Horrible quality of SmartBMS from bmsbattery.com

[powersupply]

Crossbreak, hope the scope/driver Gods are with you today!!

Don't understand the EOS1420 thing though.
I thought you want to disbalance one cell severely and monitor the SmartBMS doing it's job?

(Balance) charging them with the EOS would negate that purpose.

Or did I get it all wrong as usual?

 

[Hiconic]

Hi Guys,

I'm another victim of BMS Batteries. My BMS shorted out on the 2nd use, hadn't traveled more than 100 yds before the smoke started pouring out of the battery box. I was going to order a replacement BMS from them but thought I would check on ES first to see the lay of the land on this issue. My problem is I need to find a replacement (better quality) BMS for my 36 V 12 AH pack that will fit neatly into the same position (limited space in battery box) as the original BMS board (120 mm x 80 mm). Does anyone here have any suggestions as to where I might get one. I'm not feeling too optimistic though, as on reading these posts it seems that if there were someone reliable out there then we wouldn't be using BMS Batteries.com at all, as from what I observe and with my 1st hand experience, most of the people who use their products end up at the bar crying into their beers. Here's a thought, for all you guys out there commenting on these issues, one would think that there seems to be an opportunity going to make some (?) money doing the job properly.

If China continues to dominate this market then we will all have to get used to the fact that we will have to accept the junk they supply and shut up winging about it. Is there such a dramatic pricing differential on doing the job right and supplying a reliable product ? I'm sure that people out there having already invested a lot of dollars in their projects would pay just a bit more so as to not be let down by inferior soldering or schematics/design that could potentially cost them more than just a fried circuit board, it could cost them their lives in an on-road situation.

Regards (the ever opinionated )
Hiconic

 

[powersupply]

Sorry to say, but welcome to the bmsbattery.com club of junk victims!

They probably used fake FETs in your BMS, too.
Bigmoose pointed out that the FETs used in mine were probably counterfeit.
And he is right, I checked the datasheets, those stampings/arrangements don't exist.

In the end it is our own fault, we look for the cheapest and that's what we get.
It's true however that if we *knew* that these are junk, we would not buy them, and that's what angers me with chinese products.

They have become masters of deception, selling junk for a cheap price but pretending to deliver functionality.

 

[crossbreak]

There is a bug in chip itself, that makes proper balancing some people from balancing properly.

Tested this with two boards...the board will balance further when HVC is reached bit won't ever switch on the charge fet even if hvc threshold is reached

It will turn on the charge fet after it has detected some discharge

 

[izeman]

Hiconic: as mentioned in this thread already, and posted in several others as well: goto bestechpower.com
Those are really nice units for nearly the same price (if you take shipping into account as well). They have systems for every ebike you may need. I ordered 12s f or lipo and lifepo4 and 24s for lifepo4. All working great. Those was the hcx-d131 type.
Just make sure that you set hvc and lvc values right BEFORE ordering and check those after installation. They claim those values to be configurable, which is true. It's just that only THEY can configure them
BTW: I had horrible results with ALL four BMS I bought from BMSBATTERY. None of them is working anymore and they all have been used way within their limits (12s 48v 40a peak)

 

[circuit]

There is a bug in chip itself, that makes proper balancing some people from balancing properly.

Tested this with two boards...the board will balance further when HVC is reached bit won't ever switch on the charge fet even if hvc threshold is reached

It will turn on the charge fet after it has detected some discharge

This is strange. Could you backup eeprom settings and attach a file here? Would be interesting to check if that makes any difference!

 

[powersupply]

Got one of these to work, added LEDs (1206 fit fine, very recommened addition!).

Found another broken part: one of the 39Ohm dischagre resistors was invisibly cracked!
The crack was totally invisible, in fact I thought one of the end pins was bad, baffeled whan it came apart while soldering
Never seen such a thing before!


After reading that some got their units damaged by connecting the balance leads first and then applying the main power, I added some diodes to prevent that from ever happening to me.
Not only one thing less to keep worring about (who can remember that in a year), but in case the main fuse blows this should be saved, too.

see atatched
View attachment 1

 

[alsmith]

Here it is, C4 is not grounded, the track stops short of the greound via for a few hundret um.

Found it via this thread, http://endless-sphere.com/forums/viewtopic.php?f=14&t=48166&start=400#p808151
where methods talks about it, but couldn't find his actual posting.

Please methods, you mentioned you reverse engineered the board a bit, please share those findings, even if it is just a scribbled note somewhere.

