WetEV
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Re: New device boosts road time for Leaf by 50%

Sun Nov 26, 2017 2:38 pm

EVDRIVER wrote:Patented, that's the best part :lol:


I know that this idea is old, so I went looking. Probably older than this:

http://www.mdpi.com/1996-1073/8/3/1830/pdf

Oh, and this is off-the-shelf type technology.

http://www.linear.com/solutions/7369
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
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WetEV
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Re: New device boosts road time for Leaf by 50%

Sun Nov 26, 2017 2:46 pm

Nubo wrote:DIY builders have been achieving essentially the same result for years in terms of the cells running out at the same time. It’s called “bottom-balancing”. Doesn’t require a truckload of relays. In fact no BMS at all.


No, this is not bottom balancing.

When top balanced, all cells are fully charged when the pack is charged, and get more out of balance as the battery is discharged.

When bottom balanced, all cells are fully discharged when the pack is discharged, and get more out of balance as the battery is charged.

In both top and bottom balanced, the current is the same in all cells. So the weakest cell will go from maximum to minimum voltage, and all other cells will have a lower voltage swing.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
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2k1Toaster
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Re: New device boosts road time for Leaf by 50%

Sun Nov 26, 2017 2:52 pm

WetEV wrote:
EVDRIVER wrote:Patented, that's the best part :lol:


I know that this idea is old, so I went looking. Probably older than this:

http://www.mdpi.com/1996-1073/8/3/1830/pdf

Oh, and this is off-the-shelf type technology.

http://www.linear.com/solutions/7369


Yep, I think they will be getting some calls from lawyers in the next few weeks.
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EVDRIVER
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Re: New device boosts road time for Leaf by 50%

Sun Nov 26, 2017 3:48 pm

Prior Art...

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Nubo
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Re: New device boosts road time for Leaf by 50%

Sun Nov 26, 2017 8:13 pm

WetEV wrote:
Nubo wrote:DIY builders have been achieving essentially the same result for years in terms of the cells running out at the same time. It’s called “bottom-balancing”. Doesn’t require a truckload of relays. In fact no BMS at all.


No, this is not bottom balancing.

When top balanced, all cells are fully charged when the pack is charged, and get more out of balance as the battery is discharged.

When bottom balanced, all cells are fully discharged when the pack is discharged, and get more out of balance as the battery is charged.

In both top and bottom balanced, the current is the same in all cells. So the weakest cell will go from maximum to minimum voltage, and all other cells will have a lower voltage swing.


True, bottom-balancing is typically used in conjunction with under-charging to mitigate top end differences. . But in practice only a minor amount of energy is “left on the table”. It’s probably a better solution for stable chemistries like LiFePo though.
I noticed you're still working with polymers.

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jlv
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Re: New device boosts road time for Leaf by 50%

Mon Nov 27, 2017 8:48 am

So, to sum up this thread:

There is no "new device that boosts road time for Leaf by 50%".
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IssacZachary
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Re: New device boosts road time for Leaf by 50%

Mon Nov 27, 2017 10:08 am

From what I get of this, it's supposed to work like this.

In a new battery, it does nothing...

In an old battery, let's say you have cell one 60Ah, cell two 40AH, cell three 60AH, etc... In a normal battery management system the Leaf treats all cells as the lowest degraded cell. So if the lowest cell is 40AH the Leaf treats all cells like 40AH cells (cell one 40AH, cell two 40Ah, cell 3 40AH, etc.) and cuts off at 40AH.

But if you averaged out all the cells, then you'd have cell one 53AH, cell two 53AH, cell three 53AH, etc... And this device somehow throws AH's from better cells to the more degraded cells. Now that's 33% more than what the Leaf would have given without the device.

The alternative is to take your battery apart and replace the lower AH modules. But then again, if you have 60AH, 40AH, 50AH, then you might have a lot of replacing to do since that lowest cell will always be the weak link.

Please correct me if I got this all wrong.
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Levenkay
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Re: New device boosts road time for Leaf by 50%

Mon Nov 27, 2017 1:26 pm

Sounds like the EV version of the 200mpg magneto-vortex carburetor.

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IssacZachary
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Re: New device boosts road time for Leaf by 50%

Mon Nov 27, 2017 2:20 pm

Levenkay wrote:Sounds like the EV version of the 200mpg magneto-vortex carburetor.

Not to me.

Let's say all your cells are at 60AH, except one, which is at 30AH. When that cell is depleted all the other cells will still have half their AH's. But at that point you won't able to go any farther. The whole pack will be "empty" but only because one single cell is depleted. The other 95 cells still have another 30AH's to go. It would be technically possible to use a small amount of charge from each of the good cells in order to charge the bad cell up and keep going. It's not unicorn breeding, it's science.
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LeftieBiker
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Re: New device boosts road time for Leaf by 50%

Mon Nov 27, 2017 4:16 pm

The scenario you describe would be a manufacturing defect, because the cells generally degrade more or less uniformly. Any pack with cells at half the capacity of the rest should be eligible for warranty replacement.
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