Victor Jose Ladero Covelo Posted February 22, 2019 Share Posted February 22, 2019 (edited) The photo show the question, what´s the uso of that connector (is battery to battery connector) Edited February 22, 2019 by Victor Jose Ladero Covelo 1 Quote Link to comment Share on other sites More sharing options...
Hansolo Posted February 22, 2019 Share Posted February 22, 2019 Connection between BMS, if 1 is on error the other BMS is stopped too. 1 Quote Link to comment Share on other sites More sharing options...
Victor Jose Ladero Covelo Posted February 22, 2019 Author Share Posted February 22, 2019 2 hours ago, Hansolo said: Connection between BMS, if 1 is on error the other BMS is stopped too. Ok thanks. one more question, why 4 wires from every bms and only use 2? what is this wires? This is only curiosity Quote Link to comment Share on other sites More sharing options...
meepmeepmayer Posted February 22, 2019 Share Posted February 22, 2019 It should be balancing wires. Keeping the voltage/charge state the same between the battery packs. Never heard the BMS communication thing, but if @Hansolo says so, I believe it. Quote Link to comment Share on other sites More sharing options...
US69 Posted February 22, 2019 Share Posted February 22, 2019 5 minutes ago, meepmeepmayer said: It should be balancing wires. Keeping the voltage/charge state the same between the battery packs. Never heard the BMS communication thing, but if @Hansolo says so, I believe it. Not balancing...just shutting down the other BMS if one goes down. Would be dangerous, if one pack goes dead/down and the other still has full voltage....as paralleled packs need to be on same voltage always. Thats why DIY paralleled packs can get quite a danger if this is not taken into account... 1 1 Quote Link to comment Share on other sites More sharing options...
Heyzeus Posted February 23, 2019 Share Posted February 23, 2019 (edited) 9 hours ago, US69 said: Not balancing...just shutting down the other BMS if one goes down. Would be dangerous, if one pack goes dead/down and the other still has full voltage....as paralleled packs need to be on same voltage always. Thats why DIY paralleled packs can get quite a danger if this is not taken into account... So, this is the 340wh battery that comes in the gotway mcm4, what I see there is the thick black red cables for delivering power to the motor and then the thin black red cables for charging. I had been thinking of buying a second 340wh battery at some point to upgrade it to the 680wh version and from some reading on here and what it seemed @Pasi did, I had been under the impression that I could buy another 340why battery just like the one pictured, use a y adapter/connector for the charging cables and also use a y adapter/connector on the power cables and that would be sufficient to upgrade the system. I don't really have much current desire to do so any more, but I do like to have a better understanding of these systems so... If I am understanding your comment correctly, doing the above would be a bad move because there would be no connection between the two battery packs BMS' allowing them to communicate and shut down if they ever had an imbalance in voltage? Like in this pic you can see the power, charging and then connection between BMS' What would happen if one pack was an older slightly worn pack that say only put out 64V at full/100% charge and you connected it up with a y adapter to a new pack that had a ~67V charge at full charge? If there can't be an imbalance in voltage between the two packs, how would you even go about adding a pack in parallel where one was new and one was slightly older? Would the strategy be to drain the new one down to the max voltage the other one can put out at full charge and then connect them up? But then what would prevent one from getting to a higher voltage when charging. And if there can't be an imbalance in the voltage between the two packs wouldn't those extra sets of wires between the BMS' have to do more than just shut down one if there was an imbalance. Like wouldn't it also have to take an active role in the BMS' maintaining balance between the two separate packs. Otherwise how would it handle a scenario where one pack wore down slightly faster than the other creating a slight voltage imbalance over time. Or is a voltage balance fine as long as it is with in say no more than 3 or so 4 volts total. Sorry for the long question, just find it interesting and trying to get a better understanding. Pictures taken from this thread: https://forum.electricunicycle.org/topic/5847-gotway-mcm4-battery-installation/ Edited February 23, 2019 by Heyzeus Quote Link to comment Share on other sites More sharing options...
Hansolo Posted February 23, 2019 Share Posted February 23, 2019 11 hours ago, Victor Jose Ladero Covelo said: Ok thanks. one more question, why 4 wires from every bms and only use 2? what is this wires? This is only curiosity The 4 wires are identical (2 by 2), the red wires are connected between and the same for dark wires. Quote Link to comment Share on other sites More sharing options...
