bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
User avatar
izeman   10 GW

10 GW
Posts: 4744
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: bluetooth BMS?

Post by izeman » Jul 30 2018 2:25am

if you want to safe cells from touching each other then there are way more adequate solutions than this rubbish cell holders which really are only good for stationary application. the interconnecting nickle strips btw are a joke as well. not able to carry the current needed.
those cell holders add real flex to the whole battery, and put stress on welding spots.
there are triangular spacers that do a better job here. or you use some hot glue that does the very same job ...
i still don't know how you think that there is the slightest form of movement inside the battery, and that this could be enough to shear off enough material from two layers of heat shrink, two layers of kapton tape and hot glue to cause a short?!

jumpjack   100 W

100 W
Posts: 184
Joined: Apr 11 2011 6:16am

Re: bluetooth BMS?

Post by jumpjack » Jul 30 2018 2:41am

izeman wrote:
Jul 30 2018 2:25am
if you want to safe cells from touching each other then there are way more adequate solutions than this rubbish cell holders which really are only good for stationary application.
I really don't get why you say that. Did you ever try them, or have just seen them in picture?
the interconnecting nickle strips btw are a joke as well. not able to carry the current needed.
It of course depends on application (i.e. current flow), just do calculation. Single strips are around 10x0.3mm (=3mm 2) in section and just 40mm long. Multicell strips can of course carry much more current.

And adding tin over a nickel surface (to reduce resistance) is much easier and safe than "unwelding" a spot-welded strip and replacing it with "something bigger".
those cell holders add real flex to the whole battery, and put stress on welding spots.
Flex? It's true exactly the opposite: without any holder, nothing prevents the pack from stretching and bending and flexing, which results in rubbing of cells surface.
there are triangular spacers that do a better job here.
As far as I know, they are triangular just to save some space. (Indeed I used them in one battery to save some mm)
or you use some hot glue that does the very same job ...
Hot glue on a "device" highly sensitive to high temperatures is not good.
i still don't know how you think that there is the slightest form of movement inside the battery
Try it. The longest the battery, the easiest is to change its shape by applying pressure on one side.
, and that this could be enough to shear off enough material from two layers of heat shrink, two layers of kapton tape and hot glue to cause a short?!
Rubbing, rubbing, rubbing, continuous rubbing for years, and years, and years.
What could ever happen to a thin plastic foil between two metal cans?
Last edited by jumpjack on Jul 30 2018 3:29am, edited 1 time in total.

User avatar
izeman   10 GW

10 GW
Posts: 4744
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: bluetooth BMS?

Post by izeman » Jul 30 2018 3:03am

i give up. let's talk about it in 2-3 years when i replace my battery. but this discussion is completely off-topic here, and i will stay on topic here.

User avatar
madin88   100 MW

100 MW
Posts: 2801
Joined: May 27 2013 2:02am
Location: Austria

Re: bluetooth BMS?

Post by madin88 » Jul 30 2018 4:04am

jumpjack wrote:
Jul 28 2018 11:48am
izeman wrote:
Jul 24 2018 2:48am
IMG_0312.JPG
This is a very dangerous - but common - method to build batteries, without any holder.
Unfortunately, road vibrations will soon cause shortcircuits and falmes in such a battery.
Always use holders!
Do you see the plastic spacers on the Bionx battery (reused from the original battery!), and the heat resistant kapton (polyamid) tape between the series groups on the other battery?
I think this battery is build properly and safe enough for his application, and regarding the vibrations and rubbing thats only a guess as we don't know if this could be an issue or not. But when looking at izemans bike and the tight fit of the battery into the frame, i think it is safe enough.
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
- KTM Hardtail Pedelec / eZee V2 6T / 27,5" / Kelly KBSX @ 1,5kW / Torque PAS / CA-V3 / 13s4p Sanyo GA in Shark case

User avatar
thundercamel   1 W

1 W
Posts: 51
Joined: Jul 23 2018 2:58pm
Location: Round Lake, Illinois

Re: bluetooth BMS?

