DGJBD Bluetooth BMS - a short review

[Bhupinder]

I often wondered what voltage to use for this rating as the range is wide , say 11.5 to 13.8v , and therefor rather use the Drok inline meter that displays the energy yield.

I believe capacity figures are calculated at nominal voltage of the battery.
In case of LifePO4 it should be 3.2v per cell.

 

[Pierre]

I believe capacity figures are calculated at nominal voltage of the battery.
In case of LifePO4 it should be 3.2v per cell.

I see Will P uses 12v for a 4S pack if I am not mistaken , so for 105Ah that will be 1260Wh as a reference for comparing performance , so 1580Wh is a great result.

 

[Bhupinder]

I see Will P uses 12v for a 4S pack if I am not mistaken , so for 105Ah that will be 1260Wh as a reference for comparing performance , so 1580Wh is a great result.

Prismatic 4S LifepO4 pack should retain {[3.2v(Nominal Voltage) X 105Ah(Current Rate per cell)] X 4}= 1,344‬ Wh worth of power.
Still 1580Wh is way too good to be true for fresh cells (~15% more).
Most probably as you said, they are higher capacity cells with slightly degraded capacity. Well either ways you got good cells.

On that BMS, I've been seeking to check - how does it provide over-charge protection for individual cells?
Does it stop charging the complete pack on detecting voltage threshold for any of the 4 cells? or does it starts burning charge on one of those?
How good would you rate the balancing function of this? Do those thin voltage sensing wires get hot? and lastly whats the self consumption power it is rated at? Apologies for so many queries...only if you may.

 

[JoeHam]

Thanks for the conversion and the calculation reference , Joe Ham. I often wondered what voltage to use for this rating
as the range is wide , say 11.5 to 13.8v , and therefor rather use the Drok inline meter that displays the energy yield.

For a "quick and dirty" calculation I just used the end voltage that I saw on one of your pictures.

That would make me happy with 105 Ah cells and close enough for my work. Others may want to be more granular.

Either way the online calculator is nice and I wouldn't have been looking for one if not following your thread.

 

[Pierre]

Prismatic 4S LifepO4 pack should retain {[3.2v(Nominal Voltage) X 105Ah(Current Rate per cell)] X 4}= 1,344‬ Wh worth of power.
Still 1580Wh is way too good to be true for fresh cells (~15% more).
Most probably as you said, they are higher capacity cells with slightly degraded capacity. Well either ways you got good cells.

On that BMS, I've been seeking to check - how does it provide over-charge protection for individual cells?
Does it stop charging the complete pack on detecting voltage threshold for any of the 4 cells? or does it starts burning charge on one of those?
How good would you rate the balancing function of this? Do those thin voltage sensing wires get hot? and lastly whats the self consumption power it is rated at? Apologies for so many queries...only if you may.

Hi Bhu , (1) Over charge protection is on a cell to cell basis as each cell OV can be programmed and also on a Pack Voltage basis (2) you can turn the cell balance on during charging to start at a preset voltage but (3) I do not rate the balancing function highly as it is passive balancing that dumps voltage at a very low current , about 30mA and (4) self discharge is claimed at 0.1% but can also be configured should you find a higher self-discharge over time.

 

[Craig]

Hi Bhu , (1) Over charge protection is on a cell to cell basis as each cell OV can be programmed and also on a Pack Voltage basis (2) you can turn the cell balance on during charging to start at a preset voltage but (3) I do not rate the balancing function highly as it is passive balancing that dumps voltage at a very low current , about 30mA and (4) self discharge is claimed at 0.1% but can also be configured should you find a higher self-discharge over time.

are you saying you can set the over/undervoltage of each cell? so its not a generic x.xx v for all cells but different for every one.

 

[Pierre]

are you saying you can set the over/undervoltage of each cell? so its not a generic x.xx v for all cells but different for every one.

Terribly sorry - my bad. Do not know what I was thinking at the time of posting. There is only one setting for Cell OV and UV as well as Pack OV and UV.

 

[Bhupinder]

Hi Bhu , (1) Over charge protection is on a cell to cell basis as each cell OV can be programmed and also on a Pack Voltage basis

Thanks! Thats interesting, did you got a chance to dig into how its trying to maintain OV at cell levels?

So the BIG question to all BMS experts:

Is it good to spend money on this relatively cheaper product with limited service support post sales
V/S
Electrodacus SBMS0 - which is not only a super-set in terms of functions & price but has a super PLUS of being OPEN SOURCE.
May be one can expect some remote support with the diagnosis and repairs if need be.
Saw the guy in YT channel Everlanders doing repairs to his SBMS, which is a cool way to maintain things than just popping out old - for new ones.

