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Removing lvc on 48v controller.

Posted: Jan 17 2017 7:12pm
by EXPERIMENTAL EV
Hi there, I just found out the problem with my controller, the lvc is too high even though im using a 48v battery with a 48v controller. I was wondering if anyone could assist me in this daunting task to my noobish eyes.
This is my controller: https://www.aliexpress.com/item/1500W-1 ... 0.0.v0XVgT


Thanks in advance.

Re: Removing lvc on 48v controller.

Posted: Jan 17 2017 8:37pm
by Gregory
To mod the LVC, you will need to be able to disassemble the controller and solder. If you aren't confident doing that it will be easiest to buy a new controller.
Maybe one with software programmable LVC and other parameters.


Some controllers have pads with a resistor/link for multiple LVC options, many don't.

First step for me would be taking some hi res pics.

Re: Removing lvc on 48v controller.

Posted: Jan 17 2017 9:53pm
by EXPERIMENTAL EV
I am very confident opening it and soldering. I have already disasembled it twice while I was searching for the problem. I am very confident at soldering so that wont be a problem. Here are some pics.

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 3:31am
by wesnewell
EXPERIMENTAL EV wrote:Hi there, I just found out the problem with my controller, the lvc is too high even though im using a 48v battery with a 48v controller. I was wondering if anyone could assist me in this daunting task to my noobish eyes.
This is my controller: https://www.aliexpress.com/item/1500W-1 ... 0.0.v0XVgT
Thanks in advance.
LVC is supposed to be 37V according to the description. If anything, I'd think that was too low for any 48V battery pack. Why would you think you need to lower it more? For lead, you'd want a 42V LVC, For 13s rc lipo 42-45V, For 13s 18650's, 37V is about right, although I'd want 39V. For 16s lifepo4, you probably would want to raise it to at least 40V, with 43V being better imo. Sorry, I don't know where the lvc resistor circuit is on that controller.

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 4:38am
by EXPERIMENTAL EV
wesnewell wrote:
EXPERIMENTAL EV wrote:Hi there, I just found out the problem with my controller, the lvc is too high even though im using a 48v battery with a 48v controller. I was wondering if anyone could assist me in this daunting task to my noobish eyes.
This is my controller: https://www.aliexpress.com/item/1500W-1 ... 0.0.v0XVgT
Thanks in advance.
LVC is supposed to be 37V according to the description. If anything, I'd think that was too low for any 48V battery pack. Why would you think you need to lower it more? For lead, you'd want a 42V LVC, For 13s rc lipo 42-45V, For 13s 18650's, 37V is about right, although I'd want 39V. For 16s lifepo4, you probably would want to raise it to at least 40V, with 43V being better imo. Sorry, I don't know where the lvc resistor circuit is on that controller.


I believe they sent me the wrong one or there is a fault. I measured the battery voltage and when it goes below 53v it cuts off. If I spin it no load with the charger plugged in it stays running otherwise it only runs for about 3 second then dies.

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 5:37am
by Gregory
If I understand that correctly, I'd be looking at part of the battery either sagging down below cell level LVC (ie a bad cell) or going into over current protection.

If the battery charges to 53V (same as the charger) then surely it's not controller LVC?

More details like the battery, what LVC you think you are seeing etc would help.

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 2:18pm
by EXPERIMENTAL EV
Gregory wrote:If I understand that correctly, I'd be looking at part of the battery either sagging down below cell level LVC (ie a bad cell) or going into over current protection.

If the battery charges to 53V (same as the charger) then surely it's not controller LVC?

More details like the battery, what LVC you think you are seeing etc would help.

I will attach a video link to what it does if the charger is not plugged in. https://www.youtube.com/watch?v=8thCtsa9zto

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 3:15pm
by wesnewell
OK, if you have to turn the battery off and back on to get it to turn the motor again, it's not the controller LVC cutting it off, it's the battery bms. The controller will reset itself when it sags below lvc. Just letting up on the throttle and turning it again should start the motor turning again. But if it's the bms, you have to cut the power for it to reset, which appears what you are doing.

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 3:26pm
by EXPERIMENTAL EV
wesnewell wrote:OK, if you have to turn the battery off and back on to get it to turn the motor again, it's not the controller LVC cutting it off, it's the battery bms. The controller will reset itself when it sags below lvc. Just letting up on the throttle and turning it again should start the motor turning again. But if it's the bms, you have to cut the power for it to reset, which appears what you are doing.

