24s BestechPower BMS Thread

[sacko]

Thanks guys.

Just got to look at placement. I had originally wanted to place it like this;

But will end up having it like this and place a Perspex sheet behind it.

 

[izeman]

why do you leave so much empty space between the batteries? put them close next to each other. the cells in the 6s packs are like that. why not make a much bigger tighter pack?

 

[sacko]

There was no real need to. 24s 10ah is all ill need for this build.

This frame triangle is a lot smaller than my Giant build, so gain lot more width with the bag.

 

[izeman]

There was no real need to. 24s 10ah is all ill need for this build.

This frame triangle is a lot smaller than my Giant build, so gain lot more width with the bag.

nope. i didn't mean you should put in more batteries, but rearrange the existing one tighter, so you have more space for positioning the bms. there is no need to have 1cm between each pack. move them together and form on big pack. one big pack can't move that much as well.

 

[izeman]

just a quick hack of what i wanted to say:

 

[dnmun]

i cut off the red and black leads and after i clamped all the cells together with some 1/8" hardboard endplates with wood clamps i then wrapped duck tape around it to hold it rigid and keep the compression flat on the faces of the pouches.

i cut off all the JST plugs too and then soldered the 6S together from the red to the black, + to -, of the nest one with some 12G solid wire. then i soldered the sense wires on and soldered the black lead from the bottom cell to B- on the BMS. worked ok.

you should see if you can clamp all 4 packs together in series like this and wrap it will duck tape around some endplates too.

then see if it will all fit vertically in your battery bag. you could do two of them side by side in the bag and it would be about 4" wide.

 

[izeman]

... i then wrapped duck tape around it...

i hope there where no animals harmed doing so *scnr*

 

[dnmun]

i think sacko can get his 24S vertically compressed together in the end of that bag if it will fit in the triangle, and he can have two packs side by side connected in parallel at the cell level and the BMS in front like you photo shopped in.

i think the extra voltage drop going from one pack to the next, the extra deltaV that appears on the sense wires at each junction of those big EC4 connectors will cause early LVC cut outs so i recommend cutting out those big 10AWG leads and the JST plugs and then soldering the terminals together when the pack is assembled and compressed inside the end plate and tape again to hold it permanently in place. i have no use for the JST plugs since i use the BMS to balance and bulk charge the entire 15S lipo string on mine.

i built my pack three days ago and it is still balancing. down to 3mA now from the charger. waiting for the lowest cell to catch up. all the full ones sitting at 4.2V waiting for the one down around 4. to catch up.

 

[sacko]

I will still balance charge mine with a Cellpro PL6 every month or so, so have kept mine separated for the being.

Just need to test each cell with the meter.

 

[dnmun]

you should use the balance charger on it first while it is still in these 6S packs, but if you bulk charge with the BMS on it the pack will stay balanced by itself.

it will never need to be balanced charged again. balance chargers are just the result of hobby king selling only these small packs with no BMS.

but the deltaV on those leads will be a problem.

if the voltages walk up in series you can connect them to the BMS and then measure the gate voltages on the charging mosfets and the output mosfets to see if it is active before you put the charger on it.

by using the balance charger before assembling the pack into one then it reduces the time it takes to make the entire 24S pack balance the first time. after that the cells will remain pretty closely balanced and if it drifts off then the BMS will force it back into balance.

 

[sacko]

Ah ok.

I can definitely remove the discharge leads from packs 2 + 3 in the middle, but the leads on packs 1 + 4 are going to be difficult to reduce due to the location of the BMS.

I'll test it out she the controller arrives, if it isn't workin correctly ill have a re-shuffle as Izeman suggested.

 

[dnmun]

Ah ok.

I can definitely remove the discharge leads from packs 2 + 3 in the middle, but the leads on packs 1 + 4 are going to be difficult to reduce due to the location of the BMS.

