BMS specs for MSuper V3S 84v

[Noillek]

Hi, does anyone knows what specs are the standard bms for the 20s from gotway? I'm looking specifically at the max current rating that I need for an extra battery pack.

thank you

[zlymex]

There is no max current spec for Gotway BMS because there is no output protection at all. The two output wires are directly soldered to the battery terminal.

If you build a 20s battery and decided to incorporate an output protection , I recommend 50A or more for max current rating. I've installed a current sensor on the battery side of my Msuper3s+ and tested many occasions that the current may reach to 40A. Note that the current reading from an app is the motor current and in most cases is larger than the battery current.

Once I installed an 40A fuse on my V3S+(there is originally no fuse on my mainboard) but burned down at an obstacle, then I change the fuse to 60A.

[esaj]

No protections? Hopefully no-one will short-circuit the packs by accident when working on the wheel...  

[zlymex]

45 minutes ago, esaj said:

No protections? Hopefully no-one will short-circuit the packs by accident when working on the wheel...  

No protections what so ever. As can be seen from the photo that the output wires are soldered to B- and B+.
There is a protection circuitry but for charge protection only.

[Noillek]

On 6/20/2017 at 5:16 PM, zlymex said:

There is no max current spec for Gotway BMS because there is no output protection at all. The two output wires are directly soldered to the battery terminal.

If you build a 20s battery and decided to incorporate an output protection , I recommend 50A or more for max current rating. I've installed a current sensor on the battery side of my Msuper3s+ and tested many occasions that the current may reach to 40A. Note that the current reading from an app is the motor current and in most cases is larger than the battery current.

Once I installed an 40A fuse on my V3S+(there is originally no fuse on my mainboard) but burned down at an obstacle, then I change the fuse to 60A.

Thank you Zlymex, would you advise me not to put any BMS then?I ordered a 60A BMS... hopefully will be enough

[Chriull]

5 minutes ago, Noillek said:

Thank you Zlymex, would you advise me not to put any BMS then?I ordered a 60A BMS... hopefully will be enough

The BMS makes still sense for cell under voltage & temp monitoring and most importantly cell balancing.

If the 60A max current is not enough you can still "shunt" it : 

 

[zlymex]

7 minutes ago, Noillek said:

Thank you Zlymex, would you advise me not to put any BMS then?I ordered a 60A BMS... hopefully will be enough

I think the 60A BMS will work just fine. I've never experience any burn-down with my 60A fuse installed for over 3000km ride including very rough terrain.

Yes, an BMS functions as cell balancing and charge protection as well, to which GW also have.

Although GW removes the output protection of the BMS, the cells are still protected against under voltage when ridding because the EUC is incorporated a tilt-back once the average cell voltage reached to about 3.25V, provided of course the cells are in balancing condition.

The danger is, for example, if you leave the EUC on for a long time, the battery will be drained. While cells with output protection will cut off completely in this situation.

[Xima Lhotz]

On 6/20/2017 at 6:39 PM, zlymex said:

Is that a Gotway solder joint (on the output cables) or is the BMS redone?

It looks to me like a cold solder and there is so much of the solder, is it done with a fire poker?

If it's done by someone else with little or no experience well then it's understandable that it looks that way. 

 

[Pard]

22 minutes ago, Xima Lhotz said:

Is that a Gotway solder joint (on the output cables) or is the BMS redone?

It looks to me like a cold solder and there is so much of the solder, is it done with a fire poker?

If it's done by someone else with little or no experience well then it's understandable that it looks that way. 

 

+1  that solder work is not acceptable.  I would have that redone by someone who knows how to solder.

[zlymex]

2 hours ago, Xima Lhotz said:

Is that a Gotway solder joint (on the output cables) or is the BMS redone?

It looks to me like a cold solder and there is so much of the solder, is it done with a fire poker?

If it's done by someone else with little or no experience well then it's understandable that it looks that way. 

 

That was the original Gotway battery of my Msuper V3. They must soldered them by an electric iron or a soldering station. Here is the close-up:

There was a video posted by Jane MO(probably in 2015) on youtube of how to replace BMS including the soldering. I cannot see youtube but you can search 'how to replace the Gotway battery protection board' to find the video.