It does not have a bms and I'm just restarting the controller not touching the battery

Re: Removing lvc on 48v controller.

Posted: Jan 18 2017 11:44pm
by 999zip999
Battery what battery how about a pic in a link battery?

Re: Removing lvc on 48v controller.

Posted: Jan 19 2017 3:43am
by EXPERIMENTAL EV
999zip999 wrote:Battery what battery how about a pic in a link battery?
It is a homebuilt 9ah 48v sla panasonic pack. I dont mean to be rude but can someone please just tell me how to remove the lvc on the controller :roll:

Re: Removing lvc on 48v controller.

Posted: Jan 19 2017 3:57am
by LewTwo
EXPERIMENTAL EV wrote:
999zip999 wrote: I dont mean to be rude but can someone please just tell me how to remove the lvc on the controller :roll:
Not to be rude but probably not.

Re: Removing lvc on 48v controller.

Posted: Jan 19 2017 6:38am
by Gregory
:D Sorry I can't help either.

If you're still open to advice, I'd stop focusing on changing the LVC and check the current the motor is pulling at no load. And what the voltage sags to.

Re: Removing lvc on 48v controller.

Posted: Jan 19 2017 3:05pm
by EXPERIMENTAL EV
Gregory wrote::D Sorry I can't help either.

If you're still open to advice, I'd stop focusing on changing the LVC and check the current the motor is pulling at no load. And what the voltage sags to.

I have actually already had a look at those. The battery doesnt drop more than 2v and the motor only draws 3 amps. Do you know anyone on this forum that might be able to help?

Re: Removing lvc on 48v controller.

Posted: Jan 20 2017 1:41am
by wesnewell
Only drops 2V under a 3A load. roflmao. How much do you think it will drop under a 30A load. Those old sla batteries are shot. Under a normal takeoff, with maybe 15a draw my 10ah battery pack doesn't sag even 1V. Forget the LVC being too high. That's not your problem. The sla battery pack is. Under no load, my lithium pack doesn't sag more than 0.1V.

Re: Removing lvc on 48v controller.

Posted: Jan 20 2017 2:52am
by EXPERIMENTAL EV
wesnewell wrote:Only drops 2V under a 3A load. roflmao. How much do you think it will drop under a 30A load. Those old sla batteries are shot. Under a normal takeoff, with maybe 15a draw my 10ah battery pack doesn't sag even 1V. Forget the LVC being too high. That's not your problem. The sla battery pack is. Under no load, my lithium pack doesn't sag more than 0.1V.

You need to bear in mind that that 2v drop is from float voltage and these are brand new panasonic sla's. Im not saying these sla's are in any way superior to lithiums. But they are not sagging below the lvc listed on the website for the controller. I am going to purchase lithiums once I get the money to buy a decent pack.

Re: Removing lvc on 48v controller.

Posted: Jan 20 2017 3:34am
by amberwolf
EXPERIMENTAL EV wrote:[ I dont mean to be rude but can someone please just tell me how to remove the lvc on the controller :roll:
Every controller model and brand is different, so it's pretty hard to say what you need to do for any specific model. But there is info on ES about doing this:

There are quite a few threads on changing controller LVCs, if you look around the forum at threads with titles like that. The search function can be used to look in just topic titles and list just topics (but then you'll still need to read the threads that come up to see if they are relevant, and if the controllers they have are similar enough to your own for you to apply their fix to your controller, or adapt the information to help you figure out how).

Re: Removing lvc on 48v controller.

Posted: Jan 20 2017 3:43am
by LewTwo
You have a system with three major components:
1) Battery
2) Controler (that may include a display unit)
3) Motor
If you have eliminated (at least to you satisfaction) the battery and the wiring connections being at fault then the controller is the next logical choice. While all the controllers have some common design elements there are many variations. Unless you can find someone that is intimately familiar with the particular model you have, it is unlikely that you will be able to get instruction for testing or modifying the more obscure features. I would recommend obtaining a known good (i.e. cheapest, least sophisticated, 48 volt controller available for purchase) controller to validate that the controller is the problem.

Re: Removing lvc on 48v controller.

Posted: Jul 29 2018 5:14pm
by thorlancaster328
I have (AFAIK) the same type of controller that you have and I have figured out how to bypass the LVC.
Just solder a 47k resistor in parallel with the 24k primary resistor. The LVC will now be around 28 volts instead of 40.
The resistor to solder to is highlighted. If your controller is slightly different, it's the resistor with one end connected to VCC.
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