BMS function in Gotway MCM3 and MSuper V3

[Will]

I've been reading a lot here but I have missed out on what the exact purposes are for the BMS circuit.  I understand each battery pack in a parallel system uses one.  I am curious, does the BMS balance charge all the cells in a pack or just pairs or only the whole pack with the other packs?  Also, I'm gathering it has a function in discharge as well?

Also, I have read constantly about the "cutoff" on the Gotway models.  I'm understanding that in fact, in terms of circuit design, there is no intended turning off of the circuit and motor drive of a Gotway under any circumstance.  I understand that cutoffs occur with the Gotways either from an electrical failure (rare) or from battery depletion such that the circuit shuts down.  I'm also understanding other manufacturers have used other methods, perhaps voltage monitoring or current limiting to try to make these wheels idiot-proof.  It seems to me that Gotway has forfeited the effort to use such circuitry with the logic that the best performing wheel relies on the user listening to the tones which are voltage-driven warnings as I understand it.  This makes sense to me if it's correct and clearly results in some of the higher performing wheels.  

Lastly, there is much reference to "over-leaning" causing a crash or cutoff.  Apparently this means that the rider has pushed down on the front of the pedal so hard that the gyro is disturbed or overpowered?

I have just ordered this week my first wheels for my son and I.  Super3 from Tech Toyz and MCM3 from myfunwheel.  I'm passing the time by reading up on the forum but the above issues have managed to confound me a little. 

I know I'm asking a lot here, but I've waited till now to ask so as to ask once not many times (laugh).

Thanks for any explanations or links to information.

Will, Lincoln Nebraska, USA

 

[smallexis]

13 minutes ago, Will said:

does the BMS balance charge all the cells in a pack or just pairs or only the whole pack with the other packs?

yes BMS function is to balance charge for all the cells in a pack. Each battery pack get is own BMS.

15 minutes ago, Will said:

Also, I'm gathering it has a function in discharge as well?

Now, most of BMS don't have any function in discharge (because over discharge protection was frenquently the reason for cutoff and fall down)

According to my knowledge, every wheels have over discharge protection with mother board.

22 minutes ago, Will said:

read constantly about the "cutoff" on the Gotway models

first reason (in the past) was BMS discharge protection

second reason is no respect of bip alarm system and max motor power is exceeded

third reason is motherboard failure (or other technical problem)

Don't forget to wear protections, it's the best solution to avoid injuries.

[Will]

Really appreciate your time.  This helps my curiosity a lot.

[esaj]

5 hours ago, Will said:

I've been reading a lot here but I have missed out on what the exact purposes are for the BMS circuit.  I understand each battery pack in a parallel system uses one.  I am curious, does the BMS balance charge all the cells in a pack or just pairs or only the whole pack with the other packs?  Also, I'm gathering it has a function in discharge as well?

The BMS (Battery Management System) is a circuit board, usually placed inside the battery pack(s), but in some cases (at least older IPS-wheels), on the wheel mainboard. The purpose of the circuitry is typically to monitor/control the battery pack, taking care that charging does not push the cell voltages too high (overvoltage monitoring), balancing the cells (bypassing battery cells that have already reached the maximum voltage during charging), possibly reverse voltage protection on charging side (so the charge connector doesn't have voltage when there's no powered charger connected) and, depending on the model, the discharge overcurrent/undervoltage protection. Some BMSs also have temperature monitoring for the pack, cutting power if the pack temperature goes too high. In general, the circuitry's there to protect the battery pack from blowing up , but with certain circumstances/models/etc. it can also cause not-so-nide-things, like the wheel cutting out mid-ride. The more modern models seem at least relatively safe in the sense that the BMSs no longer seem to have the cutout-problem in "normal" circumstances.

 

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Also, I have read constantly about the "cutoff" on the Gotway models.  I'm understanding that in fact, in terms of circuit design, there is no intended turning off of the circuit and motor drive of a Gotway under any circumstance.  I understand that cutoffs occur with the Gotways either from an electrical failure (rare) or from battery depletion such that the circuit shuts down.  I'm also understanding other manufacturers have used other methods, perhaps voltage monitoring or current limiting to try to make these wheels idiot-proof.  It seems to me that Gotway has forfeited the effort to use such circuitry with the logic that the best performing wheel relies on the user listening to the tones which are voltage-driven warnings as I understand it.  This makes sense to me if it's correct and clearly results in some of the higher performing wheels.  

Earlier, the Gotway (and most other wheels) would shutdown after reaching high enough speed or if the voltage dropped low enough (happens easily with almost empty battery).  I haven't been following that closely on the issues, but it seems the newer models rarely (if ever) cutout due to too high current draw/undervoltage or speed (but don't take my word for it). While this has it's good sides, the downside is that an overloaded wheel tends to blow the mainboard instead of cutting out   Although that seems relatively rare, outside of specific circumstances, like long climbs where the current draw is high and heats up the mainboard mosfets (a specific type of transistor used in driving the motor).

 

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Lastly, there is much reference to "over-leaning" causing a crash or cutoff.  Apparently this means that the rider has pushed down on the front of the pedal so hard that the gyro is disturbed or overpowered?

Over-leaning means that the rider tries to push the wheel going even faster when you're already at the "edge" of the maximum power (torque) the wheel can produce. This is still (and probably will always be) an issue, as there are limits to the motor torque. Current high-end wheels sport very powerful motors and max speeds, so it's not as much of an issue as it was, say, 1.5 years ago. Still, technically, there's always a limit to what the motor can produce, but with current max speeds for the high end wheels being something like 35 up to 60km/h (something like 22-37mph), it's not that much of an issue, unless you deliberately push the limits (for me, 30km/h is enough, above that my self-preservation instinct starts to kick in ). Still, if you just "throw" yourself forwards, even the most powerful engines cannot provide enough torque to pick you up, so beware. But you'll probablyu learn fast not to just "fall" forward, but instead use you center of gravity to control the wheel.

 

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I have just ordered this week my first wheels for my son and I.  Super3 from Tech Toyz and MCM3 from myfunwheel.  I'm passing the time by reading up on the forum but the above issues have managed to confound me a little. 

Watch out with the high power wheels, while it's good to have extra power to protect from the accidental over lean during practice, the high top speeds can cause serious injuries should you fall. Start slow, practice your balance, turning and braking, and you'll be "road worthy" in no time. Of course, it depends a lot, some people learn to control their wheels sufficiently in hours, for others it takes days or weeks... don't rush it, it'll come, sooner or later. There are (pretty much. taken to extremes) two schools of though: others (like me) tend to go overboard with the protection (motorcycle helmet, snowboarding wrist-guards, motocross elbow/knee protectors) and those who prefer to wear minimum safety gear or not at all. I suggest that at least initially you use some protection, I'd say that some types of wrist guards and helmet at minimum, something to protect your calves for bruising at least during practice, but of course it's up to you (and possibly local law). For kids, I'd suggest full protection.

 

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I know I'm asking a lot here, but I've waited till now to ask so as to ask once not many times (laugh).

Thanks for any explanations or links to information.

Will, Lincoln Nebraska, USA

No problem, I'm too drunk to link stuff right now , but just looking around the forum, you'll find more information that you bargained for   There's a search on the top right corner, although it can be a bit unclear at times (like only searching the current topic, if you click it from an open topic, and then requiring to adjust the search parameters), but anyway...