JBD BMS Trips on Tool Start Up

[MadMacks]

I have a JBD 4S 200 amp BMS (JBD-SP04S034-L4S-200A-H) that I recently installed as a replacement for a similar JBD 100 amp BMS because I was having issues in the winter when running my generator and charging and then having the sun come out and boost up the charge from my solar panels, tripping the 100 amp BMS. This solved the problem and I was regularly charging at 100-140 amps.

Now that summer is here I am using my power tools again but now, with the higher amp BMS I am tripping it and getting a "short circuit" fault and the BMS disconnects the battery from my inverter.

The exact same power tools. The exact same inverter. But it now trips at the BMS! What the heck! A higher capacity BMS and it's tripping?

Anyone have an idea as to why this is happening?

 

[sunshine_eggo]

Motor surge can be brutal. This BMS may have the short circuit protection set differently or is less tolerant than your prior BMS.

 

[MadMacks]

I don't see a way to configure short circuit set up in the BMS other that using the discharge overcurrent setting. Everything else is identical.

And yes, the initial surge on a motor startup can be high, but the advertising and settings for the BMS specifically say it can handle surges up to 220 amps and run at 200 amps. Even with derating it should handle at least 100 amps, which is all that the previous BMS was rated for (and worked).

 

[sunshine_eggo]

I don't see a way to configure short circuit set up in the BMS other that using the discharge overcurrent setting. Everything else is identical.

And yes, the initial surge on a motor startup can be high, but the advertising and settings for the BMS specifically say it can handle surges up to 220 amps and run at 200 amps. Even with derating it should handle at least 100 amps, which is all that the previous BMS was rated for (and worked).

For how long?

Does it have a contactor, or is it still FET based?

While it would seem to be logical, these are still relatively inexpensive BMSs made in China. I would not assume that the BMS is a scaled up version of the last. It may have less surge tolerance due to the higher continuous rating.

If the overkillsolar app works with your JBD (it seems to on most if not all), the newest version of the app allows for 2nd and 3rd level protection settings. You might investigate that.

 

[MadMacks]

FET based...I believe.

can you elaborate on 2nd or 3rd level
protection?

I'm using the XiaoxiangBMS software but I also have the SmartBMSUtility app downloaded. I'll check that out...

 

[sunshine_eggo]

FET based...I believe.

can you elaborate on 2nd or 3rd level
protection?

I'm using the XiaoxiangBMS software but I also have the SmartBMSUtility app downloaded. I'll check that out...

Overkillsolar has their own app for the JBD bms. In addition to the normal protections, they define 2nd and 3rd level protections in more detail.

 

[MadMacks]

Overkillsolar has their own app for the JBD bms. In addition to the normal protections, they define 2nd and 3rd level protections in more detail.

I just downloaded it. Very nice. But I don't see any info on how to use those settings (other than playing around). Is there some explanation on optimal settings? Their manual doesn't reference anything.

 

[mikefitz]

The JBD 4S BMS 120 amp BMS has very high medium and short circuit current overloads, level 2 is 440A for 640 ms, level 3 short circuit is1700A for 32 us. In the Chinese app they were called 'hardware protection'

Mike

 

[MadMacks]

So I am trying a couple of different settings...

original settings
2nd Lvl Overcurrent 160amp, 8ms
3rd Lvl Overcurrent 440amp, 70us
new
2nd Lvl Overcurrent 160amp, 320ms
3rd Lvl Overcurrent 440amp, 100us

 

[MadMacks]

The JBD 4S BMS has very high medium and short circuit current overloads, level 2 is 440A for 640 ms, level 3 short circuit is1700A for 32 us.

Mike

My new unit was set differently (see above)

 

[mikefitz]

Why is the level 2 setting lower than the BMS rating? Level 2 is a short term surge, level 3 is short circuit.
Your unit is a 200A bms?
Made a correction, the values I gave were for a 120 A BMS.
'Discharge over current' in my BMS was set to 130 amps, 10 seconds.

Based on settings I have seen for other fet based BMS, typically;
over current, rated current plus 10
short term surge, 2 to 3 times rated current
short circuit, 7 to 10 times rated current

Mike

 

[sunshine_eggo]

I just downloaded it. Very nice. But I don't see any info on how to use those settings (other than playing around). Is there some explanation on optimal settings? Their manual doesn't reference anything.

download the settings from the BMS and post them here.

