Extra Battery, How to Integrate with 24kWh Traction Battery?

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mux said:
You run into multiple issues.

If parallelling each cell individually, the BMS will likely have too little balancing current available in the long term. The BMS in the Leaf uses table look-up for determining SOH, internal resistance, allowable charge and discharge rate, etc., which is chemistry-specific and really even cell-specific. Parallelling cells together with potentially different chemistries will make this useless and will possibly cause the battery to determine the wrong SOH, SOC and allowable current at different times.

Parallelling the entire pack together means one pack will not have cell-level balancing and monitoring. This will cause fire and death. You can't have a BMS-less pack.

If the Leaf's BMS were designed a little bit better, the first approach could actually work fine, but it's got the 285 GID maximum as well as monotonic degradation memory (meaning a battery can never get 'better', only 'worse' according to the BMS), which makes it hard to properly gauge capacity and SOC witht he existing BMS. This can't really be solved with a CAN MITM workaround.

Thank you, I am using an extra battery, and my SOH is constantly growing. It used to be 86, and now it is 91.7, but now we have a cold temperature, about - 15 degrees, and the recounting has stopped. The main problem is how to increase the GID in BMS? In a week, I will try to update the firmware of the VCM and LBC module using the 30 kW firmware, however this may not be enough to use a 50 kW / h battery.
 
Irling said:
if the second battery does not have bms, and one bms is used for two batteries, this will not work correctly?
what happens when bms 24kwh aseo counts 285 Gids?

What's this concern with GIDS all about? You've defined the battery capacity in kWh, so why mention GIDS? GIDS is just a another
term/measure of battery capacity exclusively defined for the Leaf. No other BEV uses that term, e.g. Tesla. Besides, another
common measure of battery capacity is Ahr which is more insightful than kWh, as it basically focuses on the key battery parameter
which changes whether it's via use or degradation over time.
 
lorenfb said:
Irling said:
if the second battery does not have bms, and one bms is used for two batteries, this will not work correctly?
what happens when bms 24kwh aseo counts 285 Gids?

What's this concern with GIDS all about? You've defined the battery capacity in kWh, so why mention GIDS? GIDS is just a another
term/measure of battery capacity exclusively defined for the Leaf. No other BEV uses that term, e.g. Tesla. Besides, another
common measure of battery capacity is Ahr which is more insightful than kWh, as it basically focuses on the key battery parameter
which changes whether it's via use or degradation over time.

If I'm not mistaken, It is this parameter that is used to calculate the amount of energy in LBC and VCM. As soon as the maximum limit for the GIDs ends, a turtle appears. Therefore, to solve the problem of turtles, an update to the AZEO24 firmware on the AZEO30 is required
 
Irling said:
mux said:
You run into multiple issues.

If parallelling each cell individually, the BMS will likely have too little balancing current available in the long term. The BMS in the Leaf uses table look-up for determining SOH, internal resistance, allowable charge and discharge rate, etc., which is chemistry-specific and really even cell-specific. Parallelling cells together with potentially different chemistries will make this useless and will possibly cause the battery to determine the wrong SOH, SOC and allowable current at different times.

Parallelling the entire pack together means one pack will not have cell-level balancing and monitoring. This will cause fire and death. You can't have a BMS-less pack.

If the Leaf's BMS were designed a little bit better, the first approach could actually work fine, but it's got the 285 GID maximum as well as monotonic degradation memory (meaning a battery can never get 'better', only 'worse' according to the BMS), which makes it hard to properly gauge capacity and SOC witht he existing BMS. This can't really be solved with a CAN MITM workaround.

Thank you, I am using an extra battery, and my SOH is constantly growing. It used to be 86, and now it is 91.7, but now we have a cold temperature, about - 15 degrees, and the recounting has stopped. The main problem is how to increase the GID in BMS? In a week, I will try to update the firmware of the VCM and LBC module using the 30 kW firmware, however this may not be enough to use a 50 kW / h battery.

The BMS can be reset (I don't have a tool for that, but there are multiple sources you can get this from). This will get you to a maximum of about 104% SOH / 300 GIDs.

