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DGJBD Bluetooth BMS - a short review

Hi,

parrst said:
Does this meter show charge and discharge? Or is it only one way?

Bob
Click to expand...

Possibly both, although it does say in the specs 0-100A. Which to me would imply not.

I bought this:

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19.73US $ 20% OFF|Dt24p 1000v/200a Ips Digital Display Dc Power App Voltmeter Ammeter Battery Capacity Tester Fuel Gauge Voltage Detector Meter - Voltage Meters - AliExpress

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It says in the specs 0-200A, but in on one of the pics it mentions a relay which it says will "automatically disconnect if battery is full discharged or fully charged". So it must measure current flow in either direction.

dRdoS7
 
parrst said:
Does this meter show charge and discharge? Or is it only one way?

Bob
Click to expand...
Hi

Did a quick test today and it only shows discharge. It does allow reverse current flow but does not measure it. First pic shows the voltmeter ammeter and second pic shows the BMS indicating a charge current

regards
 

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Hey all, wondering if anyone has gotten the "Protection" message of "Discharge low" with this bms?
Back story is the unit I Received from Overkill, using the 120 amp BMS, had the temp sensor lead damaged. It would not discharge. I soldered the wire back together and it worked fine. Then the plug soldered to the board popped off (obviously damaged when the wire broke). Seeing the contact points, I soldered the temp sensor wired direct to the board... Put it back together and.... Nothing. Still won't discharge.
What gives. Steve at Overkill is Sending me a new module, but in my stubbornness... I really want to fix this one.
Ideas?
 

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HRTKD said:
My only thought is that the wires are backwards. I have no idea if they are polarity sensitive.
Click to expand...
Huh... Didn't think of that! Lol... I'll go swap them and report back.
Edit: tried reversing the probe leads. Didn't work...
 
Last edited:
Those should be a resistive element, so polarity won't matter .... and it appears you are getting a temperature reading .... is it accurate?

That's a different version of the App than I have .... do you have a means of turning the battery on and off with that version of the App? If so, I would try turning if off and back on.
 
OK, solved. The exterior temp sensor is faulty. Not only broken, but when hard wired and soldered to the board it still does not read out correct. I was able to override it in a way I hadn't discovered. Temp sensor 1 was reading - 30 and number two was accurate. Obviously one sensor is on the board and one is that probe. So I changed Number 1 to read +10 C. and bingo. As the probe receiver was damaged and fell off the board, it appears soldering it direct didn't work either...
Very interesting!
Anyway, BMS is functioning now (partially) , and a replacement is on the way.
Bob B said:
Those should be a resistive element, so polarity won't matter .... and it appears you are getting a temperature reading .... is it accurate?

That's a different version of the App than I have .... do you have a means of turning the battery on and off with that version of the App? If so, I would try turning if off and back on.
Click to expand...
 
Bob B said:
Those should be a resistive element, so polarity won't matter .... and it appears you are getting a temperature reading .... is it accurate?

That's a different version of the App than I have .... do you have a means of turning the battery on and off with that version of the App? If so, I would try turning if off and back on.
Click to expand...

The temp shown on the dashboard of the app is always going to be from the sensor with the highest value. It's probably showing the temperature from the internal sensor on the BMS. If you "click" on the temp it should bring up the temperature of both sensors.
 
HRTKD said:
The temp shown on the dashboard of the app is always going to be from the sensor with the highest value. It's probably showing the temperature from the internal sensor on the BMS. If you "click" on the temp it should bring up the temperature of both sensors.
Click to expand...
EXACTLY! I'd been through every setting and menu conceivable... But didn't actually click the temperature read g on the dashboard. When one said - 30, I realized that changing it to a positive number was mentioned in the Overkill instructions. Did it and it worked!
YAY... Thanks. Loving this forum!
 
Has anyone tried using the hardware on/off switch on this BMS. I see that the Overkill Solar version has an actual 2 pin header soldered next to the Bluetooth and balance headers. And their documentation mentions adding such a switch. My BMS doesn’t have the header but it has 2 spots on the PCB that are labeled on/off or something like that.

