Quattrohead
Emperor Of Solar
If your exact model of BMS has an RS485 port, yes.
If you need that many, also consider the Waveshare 4 port models.
Overkill bms useless
- Thread starter bronxfire
- Start date
If you need that many, also consider the Waveshare 4 port models.
None of my JBD BMSs came with the RS485 chips or connector installed on the board.
You can buy a USB to 3.3V TTL RS232 converter and use it to connect to the BMS RS232 port. Unplug the Bluetooth adapter and jumper your USB converter in to Tx, Rx, and Ground. Do not connect to the +12v on the BMS side. The pinout is shown on the Bluetooth board.
When you are done, plug the Bluetooth adapter in and your BMS is back to its original configuration.
42OhmsPA
Who likes Electrical Gremlins?
I feel like it's easier working on a PC. You can adjust some additional parameters and save / import configuration files. (the overkill app can do this as well.)
I find it much easier to plug into the PC then deal with reconnecting the Bluetooth module if I need to make changes.
I used the Bluetooth connection to connect the adapter, without the 12v+.
So you can splice the USB adapter into the Bluetooth and use both?
I didn't say that. I would presume that it would work fine, but you wouldn't be able to use both at the same time. I take that back. Only one device can talk to the BMS at a time, but both could listen.
In reality, the bluetooth adapter would work fine with a PC if you convince the PC to use BLE and make a virtual COM port. A driver exists to do that, IIRC.
In my case, I removed the Bluetooth adapters and now get data from the BMSs with a small microprocessor board (a Teensy 4.0) via the RS232 connector. The Teensy updates an ePaper display and sends the data to a larger processor board to aggregate and log. The Teensy also collects data from the SCC and inverter.
Section 3.4.8 page 26 of the manual. The note is that the setting is only available on Android and PC apps. It also warns to not adjust it.
What is your charging voltage, and is your full charge voltage set to in the BMS? You need to reach a voltage higher than the full charge voltage to reset to 100%.
My guess is that the reason it hasn't reset/synced is because either your charger is set to charge at to low of voltage, or your full charge voltage in the BMS is set too high.
What is your charging voltage, and is your full charge voltage set to in the BMS? You need to reach a voltage higher than the full charge voltage to reset to 100%.
My guess is that the reason it hasn't reset/synced is because either your charger is set to charge at to low of voltage, or your full charge voltage in the BMS is set too high.
I have been using my JBD for a few days now and I had hoped that the current (hall?) sensor would serve for a relatively accurate SOC meter. BUT, from what I can see, my JBD does not use current measurements for SOC but instead relies on the voltage SOC table in it's parameters. This is not ideal, especially outside of the "knees" and a bit of a shame since there is obviously current measuring capability.
BUT, a BMS' purpose is not as a shunt nor have I seen any of them sold as one. The BMS is for protecting the pack and individual cells. As a secondary use, I am depending on it for individual cell V monitoring and that's fairly important. As a tertiary, it would be nice if it balanced effectively and sure, measured accumulated current in and out. But there are good cheap outboard devices that can do that.
If a BMS does not protect the cells, it is "useless". It absolutely must be stable and dependable at that. If it does not make coffee nor measure current nor do anything else that is not it's central purpose then ok, worth mentioning but not dramatizing! That is quite far from useless and I agree with others that it is misrepresentation to use that term. To point that out is not censure, is just injecting some reason into the discussion.
Out of curiosity, does anyone know if the JK or Seplos BMS actually track current accurately?
BUT, a BMS' purpose is not as a shunt nor have I seen any of them sold as one. The BMS is for protecting the pack and individual cells. As a secondary use, I am depending on it for individual cell V monitoring and that's fairly important. As a tertiary, it would be nice if it balanced effectively and sure, measured accumulated current in and out. But there are good cheap outboard devices that can do that.
If a BMS does not protect the cells, it is "useless". It absolutely must be stable and dependable at that. If it does not make coffee nor measure current nor do anything else that is not it's central purpose then ok, worth mentioning but not dramatizing! That is quite far from useless and I agree with others that it is misrepresentation to use that term. To point that out is not censure, is just injecting some reason into the discussion.
Out of curiosity, does anyone know if the JK or Seplos BMS actually track current accurately?
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Exactly....Use it for it's intended purpose which is not SOC calculations.
I run both in parallel and the drift is always about 7-12% off. Someone mentioned that JDB might use the voltage values in the config vs true measurements. Starting to think that individual is correct.
Quattrohead
Emperor Of Solar
As they should be.
Multiple batteries in parallel is when it gets tricky to keep track of SOC due to less charge and discharge currents, cheap $100 BMS are not so accurate under 2A
TomC4306
Solar Obsessive
Both of my Overkill/JBD reset on full charge.
They hit 100%, absorption current still flowing.
Current tapers, SOC stays at 100.
Falls to float voltage, SOC maybe drops to 99.
Works fine for me.
Quattrohead
Emperor Of Solar
Of all the BMS I have used, JBD have been the best overall.
The Toyota of the BMS world.
The Toyota of the BMS world.
42OhmsPA
Who likes Electrical Gremlins?
I'm wondering if the 200a vs 300a model doesn't calculate differently. I most likely have different fw running on them as well.
The root cause is likely not seeing a full charge regularly...
Other than the SOC issues the JBDs have been solid.
The SOC only started bugging me since I added battery coms to SA...
The root cause is likely not seeing a full charge regularly...
Other than the SOC issues the JBDs have been solid.
The SOC only started bugging me since I added battery coms to SA...
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How deep are the cycles?
Not many, about 120 total cycles and from 85-15%
No, not really. You can calibrate the JK, but it won't be as accurate as a dedicated shunt. Personally, I want my BMS just to protect the cells, not report the state of charge or anything else. I can use a shunt for that - I just want the BMS to turn it all off if something bad happens, and both the JK and the JBD/Overkill work perfectly fine for this.
You need to get it up to 100% from time to time to keep the SOC in sync. Going from 15 to 85 is always going to drift as the BMS is not hitting any reference point.
I do every 3 days, always gets to 100 to balance over 3.45v. Cells always tight:
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Nope. 1%.
The JBD gets to 0% MUCH faster than Victron.
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