I'll test it out she the controller arrives, if it isn't workin correctly ill have a re-shuffle as Izeman suggested.

yep, you should turn the pack end for end so they face the BMS and put the low end, the first cell in the series at the top since the BMS will be at the top. then you can get the lead from the B- terminal of the battery to the B- terminal of the BMS in the shortest distance. short is best, 4" is best. 2" is better. i just cut the black EC4 lead on mine and soldered it to the B- spot on the BMS.

but balance charge all those packs first. before you have to balance it under the BMS. but the D131 has the highest balancing current of all their BMSs. it is about 168mA. similar to the hyperion but less than 1/2 of the icharger balancing current.

if you mount them pressed face to face then put some of that heavy plastic double stick tape they wrapped the packs in between the two adjacent spots where the packs butt up face to face or it will short out here. i used two layers of that plastic tape and a thick foam double stick tape piece too.

 

[izeman]

...i built my pack three days ago and it is still balancing...

THREE DAYS balancing? that's really a long time. why are those cell that much unbalanced? all 6s packs i bought from hobbyking or similar where only some 20mV unbalanced. i know that balancing the packs first with a fast balancer is preferred, and the best one to use is the bc168. i did this for my 20Ah cells, as these really need AGES to balance as the come as single cells. and they need to be already at the very close same level when you start to arrange them. otherwise it takes forever to balance.
but are you sure your cells are all good? normally those are not that much unbalanced. and even if you balance them now to perfection they probably would drift in the future, and you bms will not have enough bleeding power to balance them. did you think about that?

 

[izeman]

... but the D131 has the highest balancing current of all their BMSs. it is about 168mA. similar to the hyperion but less than 1/2 of the icharger balancing current...

i don't know what icharger model you're referring to, but my 206b does 20W maximum which is super slow if you have a 6s pack connected. then it's only 3W per cell, and around 100mA per cell. so the D131 does very well compared to it.

 

[major]

I sent Henry Zhang an email last week requesting to buy a couple items. He has yet to respond. Is this normal? Looks like they make it difficult to buy their stuff :? Have others had better luck with BestechPower?

 

[izeman]

I sent Henry Zhang an email last week requesting to buy a couple items. He has yet to respond. Is this normal? Looks like they make it difficult to buy their stuff :? Have others had better luck with BestechPower?

sometimes they answer almost instantly, sometimes it takes some time but overall, even though they let some days slip after i sent them the money, it arrived shortly after they sent it. no problems so far. i had much worse buying stories.

 

[dnmun]

if you ask which of their models you are interested in we can tell you prices. i have a list i got from henry 3-4 weeks ago for some i was interested in. but i recommend the D131 for all of applications you are thinking of. all the other BMSs are smaller and have a much lower balancing current. the D131 is $58 for 24S and the D126 i am using for 15S was $19.

my collection of lipo cells was a free batch of abused 6S turnigy 20S packs. i had one cell in one of the 6S which self discharged way down to 3.49V and the good ones were sitting at 4.2V so it has been hard to make it balance because the lowest cell has only 40% charge and the other on top are fully charged. but i have got it pretty close now but i realize these pouches are really in bad shape and have high internal resistance on some that were part of the pack that over charged. so these results are not real or representative yet, and i am waiting for my order of 5X6s turnigy packs to arrive.

from my analysis of the icharger, the balancing shunt resistors have a resistance of about 9.4 ohms. it is the shunt resistor which determines the balancing current. the D131 has 25 ohms so the icharger is 25/9.4 times faster in balancing, but it has a fan to cool the resistors. the BMS does not.

 

[izeman]

... but i have got it pretty close now but i realize these pouches are really in bad shape and have high internal resistance on some that were part of the pack that over charged. so these results are not real or representative yet, and i am waiting for my order of 5X6s turnigy packs to arrive....

you may have got them close now. but this all vanishes after the first use. did you use the IR testing of the icharger? it's a pretty good indication who good the cell is even though it's not really accurate. i've got my cells from victpower. some in good shape, some in bad. IR differs quite a lot, and this makes troubles now while charging. the cells with low IR get full earlier, and the worn ones take longer, but still bleed faster afterwards. i would swap those if i could, but i haven't got any good cells left.

