bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
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ElectricGod   10 MW

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Re: bluetooth BMS?

Post by ElectricGod » Apr 05 2018 6:21pm

csc wrote:
Apr 04 2018 2:08am
Thanks again

Do you confirm that it is possible to set custom balancing values, such as 4.11 balancing and 4.12 full charge ? I can't understand in the product description where that setting would be
On both of the smart BMS types talked about here, you can set the voltages.

24/32S smart BMS
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Image

13-20S smart BMS
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Image

Image
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Re: bluetooth BMS?

Post by Inwo » Apr 05 2018 9:57pm

Email me the links or zip files.
They both look newer than my apps.

Never did get bt working on pc.

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Re: bluetooth BMS?

Post by Secular » Apr 06 2018 1:31am

This may seem like a dumb question, but can you use the larger 24S/32S boards with 14S battery pack? I saw that some of them are adjustable via software, but it looks like its still limited to 16S at a minimum.
Why is this a limitation and why cann't you run anything from 1S to the max of the board?

I'm looking at purchasing this BMS and it asks for how many batteries will be in series. Is there any difference between them? if I get a 14s, I could go upto a 15s?

Thanks.

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Re: bluetooth BMS?

Post by csc » Apr 06 2018 2:25am

ElectricGod wrote:
Apr 05 2018 6:21pm
On both of the smart BMS types talked about here, you can set the voltages. (...)
Great. Let's go then !

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Re: bluetooth BMS?

Post by zipoman » Apr 06 2018 3:30am

Hi,
i have question for balancing current. I have 4s 80A BMS with bluetooth, but 50mA balance current is not too much. Chip is bq7692003, transistor for resistor SMD Y2, and bleeding resistor value 75ohm. I try 10ohm in paralel, slightly better, but still little. I would need to get around 1A, some ideas? Thank you
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Re: bluetooth BMS?

Post by flippy » Apr 06 2018 3:42am

at 1A you are bleeding off 4W of power on each activated resistor.

that is yuge amount of power for such a small pack. might i recommend fixing the pack and prehaps redistrubute the cells to the pack is naturally more balanced.
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Re: bluetooth BMS?

Post by zipoman » Apr 06 2018 4:09am

Pack in background is only test 12V battery (app 7Ah from defective assistant starting car box). Determining of BMS is 12V 100Ah LFP battery for boat motor. I carefully select the cells according to their capacity, the charging voltage is 3.5V/cell, discharging not exceed 3V. At the end of the charge, a higher balancing current is needed.

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Re: bluetooth BMS?

Post by flippy » Apr 06 2018 6:57am

i would put in a second transitor instead of the resistor and use a external power resistor to bleed off if you have such a big pack. but seriously: why have such a kiddy bms for such a huge 12V pack?

basically with a 12V LFP battery you only need a balance board, not a full blown BMS of your cells are identical and from the same batch.

just get these: http://bestechpower.com/balanceboard/HCX-D162.html

add a big ass megafuse rated at triple the current the battery will ever see and be done.

you can still keep the bms connected (without the P- connected, just bypass the BMS for main load. if you want the bleutooth stuff.
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Re: bluetooth BMS?

Post by Inwo » Apr 06 2018 9:06am

zipoman wrote:
Apr 06 2018 3:30am
Hi,
i have question for balancing current. I have 4s 80A BMS with bluetooth, but 50mA balance current is not too much. Chip is bq7692003, transistor for resistor SMD Y2, and bleeding resistor value 75ohm. I try 10ohm in paralel, slightly better, but still little. I would need to get around 1A, some ideas? Thank you
Where did you find that? I can't find a 6s with bt.

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Re: bluetooth BMS?

Post by zipoman » Apr 06 2018 9:09am

I asked the seller for it and put it on the web.
https://www.aliexpress.com/item/4S-80A- ... 0.0.cgm0eP

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Re: bluetooth BMS?

Post by ElectricGod » Apr 06 2018 1:47pm

Secular wrote:
Apr 06 2018 1:31am
This may seem like a dumb question, but can you use the larger 24S/32S boards with 14S battery pack? I saw that some of them are adjustable via software, but it looks like its still limited to 16S at a minimum.
Why is this a limitation and why cann't you run anything from 1S to the max of the board?

I'm looking at purchasing this BMS and it asks for how many batteries will be in series. Is there any difference between them? if I get a 14s, I could go upto a 15s?