Post by thundercamel » Jul 30 2018 11:57am

izeman wrote:
Jul 30 2018 3:03am
i give up. let's talk about it in 2-3 years when i replace my battery. but this discussion is completely off-topic here, and i will stay on topic here.
Agreed. The proof is in the pudding :)

Still good news on my front. This cycle the BMS never cut out when the battery got low, because none of the cell groups were too low. The motor controller actually progressively limited current draw based on incoming total voltage, which was nice to limp home. I also figured out that you can tap on one of the cell groups to get a nice graph. Look at that current reduction slope!

Image

I also didn't realize that you could set the balancing precision to the thousands of a volt, as I believe it came factory set to 0.05 volts. I started balancing at 3.8 volts just for this one time, and the results are good. Is the downside to balancing early just a longer charge time and/or more energy consumed by the charger (spent on the balancing resistors)?

Image

Image

Also interesting graph from back when group 13 was low:
Image
My Ebike builds - Existing bikes, affordable motor kits, self built 14s6p batteries

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Jul 30 2018 12:22pm

parabellum wrote:
Jul 28 2018 12:33pm
jumpjack wrote:
Jul 28 2018 11:48am
I see there are some firmwares around, for BT BMS.
Is there any opensource firmware available for this BMS?
It is even worse, there are same type Bms's that only work with its own tier of software. Open source would be so nice, I already miss some settings.
An open source app that worked with all BMS would be great.

Does anyone have firmware for these BMS? I'd like to get all of mine on whatever is the latest. This is 16/20S, but it ought to be the same thing for the entire product line. I have several firmware versions.

Image
Last edited by ElectricGod on Jul 30 2018 12:37pm, edited 1 time in total.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
izeman   10 GW

10 GW
Posts: 4744
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: bluetooth BMS?

Post by izeman » Jul 30 2018 12:28pm

i wouldn't dare to flash any of those chinese BMS with any firmware NOT sent by the official supplier/manufacturer. who knows how many clones of theses things exist and if they all work exaclty the same way - and not only LOOK the same.

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Jul 30 2018 12:38pm

izeman wrote:
Jul 30 2018 12:28pm
i wouldn't dare to flash any of those chinese BMS with any firmware NOT sent by the official supplier/manufacturer. who knows how many clones of theses things exist and if they all work exaclty the same way - and not only LOOK the same.
Of course...was looking for the link to the manufacturers ROM pages.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
flippy   10 kW

10 kW
Posts: 851
Joined: Aug 12 2015 3:07pm

Re: bluetooth BMS?

Post by flippy » Jul 30 2018 2:31pm

good luck finding the original factory in the first place. i tried. some retailers point to other retailers and those aint talking.
Lithium beats liquid dinosaurs.

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Jul 30 2018 5:58pm

flippy wrote:
Jul 30 2018 2:31pm
good luck finding the original factory in the first place. i tried. some retailers point to other retailers and those aint talking.
Right...been what I've gotten too...why I asked.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
eee291   10 kW

10 kW
Posts: 708
Joined: Nov 05 2015 4:35pm
Location: Austria, Burgenland: Güssing

Re: bluetooth BMS?

Post by eee291 » Jul 31 2018 7:04am

This is as far as I was able to get with the support person from: https://www.lithiumbatterypcb.com

He/She did say that they make those Smart BMS themselves.
save.PNG
No response afterwards.

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Jul 31 2018 11:35am

THat's pretty typical...no answer. THe idea is you will give up and go away and we don't have to do anything.

Don't ask them "If you can update". Just ask them for the latest firmware. Don't give them the option to say no. Just say you want the latest firmware and that's all.

