Battery Upgrades are very possible

[DaveinOlyWA]

What gets me is your 332 volts to turtle? That is far far far above any previous LEAF pack of any size?

Remember the LBC math error that was forcing the BMS to report false degradation which led it to restrict full usage of the pack? Sounds like you got the same thing going on there.

The BMS upgrade has already been done on the 30kWh pack before the modification. Unfortunately the original 40kWh BMS does not work with the systems of the 30kWh LEAF.

For me, it seems, that the turtle mode is not only depending on the voltage of the pack, but some other factors, as the internal resistance or different calculations.

Yesterday, I measured the charging power, and I have consumed 24.5kWh, to charge from 22% to 100% (according to the 30kWh BMS / displayed percentage) by means of 32A wall box / 6.6kW onboard charger.

Its the LBC that dictates to the BMS the state of the pack. Remember the BMS restricted access to "good" parts of the pack based on reports from LBC. So you need an LBC that can see the entire pack capacity.

[bkvszomorito]

Its the LBC that dictates to the BMS the state of the pack. Remember the BMS restricted access to "good" parts of the pack based on reports from LBC. So you need an LBC that can see the entire pack capacity.

BMS=LBC in case of LEAF. Unfortunately there is no software for the 30kWh LBC, that has access to all 40kWh, and the LBC from the 40kWh pack is different (there are 2 control modules integrated), so it is incompatible with the rest of the 30kWh vehicle.

Until someone is able to modify the 30kWh LBC software, there seems to be no solution for this issue.

[bkvszomorito]

What happens when you fully charge it? Does it try to equalize the cells longer, or for the usual amount of time, at a lower voltage than they can safely accept? I'm not sure why the BMS isn't just trying for the usual top voltage, and more fully charging the 40kwh modules than it is...

The maximum cell voltage difference is 13mV. I checked, and the max voltage for 30kWh modules is around 395V. I guess the charging stops, as this voltage is reached. The best would be to know, what SOC is at 395V in case of the original 40kWh battery with it’s own LBC. Maybe the missing capacity is hiding there.

I also do not understand the low SOH and even lower Hx values...

[bkvszomorito]

If this discharge curve is real for the 40kWh battery modules, my values are understandable.



My top battery voltage is 395V - cell voltage in this case is 4.11V
My minimum battery voltage is 332V - cell voltage in this case is 3.45V

Based on the diagram, I use 40Ah from the 56,3Ah.

Nominal cell voltage is 3.65V

Now we can calculate the battery real capacity:
192 x 3,65 V x 40 Ah = 28,03 kWh

If I'm correct, the only reason not to have the full capacity available is the BMS...

Until somebody makes the BMS software available, do you think it is safe to use the car like this? Will it harm the 40kWh modules or not?

[Lothsahn]

Until somebody makes the BMS software available, do you think it is safe to use the car like this? Will it harm the 40kWh modules or not?

Your chart is correct.[1] This shows why the 24 kWh LBC shows the 40 kwH battery as VLBW for half the charge.

It won't be catastrophic, but the 24 kWh LBC may charge the 40 kWh cells slightly higher than the 40 kWh LBC, resulting in reduced battery life. This is because the cutoff voltage for the 24 kWh is 4V-4.1V per cell [2] [3].

The other problem is turtle mode: I don't know what voltage turtle mode kicks in, but if you drove to turtle frequently (since you have no charge indicator), that won't be good for the battery. What would be safe is charging to 80% and never driving the car below 3.4V on the lowest cell using a 24 kWh BMS, but your range may not be not good.

Does anyone have the chart for 30 kWh cells?

[1] https://pushevs.com/2018/01/29/2018-nis ... eal-specs/
[2] https://qnovo.com/inside-the-battery-of-a-nissan-leaf/
[3] http://www.mynissanleaf.com/viewtopic.php?t=14143

[Dala]

Is it the BMS or the VCM that decides that it's turtle time?

If it is the VCM, it is possible to simply spoof some of the CAN messages, to get the cluster to read out a better GOM, and also avoid the premature turtling. A CAN-in-the-middle attack on the canbus is easy to perform.

If the BMS calls the shots, it's game over instantly :/

[bkvszomorito]

Until somebody makes the BMS software available, do you think it is safe to use the car like this? Will it harm the 40kWh modules or not?

Your chart is correct.[1] This shows why the 24 kWh LBC shows the 40 kwH battery as VLBW for half the charge.

It won't be catastrophic, but the 24 kWh LBC may charge the 40 kWh cells slightly higher than the 40 kWh LBC, resulting in reduced battery life. This is because the cutoff voltage for the 24 kWh is 4V-4.1V per cell [2] [3].

The other problem is turtle mode: I don't know what voltage turtle mode kicks in, but if you drove to turtle frequently (since you have no charge indicator), that won't be good for the battery. What would be safe is charging to 80% and never driving the car below 3.4V on the lowest cell using a 24 kWh BMS, but your range may not be not good.

Does anyone have the chart for 30 kWh cells?

[1] https://pushevs.com/2018/01/29/2018-nis ... eal-specs/
[2] https://qnovo.com/inside-the-battery-of-a-nissan-leaf/
[3] http://www.mynissanleaf.com/viewtopic.php?t=14143

Unfortunately I do not have the 30kWh cell chart, but I have some data, that may help. The warnings, the turtle and the range are quit accurate with the 40kWh modules, so it should be similar.

I had the LBW after 191.6km, voltage was 335V:


I had WLBW after 206.8km, voltage was 332V:


Another info: For 40kWh LEAF, around 100% SOC, the battery voltage is above 403V:

[Lothsahn]

Another info: For 40kWh LEAF, around 100% SOC, the battery voltage is above 403V.

What matters is voltage per cell.

This image you attached... is this a 40 kWh car with a 40 kWh BMS? If so, this says that the resting full charge is around 4.2V per cell.

The turtle at 332V: Was that with a 40 kWh BMS or a 24 kWh BMS? What was the minimum cell voltage right when that triggered?

[bkvszomorito]

On the LEAFSPY image the 40kWh car is present with 40kWh BMS.

When turtle appeared on my car, with 30kWh BMS + 40kWh modules the cell voltage was 3.45V.

One strange thing: minimum cell voltage in case of 30kWh battery with 30kWh BMS around 0%SOC is 3.0V. Based on this, the turtle is not triggered only based on the cell voltage, as with 40kWh modules, it appeared around 3.45V (with 30kWh BMS).

[Lothsahn]

On the LEAFSPY image the 40kWh car is present with 40kWh BMS.

When turtle appeared on my car, with 30kWh BMS + 40kWh modules the cell voltage was 3.45V.

One strange thing: minimum cell voltage in case of 30kWh battery with 30kWh BMS around 0%SOC is 3.0V. Based on this, the turtle is not triggered only based on the cell voltage, as with 40kWh modules, it appeared around 3.45V (with 30kWh BMS).

Interesting. The BMS may also be measuring the total power draw or possibly the internal resistance of the module. 3.45V indicates that roughly 12Wh (22%) of the capacity is not being used. Have you tried charging the car for only a short time (1 hour) and seeing if driving it again would trigger turtle at a lower voltage?

What this means is that the 30 kWh BMS will likely not over-discharge the 40 kWh cells, so you are safe there. However, you're not getting the full possible range.

When you charge the 40 kWh modules with the 30 kWh BMS to 100%, what does Leafspy show when the charge to 100% is done? What is the min/avg/max voltage of the cells?