Thanks.
Any BMS is going to have a minimum voltage needed to operate it. Smart BMS need to have some kind of on board power supply as well to power the CPU and other things that are central to the "smart" functionality. That power supply will have a voltage range that it operates within. Quite often these sorts of things define the minimum cell counts for a BMS. I have a BMS that is 20S. The design of the charge controller disables the mosfets if it can't detect 20 cells. The charge controller assumes it has a bad cell and does exactly what it was intended to do...protect the battery pack. You will run into this sort of thing.
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Re: bluetooth BMS?

Post by ElectricGod » Apr 06 2018 1:51pm

flippy wrote:
Apr 06 2018 6:57am
basically with a 12V LFP battery you only need a balance board, not a full blown BMS of your cells are identical and from the same batch.

just get these: http://bestechpower.com/balanceboard/HCX-D162.html
Flippy...
Do you know how to set these modules? I've looked at them in the past and wanted to use them on LTO. Bestech doesn't openly support LTO and getting them to say "X product" can work at LTO voltages is virtually impossible.
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Re: bluetooth BMS?

Post by Secular » Apr 06 2018 9:14pm

ElectricGod wrote:
Apr 06 2018 1:47pm
Secular wrote:
Apr 06 2018 1:31am
This may seem like a dumb question, but can you use the larger 24S/32S boards with 14S battery pack? I saw that some of them are adjustable via software, but it looks like its still limited to 16S at a minimum.
Why is this a limitation and why cann't you run anything from 1S to the max of the board?

I'm looking at purchasing this BMS and it asks for how many batteries will be in series. Is there any difference between them? if I get a 14s, I could go upto a 15s?

Thanks.
Any BMS is going to have a minimum voltage needed to operate it. Smart BMS need to have some kind of on board power supply as well to power the CPU and other things that are central to the "smart" functionality. That power supply will have a voltage range that it operates within. Quite often these sorts of things define the minimum cell counts for a BMS. I have a BMS that is 20S. The design of the charge controller disables the mosfets if it can't detect 20 cells. The charge controller assumes it has a bad cell and does exactly what it was intended to do...protect the battery pack. You will run into this sort of thing.
Thanks for explaining that. Looks like the 14s or the 15s selection from their website might be the range for that particular BMS.

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Re: bluetooth BMS?

Post by flippy » Apr 07 2018 6:15am

ElectricGod wrote:
Apr 06 2018 1:51pm
flippy wrote:
Apr 06 2018 6:57am
basically with a 12V LFP battery you only need a balance board, not a full blown BMS of your cells are identical and from the same batch.

just get these: http://bestechpower.com/balanceboard/HCX-D162.html
Flippy...
Do you know how to set these modules? I've looked at them in the past and wanted to use them on LTO. Bestech doesn't openly support LTO and getting them to say "X product" can work at LTO voltages is virtually impossible.
if you have a actual LTO battery (i would not understand why considering the size, weight and cost are usually worse then a lifepo4 or 18650 solution) you can replace the resistors on the back of the unit for different trigger values. i dont know if the transitors would trigger properly at 3V but bestech makes custom batches, you might be able to get them to make a dozen or so that trigger at 3V. if you spend that money on LTO cells a handful of those boards should not be that much of a issue.
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Re: bluetooth BMS?

Post by ElectricGod » Apr 09 2018 1:58pm

flippy wrote:
Apr 07 2018 6:15am
ElectricGod wrote:
Apr 06 2018 1:51pm
flippy wrote:
Apr 06 2018 6:57am
basically with a 12V LFP battery you only need a balance board, not a full blown BMS of your cells are identical and from the same batch.

just get these: http://bestechpower.com/balanceboard/HCX-D162.html
Flippy...
Do you know how to set these modules? I've looked at them in the past and wanted to use them on LTO. Bestech doesn't openly support LTO and getting them to say "X product" can work at LTO voltages is virtually impossible.
if you have a actual LTO battery (i would not understand why considering the size, weight and cost are usually worse then a lifepo4 or 18650 solution) you can replace the resistors on the back of the unit for different trigger values. i dont know if the transitors would trigger properly at 3V but bestech makes custom batches, you might be able to get them to make a dozen or so that trigger at 3V. if you spend that money on LTO cells a handful of those boards should not be that much of a issue.
You are right that they weigh more and are larger than pretty much any other lithium solution, but they have advantages too. Like any lithium battery, they don't tolerate over charging.