I have BMS with 4 different versions and yet they are hardware wise identical. Once I have the firmware, I'll take the "risk" on the oldest BMS and report back if it works or not. I think it won't be a problem. I've updated firmware in devices for the last 30 years and usually it works great. Since all these BMS are using the Atmel 328, the firmware will run in the 328. Most likely the newer versions help the BMS run on less power and shut things down more often. Maybe they fix some issues with reading the BMS correctly. This is the big reason why I want to update the oldest BMS. It doesn't display data as well as the newer ones. Sometimes it will delay or be just a little glitchy before data comes up. Most likely a firmware upgrade will fix these details.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
flippy   10 kW

10 kW
Posts: 851
Joined: Aug 12 2015 3:07pm

Re: bluetooth BMS?

Post by flippy » Jul 31 2018 3:57pm

Anything simmilair on those high power 32S ones? I got a bunch of those. They dont make these models in 150~300A do they?
Lithium beats liquid dinosaurs.

Gab   100 W

100 W
Posts: 282
Joined: Aug 05 2012 7:18am

Re: bluetooth BMS?

Post by Gab » Aug 02 2018 11:01pm

Hi I have this BMS, but I am not sure if I have set the BMS values right as it seems to cut off early when one cell hits 4.2v

but them immediately the pack stops charging and seems to end up under 41v. This is a 10S Lion pack so should charge to 41.5 to 42v .

Is their something I need to change on the settings.

And for the balance mode is it best to set it to charge balance in normal operation ? to balance a new pack I left it on static balance and it charged after 1 week i.e very slowly but it worked
Attachments
Bluetooth BMS.png

User avatar
izeman   10 GW

10 GW
Posts: 4744
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: bluetooth BMS?

Post by izeman » Aug 03 2018 3:30am

unfortunately the non existant manual makes us guess how this works. i did some guess working, and got some experience which i'd like to share, but pls bear in mind, that this may not be 100% true.

as you wrote, there are two modes for balancing: charge and static.

charge balancing is only enabled if the charging FETs are turned on, whereas static is always on. in balance mode the BMS will try to discharge every single cell until they ALL match the set delta (default is 5mV i guess). because of the fluctuation of voltage in a pack it's hard to achieve less than that. so 5mV is a good value for a pack of new quality cells. my pack matches up to 2-3mV, but this is not necessary.
so if you set this value too low and enable static balance, the bms will discharge your pack until one cell reaches LVC, as it will never be able to get all cells in the same range.
it's good to use that mode for the FIRST time you build the pack and charge it to get all cells uniform (which they idealy already are when you choose them right).
for everyday use i use charge balancing. as said, this only work while charge FETs are on. so you need a bulk charger that does NOT shut down when it reaches it's full voltage. it will NOT output any current at that stage, because the pack has the same voltage already, but it will be enough to keep the BMS activated and do the balacing, which can take quite long if your pack is big and you ain't got quality matched cells.
the balancing will stop if you disconnect the charger, and your battery will not be discharged after that - which is what i want.

regarding your question about HVC. if you set the overvoltage to 4.2V, which is the fully charged voltage for li.ion and li.po, you will NEVER be able to fully charge it. this value is a SAFETY feature. it's set to stop charging if a cell exceeds this (a bit) unhealthy, but not dangerous voltage.
you need some extra voltage as some cells charge a bit faster than others. so some may be at 4.21V and some still at 4.19V. the BMS will discharge those at 4.21 and still charge those at 4.19, so that after some time they all can be 4.20.

HVC should NEVER be reached under normal charging operation. it's just a safety measure.

so i suggest setting HVC to 4.25 or even 4.30 and release to 4.20. if you decide to charge that high. your pack will live MUCH longer if you charge to 4.1 or 4.15 only. you loose some range of course.

User avatar
madin88   100 MW

100 MW
Posts: 2801
Joined: May 27 2013 2:02am
Location: Austria

Re: bluetooth BMS?

