Masters 32s4p configuration

[No1up]

So you battery fellas out there. Will it cut out if one cell or pack goes bad or no? I keep seeing two different views on this.. 

[Tawpie]

1 hour ago, No1up said:

Will it cut out if one cell or pack goes bad or no?

It sort of depends on how it goes "bad" and how GW is wiring them together.

GW is wiring 4 cells in parallel, then stacking 8 sets in series. A single cell failing open circuit shouldn't cause an immediate cutout because it has three buddies side-by-side that are still working. But the system is now weaker than it was and easier to cause stress damage.

The 'issue' is if for some reason an entire pack gets disconnected either because a pack BMS decided it was hazardous to continue or there was a wiring failure—this will cause a cutout because it effectively unplugs all the batteries at the same time.

GW is now on v3 of their main board—there was a lot of outcry about the initial design so I'm hoping they are incorporating some feature set so that losing an entire pack doesn't mean a total loss of power. A really fast cross point switch could rearrange the series stackup, but even if you could restore current flow you'd have lost 34V and would likely be below the low voltage threshold. Dealing with a failure in a series connected system is not a cakewalk (or piewalk for those so inclined).

An analogy that may help is water.

Let's say you take 4 short hoses and connect them end to end. Put water in at one end and it comes out the other, all is good. But disconnect any one of the hoses, and you get no water out the end. This is the original Master configuration.

But if you connected all 4 hoses to the faucet/spigot with a 4-gang connector, you still get water from 3 after disconnecting 1 of the hoses. Not as good as all 4, but still some.

Water flow is analogous to current flow (and water pressure is analogous to voltage). You must have both to get water out the end, and without water out the end there's no power.

Edited July 5, 2022 by Tawpie

[No1up]

2 minutes ago, Tawpie said:

It sort of depends on how it goes "bad" and how GW is wiring them together.

GW is wiring 4 cells in parallel, then stacking 8 sets in series. A single cell failing open circuit shouldn't cause an immediate cutout because it has three buddies side-by-side that are still working. But the system is now weaker than it was and easier to cause stress damage.

The 'issue' is if for some reason an entire pack gets disconnected either because a pack BMS decided it was hazardous to continue or there was a wiring failure—this will cause a cutout because it effectively unplugs all the batteries at the same time.

GW is now on v3 of their main board—there was a lot of outcry about the initial design so I'm hoping they are incorporating some feature set so that losing an entire pack doesn't mean a total loss of power. A really fast cross point switch could rearrange the series stackup, but even if you could restore current flow you'd have lost 34V and would likely be below the low voltage threshold. Dealing with a failure in a series connected system is not a cakewalk (or piewalk for those so inclined).

How does the OH sherman 10p configuration work? 

[Tawpie]

6 minutes ago, No1up said:

How does the OH sherman 10p configuration work? 

It's 10 hoses on a 10 gang connector! But actually, I read somewhere that the packs are arranged in 50.4V groups. That could be false, but I did read it on the internet so...

[No1up]

20 minutes ago, Tawpie said:

It's 10 hoses on a 10 gang connector! But actually, I read somewhere that the packs are arranged in 50.4V groups. That could be false, but I did read it on the internet so...

So… that’s a good thing? Or no…

[alcatraz]

Wasn't the Master supposed to change to a Sherman configuration? Are those wheels out yet?

From 4x 8S4P in series (one pack)

to

4x 16S2P connected both in series and parallel (two packs)

 

Much like the Sherman

4x 12S5P (two packs)

[Tawpie]

4 hours ago, No1up said:

So… that’s a good thing? Or no…

It's a very good thing. With more hoses in parallel, each individual hose has to supply less water to deliver the sum total being requested by the motor. If the motor is asking for 100 units of water, each hose is only going to have to deliver 10 of those. And if we imagine that a unit of water = a unit of current, that means less of a current demand on each of the parallel strings. Which in turn lowers your chance of a cutout because you're operating well inside of the acceptable operating range of each pack, not asking them for more current than they are 'comfortable' delivering.

[No1up]

12 hours ago, Tawpie said:

It sort of depends on how it goes "bad" and how GW is wiring them together.

GW is wiring 4 cells in parallel, then stacking 8 sets in series. A single cell failing open circuit shouldn't cause an immediate cutout because it has three buddies side-by-side that are still working. But the system is now weaker than it was and easier to cause stress damage.

The 'issue' is if for some reason an entire pack gets disconnected either because a pack BMS decided it was hazardous to continue or there was a wiring failure—this will cause a cutout because it effectively unplugs all the batteries at the same time.

GW is now on v3 of their main board—there was a lot of outcry about the initial design so I'm hoping they are incorporating some feature set so that losing an entire pack doesn't mean a total loss of power. A really fast cross point switch could rearrange the series stackup, but even if you could restore current flow you'd have lost 34V and would likely be below the low voltage threshold. Dealing with a failure in a series connected system is not a cakewalk (or piewalk for those so inclined).

An analogy that may help is water.

Let's say you take 4 short hoses and connect them end to end. Put water in at one end and it comes out the other, all is good. But disconnect any one of the hoses, and you get no water out the end. This is the original Master configuration.

But if you connected all 4 hoses to the faucet/spigot with a 4-gang connector, you still get water from 3 after disconnecting 1 of the hoses. Not as good as all 4, but still some.

Water flow is analogous to current flow (and water pressure is analogous to voltage). You must have both to get water out the end, and without water out the end there's no power.

So if one hose fails, will you at least have enough water to stop or slow down or will the house of cars come tumbling down the Christmas chimney? 😂 I tried to fit as many analogies in there for fun. 

[Tawpie]

4 hours ago, No1up said:

So if one hose fails, will you at least have enough water to stop or slow down or will the house of cars come tumbling down the Christmas chimney? 😂 I tried to fit as many analogies in there for fun. 

Correct! Shermans at speed have a stellar track record. You can overtorque them at low speed, but when you're flying along their battery setup is as good as you can buy.