Three wire Bms to two, is it possible?

[Sturmey]

I need to order a BMS myself. I was thinking of this one below. It seems to have 2 white wires for a switch and an external thermistor and 60A peak/30A continuous rating along with balance function. 5 amp maximum charge current. Looks good for about £8 plus another £7.38 for delivery.
What do you think?

Small BMS,10S 36V 30A or 13S 48V 30A li-ion battery BMS, For 18650 21700 cell HaiLong Dolphin Shark case ebike battery BMS

Small BMS,10S 36V 30A or 13S 48V 30A li-ion battery BMS, For 18650 21700 cell HaiLong Dolphin Shark case ebike battery BMS

www.pswpower.com

 

[Nealh]

Thanks I think I will go with this one without switch but with balancing.

BeMuchSafer 13S 35A 30A 48V Battery BMS With On/Off Switch Balance Function Temperature Sensor 13S30A 13S35A BMS for DIY E-Bike - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

To tide me over I ordered a daly from Amazon ,

https://www.amazon.co.uk/dp/B0D114YHVR?ref=ppx_yo2ov_dt_b_fed_asin_title

I went to fit it this morning and as I was checking I noticed the polarity for the ribbon connection is reversed so can’t use it. I think the BeMuchSafer shows the correct way round.
Is there a ribbon reversal adapter, and if so what’s the proper name? I have had a search but I only get results for typewriters…..

With the BMS sense wire ribbon in most cases on has to resolder all of the wires again , typically unless an exact replacement is found. Even then one has to be 100% sure the BMS order is correct and not reversed.


If one can't access the cell ends directly to solder then one can cut the sense wires on both sides in the correct number sequence/order ( one at a time and solder/shrink the joint to the new sense ribbon). It is prudent though to be 100% certain and use a meter on the battery side sense to confirm voltage reading and correct cell order.

 

[Nealh]

I need to order a BMS myself. I was thinking of this one below. It seems to have 2 white wires for a switch and an external thermistor and 60A peak/30A continuous rating along with balance function. 5 amp maximum charge current. Looks good for about £8 plus another £7.38 for delivery.
What do you think?

Small BMS,10S 36V 30A or 13S 48V 30A li-ion battery BMS, For 18650 21700 cell HaiLong Dolphin Shark case ebike battery BMS

Small BMS,10S 36V 30A or 13S 48V 30A li-ion battery BMS, For 18650 21700 cell HaiLong Dolphin Shark case ebike battery BMS

www.pswpower.com

It's cheap enough even with the p&p, one will have to be the forum test guinea pig on this one.

 

[saneagle]

I went to fit it this morning and as I was checking I noticed the polarity for the ribbon connection is reversed so can’t use it. I think the BeMuchSafer shows the correct way round.
Is there a ribbon reversal adapter, and if so what’s the proper name? I have had a search but I only get results for typewriters…..

Yes, it's called a pair of scissors and a soldering iron.

 

[Lazeyboy]

Yes, it's called a pair of scissors and a soldering iron.

Sorry but your more confident than me. I only have about an inch of ribbon to get to. I cant get the cell pack out as its stuck in there with thick foam strips and silicon. Cutting live wires with sissors might cause more probs, and i'm sure your not suggesting that.
I did find a useful youtube video which may help keeping a note of the positive and negative sides of the ribbon.

 

[saneagle]

Sorry but your more confident than me. I only have about an inch of ribbon to get to. I cant get the cell pack out as its stuck in there with thick foam strips and silicon. Cutting live wires with sissors might cause more probs, and i'm sure your not suggesting that.
I did find a useful youtube video which may help keeping a note of the positive and negative sides of the ribbon.

You separate them from the ribbon and cut them one at a time!

 

[harrys]

1) I also was careless when I ordered a BMS from Be Much Safer and didn't check to order it with an on/off switch. I noticed it had the two solder holes for an on/off switch but they told me it couldn't be added, so I reordered,

On some other designs , the BMS boards will omit the switch wires and put a jumper between the two solder holes.

When the second Be Much Safer part came in, I couldn't find any difference in components or layout, but the two solder holes were tied together somehow. Perhaps there's some programmable logic on it.

2) I recently ordered another Annpower BMS with on/off switch. I
I've used a few of these w/o problems. They sent me a faulty one. The switch didn't work and it only powered up if I plugged in the charger, Aliexpress gave me a refund, but I had to return the old BMS using a pre-paid mailing label. I bought a second Annpower from a different aliexpress vendor and that was OK,

3) It usually costs me $20USD or more for a balance BMS with on/off switch, A $10 balance BMS from PSWpower? Must be a $30 shipping fee.

 

[thelarkbox]

Fwiw, Small aerosol pump spray bottles sold full of spectacle cleaning fluid are solvent resistant and can contain and spray 99% iso-propanol. And this is the perfect delivery method to get the glue releasing solvent into the nooks and crannies' of such containers as a battery box... spray down a drinking straw to target specific areas.. spray leave, spray again and leave again for half an hour and anything glued should now start to come free.. some puling will still be required tho..

 

[Lazeyboy]

1) I also was careless when I ordered a BMS from Be Much Safer and didn't check to order it with an on/off switch. I noticed it had the two solder holes for an on/off switch but they told me it couldn't be added, so I reordered,

On some other designs , the BMS boards will omit the switch wires and put a jumper between the two solder holes.

When the second Be Much Safer part came in, I couldn't find any difference in components or layout, but the two solder holes were tied together somehow. Perhaps there's some programmable logic on it.

2) I recently ordered another Annpower BMS with on/off switch. I
I've used a few of these w/o problems. They sent me a faulty one. The switch didn't work and it only powered up if I plugged in the charger, Aliexpress gave me a refund, but I had to return the old BMS using a pre-paid mailing label. I bought a second Annpower from a different aliexpress vendor and that was OK,

3) It usually costs me $20USD or more for a balance BMS with on/off switch, A $10 balance BMS from PSWpower? Must be a $30 shipping fee.

Thanks for your help. I have ordered a 13s Be Much Safer BMS with switch.
Even though my silverfish battery has a key to lock and power the bike, I’m guessing that I may not need the wire from the bms. I will just need to join the ends together to bridge it? (It looks a small enough wire not to be sending too much current, though I will measure it first with a multi meter.)
Thank again.

 

[Lazeyboy]

Just to say the bms arrived and is now fitted and works a dream! I have discharged and recharged and the balancing is better than I expected, well with in 0.2v of each other, most 0.1v The switch wire was not needed so I just joined the two ends together. Thanks for all your advice and patience.