There is another similar video also posted by Jane MO later, the place looks to me like a Gotway service
http://v.youku.com/v_show/id_XMTU4MTU1MzMxMg==.html

[Rehab1]

9 hours ago, zlymex said:

That was the original Gotway battery of my Msuper V3. They must soldered them by an electric iron or a soldering station. Here is the close-up:

There was a video posted by Jane MO(probably in 2015) on youtube of how to replace BMS including the soldering. I cannot see youtube but you can search 'how to replace the Gotway battery protection board' to find the video.

There is another similar video also posted by Jane MO later, the place looks to me like a Gotway service
http://v.youku.com/v_show/id_XMTU4MTU1MzMxMg==.html

This looks very familar. Looking at the globs of solder on the BMS reminds me of the first Heathkit I built at age 8 . Does GW build their own BMS or do they outsource it?

[Noillek]

On 6/29/2017 at 3:53 PM, zlymex said:

I think the 60A BMS will work just fine. I've never experience any burn-down with my 60A fuse installed for over 3000km ride including very rough terrain.

Yes, an BMS functions as cell balancing and charge protection as well, to which GW also have.

Although GW removes the output protection of the BMS, the cells are still protected against under voltage when ridding because the EUC is incorporated a tilt-back once the average cell voltage reached to about 3.25V, provided of course the cells are in balancing condition.

The danger is, for example, if you leave the EUC on for a long time, the battery will be drained. While cells with output protection will cut off completely in this situation.

Thank you Zylmex, since i want to do things right its taking long time to get all the components together... just go the battery pack together a 20S2P, so that can fit in the Msuper seat. The BMS that i got i did a mistake it was for Lithium Iron instead of Lithium Ion... now waiting for the correct one.

Thanks to everyones contribution now i know which settings i need to get for my BMS, regarding current is just the max that the battery can burst in this case is 20A, all bms's include as well the peak current that often is way higher.... but since i ordered a 50A now, i should be safe even without removing the output protection (since i dont know how), also this bms that im waiting has peak current 100A... more than enough even if i plan to expand the battery pack (that i intend to

Playing with the new Vruzend kit, to make everything easy and also upgradable, used same as my original batteries Panasonic 2900mah 10A, the crappy wrap is just to cover it in not to protect... while I'm waiting for the new BMS

[Chriull]

50 minutes ago, Noillek said:

Thank you Zylmex, since i want to do things right its taking long time to get all the components together... just go the battery pack together a 20S2P, so that can fit in the Msuper seat. The BMS that i got i did a mistake it was for Lithium Iron instead of Lithium Ion... now waiting for the correct one.

Thanks to everyones contribution now i know which settings i need to get for my BMS, regarding current is just the max that the battery can burst in this case is 20A, all bms's include as well the peak current that often is way higher.... but since i ordered a 50A now, i should be safe even without removing the output protection (since i dont know how), also this bms that im waiting has peak current 100A... more than enough even if i plan to expand the battery pack (that i intend to

Playing with the new Vruzend kit, to make everything easy and also upgradable, used same as my original batteries Panasonic 2900mah 10A, the crappy wrap is just to cover it in not to protect... while I'm waiting for the new BMS

You have read on vruzend.com/faq :

"How much current can the terminal caps support?

So far the caps have been tested and confirmed to withstand up to 3.5 A of current each. However, we are quite confident that they can carry higher levels of current and will testing this further soon!"

?

[Noillek]

7 hours ago, Chriull said:

You have read on vruzend.com/faq :

"How much current can the terminal caps support?

So far the caps have been tested and confirmed to withstand up to 3.5 A of current each. However, we are quite confident that they can carry higher levels of current and will testing this further soon!"

?

Thanks haven't see that, I will pay attention, my first tests i will be very cautious and check after short rides, where i will increase the current consumption.

[Noillek]

Hi all,

 

Just to keep you updated, there are still some mysteries in my project by i decided to go ahead and finalize it.

1) Battery pack was a struggle to get all cells connected with this Vruzend Kit... next one i will definetly try welding instead, BMS was pretty straight forward and easy to connect all the cables.

2) Parallel cables created to be able to easily plug the extra Battery, top connector is a XT30 for charging circuit and the bottom one is a XT60 for output for the PCB, only had 14 AWG cable so i used for everything.

3) Created as well an adapter to charge the battery extra pack separately from the original batteries, only needed if the pack is not connected to the wheel, so it minimizes the risk of sparks and fireworks.Charging so i can have same tension and connect all cables safely.

4) Last part was to get all cables connected and make sure that i have tension everywhere.

Next challenge is to secure well and nicely the extra pack, ideally allowing me to still use the seat... more to come on this one. Before i will still take it for a test drive even if ugly

Thank you all for the tips and advises, will keep posting while this experiment develops.

