I think I need a new controller.......LVC occuring 39V, not 30V.

[pullin-gs]

36V (10S) controller Low Voltage Cutoff kicks in at around 39V when riding.
I tried two good batteries and behavior is the same....kicks in after about 5 miles off full charge.
Here is the odd part.....on bench using power-supply and everything is cold "battery cutoff" occurs at normal 30V.
Controller is Battery-Brain 1000W (36V Q128C only draws 18amps maximum under load) 36V 38A.

[wturber]

Sounds like battery sag to me. You don't tell us what the load is or what kind of batteries your are using or what "good" means. Are you monitoring the actual voltage under load when it cuts out or just the voltage afterwards? It would be good to know what the actual amp draw at cutout is as well.

If you are measuring the voltage as 39v at cutout, then I'd suggest double-checking all wiring and connections. Be on the lookout for corrosion on any connections as well as in the stranded wiring itself.

[Drunkskunk]

Where are you measuring 39 volts when the controller cuts out? is that an active volt meter that you see drop to 39 under load and then cut? or is it the pack voltage after the controller has cut?

If it's under load, is it read from the battery, or from the controller? If it's from the battery, you could have a high resistance connection between the controller and the battery and the controller.

[E-HP]

Sounds like your controller doesn't detect it's a 36v battery and is applying the LVC as though it's a 48v battery.

[pullin-gs]

Battery #1: 11S 8AH LIPO......rated for 150A. Sag is nill. Observed LVC occurs at 39V
Battery #2: 10S6P 18AH Samsung 29E cells. Observed LVC occurs at 39V.

Amp draw.....15A under maximum load.
Voltage is monitored at battery (before controller) while on trike.
Max throttle Performance is 21MPH when it cuts at 39V....trike goes 22.5MPH fresh off charger.
At 3.0 normal cutoff speed is about 16MPH on flats due to voltage sag of depleted pack.

Already went over cabling......will check again.

Controller LVC was fine at 30.0V.
I added a cell to the LIPO pack last week and was using it when LVC quit about at 8 miles (vs 17 I was expecting).
Controller is 36V/48V capable (auto sensing)....I wonder if the 11S pack threw the LVC out of wack??

[wturber]

Controller is 36V/48V capable (auto sensing)....I wonder if the 11S pack threw the LVC out of wack??

Based on everything you've reported, that'd be my bet.

[pullin-gs]

Controller is 36V/48V capable (auto sensing)....I wonder if the 11S pack threw the LVC out of wack??

Based on everything you've reported, that'd be my bet.

OK....I think your right. Now I need to figure out how to undo 48V LVC.
Today I mounted my 10S sanyo pack back on (its been 48 hours since I had the 11S pack on) and LVC still kicked in at 39V.

[john61ct]

Yah first thing I saw 11S, thought, wait that's not 36V nominal schlominal.

Besides trying to factory-reset the controller, program from scratch

is there a BMS involved?

[pullin-gs]

Samsung pack has BMS.......11S LIPO does not.

[wturber]

Maybe discharge pack to below 36 volts and re-connect? Not really sure. Have never used a 36v/48v controller and am not sure what triggers the auto-config.

[amberwolf]

This has been reported before, though I don't recall the brand name of the controller for sure, I think it was the S06S and S12S, possibly by docnjoj.

AFAICR the main problem is that the logic the controllers use to autodetect may be a little "fuzzy", so sometimes a full 36v pack detects as a 48v pack instead, and an empty 48v pack detects as a 36v pack. :/

IIRC, The solutions that have worked in the past, because they detected the voltage at battery connection:

--ensure the 48v pack is always full when connecting it

--ensure the 36v pack is always partly discharged when connecting it (like maybe halfway empty)

--always leave the system connected to the battery once it's correctly selected the right pack voltage, and only turn off the system at the LCD screen

--if it doesnt have one then just keep it on the charger when not in use (or connect the charger periodically) so the batteyr doesn't run down too far.

(using a keyswitch/ignition wouldn't work because it disconnects the MCU from power, just like unplugging the battery would, so when it is repowered that's when it would redetect battery voltage).

[Overclocker]

Controller is 36V/48V capable (auto sensing)....I wonder if the 11S pack threw the LVC out of wack??

discharge the pack to the "proper" 36v range then connect the auto-learn wire to set the controller to the proper 36v LVC

[Matador]

Sounds like your controller doesn't detect it's a 36v battery and is applying the LVC as though it's a 48v battery.

That was my first thought too. I hearr in some dual voltage capable controllers, you may have to solder certain pins togoether to enable the right LVC combo. But then he said on the bench it cuts out at 30V so now i'm a bit confused...
.
Matador

[fechter]

What kind of controller is it? Programming the LVC varies widely between models. There is usually an easy hardware approach too if the programming doesn't cooperate.

[wturber]

Sounds like your controller doesn't detect it's a 36v battery and is applying the LVC as though it's a 48v battery.

That was my first thought too. I hearr in some dual voltage capable controllers, you may have to solder certain pins togoether to enable the right LVC combo. But then he said on the bench it cuts out at 30V so now i'm a bit confused...
.
Matador

Yes, but what is his starting voltage on the bench?

[pullin-gs]

Thanks for the help all....I went to buy a new one (I paid $14) but none to be found....cost $40+ now.
So I went to work on this one.
I blew up my 60V-max PS today, so could not test at 48V. This is 4th time I blew out the post-switching-stage MOSFET. I'm done with this $57 dollar eBay special 60V/5A PS. Any recommendations for a good 60V 5A minimums bench PS?

I need to be able to run on 11S pack, so LVC needed hard-adjustment
I think it is fixed....will know for sure when I run a 11S pack on trike.
I used my old trusty analog 30V/3A PS to test.
I effectively eliminated LVC protection by reducing LVC down to 24V
I bumped 2K resistor up to 3.3K (the one pointed to by tweezers) which did the trick.

Lower LVC to 24v.jpg (94.2 KiB) Viewed 1124 times

[bigchief]

I have a very similar looking controller:

https://imgur.com/a/Z2u2Zfv

Mine controller is 48v, and I want it to run on my 36v battery. If I have the 36v battery charged to 42 volts it will run until I try to hit a high speed or climb a hill, when it cuts out from the voltage drop.

I tried to do the same thing as you, so first I soldered a in a 3.3k ohm resistor in parallel with the "2001", but this made the battery cut out way faster (a split second after I hit the throttle, each time). Then I desoldered the "2001" and put in the 3.3k in that spot on it's own. This made it work again, but it cuts out with exactly the same behavior. Maybe mine needs a different value, or my PCB is different enough that it is adjusting the HVC instead of the LVC, or something? I'm stumped.

y8Ds98V.jpg (455.04 KiB) Viewed 1016 times