1. 10,000 charge cycles!!! If you charged every day, they would last something like 25+ years.
2. They tolerate being ran down dead flat with no harm. However, below about 1.95 volts they have spent their capacity.
3. VERY safe...virtually no possibility of going thermal.
4. Highly tolerant of low temperature...far better than LION.
5. I can get them super cheap! 11,000mah cells for $8.33 or less each...for new cells. I know they handle 30C without issues.
6. I already have 24 of them and will probably buy another 200+ soon.
7. You don't need a BMS since the only thing that matters is balancing and over voltage.

AKA..cheap resilient solution that will last longer than you will.
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Re: bluetooth BMS?

Post by flippy » Apr 09 2018 3:18pm

if you can get them basically free it is a nice fun project.

but lifespan is not really much of an arguement if a properly sized pack of 18650's and 4.05v top charge will last you several thousands of cycles and is half the size and a fraction of the weight i dont see the advantage in a mobile solution.
i have seen them used in buses and stuff that get charged every few stops or so but it is not a battery type anyone should invest in for their daily driver.

i think you can get bestech to make a LFP series if you ask nicely. you can either sell them with a balance board or use them yourself but if you get 200 you can probably get your own custom ones made.
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Re: bluetooth BMS?

Post by themelon » Apr 09 2018 3:28pm

flippy wrote:
Apr 09 2018 3:18pm
i think you can get bestech to make a LFP series if you ask nicely. you can either sell them with a balance board or use them yourself but if you get 200 you can probably get your own custom ones made.
Perhaps a group buy for LTO balance boards? It may not be necessary though if the SuperCap boards work out well enough. Unless you want to downsize the board because they will have allot of wasted PCB space for mounting the actual caps.

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Re: bluetooth BMS?

Post by ElectricGod » Apr 09 2018 11:33pm

themelon wrote:
Apr 09 2018 3:28pm
flippy wrote:
Apr 09 2018 3:18pm
i think you can get bestech to make a LFP series if you ask nicely. you can either sell them with a balance board or use them yourself but if you get 200 you can probably get your own custom ones made.
Perhaps a group buy for LTO balance boards? It may not be necessary though if the SuperCap boards work out well enough. Unless you want to downsize the board because they will have allot of wasted PCB space for mounting the actual caps.
That's my current solution...super cap boards.
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Re: bluetooth BMS?

Post by ElectricGod » Apr 09 2018 11:56pm

flippy wrote:
Apr 09 2018 3:18pm
if you can get them basically free it is a nice fun project.

but lifespan is not really much of an arguement if a properly sized pack of 18650's and 4.05v top charge will last you several thousands of cycles and is half the size and a fraction of the weight i dont see the advantage in a mobile solution.
i have seen them used in buses and stuff that get charged every few stops or so but it is not a battery type anyone should invest in for their daily driver.

i think you can get bestech to make a LFP series if you ask nicely. you can either sell them with a balance board or use them yourself but if you get 200 you can probably get your own custom ones made.
I'll post my LTO build in my battery build thread. It's not really relevant to this thread.
My excellent adventure through some battery builds: https://endless-sphere.com/forums/viewt ... 14&t=76013

LTO's at 10X the charge cycles of LION...that sounds like a really big argument for LTO IMHO. Admittedly by the time you run out of life in your LTO pack (20-30 years is a loooong time for technology!) there will be LOTS of new battery tech that just destroys anything we have today.

You are right about weight when you compare on capacity alone. Four 21700's in parallel have the same capacity of a single 11Ah LTO cell and do weigh a good bit less than the LTO cell. However to get 300 amps discharge, that's going to take quite a few MORE 21700's to deliver that much amperage. So depending on how you measure "apples to apples", then LTO can be the same weight or LESS and similar size as LION to get the same discharge rate. I think it has it's place. My next EV build will start out hybrid (LIPO and LTO), but later will go all LTO. IE: The proof will be in the pudding. At the price I'll pay for a couple hundred LTO's, that will be cheaper by 80% as compared to LION for way higher discharge rates and similar capacity. What's more, the LTO build will be far easier to do than any amount of cell welding could ever be.
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Re: bluetooth BMS?