[Hansolo]

Perhaps you have the same BMS as my extension, on the opposite side to the cooler there is a led by cells which light on during ballancing

 

 

[Noillek]

5 minutes ago, Hansolo said:

Perhaps you have the same BMS as my extension, on the opposite side to the cooler there is a led by cells which light on during ballancing

 

 

looks super cool... mine doesn't light, I'm not even sure if my BMS is correctly setup... as i'm not getting 84V from the pack just 76v, guess that the bms is not adjusted for 84v? (wild guess).

I got a 20S2P of original batteries so is an extra 418Wh, if i manage to weld them i will try to fit inside of the shell but for now goes on top of the seat.

Thanks Hansolo

[US69]

26 minutes ago, Noillek said:

looks super cool... mine doesn't light, I'm not even sure if my BMS is correctly setup... as i'm not getting 84V from the pack just 76v, guess that the bms is not adjusted for 84v? (wild guess).

Wild guess :-) If your pack delivers 84Volt, what should your BMS do with the missing 8?

Have you checked what voltage is coming from the pack directly???

Please Pay Attention, if some cells dont make good contact on the vruzend kit, and you connect/parallel a 76 Volt pack to your 84 Volt wheel.. you may end up with  a nice fire/vent in the house!

Edited August 4, 2017 by KingSong69

[Noillek]

1 hour ago, KingSong69 said:

Wild guess :-) If your pack delivers 84Volt, what should your BMS do with the missing 8?

Have you checked what voltage is coming from the pack directly???

Please Pay Attention, if some cells dont make good contact on the vruzend kit, and you connect/parallel a 76 Volt pack to your 84 Volt wheel.. you may end up with  a nice fire/vent in the house!

Thank you @KingSong69, i did measure directly the pack and individual cells... pack was 70.4V and individual cells were 3.52v... which matches correctly.

After assembling everything i connected a charge doctor setup to cut off at 84.4v and after reached this amount charger light was green and when i measured again the battery directly i got only 76V. even when i connected to the original pack there were no sparks or anything it was all fine. but again measuring the full pack with the 3 connected the voltage was at 81v. The original were at 83.3v and the extra was at 76v... so i gues that they leveled to 81v. But im curious to understand more details.

Today i will charge all of them together and i will be there to measure everything and see if i get the correct voltage as 100% charged... after that will go for a ride and check autonomy (approx. range should be now real 100km at and avg speed of 30/35 km/h).

 

[Keith]

8 minutes ago, Noillek said:

After assembling everything i connected a charge doctor setup to cut off at 84.4v and after reached this amount charger light was green and when i measured again the battery directly i got only 76V.

Like @KingSong69 I think there is something seriously wrong with your set up - 76V is only 3.8V per cell. If it dropped to that after taking it off of charge there has to be something wrong with the charging or some of the cells. If connecting a pack that is not much over 50-60% charged (if all the cells are at 3.8V) did not cause a huge current flow from the fully charged pack(s) to that pack then there has to be something actually preventing current flow out of the pack. To be honest sounds like you actually have a very high resistance output from that pack - I.e. As if the cells are not properly connected in series? That would also explain why the charger went green even though the cells were nowhere near 4.2V each i.e. The rest of the voltage from the charger was a resistance voltage drop across the pack.

I find it difficult to understand why you would set charge doctor to cut off at slightly over 4.2V per cell - all that is going to do is prevent proper balance charging when the pack gets to full voltage I.e. You will allow full constant current charging and cut off immediately it starts the constant voltage phase of balance charging.

[Noillek]

2 minutes ago, Keith said:

Like @KingSong69 I think there is something seriously wrong with your set up - 76V is only 3.8V per cell. If it dropped to that after taking it off of charge there has to be something wrong with the charging or some of the cells. If connecting a pack that is not much over 50-60% charged (if all the cells are at 3.8V) did not cause a huge current flow from the fully charged pack(s) to that pack then there has to be something actually preventing current flow out of the pack. To be honest sounds like you actually have a very high resistance output from that pack - I.e. As if the cells are not properly connected in series? That would also explain why the charger went green even though the cells were nowhere near 4.2V each i.e. The rest of the voltage from the charger was a resistance voltage drop across the pack.

I find it difficult to understand why you would set charge doctor to cut off at slightly over 4.2V per cell - all that is going to do is prevent proper balance charging when the pack gets to full voltage I.e. You will allow full constant current charging and cut off immediately it starts the constant voltage phase of balance charging.