Post by madin88 » Aug 03 2018 1:35pm

izeman wrote:
Aug 03 2018 3:30am
HVC should NEVER be reached under normal charging operation. it's just a safety measure.

so i suggest setting HVC to 4.25 or even 4.30 and release to 4.20. if you decide to charge that high.
That makes alot of sense, and many non-adjustable BMS's also have 4,25V or even 4,3V HVC as default.

I do the same on my adjustable BMS, but mostly for the reason that i can use regen when fully charged.
Even if i charge to only 4.1 - 4.15V, the voltage could go up to 4.20V or higher during hard regen and i don't want to have cut out's from the BMS when using the brake (can be dangerous).
Yes, HVC should never been reached during charge unless there is anyway a huge problem with one or more group of cells, but even than, no LiIon battery will turn into flames when it get's overcharged such a little bit.
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
- Fully road legal (L1E approval) e-bike based on Votec V-FR frame
/ MXUS 3T / 17" Mitas MC11 / Adaptto Max-E / 20s12p 25R
- KTM Hardtail Pedelec / eZee V2 6T / 27,5" / Kelly KBSX @ 1,5kW / Torque PAS / CA-V3 / 13s4p Sanyo GA in Shark case

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Big brother BT smart BMS

Post by ElectricGod » Aug 03 2018 5:46pm

I mentioned getting this 80 amp BMS back a few pages. Last night I got around to upgrading it. Like it's smaller siblings it too has the same issues with poorly soldered down mosfets and copper. In pulling off the P- mosfets and copper from everywhere, I found lots of voids under things or flat out no solder contact.

Image
Image

You will want to get thermal gap filler as what is there already is insufficient and you may have damaged it getting the BMS apart. The tops of the mosfets aren't going to be all the same height and gaps can be 1mm to 1.5mm between the tops of the mosfets and the heat sink. Thermal gap filler is the best option since it squishes into the gaps. If you don't know what this is, there's a soft rubbery strip on top of the mosfets that contacts the heat sink. That's thermal gap filler. It's not overly expensive and this much gap filler will do quite a few BMS upgrades.

https://www.ebay.com/itm/GPU-CPU-Heatsi ... 2749.l2649

I upgraded this BMS last night. It was several hours of work. The mosfets (HY3712) are really poor...450 mOhms and 30 amps. I replaced them with IRF4110 which are 3.7 mOhms and 180 amps. Not all the P- mosfet positions are populated from the factory. I'm no longer limited by crappy mosfets and now all positions in P- hold a mosfet. The manufacturer sold the BMS as 80 amps and now it's more like 300 amps thanks to more and better mosfets, shunts and copper. Since I used 100 volt mosfets and the BMS can do 30S, I'll never be able to use it above 24S, but that's fine. It will go in an EV that runs on 20S or 82 volts that currently has 2 dumb BMS in it.

As you can see the P- copper does not cover the entire P- buss and doesn't overlap those 3 holes at the right edge of the board where you connect to P-. You can't see it under the solder, but the 2 B- power busses on either side of the shunts don't have full copper coverage either. The copper on them is exactly the same length as is the P- copper. It's better than no copper, but fails to do the job the added copper is there for.

Image
Image

I took a few photos of the final product, but neglected to uplaod them. I'll add them later.

The first thing I did was pull up all the existing copper because it was like the below picture in places...and that's BAD. The whole point of the added copper is to reinforce the solder traces so they handle current better. Being lifted off the traces completely fails that goal. Not being soldered down at all fails that goal. Being too short to cover the entire buss fails that goal. NOT overlapping the P- and B- solder pads fails that goal. Once all the copper was pulled up, I tinned every surface of the copper so they would solder down correctly later. BTW..all that copper really pulls away heat. I had my Hakko at max heat just to put out enough heat to pull up that copper. I'm thinking I need a higher power solder station. Until now, I've rarely needed MAX power. A lot of the copper was nearly bare on the back side (no solder on it). FAT LOT of good that does for carrying current!