Post by themelon » Apr 10 2018 1:19am

ElectricGod wrote:
Apr 09 2018 11:33pm

That's my current solution...super cap boards.
I just received a couple of them today not realizing that what I had ordered didn't actually have board space dedicated for mounting the caps. It has balance leads. So there is likely not much point, at least right now, in trying to get custom ones made. They do have a fair bit of open space but not enough for me to care about for my needs.

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Re: bluetooth BMS?

Post by flippy » Apr 10 2018 3:23am

Slighty more ontopic:

If you want to keep the bms from cutting out the bluetooth you can, The bluetooth dies when there is no current flow. On itself that is fine for most people but i would like to see the bms settings when it is done charging the next morning without having to turn on the controller to wake it up again.
Right now i tried setting the sleep timer to 9999 and see if it sticks. That should be 7 days before it sleeps.
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Re: bluetooth BMS?

Post by ElectricGod » Apr 10 2018 10:33am

flippy wrote:
Apr 10 2018 3:23am
Slighty more ontopic:

If you want to keep the bms from cutting out the bluetooth you can, The bluetooth dies when there is no current flow. On itself that is fine for most people but i would like to see the bms settings when it is done charging the next morning without having to turn on the controller to wake it up again.
Right now i tried setting the sleep timer to 9999 and see if it sticks. That should be 7 days before it sleeps.
I noticed that too. My BMS turns off if it's just hooked up but not actively charging or discharging regularly. I had intended to mess with settings to get this behavior to either stop or extend beyond the 1 or 2 days I see right now. BTW...0 typically means off. If you are wanting week long on periods, then 999 ought to accomplish that, but I think if you want the sleep function disabled, that's probably 0.
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Re: bluetooth BMS?

Post by ElectricGod » Apr 10 2018 10:35am

themelon wrote:
Apr 10 2018 1:19am
ElectricGod wrote:
Apr 09 2018 11:33pm

That's my current solution...super cap boards.
I just received a couple of them today not realizing that what I had ordered didn't actually have board space dedicated for mounting the caps. It has balance leads. So there is likely not much point, at least right now, in trying to get custom ones made. They do have a fair bit of open space but not enough for me to care about for my needs.
Let's move our LTO discussion to this thread. This is something of great interest to me and very few people know much about this battery tech.

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Re: bluetooth BMS?

Post by themelon » Apr 10 2018 11:47am

ElectricGod wrote:
Mar 28 2018 2:50pm

Hey Circuit...
I have an idea for you. Your BMS is an all in one device. How about split out the power mosfets to a separate board and then make the balancing and monitoring boards stack-able. This allows your product to reach a far broader market (people like me!!!) where 16S is flat out a show stopper. The larger my pack is, the more it costs and the more I'm willing to pay for battery protection. At 16S, IMHO, I'm going to go with whatever is cheap for no other reason than the battery pack cost is not that great. IE: It's NOT compelling to spend a lot of money on a BMS that costs almost as much as my batteries do. With a stack-able board option and separate mosfet board, you can build 16S BMS all you want and then expand it to a 32S option that works at 20-32S. Add a third balance board and now you've reached 95% of the DIY market and probably a lot of the high end commercial builders too! The mosfet board can then be built in several options...such as 50, 100, 200, 300 amps. And of course build them to voltage requirements. The Chinese do this all day long. Why can't Western world BMS makers figure this out and then do it for a reasonable price?
This one looks interesting:

https://www.aliexpress.com/store/produc ... 22313.html

Modular balance section, from 3s to 112s, mentions Bluetooth, separate power board. Not enough detail on the product listing page though. I'll contact the seller and probably order what appears to be the basic needed modules.


Another not quite as modular one:

https://www.aliexpress.com/store/produc ... 93603.html


And yet two more:

https://www.aliexpress.com/store/produc ... 52304.html
https://www.aliexpress.com/store/produc ... 65318.html

I'm going to end up going broke today...

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Re: bluetooth BMS?

Post by flippy » Apr 10 2018 4:32pm

ElectricGod wrote:
Apr 10 2018 10:33am
I noticed that too. My BMS turns off if it's just hooked up but not actively charging or discharging regularly. I had intended to mess with settings to get this behavior to either stop or extend beyond the 1 or 2 days I see right now. BTW...0 typically means off. If you are wanting week long on periods, then 999 ought to accomplish that, but I think if you want the sleep function disabled, that's probably 0.
9999 does not work, came back after 8 hours and BT was off. 999 is only 16 hours. will mess around but 0 did not turn it off.
i will email them and ask if they can add the option.
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