Victor Jose Ladero Covelo Posted February 23, 2019 Author Share Posted February 23, 2019 3 hours ago, Hansolo said: The 4 wires are identical (2 by 2), the red wires are connected between and the same for dark wires. really thanks, and now I see why charge batteries separately is bad idea xD Quote Link to comment Share on other sites More sharing options...
US69 Posted March 3, 2019 Share Posted March 3, 2019 On 2/23/2019 at 8:21 AM, Heyzeus said: understanding your comment correctly, doing the above would be a bad move because there would be no connection between the two battery packs BMS' allowing them to communicate and shut down if they ever had an imbalance in voltage? Like in this pic you can see the power, charging and then connection between BMS' It is not exactly a “very bad move”.... Older GW models never had a “controlling” between 2 parallel battery packs...That goes especially for the “older” 67Volt models. And i have never heard of houses burning down, or something worse. Nonetheless: What they have in their actual wheels is better, more safe, and thinks about all possible bad things that can happen. So -i personally- would have no problem connecting packs without these control cables...as said: i personally. Quote Link to comment Share on other sites More sharing options...
WI_Hedgehog Posted April 29, 2020 Share Posted April 29, 2020 Here's a [complex] idea, please give your thoughts on how [un]reasonable it is: Purchase a Gotway Monster with 100V control board, without batteries from eWheels (an authorized Gotway retailer). Build six 24S1P battery packs, having no Battery Management System.* Add a 15-amp fuse to each 24S1P pack. (each pack should only supply a max of 10-amps if using cells with a 10A max output rating) Wire three 24S1P battery packs in parallel, twice, forming two 24S3P packs, no BMS. Put the two 24S3P packs in the Monster, plug into + & - wires only. Add low-voltage alarms to the balance wires so if any of the 24S cell banks goes low an alarm sounds.** Charge the packs as 24S1P via an external charger that monitors each cell & saves data to a log on a laptop.*** *Since the Gotway BMS connects the battery straight to the main control board, no BMS is needed on the battery output side. *Because the external programmable LiPo charger monitors & logs each LiPo cell, no BMS is needed on the battery input side. **This should be safer than the Gotway method of monitoring total voltage (and ignoring individual bank voltages). ***If a cell dies in a parallel pack, the remaining cells in the bank are under additional stress and could also fail. If a cell dies in a series pack it is detected by the charger. A logging charger will probably see a drop-off in cell capacity well before cell failure and initiate an alert. With this configuration, If one of six packs fail there is no "BMS lead to the other BMS" (the purpose of the lead being to shut down the non-problem Gotway BMS along with the problem BMS, causing total wheel shutdown which could lead to a face-plant). Therefore, having no "BMS lead to the other BMS" should reduce the possibility of a face-plant as the other five packs will still have power (assuming the failed pack blows a 15-amp fuse). Assuming the pack failure occurs during a time of high current draw, the worst case scenario should be the remaining five packs cannot support as much current as the six packs were providing, resulting in a low voltage condition which should be detected by the mainboard and result in tilt-back, therefore reducing current draw to something the five packs can provide. Does the mainboard require a +5V signal from the two Battery Management Systems in order to function? Is it a simple +5V signal? Is it correct Gotway does not monitor battery pack temperature? NOTES: The 100-volt Gotway Monster uses two 24S3P battery packs, each with BMS. (3 cells in parallel, with 24 cells in series) (24 cells in series) x (4.2 volts per cell) = 100.8 volts. (20 cells in series) x (4.2 volts per cell) = 84.0 volts. The 84-volt Monster has 180 cells: (20S3P packs) x (3 packs): 20 x 3 x 3 = 180. The 100-volt Monster has 144 cells: (24S3P packs) x (2 packs): 24 x 3 x 2 = 144. Because the 100-volt Monster has 144 cells instead of 180, there is room for the additional plugs and alarms. There is not room for a third pack in the 100v Monster: (24S3P packs) x (3 packs): 24 x 3 x 3 = 216 cells. Important Requirements: 25 balance wires for each 24S1P battery pack, and a positive and negative high current lead. 24S capable charger (not a problem). 24S capable alarms (not a problem). 24S plugs (not a problem). Two adapters that merge three serial packs into one 3P parallel pack (not a problem). Please kindly remember any or all of the above assumptions may be wrong, I do not yet own a Gotway Monster. Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 28, 2021 Share Posted March 28, 2021 Dragging up old topic....I too am confused about the role of the 4 wire 'comm wire' used by Gotway. It job seems to be that if one pack gets an issue, it tells the other pack to shut down. Does anyone know what signal is actually sent down the 4 wires? Over voltage? Under voltage? In what circumstance would this connection come in to play? I can't imagine it is able to actually shut down the output of one pack given that the packs output directly off the cells, so whatever the comm wire does can only affect the BMS. But if thats the case, why link the 2 packs at all when both packs have their own BMS' with their own protections? Really confused about the comm wire as you can probably tell, although I am sure gotway wouldn't have used one without a reason (due to more time and effort). Anyone got any further info since this thread was last updated? Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 28, 2021 Share Posted March 28, 2021 11 minutes ago, Planemo said: Really confused about the comm wire as you can probably tell, although I am sure gotway wouldn't have used one without a reason (due to more time and effort). Anyone got any further info since this thread was last updated? Wrong Topic The answer lies in https://forum.electricunicycle.org/topic/18374-how-bms-works-gotway-pack-teardown/ " According to my diagram below, only one pack is connected to the charger, and therefore Charge Stop is performed at this 'master' pack only. The two 'slave' packs can trigger Charge Stop using the trigger link connection. If any pack drives a positive voltage across these "HV" and "LV" Trigger Link terminals, all packs will disconnect their Charger input. The trigger link wires are redundant- two "HV" and two "LV" leads are used between each pack, but they are electrically the same circuit. This provides fault-tolerance to open-circuit conditions in the wiring. If the trigger link was broken or not connected, Charge Stop would not be possible, and therefore overvoltage and undervoltage protection will be defeated." 2 Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 28, 2021 Share Posted March 28, 2021 1 hour ago, Chriull said: According to my diagram below, only one pack is connected to the charger, Cheers, I remember that other topic now But in relation to your quote above, both the packs on my MSX are definitely connected to the charge port. So there is no 'master' pack. The charge port has 4 wires, and they split off to the packs on each side. Each pack has it's own XT30 charge plug. So again, I am struggling to see the need for the 4 wire plug... Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 28, 2021 Share Posted March 28, 2021 8 minutes ago, Planemo said: Cheers, I remember that other topic now But in relation to your quote above, both the packs on my MSX are definitely connected to the charge port. So there is no 'master' pack. The charge port has 4 wires, and they split off to the packs on each side. Each pack has it's own XT30 charge plug. So again, I am struggling to see the need for the 4 wire plug... Seems that's the "other system" as also ks uses: all the inputs are connected and all the outputs. Still the syncronisation is needed - if one bms notices a cell overvoltage and wants to cut off charging it has to notify all others to cut off too. Otherwise this pack would still be charged through the outputs of the other packs. So reasoning is till exactly the same. 1 Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 28, 2021 Share Posted March 28, 2021 1 hour ago, Chriull said: Still the syncronisation is needed - if one bms notices a cell overvoltage and wants to cut off charging it has to notify all others to cut off too. Otherwise this pack would still be charged through the outputs of the other packs. Hmm... OK I am getting there slowly...but as a side note, if the packs can charge each other from their outputs, it would stand to reason that both packs should always show identical voltage then? Or is the sync wire only 'active' during charging? IE when an input is seen on the charge wires? Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 28, 2021 Share Posted March 28, 2021 19 minutes ago, Planemo said: Hmm... OK I am getting there slowly...but as a side note, if the packs can charge each other from their outputs, it would stand to reason that both packs should always show identical voltage then? Yes. And as gw bms have no output protection the cells are "hard wired" together and have no chance to diverge. Other wheels with overcurrent/short curcuit protection this outputs could be cut off, too. 19 minutes ago, Planemo said: Or is the sync wire only 'active' during charging? IE when an input is seen on the charge wires? The sync wire can ve active everytime - as long as a cell group has overvoltage _all_ the inputs will be cut off. 1 Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 28, 2021 Share Posted March 28, 2021 13 minutes ago, Chriull said: The sync wire can ve active everytime - as long as a cell group has overvoltage _all_ the inputs will be cut off. OK I think I've got it... the reason we need the comm wire is primarily because the packs can charge each other via their outputs. So during charging, without the comm wire, if one pack goes over voltage, the other will also do the same, irrespective of what the BMS is trying to do/help. And cutting the charge input via BMS on just the over voltage pack won't help, as the linked pack (which may not be over, and still charging) can still send current into the over-voltaged pack via the outputs. Am I getting warm yet? 1 Quote Link to comment Share on other sites More sharing options...
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