 

[Pierre]

I use this BMS only as a developmental tool for the packs that I build. After testing and evaluation I strap on a Daly plug&play BMS , test it and give it to the client.
As to your question above Bhu , as soon as the BMS detects an OV condition it opens the Charge FET and UV condition the Discharge FET.
So far I have not had any problems with this BMS but time will tell.

 

[Bhupinder]

Thanks for the response, so in nutshell it would stop charging as soon as any of the cells hit OV condition. Right?

 

[Pierre]

Thanks for the response, so in nutshell it would stop charging as soon as any of the cells hit OV condition. Right?

That is correct.

 

[Pierre]

Terribly sorry - my bad. Do not know what I was thinking at the time of posting. There is only one setting for Cell OV and UV as well as Pack OV and UV.

I meant to say "one setting each for Cell OV and UV and one setting each for Pack OV and UV" Sorry for the confusion.

 

[thedodgersonline]

It is still better to get the Windows app to run on your computer via RS232/UART as you get access to a few more settings and the best of all , while testing the capacity of your battery pack , you do not have to wait up for 5hrs or so to monitor / record the performance . The Windows app has a feature called 'Save data' . Once activated the app saves the state of the pack to an Excel file every 1 second. Which other BMS has this function ?

Hi Pierre
Received mine yesterday and all wired up and installed. Works great. Took 6 days from dispatch to my door. They did not have any RS232 connectors so just using the Bluetooth. Busy running a discharge cycle at the minute. It did a great job balancing the cells overnight too.
You have your voltage range set very narrow (2.9 to 3.4) is that for maximum cycles?

regards

 

[Pierre]

Hi Dodger , great news man ! That really was quick service. I have about 12 different profiles developed so far and that particular profile is a more ‘conservative’ one which should result in increased lifespan - not that it is really important as the pack will outlast me anyway As mentioned before , two of the cells are slightly out of whack on the upper and lower limits and that narrow voltage range favors the current pack makeup. I am waiting for more cells but my order is delayed due to Covid.
Once you start using the RS232 you can really capture so much data which will enable you to optimize your setup. I think that you could ’push’ your cells to near their limits for a few charge / discharge cycles to condition them. Enjoy experimenting and keep feedback coming.

 

[thedodgersonline]

Hi Pierre
Currently doing a capacity test and the BMS is keeping them well in line. Do you get your batteries via Alibaba. There are some great deals there. Some comprehensive threads on here about experiences with different sellers.
How is Cape Town doing under the lockdown! It is still my most favourite city in the world. Mulled wine at the restaurants in Fish Hoek. Hmmmmm.
Regards

 

[Pierre]

Your cells delta V is perfect ! I ordered the new batch on Alibaba but tracking info is sketchy at best - apparently in customs clearance at the moment and I think delivery will only take place after lockdown is lifted.
Yeah , CT is a special place to many. Where are you located now ? Our lockdown has been extended to end April and the place is like a ghost town and authorities are very strict about outside movements - offenders getting arrested and huge fines levied. Can only get essential deliveries like food / meds . I want to order a Klein Clamp meter from the US to measure DC current but shipping is dodgy at the moment.

 

[thedodgersonline]

Hi Pierre
Lived Pietermaritzburg, then Durban, then Melbourne and now Sunshine Coast hinterland.
I use 17net for tracking. Seems to work well with Chinese shippers. If buying from the US of A I use a service like ReShip or ShipItTo. They are great and not that expensive. I have them setup as an address on Amazon and select that for shipping.
We are under lockdown too, but can go out ‘for essentials’ but deliveries are working well. Online shopping works really well. Am about to buy some more cells too. Will get them from Amy on AliBaba.
Cheers.

 

[Pierre]

Hi Dodger , so you know ZA very well ! You live in a lovely part of the world now. I also make use of USaddress in NJ for USA shipments - they also consolidate a few parcels and send out 1 box. These days my orders from the States are rather small and I rather make use of Amazon / Ebay with their International Shipping Program , so all import duties / VAT are paid up front when you pay for your goods.
No wonder you got your order so quickly - China is just up the drag from you . Which company is Amy with ? Her name seems to come up quite often.
Keep that BMS humming.
Regards

 

[thedodgersonline]

Amy is with Shenzhen Xuba - everyone seems very happy with their service / products.

 

[Pierre]

First time that I really tested the BMS over discharge current protection happened yesterday when I plugged in (without thinking) a vacuum cleaner rated at 230v 1800w. This equates to a constant current demand of around 140a from the battery. However the inrush current on start up must have been quite a bit higher. The VC ran for about 5 sec before the BMS and inverter OC protection activated , disconnecting the load. Which one disconnected first I cannot tell for sure as both devices indicated an over current alarm. The OC setting on the BMS at present is 130a and I am very satisfied with this result. Testing is ongoing and until now I have only praise for this device.