Just a quick question going back a few places in this thread about C4 not being connected. The track is offset from the component leg- why can't there be a through hole under the component? If it is a 3 or more layer board this wouldn't necessarily show on the underside layer.

It would be very out of character to find redundant components on an assembled board- can't say I've seen it often, if at all.

 

[powersupply]

The board has two layers only, and I checked that end from the cap, it is indeed floating.
No buried vias, sorry.
Also, that cap is not redundant, it is needed per chip manufacturer.
In fact, a smaller cap needed to kill high frequencies is omitted on these boards.
I don't know of any high voltag linear regulator which would not need a cap at its input.

I am amazed that people have used this without the cap, though it might explain intermittent issues they had.

 

[granolaboy]

Thanks for the thread! I was considering getting a BMS from bmsbattery, but not now.

I've got chargers from them before, and never had any issues. Has anyone had issues with other products from bmsbattery?

 

[Erikjan]

I have 4 batterypacks with smartbms.

No problems here.

 

[calab]

Now thast is horrible surface mount soldering, I used to work at Nortel Networks doing the cell site stuff, it takes skill to solder.
I have heard BMSBattery is horrible from numerous sources and decided its not worth the risk of bad products being shipped, no matter how cheap their stuff is.

 

[crossbreak]

I can say that from 9 BMS I ordered within the last 2 years, 9 where working great. One was toasted (my fault).

I would pay more for better quality. But I have no idea whre to actually buy such an alternative?? Please tell me where you buy better boards!!!

 

[alsmith]

I'v had one for over 3 years, and two more for just over 2years. No problems with any of them.

I did wonder if they were balancing the batteries properly in conjunction with the BMS chargers for ages after some posts I had seen, but about a month ago one of the batteries restarted charging after a time so it must work properly.

 

[crossbreak]

as said, it's recommended to calbrate them. It usually takes me about half an hour to perform the mods (short the unused balancers, solder the main cap and check for shorts), flash proper values and calibrate.

 

[izeman]

I would pay more for better quality. But I have no idea whre to actually buy such an alternative?? Please tell me where you buy better boards!!!

if you're asking for BMS at all, then look at bestechpower.com. very nice products, and reasonably priced. i got 3 bms for lifepo4 and they work very solid. they offer lipo bms as well, and you can define (within limits) the different voltages.
i you want to know where to buy smartbms products - i can't tell you.

 

[circuit]

[..]No problems here[..]

[..]No problems with any of them[..]

[..]they work very solid[..]

I hate to say this, but such statement really need some background... Have you measured voltages at the end of charge currently and at first day of usage? Have you measured cell voltages at the end of discharge currently and at first day of usage? What is your capacity loss since you started to use it?

I am asking because it have taken a real pack, balanced it perfectly and then slightly discharged one cell. And saw that this BMS is hopeless in such situation. So it is really hard to believe it could work fine for someone.

 

[izeman]

[..]No problems here[..]

[..]No problems with any of them[..]

[..]they work very solid[..]

I hate to say this, but such statement really need some background... Have you measured voltages at the end of charge currently and at first day of usage? Have you measured cell voltages at the end of discharge currently and at first day of usage? What is your capacity loss since you started to use it?

I am asking because it have taken a real pack, balanced it perfectly and then slightly discharged one cell. And saw that this BMS is hopeless in such situation. So it is really hard to believe it could work fine for someone.

you're quoting wrong here. i stated that the bestechpower bms works solid. the smartbms was crap from the very beginning. regarding the bestechpower bms there are at least 2 seperate threads, and i just posted this because crossbreak was looking for a high quality bms - still those are not perfect they do a great job.

 

[circuit]

Yes, I understand that, however I have no knowledge what is being discussed on other threads, as I was not following them. But good to know those are better.

 

[crossbreak]

I had a look at this board: http://www.bestechpower.com/444v12spcmbmspcbforli-ionli-polymerbatterypack/PCM-D131.html

the HCX-D131. quite large, wont fit into my pack maybe I should give it a try.

 

[izeman]

yes. the 131 is the one most of us use. VERY capable and really conservative power ratings. someone (dnmun?) mentioned they could handle at least double the current. mine doesn't even get warm at 60a load.

 

[dnmun]

i cannot image a 24S BMS smaller than the D131.

the D131 will handle 80A continuous, 150A surge, balances at 175mA so show me something else that will balance a 24S lipo pack and costs less than $60.

 

[crossbreak]

great, thx for that info. Is there some way to read cell voltages? Does it have any communication?

 

[izeman]

not that i know. you can connect cellogs in parallel. but that's it. connect the battery and leave as is

 

[crossbreak]

how is it configured/ calibrated then?