I was going to put a high current battery cutoff switch on my battery box, but if I can just use a small low current switch instead I’d prefer that option. I’ll have a high current breaker I can use as a cutoff downstream in my system instead.

Also curious if anyone has tried disassembling their BMS. I need to pull the aluminum plate off to get access to the on/off pins so I can solder a header on there. Just wondering if the thermal paste between the FET’s and the aluminum plate releases easily and how much fiddling it will take to touch up the paste and get it back together.

-uberpixel
 

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uberpixel said:
Has anyone tried using the hardware on/off switch on this BMS. I see that the Overkill Solar version has an actual 2 pin header soldered next to the Bluetooth and balance headers. And their documentation mentions adding such a switch. My BMS doesn’t have the header but it has 2 spots on the PCB that are labeled on/off or something like that.

I was going to put a high current battery cutoff switch on my battery box, but if I can just use a small low current switch instead I’d prefer that option. I’ll have a high current breaker I can use as a cutoff downstream in my system instead.

Also curious if anyone has tried disassembling their BMS. I need to pull the aluminum plate off to get access to the on/off pins so I can solder a header on there. Just wondering if the thermal paste between the FET’s and the aluminum plate releases easily and how much fiddling it will take to touch up the paste and get it back together.

-uberpixel
Click to expand...
Or you can use the software On / Off buttons in the app.
 
pierre said:
Or you can use the software On / Off buttons in the app.
Click to expand...
Good suggestion. I kind of like having a physical switch so I don’t have to use my phone to turn off the battery. Maybe the software switch would be adequate for my application.

Not sure I like relying on software for this function, but you could argue that neither option is a true cutoff. At least the physical switch would bypass the Bluetooth/phone requirement.

-uberpixel
 
pierre said:
Or you can use the software On / Off buttons in the app.
Click to expand...
Even with it off via the app, how much power is still consumed? It has to keep somewhat powered up so you can turn it back on via the ap right? I am planning for RV usage. 2 weeks "off" won't drain the battery will it?
 
smileyman57 said:
Even with it off via the app, how much power is still consumed? It has to keep somewhat powered up so you can turn it back on via the ap right? I am planning for RV usage. 2 weeks "off" won't drain the battery will it?
Click to expand...
Should be ok.

Q: What is the quiescent current? What can I do for long-term storage?
A: The quiescent current is as follows: (this was measured on a 4 cell BMS)
● 5.5 milliamps with everything off, when the BMS is active, but no bluetooth.
● 15 milliamps with the bluetooth active (after about 10 seconds it drops to 0.8 milliamps.
Reconnecting it wakes it up again).
● 0.8 milliamps when the BMS is inactive.
So, assuming your battery setup is 100 amp hours, the BMS would run for 17 years. This proves that the BMS can be connected for long periods of time without any fear of it draining the battery.
Unplugging the balance connector would ensure complete shutdown
NOTE: The cell’s self-discharge rate will always cause the battery to drain over time, which may be several percent per month. This is simple chemistry and physics; there’s nothing that you or the BMS can do to avoid the battery cells from self-discharging over time, other than to occasionally top up the batteries.
Click to expand...
Taken from https://github.com/FurTrader/OverkillSolarBMS/raw/master/Overkill_Solar_BMS_Instruction_Manual.pdf

Page 28
 
Here is that Video I mentioned... Had a YouTube issue, so it didn't post right away. I also re-rendered it this morning with an adjustment.
 
SoundinSpirit said:
Here is that Video I mentioned... Had a YouTube issue, so it didn't post right away. I also re-rendered it this morning with an adjustment.
Click to expand...
Thanks for your contribution but it is a bit difficult to watch the video as the camera moves around a lot. Maybe a static mount for the camera will help in this respect. I would very much like to watch the video without this issue. Regards.
 
I'd highly recommend using a gimball. This movement is pretty annoying. Also, adjust sound in post, its hard to understand.

As for the 'fix': You've wired the sensor to the supporting pins of the plug, which basicly don't do anything else than supporting the connector.
The actual pins are the 2 on the back of the connector

If you're in doubt of the sensor: It's just a regular 10kohm NTC


1615925195573.png
 
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