 

[major]

if you ask which of their models you are interested in we can tell you prices. i have a list i got from henry 3-4 weeks ago for some i was interested in. but i recommend the D131 for all of applications you are thinking of. all the other BMSs are smaller and have a much lower balancing current. the D131 is $58 for 24S and the D126 i am using for 15S was $19.

Thanks. I inquired about the HCX-0131A for 12S cells at 4.2 volts per cell, Balancing/Equilibrium Modules. I want to use it (them) on EnerDel 2P12S modules (35Ah) independent of charger and load.

 

[dnmun]

the HCX-D131, which i just call the D131, is $58 plus shipping. shipping has been about $15 for one on DHL. i have two here i was gonna use to build a 24S BMS for silverheels or greg to test under high current discharge and charge operation. one of them i am gonna hack to 20S now but the hack will be reversable so it will always be 24S capable.

i asked him if they would ship by hong kong post but he said it is too far to drive since they are over in shenzen. they mostly do big shipments that go by air or china local delivery i guess.

i actually went and looked at the location of their plant on google earth. i was really impressed by the shenzen bay bridge. it finally hit me too, 25 million people. most in the last few decades.

also like i mentioned i just decided to hack my new 24S D131 down to 20S so i can use it to control another battery i am gonna build from the donated lipo packs from silverheels.

i built the 15S pack and got it to balance on my other thread, but i decided now it has kinda helped me learn that BMS so i am gonna take the pack apart again and remove the top 3 cells which were from the pack that died and i had in the wood clamp press for two months to flatten.

then use just the two 6S sections left, but #9 had the high self discharge rate, but i have a group of 4 of the 5200mAh hardcase packs which are each 2S so i am gonna add them to the 12S of the turnigy 20C so i will end up with a hybrid pack of different components. totally mongroid. except the turnigy is now charged up to 4.2V and the hardcase are all down around 3.79V so i gotta get them all close somehow first. i think a bulk charger on the 8S of the hardcase will push them up to 4.2V so i will do that when i do the 20S hack of the D131. i should be able to test the 15S BMS too when i create this by just leaving the sense wires on the first 12 now and then add them to the first three of the 8S i am gonna add.

 

[dnmun]

if you ask which of their models you are interested in we can tell you prices. i have a list i got from henry 3-4 weeks ago for some i was interested in. but i recommend the D131 for all of applications you are thinking of. all the other BMSs are smaller and have a much lower balancing current. the D131 is $58 for 24S and the D126 i am using for 15S was $19.

Thanks. I inquired about the HCX-0131A for 12S cells at 4.2 volts per cell, Balancing/Equilibrium Modules. I want to use it (them) on EnerDel 2P12S modules (35Ah) independent of charger and load.

they do not sell this D131A balancing board it turns out. i was able to talk him into donating one to me that did not have the HVC and LVC components mounted so i could examine the traces hidden underneath the surface mount parts. that was what i put in the picture.

if you want to use just the balancing board and use their HVC and LVC signals to drive your enerdel controls then i would recommend that you order the D131 and hack it by either using their mosfet gate driver signal or even use the entire BMS itself for current control. the 80A is very conservative. they have 15 of the irfb4310 in parallel. each one is capable of 30A easily imo. the shunt wires can be hacked to increase the cutout current from 180A up to maybe 300A imo. that overclocking of the shunt is still only 20A for each of the irfb4310. most use them in the hi voltage controllers at 100V on top of that are used at 80A in the controllers and the controller pwm switches them at high frequency so i think the current rating is overly conservative given the huge heat sink and thermal breaker.

i think it is maybe even 400A capable. 150 continuous.

maybe if enuff people get interested here in the states it would make sense to combine a few orders into one and then use the small flat rate box in the states to split it up. but shipping is the biggest component of the pricing now because these guys are selling us these units at really low distributor level prices imo. that is why i worry that someone is gonna screw it up.

