Yet another 18650 battery build.

[llile]

[strike]I'm looking at this BMS from BMSBattery.com.

I don't see a heat sink int he pictures, but I do see screws where BMS heat sinks are normally attached. Perhaps the sink is removed for the photos? This looks like a good basic unit, good specs, no frills like bluetooth and so on which I don't really need.[/strike]

[EDIT] I just took Flippy's advice and checked out the bluetooth BMS thread here. Well, I never had any idea how much these things would do.

One of my goals might be to reduce my capacity somewhat, in order to increase life, by not charging to full voltage and discharging to full empty. Apparently the right programmable BMS will allow these settings to be changed, balance at less than 4.2 V, low voltage cutoff at maybe 3.0 or 3.1 volts, etc. Now that might well be worth the extra cash.

Some complaints on that thread about unreliable aliexpress vendors. I'm going to peruse the thread a little longer. BMSbattery, whom I kinda trust, has a bluetooth BMS but very little information about what that actually means. Is it a simple battery capacity gauge or a complex way of setting every parameter and measuring the health of the battery? Maybe someone reviews it, so far I've only found one mention of that vendor. Not much more expensive than the one I linked above.

Here's a link to one of the smart BMS vendors mentioned in that thread. This may be a good fit.

 

[flippy]

i had no issues with this vendor:

https://www.aliexpress.com/store/product/150A-8S-24S-Lithium-Battery-Protection-Board-Smart-Display-Balance-BMS-Coulomb-Meter-Ternary-lifepo4-iron/2856009_32849338845.html

 

[llile]

Here is a smart BMS from the vendor Flippy recommended above. Flippy, you mention you had good luck, however I'm finding their translated webpage a little hard to fathom. Can't tell for sure if I need to order a bluetooth module separately or not, for instance. It's kinda vague on that. I think it is telling me I have to order the bluetooth module separate. Oh well, it's $8 wasted if I order and I'm wrong, I've wasted more on this crazy build already.

These products, discussed on the bluetooth BMS thread mentioned above, appear to be the same thing - identical boards, identical phone app screenshots, all about the same price:

From Lithiumbatterypcb.com

From AliExpress

From BMSBattery.com

 

[llile]

Well this same aliexpress vendor IC Gogogo also has big heat shrink tubing and fish paper, one shipment from China. I think I'm convinced to pop for their bluetooth BMS board, a bluetooth communication module, and accessories.

Originally I was worried about heat. Testing these battery modules at rated output current proved they do not even warm up. I should quit screwing around with homemade insulating covers and just get some 350mm flat-width heat shrink tubing.

 

[flippy]

all vendors have chinglish as their main language, that is inherent to aliexpress, ebay and other shops from the orient.

pro tip: overspec your bms by at least half. if you need 50A you need to buy a 100A bms.

 

[llile]

Good points! I need 35A and I bought a 60A BMS, that's not quite overspecced by half but pretty close. Well it's coming on the boat regardless.

 

[garolittle]

pro tip: overspec your bms by at least half. if you need 50A you need to buy a 100A bms.

Great thread! I am learning lots of new things. Regarding the BMS tip above, my go kart will pull 50-60 amps continuous with a max of 200 amps (only for a few seconds). Any recommendations on where I can get a BMS for this application? Bluetooth sounds great. Thanks!

 

[flippy]

pro tip: overspec your bms by at least half. if you need 50A you need to buy a 100A bms.

Great thread! I am learning lots of new things. Regarding the BMS tip above, my go kart will pull 50-60 amps continuous with a max of 200 amps (only for a few seconds). Any recommendations on where I can get a BMS for this application? Bluetooth sounds great. Thanks!

https://m.aliexpress.com/item/32826469363.html?

(Apologies for mobile link)

Check the bluetooth bms thread. There you can find instructions to replace the mosfets with much better ones so you can draw hunderds of amps without issue.

But i would start with the 300A version and try it and see how hot it gets.

 

[garolittle]

Thanks flippy. I will check it out.

 

[llile]

BMS recieved, installed. Haven't tested it yet on the bench.

Sooooo, the app for Android that is supposed to come with this BMS is not on Google's Android "Play Store". I can find a link to it on BMSBattery,com (that's not where I bought the BMS, but it looks very much like all these guys are using the same app labeled "XiaoXiang" on the screenshots.

I'm really nervous about running an android app that came from some Chinese Website. You guys run this before? Any suspicious credit card activity after that?

[EDIT] well, I turned off the security setting on my phone that prevented un-approved apps, and installed it. Not really working tho' see next post. I wish I'd bought the computer interface instead of bluetooth.

 

[llile]

So far, the bluetooth app I downloaded from here isn't working. It will connect with the bluetooth module on the BMS, however locks up after that, so no functionality other than connecting via bluetooth. Can't see any settings, parameters, etc, screen just freezes. Tried it out on an older android phone, but wouldn't run at all. I'm not impressed so far.

Due to some snafu on AliExpress, I am unable to contact the seller to get their link, which may work better. Or not. This is one of the reasons I'm not a fan of AliExpress - there are language barriers, slow shipping, their security features are crude and now I find they lock you out of the system when you most need to get in. Seller is supposed to send something to me "today" (whenever today is in China).