Thank you Keith, i charge my wheels always at 100% and rarely use the charge doctor, i use it this time to make sure that i could have both pack with same voltage. I will charge everything again with the stock charger and see if everything goes well, indeed if there's a resistance issue with one of the connections that might be the problem. Will keep investigating, and keep you all informed.

[US69]

1 hour ago, Noillek said:

Today i will charge all of them together and i will be there to measure everything and see if i get the correct voltage as 100% charged... after that will go for a ride and check autonomy (approx. range should be now real 100km at and avg speed of 30/35 km/h).

What means "Charge them together"??? You will not  connect the extra pack in parallel with the original, i hope?

Do not do that as Long they are not on the same voltage!!! It is total dangerous to connect a 84Volt and a 78 Volt pack in parallel! This can result in a bomb...thats no joke!

Something seams totally wrong here....

 

[esaj]

On 8/4/2017 at 0:02 PM, Noillek said:

looks super cool... mine doesn't light, I'm not even sure if my BMS is correctly setup... as i'm not getting 84V from the pack just 76v, guess that the bms is not adjusted for 84v? (wild guess).

Are you sure your new BMS isn't (again) a LiFePo-BMS? Those have lower voltages than "normal" lithium-ions, and the BMS would then be accordingly programmed to stop the charging at LiFePo maximum voltage.

And like KingSong69 said above, DO NOT connect the batteries in parallel if the voltages are that different. The resulting current as the pack voltages start to equalize will be HUGE and will likely at least burn the connectors, if not melt the wires and/or make the batteries "vent with flame".

 

EDIT: LiFePo's apparently have around 3.6-3.65V / cell maximum voltage, so probably it's not a LiFePo-BMS, as 76V (3.8V / cell) would already be above LiFePo maximum.

Edited August 5, 2017 by esaj

[Noillek]

On 8/4/2017 at 2:56 PM, KingSong69 said:

What means "Charge them together"??? You will not  connect the extra pack in parallel with the original, i hope?

Do not do that as Long they are not on the same voltage!!! It is total dangerous to connect a 84Volt and a 78 Volt pack in parallel! This can result in a bomb...thats no joke!

Something seams totally wrong here....

 

 

On 8/5/2017 at 3:36 PM, esaj said:

Are you sure your new BMS isn't (again) a LiFePo-BMS? Those have lower voltages than "normal" lithium-ions, and the BMS would then be accordingly programmed to stop the charging at LiFePo maximum voltage.

And like KingSong69 said above, DO NOT connect the batteries in parallel if the voltages are that different. The resulting current as the pack voltages start to equalize will be HUGE and will likely at least burn the connectors, if not melt the wires and/or make the batteries "vent with flame".

 

EDIT: LiFePo's apparently have around 3.6-3.65V / cell maximum voltage, so probably it's not a LiFePo-BMS, as 76V (3.8V / cell) would already be above LiFePo maximum.

Thank you guys, mystery solved... nothing wrong with BMS or batteries... it was the charger, it seems that i like to plug things in parallel, by connecting 2 chargers in parallel to be quicker the charge as soon as current gets below 1,5A one of the chargers gives the green light, while the other one keeps pushing current into the batteries... if you use the Charge doctor, it will immediately give you the message that is full as soon as one of the chargers turns green.

Solved charged the batteries plugged in parallel with just the original charger and tchatcham... 84v everywhere

Went for a few rides this weekend... and there's an amazing improvement, 26km round in a more or less stable speed between 38/42km/h and got home with 60% battery still. Yesterday spend around 15% to do 15km at cruising speeds of 38km/h and below 50% battery... no bips or tilt backs during both rides, already charged twice and no problem .

 

It doesn't look pretty and i also don't feel confortable to seat on it... I'm afraid to damage the battery pack (although i build in a way that i can seat). I can unplug everything easily and remove the seat+Battery pack (attached to each other).

 

 

 

[US69]

7 minutes ago, Noillek said:

It doesn't look pretty and i also don't feel confortable to seat on it... I'm afraid to damage the battery pack (although i build in a way that i can seat). I can unplug everything easily and remove the seat+Battery pack (attached to each other).

I am with you..Looks a "bit" awkward ;-)

But i am happy to hear you have solved your technical Problems! Than now you can work on the appearance or even think about soldering and putting the batteries into the wheel...