Looking to buy the Bestech BMS (http://bestechpower.com/444v12spcmbmspcbforli-ionli-polymerbatterypack/PCM-D223V1.html), Or something similar. Does anyone have an extra from the minimum of two purchase? Or is anyone else interested in both going in on a deal to buy new?
I’m up for one of those…
I’m based in the UK, where are you?
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Whats the price for one of those. Im interrested aswell but depends on the price. But seen some other ones from same page. But smaller and only for charging then. Because of the discharge current.
Do you think 80A is enough for discharge too?
Im located in Denmark
@korryh completed a gb for these exact same bms, u could probably ask for more info. I got one 12s waiting to be installed.
Most people bypass bms discharge and connect directly to battery. Use bms just for charging. A lil bit trickier but don’t have to stress and rely on bms for discharge.
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Yea i know that but why get the expensive one that got 80a?
But this one mentioned does have a on/off feature that you’re loosing right?
Some of the settings are optional, any idea what the best values for these are?
Overcharge Protection Over charge detection voltage 4.2V~4.35V(Adjustable) Over charge release voltage 4.0V~4.2V(Adjustable)
Over Discharge Protection Over discharge detection voltage 2.3V~3.0V(Adjustable) Over discharge release voltage 2.3V~3.0V(Adjustable)
Over Current Protection Over current detection voltage 0.1V~0.2V(Adjustable)
good point, one could get a cheap one that has low discharge current if bypassed, i think there’s plenty of people who’ve done this.
yes, i don’t think the bms switch is robust or reliable enough as a main switch anyway.
here’s the values that were used in the gb i was in:
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thanks @thisguyhere
yes, i don’t think the bms switch is robust or reliable enough as a main switch anyway.
mmmmm, this is the first time I have heard this, I was planning on using the BMS instead of an anti-spark… What are the problems that have been reported with the BMS soft switch?
anecdotally it’s very common for bms to burn out, especially in these high current applications. in this case you’d lose your on/off capability altogether.
everyone i’ve seen use a bms uses a dedicated switch (loop, vedder). i plan on doing the same.
but of course your results may vary.
Then i dont see the point in getting the expensive one. But im Up for another one from the site.
Hey, sorry about the long response time I was away for the weekend. The BMS linked above comes out to be about 38.00/each. Which I agree with the not needed the discharge feature. The reason behind choosing this BMS was just seeing other were using it. If you guys have any other suggestions I would love to look at them. Just so you know I am in the mid-west of the USA.
@thisguyhere Do you by any chance know of a good wiring diagram that would help us out?
Also I am open to shipping most places
I was looking at this one from same site: http://bestechpower.com/444v12spcmbmspcbforli-ionli-polymerbatterypack/PCM-D108.html
Just because it is probably cheaper. But i dont know the price of that one. So i have also found this one from aliexpress but dont know if it is okay for the task.
Also this one but this one doesent have balance charging. But i dont really understand what that means then. Whats the point then.
@Migro The other one you linked may work, but I am struggling to find a source that talks about bypassing the discharging. The Aliexpress BMS is a 50.4v which is more in the electronic bike range. A 12s is 44.4v which comes from each lipo cell being 3.7v each. The balance charging is important in order to not overcharge or over discharge(because of one cell is a lower voltage and dips into the damaged area) balance charging basically looks at an array of cells say [cell1, cell2, cell3, cell4] at the voltage of [3.3, 3.4, 3.3, 3.2]. When you charge the battery it will look at them and when the one of the cells top off for example[3.6, 3.7, 3.6, 3.5] where cell2 is at the charge voltage cutoff. The power that would go into cell two is moved by the BMS into the other cells until they all meet the voltage cutoff.
All in all the balance charging is one of the most important parts of the BMS in my opinion
@Migro These bms’s are good for 80a continuous and 240a peak.
I am running dual Vescs set at 60a batt max each through the same bms for 10s with no problem at all.
You can bypass on discharge but it’s much better if you don’t bypass so you can have all the protection for your battery while riding. Short protection and Cell level low voltage protection.
Then do you think that this BMS is a good place to start if for expansion later down the road to dual motors?
Yes this bms will handle dual motors with no problem
@Namasaki But would’nt the vesc be able to handle the off cut so you dont damage your batteries? How do you know how many a continuas you use? Only real time use right?
@OverHillier I see what ur saying with 50.4V. Good point.
Anyone know the price of this one
You have me convinced to ethier the one you linked or the one i linked above.
first to answer your question, The Vesc monitors total battery pack voltage. A bms will monitor individual cell or cell group voltages so if any cell or cell group drops too low, the bms will shut the system down. Check out this thread. This poor guy’s battery started popping and burned his board to the ground. Not sure if he had a short or if some cells just overheated. He had a bms but he thinks it was bypassed for discharge. If it had not been bypassed, the bms would have detected the short or an abnormal drop in cell voltage and immediately shut the circuit down.
The bms you linked is only rated for 10a and would have to be bypassed. I simply do not recommend bypassing…
It’s plenty with the Bestech HCX-D223v1 Because they are 80a continuous 240a peak!!! They are built for heavy duty use. I’m running dual Vescs 80a motor max 60a batt max That’s 120a batt max total. And no problem for the bms. Another advantage is braking downhill on a full battery. Some have reported their board shutting off while doing this. I have gone braking down a steep hill numerous times on a full battery while monitoring voltage. The bms appears to control the voltage in this situation. The highest the voltage would go is 42.8 and as soon as I stop braking, the bms brought the voltage back down to 42.
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