 

[Fish Freak]

I have been playing with this BMS for a while now and must must say that I am very satisfied with the performance. All the protection functions work great - the only one that I have not tested is the 'low temp cut off'.
Testing is ongoing and I will report on future performance.
For $68 this is a one of the best BMS buys out there ! As Will always says " I am not sponsored and bought it with my own money"

Hey Pierre;

Thank you for this thread, it's making me consider experimenting with it to see if it will suit my needs, which is not solar, but marine deep draw. Looks like the price of the BMS has come down and even cells are amazingly cheap now. Can you tell me, for that $68 did it include the bluetooth module that works with Apple? Did you have to order a GPRS module? I looked at battery hookup and not only were they out of stock, but they didn't have the 120A version that I must have, so I guess I'll get this one on Alibaba? Is this the same one you're using?

I'm going to try to connect two 12v 120Ah batteries with this BMS in series to make 24v. My amp draw is low, max 60 amps, circuit breaker limited, so I'm going to take my chances. You think that's possible?

Lol, I'm also going to experiment with one of these as a marine engine starting battery, about 250-300 amps. I've seen drop-ins like Battleborn do it with only a 100A BMS. I hope the high amp draw of these cell types won't fry my 60 amp alternator. If anyone has ideas to restrict charge draw to soften the pull on a car/marine alternator, please let me know. I've thought of a DC/DC charger, but then I'd still need a lead-acid battery for the engine alternator to hook up to, and space is limited.

 

[Pierre]

Hi Fish Freak , thanks for your interest. I got mine on Alibaba from : https://www.alibaba.com/product-det...13.html?spm=a2700.12243863.0.0.2dee3e5fmAkZRT. Cherry gave excellent service and replied to all my emails etc.
It looks like the one you refer to in your post with the leads already soldered to the pads.
Came complete with Bluetooth dongle and UART/ RS232 interface with cable to connect to PC. You can download the Apple app from the APP Store.
Follow my other links to download the drivers for PC.
Are you going to assemble the 2 x 12v packs for series connection yourself from LFP cells ? In this case you would need an 8S BMS.
'Drop in' replacements like Battleborn have the BMS already built in. Just make sure that the pre-built packs you buy can be connected in series.
I have seen a few ideas on the forum re switching heavy loads and also alternator protection etc. Enjoy the experimentation.

 

[Fish Freak]

Hi Fish Freak , thanks for your interest. I got mine on Alibaba from : https://www.alibaba.com/product-det...13.html?spm=a2700.12243863.0.0.2dee3e5fmAkZRT. Cherry gave excellent service and replied to all my emails etc.
It looks like the one you refer to in your post with the leads already soldered to the pads.
Came complete with Bluetooth dongle and UART/ RS232 interface with cable to connect to PC. You can download the Apple app from the APP Store.
Follow my other links to download the drivers for PC.
Are you going to assemble the 2 x 12v packs for series connection yourself from LFP cells ? In this case you would need an 8S BMS.
'Drop in' replacements like Battleborn have the BMS already built in. Just make sure that the pre-built packs you buy can be connected in series.
I have seen a few ideas on the forum re switching heavy loads and also alternator protection etc. Enjoy the experimentation.

Thank you Pierre;

I can't use 8s bms 24v because my electrical system works better with modular 12v cells: 12v for starting, and 24v or 36v for electric propulsion. Plus a/c charging system is designed to charge 4 - 12v lead deep cycle batteries. The loads aren't that heavy, on the electric motor 60 amp breaker, average draw is usually half that. If I've made two 12v 100 Ah batteries with their own BMS, and separate 12v charging, why does the BMS care if it's used solo or two batteries in series? Is it a balance problem? What's the difference.

The amp draw is the same, all circumstances, is that not correct? Hold my beer. What could possibly go wrong?

 

[Pierre]

Thank you Pierre;

I can't use 8s bms 24v because my electrical system works better with modular 12v cells: 12v for starting, and 24v or 36v for electric propulsion. Plus a/c charging system is designed to charge 4 - 12v lead deep cycle batteries. The loads aren't that heavy, on the electric motor 60 amp breaker, average draw is usually half that. If I've made two 12v 100 Ah batteries with their own BMS, and separate 12v charging, why does the BMS care if it's used solo or two batteries in series? Is it a balance problem? What's the difference.

The amp draw is the same, all circumstances, is that not correct? Hold my beer. What could possibly go wrong?

Hi FF , my experiments thus far only involve single 12v packs for camping / off roading and I have not experimented with multiple packs in series. I do not want to give you incorrect info or advice - maybe someone more informed can assist here.

 

[Pierre]

So far very satisfied with this BMS and all its functionality. For now I am moving on to testing another BMS.