Even without the bluetooth connection, it's still supposed to be a better BMS than I bought earlier. Perhaps I should have skipped the whole bluetooth thing, and connected it with a computer? I'd need their UART module, which would involve another shipping delay ....

 

[flippy]

wich bms did you exactly buy?

 

[llile]

I got a variant of this one from IC GOGOGO aliexpress store rated 10S and 60A. Added a bluetooth module. Then AliExpress decided I didn't exist, so I can't get a download link from the seller. I thought computers were gonna make everything easier?



I was able to download working Android BMS software from here, also with the caveat to make sure GPS is turned on first. Apparently it won't work at all without GPS.The GPS issue may have been why it was locking up. Also when you furst try it, there is a question box in chinese asking about GPS, I assume this is about permission. I pressed the right-hand chinese character, and apparently that was the right answer. Or maybe I promised to send my firstborn to slave in a Chinese factory and ship him via DHL, I'm not sure.

I've gone through the menus and so far everything seems to be working. Next I'll test the battery with a dummy load on the bench, and watch it with the software to see if it really does what it says it does. Except for the permission notice about GPS, everything else is in English.
Nice!

 

[llile]

Pro tip: If you get this bluetooth BMS, or one of its many clones, you have to get a bluetooth module to use that feature. For a couple of bucks more, get a PC UART module too, in case bluetooth doesn't work.

 

[garolittle]

Sorry for all the problems. I really appreciate that you posed in experiences on this forum. I am learning a lot and will probably purchase a Bluetooth BMS soon.

 

[llile]

If this was easy, they'd have hired someone else to do it! The trouble with trying to catch a greased pig is, that the pig likes it. The trouble with endless sphere types, is that the problems are what we live for!

 

[llile]

OK, the first BMS battery is on the test bench, with a heavy ammeter, a voltmeter across the terminals, and a load made of four 10 ohm power resistors in parallel. Draws 16-17 amps. Bluetooth parameters match up pretty good, I'll test them against the external meters until I trust them. Just waiting a few minutes for the balance charge to finish up before starting the tests.

 

[garolittle]

If this was easy, they'd have hired someone else to do it! The trouble with trying to catch a greased pig is, that the pig likes it. The trouble with endless sphere types, is that the problems are what we live for!

Agreed. Imagine trying to do this 25 years ago without the help of the internet.

 

[llile]

[

Agreed. Imagine trying to do this 25 years ago without the help of the internet.

Been there, done that, got the blood-stained and torn t-shirt. Used to be you had to actually read the friggin' datasheet (imagine that) and try to noodle out what it meant. Of course, the people writing the datasheets were native English speakers so that helped some. I would actually buy datasheets and wait for them to come in the *mail*. The few times I found a buddy that was as bad a geek as I was, it was incredible. Then the frakkers always moved away to attend MIT or something.

I'm on two builds right now (this battery build and a rocket stove ) that would basically be impossible without the collaboration of far flung folks all over the planet. This is the part of the 21st century that is really amazing - We've basically crowdsourced a huge amount of knowledge in places like Endless Sphere, and some of the greatest minds in the world can be found on experimenter's boards like this one geeking out on some innovative new idea. (I'm talking about Justin if you didn't know)

 

[garolittle]

Agreed. This form and others are a remarkable resource. It’s a good time to be alive.

 

[Ecyclist]

I built my own 18650 battery pack and decided on not using BMS. I have a volt meter, the anti spark connector, two battery testers and a maxi fuse. For BMS I use my brain. It works for me.

 

[JuergenH]

smartBMS APP can only suitable for Android 4.3 and supports Android device only with bluetooth version 4.0 or higher ,try this Bluetooth Android APP-2.1.1012, see if it can work?

 

[llile]

I built my own 18650 battery pack and decided on not using BMS. I have a volt meter, the anti spark connector, two battery testers and a maxi fuse. For BMS I use my brain. It works for me.

Good luck man, don't have a brain fart, they are explosive!

 

[llile]

This Bluetooth BMS has paid off!

Using the BMS, I realized that I was not getting full capacity out of the pack. The BMS report that one of the packs has a weak 10th layer. Using this setup, I pulled apart the pack, disconnected the individual batteries and soldered a bit of wire so I could jumper it to my 18650 Capacity tester, also with some soldered wires on the positive terminals. The spring loaded bit on the negative terminal is all connected together.

Found one bad cell (0.00 mAH charge) and three weak ones (Less than 1000 maH when spec says 1300)

Here's a link to the tester I am using. I understand there are better ones, but this is adequate.

 

[Ecyclist]

I built my own 18650 battery pack and decided on not using BMS. I have a volt meter, the anti spark connector, two battery testers and a maxi fuse. For BMS I use my brain. It works for me.

Good luck man, don't have a brain fart, they are explosive!

I've been using my pack for over 9 months and have no problems. Battery testers keep track of battery groups and I can tell exactly what is going on. I can charge it bulk or have it perfectly balanced with a hobby charger. With BMS you don't know what is going on until your pack is not working. I don't trust BMS boards made in China and I'm definitely not paranoid if comes to Li-ion batteries.