Image

Once I had all the copper pulled, I heated all the P- mosfet legs and pulled them away from their solder pads. With no copper to soak up heat, the mosfets come up much easier, but they still take a lot of heat to melt the solder under the tab. I would add solder to each tab to get maximum heat transfer to the mosfet tab from the soldering iron. You don't have to pry or anything. In fact that's bad as it lifts off the solder pads from the board. Once the solder melts, the mosfet will slide off with very little effort. IF you can't get this to happen, your soldering iron is too weak.

After all the P- mosfets were removed, I unsolderd all the existing shunts. There were 20 .004 ohm, .5 watt shunts. I had .005 ohm, 2 watt shunts so I had to add another 5 to maintain the same total resistance. If I had put in 20 .005 ohm shunts, the current measurement would have been off by 20%. There was plenty of space on the BMS for another 5 shunts. In the below picture, you can see they are NOT very closely packed together and they are on both sides of the BMS. There was lots of room for 25 2 watt shunts.

Image

I kept running into problems with the solder the manufacturer used. It was garbage solder and took far too much heat to get it to melt. It also was very brittle and doesn't flow well. I melted off as much of the original solder as I could get off the BMS. I use only real lead/tin 60:40 solder. Nearly all of the Chinese lead free stuff is garbage like what this BMS was made with. Real solder flows sooo much better, melts right, cools without crystallization and voids and other issues. In this thread towards the top half of page 2, I did a whole set of posts on soldering and good vs bad solder. If you don't have it, get real lead/tin solder from weller or kester. Don't ever buy chinese solder...every brand I've ever tried has been garbage. If you think lead is bad (that's not me and I'm not going to eat it), then get high silver content solder from a well known company like kester or weller. AVOID CHINESE SOLDER!!!

viewtopic.php?f=35&t=94527&p=1395677#p1395677

Anyway, once the BMS was depopulated of mosfets, copper, shunts and crap solder, I then put flux on all the places where things would get soldered down and thoroughly tinned them with good solder. One of the things I've run into multiple times with these BMS is the mosfets are not soldered down. I've found the copper is commonly floating and has minimal or no solder on its underside. We want maximum unhindered current flow. That's the whole point of the added copper. That's the job of the mosfets. Getting every traced properly tinned, makes soldering things in place pretty much guaranteed. Getting rid of as much of the garbage solder as possible was also very helpful in this regard.

Finally I was in a place where I could start soldering down parts. I started with the B- and shunt copper reinforcing. It takes loads of heat since you have to transfer the heat from the iron, through the copper and to the trace under it. Having everything coated in solder already makes this much easier. Still, I add more good solder so that no gaps and voids can exist between the trace and the copper. Then I heat a section of the copper, push it down and make it sit tight to the trace under it. It takes working down the copper strip several times, pushing it flat until there are no gaps under it. Since none of the lengths of copper were long enough, I used the copper I pulled up from C- to fill in the missing lengths needed on B- and P-. I won't be using C- for more than 30 amps so I don't care about copper on those traces and more likely I won't use C- at all ever...so I really don't care if C- is reinforced or not.

Next came the 2 watt shunts. They are 4X larger than the .5 watt shunt so they sit on top of the copper instead of in between them. I'm adding more and more mass...lots of copper, solder and parts. I was soldering at MAX power on my Hakko. I would place a single shunt, solder down one side, get it straight and then add the next shunt. Conveniently there was room for 15 shunts on the top of the board. The other 10 went on the bottom of the BMS. Good solder flows well, but with overcoming this much copper mass, it would barely heat up enough to flow well with my largest flat tip and MAX power. I'm seriously considering buying a higher power solder station.

