BMS that does not have to be hacked in Chinese to work

[perryg114]

So are their any BMS units that actually work and don't have to be hacked in Chinese to make them work properly? I want something that can measure individual cell voltages and stop charging at the correct voltage levels and it allows those voltage levels to be changed to prevent deep cycling. Proper documentation would be a good thing (in English}.

I would like to consider an external shunt and contactor based BMS at some point but am not against trying a more conventional BMS in a charge only configuration for an EV and Full charge and load control for a 12V 100AH system for an RV.

 

[Horsefly]

hacked in Chinese

Not sure what this means. I'm not aware of any BMS's that you CAN hack in Chinese, much less that you HAVE TO hack in Chinese.

Most of the BMSs that are labeled "smart" can be configured with a Bluetooth app. Then you can set all the voltage, current, and temperature limits.

I want something that can measure individual cell voltages and stop charging at the correct voltage levels

Just to be clear: The BMS has the job of protecting the cells in your battery. It isn't meant to routinely control the charging. You should have your charging source (charge controller, inverter/charger, etc.) configured to stop charging at the right point. It is only if that fails somehow that the BMS should have to cut off charging.

 

[Goboatingnow]

Not sure what this means. I'm not aware of any BMS's that you CAN hack in Chinese, much less that you HAVE TO hack in Chinese.

Most of the BMSs that are labeled "smart" can be configured with a Bluetooth app. Then you can set all the voltage, current, and temperature limits.


Just to be clear: The BMS has the job of protecting the cells in your battery. It isn't meant to routinely control the charging. You should have your charging source (charge controller, inverter/charger, etc.) configured to stop charging at the right point. It is only if that fails somehow that the BMS should have to cut off charging.

The last paragraph is actually not the optimum. The optimum is the BMS controls all aspects of the battery , safety disconnects , plus charging control not having that control spread around the charge sources.

In addition unless charge sources measure battery current as opposed to charge current , they can never really know when to end the charge cycle. Sadly few system do.

 

[Horsefly]

The last paragraph is actually not the optimum. The optimum is the BMS controls all aspects of the battery , safety disconnects , plus charging control not having that control spread around the charge sources.

In addition unless charge sources measure battery current as opposed to charge current , they can never really know when to end the charge cycle. Sadly few system do.

Well, I would say the BMS does not do what you are suggesting. In some rare cases, the BMS can communicate with the charging sources, and in even rarer cases those charging source can control the charging current in response to the BMS. Not clear the OP is looking to get one of those rare systems. If he is, he will have to do lots more research besides just picking a BMS (which is the section this post was made).

 

[Goboatingnow]

Well, I would say the BMS does not do what you are suggesting. In some rare cases, the BMS can communicate with the charging sources, and in even rarer cases those charging source can control the charging current in response to the BMS. Not clear the OP is looking to get one of those rare systems. If he is, he will have to do lots more research besides just picking a BMS (which is the section this post was made).

I agree it’s not common , the REC BMS communicating with a victron CerboGx is close , hers an excellent write up round the issue just discussed https://nordkyndesign.com/charging-marine-lithium-battery-banks/

 

[perryg114]

Ok was being somewhat sarcastic. It seems that most of these cheaper BMS units have little or no documentation and what little they do have is in Chinglish. I don't want to buy half a dozen of these things to find out most don't work as advertised. My application is solar and Electric Vehicle which does the latter does not have a charge controller. I know what a BMS does but which ones actually work. Not hearing good things about the Daly BMS units. Not a lot of documentation out there and many different versions and software interfaces are not ready for prime time. Install programs written in Chinese etc. (AKA CHINESE HACKING).

 

[A.Justice]

JBD (Jiabaida, overkill solar) is a decent smart BMS brand with an app in useable English. Overkill solar sells JBD BMS's and has clear English documentation for them as well.

 

[Ampster]

In addition unless charge sources measure battery current as opposed to charge current , they can never really know when to end the charge cycle. Sadly few system do.

Can you explain how those few systems do that. My BMS and the charging circuit in my Inverter tell me the current that goes in and out of my pack. Those numbers agree every time I have checked. I have adjusted my inverter settings so the charge cycle ends where I want it to end.

 

[mikefitz]

A range of JBD brand BMS , as also supplied by Overkill ( useful documentation), from LLT,

Home Page - LLT POWER ELECTRONIC

Mike

 

[perryg114]

JBD (Jiabaida, overkill solar) is a decent smart BMS brand with an app in useable English. Overkill solar sells JBD BMS's and has clear English documentation for them as well.

I am leaning towards them. I did some research last night.

 

[Horsefly]

The JK BMS seems to be an improvement over the JBD, but with some caveats. I have purchased several JBDs and have been generally happy with them. The only two things I don't like about them is (1) they only have passive balancing, which for the gray market unmatched cells most of us can buy can be a problem, and (2) the app is.... well, a bit quirky.

The JK BMS has very good active balancing (actually moves energy from high cells and low cells above the upper knee of the charge curve), and it has a better app. I have purchased two of the JK 8S BMSs.

