smart ESC's combined with a Smart Lipo.) Yes they average out based on voltage across all cells. LVC circuits I find can be so inconsistent from ESC to ESC. I have 4 identical ESC's that trigger consistently different using the same lipo.
Just my observations.
 
I keep having the same issue. I'm on my 3rd blx100 and they all shut down around 3.8-3.9. I think one of them was shutting down at 3.6-3.7 for a couple days but went back up to 3.9 eventually. I guess my only option is new esc or lipo alarm.
 
I keep having the same issue. I'm on my 3rd blx100 and they all shut down around 3.8-3.9. I think one of them was shutting down at 3.6-3.7 for a couple days but went back up to 3.9 eventually. I guess my only option is new esc or lipo alarm.
They sent me a BLX120 so you might ask for that on your next attempt if you run 3s. It’s cutting off at 3.5-3.6
 
Looks like horizon is updating firmware on them now. Will see if it fixed the issue
 
Looks like horizon is updating firmware on them now. Will see if it fixed the issue
Do you know if they are allowing end users to flash the firmware? Do you have to send it in?
 
Have to send them in I sent back two bad ones and both were updated.
Dang I had a glimmer of hope we could get our hands on a firmware file. Would love to poke around and see what we could unlock.
 
Interested in turn around time as well, I've only had my Granite BLX for a few days and noticed it cuts out when voltage gets to around 3.8. When it cutoff today, voltage was showing 7.75 and both cells were equal. Have only run 2s so far.

Still anecdotal at this point, need to do more testing and probably get a cell checker.
 
Only a couple days. Flash fixed the issue too. Batteries read 3.4-3.5 and longer run time. Before it was cutting at 3.9 and less than 10 minutes.
 
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.
Back
Top