You can buy mosfets with the tabs cut off and the legs already bent for surface mount use, but I do motor controller modding and use mosfets for other things too. It doesn't make sense to buy mosfets for surface mount only. I buy them like I'd use in a controller and then bend the legs like a surface mount mosfet would have. It's easy to do and takes a few seconds per mosfet. The center leg (drain) is not used so I snip it off. Once all the mosfet legs are bent and trimmed, I tin all the legs and tin the back of the mosfet. I want good solder flow everywhere. Anything that isn't already coated in solder won't flow solder particularly well.

NOTE: It is possible to get a defective mosfet straight from a manufacturer. I test all the mosfets on a component tester to make sure they work before they get soldered down.

Image

I start with placing a single mosfet on the BMS and getting it straight. I don't need MAX soldering iron power for this. Since everything is pre-tinned, all I need to do is heat up the solder already on the pad and melt the leg solder into it to get the legs properly soldered down. The mosfets won't sit flat yet since the area under it's back is somewhat lumpy and the solder on the back of the mosfet is too. This will get fixed in a minute when the tab gets soldered down.

Now it's time to crank up the power again. It takes a lot of heat to melt the solder under the back of each mosfet. I apply solder to the hole in the tab and fill it full. The tip of the iron stays in that puddle of solder in the hole until I'm satisfied the mosfet is properly soldered down. I'm also pressing down on the mosfet to get it to lay flat. Soon the solder on the pad and on the back of the mosfet start melting and the mosfet lays flat. It all flows together since it's all pre-tinned. IF the hole in the tab is less than full of solder, I add a bit more. Now I tin the top of the mosfet tab since it's already nice and hot. Copper will be soldered here for reinforcing P-. Repeat for all 20 mosfets that went into P-on both sides of the board. The more parts get laid down, the longer it takes to get everything hot enough to flow the solder. The first mosfet was quick...5-10 seconds and it was fully soldered down. The back side of the board took more like a minute each since I was heating the top side of the board too before the mosfet tabs were hot enough on the back side to melt the solder properly.

Finally it was time for the P- copper. This was sloooooow going! It sits on top of the mosfet tabs and overlaps the P- solder pad. With everything pre-tinned, it's mostly a matter of heat and getting solder to flow, but there is so much mass to heat up that the soldering iron was really working at it's maximum limits 100% of the time. I had to heat up the copper and the mosfet tabs under them and then get the solder to flow. This BMS was the first time I really challenged my Hakko. There was sooo much mass to heat up, that it could not do the job by itself. I would play my butane mini torch over the copper to pre-heat it and then put the soldering iron on the hot spot and get the solder flowed together. The torch is far too hot for electronics, so I couldn't do this for long without causing damage.

This BMS is pretty big and beefing it up took lots of patience and heat. Now that it's done, I'm betting 300 amps is possible. The last thing I did last night was plug it into a 20S pack and make sure it still worked. 100% success!

Pictures of the upgraded BMS to come later.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Aug 03 2018 5:49pm

madin88 wrote:
Aug 03 2018 1:35pm
izeman wrote:
Aug 03 2018 3:30am
HVC should NEVER be reached under normal charging operation. it's just a safety measure.

so i suggest setting HVC to 4.25 or even 4.30 and release to 4.20. if you decide to charge that high.
That makes alot of sense, and many non-adjustable BMS's also have 4,25V or even 4,3V HVC as default.

I do the same on my adjustable BMS, but mostly for the reason that i can use regen when fully charged.
Even if i charge to only 4.1 - 4.15V, the voltage could go up to 4.20V or higher during hard regen and i don't want to have cut out's from the BMS when using the brake (can be dangerous).
Yes, HVC should never been reached during charge unless there is anyway a huge problem with one or more group of cells, but even than, no LiIon battery will turn into flames when it get's overcharged such a little bit.
THat's a really good point. I use regen and so far it hasn't been a problem that the BMS cuts out. I set HVC to 4.1 volts and realistically I should set it higher so full charge regen doesn't create issues. I'll never charge over 4.1 volts per cell since my charger can't make that happen.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

glyndwr   10 mW

10 mW
Posts: 24
Joined: Apr 15 2014 11:16am

Re: bluetooth BMS?