 

[major]

if you ask which of their models you are interested in we can tell you prices. i have a list i got from henry 3-4 weeks ago for some i was interested in. but i recommend the D131 for all of applications you are thinking of. all the other BMSs are smaller and have a much lower balancing current. the D131 is $58 for 24S and the D126 i am using for 15S was $19.

Thanks. I inquired about the HCX-0131A for 12S cells at 4.2 volts per cell, Balancing/Equilibrium Modules. I want to use it (them) on EnerDel 2P12S modules (35Ah) independent of charger and load.

they do not sell this D131A balancing board it turns out. i was able to talk him into donating one to me that did not have the HVC and LVC components mounted so i could examine the traces hidden underneath the surface mount parts. that was what i put in the picture.

if you want to use just the balancing board and use their HVC and LVC signals to drive your enerdel controls then i would recommend that you order the D131 and hack it by either using their mosfet gate driver signal or even use the entire BMS itself for current control. the 80A is very conservative. they have 15 of the irfb4310 in parallel. each one is capable of 30A easily imo. the shunt wires can be hacked to increase the cutout current from 180A up to maybe 300A imo. that overclocking of the shunt is still only 20A for each of the irfb4310. most use them in the hi voltage controllers at 100V on top of that are used at 80A in the controllers and the controller pwm switches them at high frequency so i think the current rating is overly conservative given the huge heat sink and thermal breaker.

i think it is maybe even 400A capable. 150 continuous.

maybe if enuff people get interested here in the states it would make sense to combine a few orders into one and then use the small flat rate box in the states to split it up. but shipping is the biggest component of the pricing now because these guys are selling us these units at really low distributor level prices imo. that is why i worry that someone is gonna screw it up.

Sorry, I made a mistake on part number. Should be HCX-D131A. And thanks again for the explanation. But I do not want anything more than a device to balance the 12S pack. Just balance with the pack on the bench, nothing connected to it except the balance circuit. No charger, no load. I get tired of doing it manually. From the webpage description of that part, it sounds like that is what it will do.

 

[dnmun]

if they sold it by itself that is.

 

[dnmun]

finally built the 20S pack from the 12S +8S hardcase, charged up to 63V on the 15S section, and then discharged it into my dummy load but never connected the watt meter , just an ammeter so i only estimated the 5Ah pouches are down to about 4.2Ah now on the shortest one.

but i was able to get the HVC function and the LVC to function so i know it is there to protect it. just glad it worked. gate voltage was flat for the entire discharge, something the other BMS does not have. about 8.5V and the charging mosfet gate sat around 6.7V. it does balance up to the 4.2level though and the HVC cycles up to 4.35V before it cuts off snd then resets at 4.15V but i have not had a chance to balance it yet so i hope that will finally stay below 4.2.

i just did the first discharge and charging it up again now to see if i can find a bigger load and get the load up to 25A. gotta find more heaters and rewire them.

 

[Bazaki]

I love this BMS, it is now working thanks to dnmun.

The second from below mosfet was shorted somehow and dnmun explained me to just cut the legs and that's it. It has a nice HVC at 4,25v LVC at 2,50 V which is good for heavy load.

I can recommend this stuff:
http://www.plastidip.com/home_solutions/Liquid_Tape
https://www.youtube.com/watch?v=A7x_Xl1N7l0

I use this stuff for other applications as well, but I plasti dipped the whole BMS except the cooling plate.
This liquid tape is also very good for building packs like the one of dnmun, just put in top of all your lipo connections.

Anyway, I don't use a casing for this BMS I have put a lot of liquid tape on it, so my BMS is in some sort of rubber casing inside the triangle bag.

About the balancing I'm not sure, the resistors don't get hot anymore and I manually imbalanced cell 6 so one 6s pack has about 40mV imbalance and it doesn't seem to happen that the BMS is balancing it.