The only caveat is that some of the JK's currently have some sort of issue that causes some strange noise during charging. The noise actually comes from other equipment (in my case, a Schneider inverter/charger), and I can't say for sure if it is actually causing a problem. I'm hoping JK fixes the problem. (hello @Nami).

 

[perryg114]

The JK BMS seems to be an improvement over the JBD, but with some caveats. I have purchased several JBDs and have been generally happy with them. The only two things I don't like about them is (1) they only have passive balancing, which for the gray market unmatched cells most of us can buy can be a problem, and (2) the app is.... well, a bit quirky.

The JK BMS has very good active balancing (actually moves energy from high cells and low cells above the upper knee of the charge curve), and it has a better app. I have purchased two of the JK 8S BMSs.

The only caveat is that some of the JK's currently have some sort of issue that causes some strange noise during charging. The noise actually comes from other equipment (in my case, a Schneider inverter/charger), and I can't say for sure if it is actually causing a problem. I'm hoping JK fixes the problem. (hello @Nami).

Where do you get a JK BMS?

 

[Horsefly]

Where do you get a JK BMS?

The Hankzor store on Aliexpress. I'm unaware of anyone in the U.S. currently reselling them, but there may be someone.

Edit: I don't have a link right now, but can provide one later when I have a bit more time.

 

[Goboatingnow]

jK bms don’t seem to support external contractors which is a pity.

 

[Horsefly]

jK bms don’t seem to support external contractors which is a pity.

I assume you mean contactor, rather than "contractor".

Yep, that can be an issue for some. I actually don't need the extra current capacity, and I prefer having separate control on charging vs. discharging, which is not possible if using a contactor.

 

[perryg114]

I assume you mean contactor, rather than "contractor".

Yep, that can be an issue for some. I actually don't need the extra current capacity, and I prefer having separate control on charging vs. discharging, which is not possible if using a contactor.

I would only use a contactor for the load side on a high current application like an EV. The BMS can handle charge cutoff since that will be below load currents in most cases.

 

[Horsefly]

I would only use a contactor for the load side on a high current application like an EV. The BMS can handle charge cutoff since that will be below load currents in most cases.

I think there may be some confusion here. All of the BMS's we have been talking about - and almost all BMS's on the market - are "common port" meaning that both the load (discharge) and charge go through the same port. So you can't "only use a contactor for the load side". If the contactor cuts off the load, it also cuts off the charging.

MOSFET-based BMS's generally can separately control charging and discharging, because there are separate directional MOSFET circuits set up for each of the two current directions - In and out of the battery. A contactor is not directional, so either both charge and discharge are ON, or they are both OFF.

 

[Goboatingnow]

I think there may be some confusion here. All of the BMS's we have been talking about - and almost all BMS's on the market - are "common port" meaning that both the load (discharge) and charge go through the same port. So you can't "only use a contactor for the load side". If the contactor cuts off the load, it also cuts off the charging.

MOSFET-based BMS's generally can separately control charging and discharging, because there are separate directional MOSFET circuits set up for each of the two current directions - In and out of the battery. A contactor is not directional, so either both charge and discharge are ON, or they are both OFF.

Huh. If you separate the charge bus and load bus then you can switch them seperately , using two contactors. ( or mosfet switches )

Why anyone would want to only switch load only or charge only is beyond me.

There no way in my opinion after a LVC HVC or other safety trip automatic recharge should begin.

 

[Horsefly]

Huh. If you separate the charge bus and load bus then you can switch them seperately , using two contactors. ( or mosfet switches )

If you separate them, then it is not a "common-port" BMS. JK, JBD, Daly, etc. are all common port. I think you can get much more expensive BMSs that let you do them separately, but those have not been the subject here.

Why anyone would want to only switch load only or charge only is beyond me.

There are a number of reasons. For one in my case: If the temperature gets close to freezing, I don't want to charge my cells, so that is disabled. However, leaving discharge ON presents a voltage to the solar charge controller, so it can use PV to power the heating elements to warm the cells back up so they can be charged.

More generally, if the BMS turns off due to the cells being discharged below some level, turning off charging as well doesn't allow the cells to ever get recharged. I guess in your world a discharged battery doesn't ever get recharged. Do you throw it away?

 

[Goboatingnow]

If you separate them, then it is not a "common-port" BMS. JK, JBD, Daly, etc. are all common port. I think you can get much more expensive BMSs that let you do them separately, but those have not been the subject here.

There are a number of reasons. For one in my case: If the temperature gets close to freezing, I don't want to charge my cells, so that is disabled. However, leaving discharge ON presents a voltage to the solar charge controller, so it can use PV to power the heating elements to warm the cells back up so they can be charged.

More generally, if the BMS turns off due to the cells being discharged below some level, turning off charging as well doesn't allow the cells to ever get recharged. I guess in your world a discharged battery doesn't ever get recharged. Do you throw it away?

No it’s just I manually command a reconnect