Post by glyndwr » Aug 03 2018 6:14pm

Hi vipster,

i`m from the uk too and looking for one of these, been searching forums and sellers in the EU but am struggling to find any, of course from china looks the only option, but sadly then import duties and vat get in the way.

User avatar
eee291   10 kW

10 kW
Posts: 708
Joined: Nov 05 2015 4:35pm
Location: Austria, Burgenland: Güssing

Re: bluetooth BMS?

Post by eee291 » Aug 04 2018 5:09am

Hey Electricgod, I want to buy the same BMS for my 24S battery. But I need 150A Cont. not 100A, So I was thinking of buying the 40A model and replace the Mosfets same as you.

I just have a few questions though.

Can't you recalibrate the BMS in the software to show the correct current?

Also if I don't use the C- and charge through the P- will I still get overcharge protection? Will it also display charge current correctly in the App?

Is the Overcurrent Protection programmable? I don't want it shutting down on me.

And aren't 100V Mosfets for 24S a bit low? I was thinking 120V Mosfets would be a bit safer.

User avatar
izeman   10 GW

10 GW
Posts: 4744
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: bluetooth BMS?

Post by izeman » Aug 04 2018 5:37am

Yes
No, Yes
Yes
Yes

User avatar
eee291   10 kW

10 kW
Posts: 708
Joined: Nov 05 2015 4:35pm
Location: Austria, Burgenland: Güssing

Re: bluetooth BMS?

Post by eee291 » Aug 04 2018 7:36am

:lol: Thanks

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Aug 04 2018 10:57am

eee291 wrote:
Aug 04 2018 5:09am
Hey Electricgod, I want to buy the same BMS for my 24S battery. But I need 150A Cont. not 100A, So I was thinking of buying the 40A model and replace the Mosfets same as you.

I just have a few questions though.

Can't you recalibrate the BMS in the software to show the correct current?

Also if I don't use the C- and charge through the P- will I still get overcharge protection? Will it also display charge current correctly in the App?

Is the Overcurrent Protection programmable? I don't want it shutting down on me.

And aren't 100V Mosfets for 24S a bit low? I was thinking 120V Mosfets would be a bit safer.
100v mosfets are barely enough for 24S, but yes...I prefer to have a bit more room for issues. Since I'm using mine at 20S, I didn't really care too much. Realistically for optimal results we should be using 150 volt mosfets so the BMS can run at 30S...it's upper cell limit.

I don't know of a way to re-calibrate the BMS for current, but then it's possible I've missed some setting. It so easy to use the same resistance as is already there so why bother doing anything else?
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

Re: bluetooth BMS?

Post by ElectricGod » Aug 04 2018 11:06am

izeman wrote:
Aug 04 2018 5:37am
Yes
No, Yes
Yes
Yes
How do you re-calibrate the BMS?
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod   10 MW

10 MW
Posts: 2204
Joined: Nov 01 2015 5:24pm
Location: 3 OH 3

20-30S smart BMS upgrde

Post by ElectricGod » Aug 04 2018 11:16am

Uploaded the finished pics of the BMS.

I need to pull the 5.5mm bullets and use 8mm instead. They are too small for this much current handling. My test pack has 5.5mm bullets so I soldered these on for testing. I just noticed I need to add 1 more shunt.

Image
Image

Bottom of the board. Full length copper on the shunt and B- busses and 2 watt shunts. I have 10 shunts on the bottom.

Image

Top of the BMS. Full length copper at P- that feeds into the 5.5mm bullet.

Image

Top of the board. No reinforcing or upgrades at C-...I could care less about C-. The P- copper completely over laps the P- solder pad. Top side shunts and full length copper on the busses. Looks like I have 14 shunts on top. LOL...one shunt short...need to add another one to the bottom.

Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

Post Reply