There are the ones from my 120A JBD:

 

[MadMacks]

I just did an update...

original settings screenshot

new settings

 

[MadMacks]

Interestingly I got a FET Locked error after the write. I also got that error when I reread using the XiaoxiangBMS software. But it cleared when I closed and reread from the BMS.

 

[sunshine_eggo]

So yeah... it looks like that BMS has 2nd level protection lower than max continuous. I would expect it to shut down at 160A for 160ms. I'd set that level to to the same as the level 1.

 

[MadMacks]

Why is the level 2 setting lower than the BMS rating? Level 2 is a short term surge, level 3 is short circuit.
Your unit is a 200A bms?
Made a correction, the values I gave were for a 120 A BMS.
'Discharge over current' in my BMS was set to 130 amps, 10 seconds.

Based on settings I have seen for other fet based BMS, typically;
over current, rated current plus 10
short term surge, 2 to 3 times rated current
short circuit, 7 to 10 times rated current

Mike

Good question...but that's what I read originally...

I may adjust the basic setting down actually...

 

[MadMacks]

So I now have the following...

Basic Protection, 200 amps for 32 Seconds
2nd Level, 220 amps for 160 mS
3rd Level, 440 amps for 100 uS

i will bump up the 2nd level time to higher values if those settings don't solve the problem. But I still very much doubt I have ever hit a 200 amp draw...ever...

 

[sunshine_eggo]

So I now have the following...

Basic Protection, 200 amps for 32 Seconds
2nd Level, 220 amps for 160 mS
3rd Level, 440 amps for 100 uS

i will bump up the 2nd level time to higher values if those settings don't solve the problem. But I still very much doubt I have ever hit a 200 amp draw...ever...

12V current is 10X that used at 120VAC. Electric motors can easily have 5X the run current, so unless your 120VAC tools are all under 4A continuous rating, then you've almost certainly gone over 200A.

 

[MadMacks]

200a @ 12v dc is 2400 watts
2400 watts x .9 (ac conversion loss) = 2,160 watts

2160 watts / 120v ac = 18 amps

I should easily be able to run a tool that draws 15 to 20 amps when it kicks on, initial draw...

My AIMs inverter is rated at 2500 watts run and 300% of that for 20 seconds at start.

My BMS is rated at 200 amps continuous use (although I do not trust that rating).

The obvious limit to my system is the BMS being able to deliver its "200 amps" when a tool starts up.

The tool in question is a DeWalt Jigsaw rated at 4.5 amps. It should not trip the system.

Prior to the "upgrade" I was able to run a Ryobi chop saw rated at 15 amps as long as I wasn't cutting thru large material and I took it easy. The start surge on that tool was MUCH higher for sure than the DeWalt.

I agree with your comment, tools can have a wicked draw when they start, but an allegedly upgraded BMS should not result in a lower amp capacity and a fault trip.

Generally, when I run "tools" I start my generator, no point in blowing thru the battery capacity or stressing my components.

Guess I'll find out if the reconfigured BMS settings make a difference.

 

[Loadtoad]

200a @ 12v dc is 2400 watts
2400 watts x .9 (ac conversion loss) = 2,160 watts

2160 watts / 120v ac = 18 amps

I should easily be able to run a tool that draws 15 to 20 amps when it kicks on, initial draw...

My AIMs inverter is rated at 2500 watts run and 300% of that for 20 seconds at start.

My BMS is rated at 200 amps continuous use (although I do not trust that rating).

The obvious limit to my system is the BMS being able to deliver its "200 amps" when a tool starts up.

The tool in question is a DeWalt Jigsaw rated at 4.5 amps. It should not trip the system.

Prior to the "upgrade" I was able to run a Ryobi chop saw rated at 15 amps as long as I wasn't cutting thru large material and I took it easy. The start surge on that tool was MUCH higher for sure than the DeWalt.

I agree with your comment, tools can have a wicked draw when they start, but an allegedly upgraded BMS should not result in a lower amp capacity and a fault trip.

Generally, when I run "tools" I start my generator, no point in blowing thru the battery capacity or stressing my components.

Guess I'll find out if the reconfigured BMS settings make a difference.

Did your reconfigured settings solve your problem?