Few questions about the 13s BMS boards on ebay from china

[ÆLYUS Energy]

I am not 100% clear on the rules for this site on linking to ebay things so i am just going to insert the pictures instead.

What you see is exactly the information they give besides its title which reads "13S 48V Li-ion Lithium Cell 20A 18650 Battery Protection BMS PCB Board w Balance" They give no other specs than that.

I am sure a few of you have them already and was hoping to get a few ?'s answered.

As it does not really specify anywhere what the exact voltages are on the unit as a whole. Does anyone know the input voltage range on this unit? Meaning can i input only exactly 48v to the board to charge a 13s12p pack? or can i feed 12v,24v or whatever In to the board to charge and still pull the 48v out?

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Would you recommend using a separate +/- for drawing power from a 13s12p with its own fuse inline or do you think it would be safe/better to just draw the power off the board as well?

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Is there anything easier out there than this informationless ebay deal? I see this one does not have thermal protection. Not sure how important that is. I have found hundreds of them on different websites and through links from this site, but every link i find takes here takes me to manufacturers websites with no listings on where to purchase.

Thanks for any help recieved

 

[Punx0r]

When it comes to dicharge or charge voltages think of the BMS as a safety-cutout like an intelligent fuse. The voltage you apply the charge the pack must be correct for the pack (e.g. if LiCo, 13 x 4.2V) if your power supply goes haywire and puts out too much voltage, the BMS will disconnect the pack when that excess voltages causes any cell to be pushed to 4.25V. The BMS cannot boost-convert the applied voltage - if you want 48V out, you must put 48V in.

 

[Lurkin]

The more expensive options have better disclosure. Have a look at Bestech, I have summarised the 13S options in a spreadsheet for your convenience here: https://endless-sphere.com/forums/viewtopic.php?f=14&t=75415

I've gone with an Aliexpress one being: http://www.aliexpress.com/store/product/Free-Shipping-48V-40A-BMS-13S-48V-54-6V-li-ion-battery-BMS-PCM-40A-continuous/1708497_32283657890.html

 

[ÆLYUS Energy]

The more expensive options have better disclosure. Have a look at Bestech, I have summarised the 13S options in a spreadsheet for your convenience here: https://endless-sphere.com/forums/viewtopic.php?f=14&t=75415

I've gone with an Aliexpress one being: http://www.aliexpress.com/store/product/Free-Shipping-48V-40A-BMS-13S-48V-54-6V-li-ion-battery-BMS-PCM-40A-continuous/1708497_32283657890.html

Thank you Lurkin, between those two links i was able to find everything i needed. What a great thing to wake up to this morning Going to go grab a coffee and i have to come back and read that thread about the bike, that looks like an awesome project.

 

[Lurkin]

Bear in mind I haven't received or tested that bms as of yet.. I've found that seller is pretty good at responding to aliexpress messages and will accept PayPal as well.

All the best, post up how it turns out!

 

[ÆLYUS Energy]

Bear in mind I haven't received or tested that bms as of yet.. I've found that seller is pretty good at responding to aliexpress messages and will accept PayPal as well.

All the best, post up how it turns out!

Will do, i decided i am just going to go a little crazy and order about a dozen different 13s BMS's then just put them through the paces to see which one performs the best for the best price. Probably blow up a few 18650's, start a few board fires and melt some wires along the way. (i have a controlled environment where that can be safe) I guess the only real way to find out whats what is to push them all to their breaking points and see who really has a solid BMS that doesn't break the bank in china. Most seem to be in the $20-$50 range so i think i can sacrifice a little money for a weekend of blowing things up and starting fires. Will start a new thread once its done. No idea how long it will take for it all to get here.

 

[Lurkin]

That's awesome! Take videos man keen to see this. I think there would be real value in starting a list of tried and tested products from China! Looking forward to seeing this!

 

[Ykick]

I highly recommend a parallel dongle for the balance channel wiring in order to use something like a CellLog or iCharger logging function to help graph cells’ BMS performance.

Here’s a graph I captured 8S - it shows a Besttech BMS reaching ODDV on one cell and cutting the load. You could of course watch a channel with a DVM but even that is much easier with a parallel dongle to connect into the BMS balance wiring.

 

[ÆLYUS Energy]

I highly recommend a parallel dongle for the balance channel wiring in order to use something like a CellLog or iCharger logging function to help graph cells’ BMS performance.

Here’s a graph I captured 8S - it shows a Besttech BMS reaching ODDV on one cell and cutting the load. You could of course watch a channel with a DVM but even that is much easier with a parallel dongle to connect into the BMS balance wiring.

Man, you tell me where to buy one, how much they are, and tell me how to hook it up right, and if it wont break the bank i would be all for it.

 

[Lurkin]

Ditto. I need one that has logging.

Be careful with cell logs - there is two versions, one which has USB logging and another which does not.

Hobbyking typically advertises the USB logging version, but sends the one with a blank USB port (which I now have, courtesy of HK).

 

[Ykick]

Seemed pretty clear to me CellLog 8S is/was always the one with logging function and 8M doesn’t have it. But it would appear HK (hobby king) no longer sells 8S.

I know Buddy RC (USA) has some in stock: http://www.buddyrc.com/junsi-celllog-8s.html

However, for that cost a person might simply be better off putting their money towards an iCharger and access practically the same logging function along with much much more?

Anyway, once you have the logging device available a parallel dongle is not something you can readily buy on Amazon, eBay, etc.

I fabricated mine using various JST bits & pieces. It’s not elegant enough for picture but suffice to say, it should not be any mystery how to parallel tap BMS balance channels. If it is, then you probably shouldn’t be going down this path anyway…

 

[Lurkin]

Dunno, both were advertised when I bought mine. Ditto, also tried to purchase two different RC chargers with HK clearly advertising USB logging functions and confirmed with their online people before hitting buy..

when they turned up, more blank ports. Needless to say, I don't buy charging devices from HK anymore.

Thanks for the link!