You cannot use the other BMS software, as the 30, 40 and 50 use a different chemistry and have a slightly different BMS chip.
 
mux said:
The BMS can be reset (I don't have a tool for that, but there are multiple sources you can get this from). This will get you to a maximum of about 104% SOH / 300 GIDs.

You cannot use the other BMS software, as the 30, 40 and 50 use a different chemistry and have a slightly different BMS chip.

There is no need to reset, SOH grows independently if the second battery is connected correctly (it is necessary to transfer the current sensor to another location) I will update the firmware of my azeo in about a week, take a screenshot :)
 
Irling said:
lorenfb said:
Irling said:
if the second battery does not have bms, and one bms is used for two batteries, this will not work correctly?
what happens when bms 24kwh aseo counts 285 Gids?

What's this concern with GIDS all about? You've defined the battery capacity in kWh, so why mention GIDS? GIDS is just a another
term/measure of battery capacity exclusively defined for the Leaf. No other BEV uses that term, e.g. Tesla. Besides, another
common measure of battery capacity is Ahr which is more insightful than kWh, as it basically focuses on the key battery parameter
which changes whether it's via use or degradation over time.

If I'm not mistaken, It is this parameter that is used to calculate the amount of energy in LBC and VCM. As soon as the maximum limit for the GIDs ends, a turtle appears. Therefore, to solve the problem of turtles, an update to the AZEO24 firmware on the AZEO30 is required

The GIDS calculation, e.g. using LeafSpy, is most likely done by using the present kWh/Ahr, compared to those values at 100% SOC.
The result affects when the VLB is displayed.
 
mux said:
My solution only works for batteries that have a separate BMS and are switched in parallel to the main battery on the HV bus. It is HIGHLY discouraged for a multitude of reasons to either replace the main cells with a different chemistry or to parallel them inside the main battery. Different battery = different BMS.

My boards are ordered in bulk, they should arrive *somewhere* this month, after which I'll be happy to sell them to anyone.

Thanks for the answer. I want one. If I understand correctly, I just need:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)
2) Connection to the power cables out of the battery to parallel the new pack (with a nice reseteable fuse in the middle for safety)
3) Relays to connect/disconnect the extender so there is no damage to the resistor in case you turn off the car and the extender is still connected. (By the way, is it possible that you could sell us the wiring diagram for those relays?)
4) CAN in the middle attack board

Am I missing something?

Once again, thanks Mux, looking forward for you to share with us your knowledge.
 
map40home said:
Thanks for the answer. I want one. If I understand correctly, I just need:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)
2) Connection to the power cables out of the battery to parallel the new pack (with a nice reseteable fuse in the middle for safety)
3) Relays to connect/disconnect the extender so there is no damage to the resistor in case you turn off the car and the extender is still connected. (By the way, is it possible that you could sell us the wiring diagram for those relays?)
4) CAN in the middle attack board

Am I missing something?

Once again, thanks Mux, looking forward for you to share with us your knowledge.

I really don't advise using LiFePO4 with an extender unless you expect your extender battery to be able to handle the full charging and discharging current (120A charging, 280A discharging). LiFePO4 is such a vastly different chemistry than LMO that I foresee a lot of problems trying to parallel the 2, not even getting into the different charging profile and termination characteristic.

What kind of resettable fuse have you found that can interrupt 400VDC at 300A? I would be interested in such a part.

I can provide the wiring diagram for the contactors, it will basically be identical to the ones already in the car main battery, sharing the same control lines also. If you're new to EVs, you need to use things called contactors which are specially designed to stop DC arcs and have a much higher rating than a typical AC relay, which can get away with less since there's a zero crossing in the waveform.
 
map40home said:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)


You need to use 114 elements. However, if you plan to install an additional battery in AZEO, then you will encounter the same problem as me. First, the COX will increase to 103% (if the second battery is connected correctly, transfer the current sensor), you will receive 285 energy GID for work. As soon as your battery is discharged to approximately 5 GIDs, you will get a turtle despite the fact that the voltage of your battery is still high and half of the energy reserve is left. This is the main problem that needs to be addressed ..
I thought the Mux solution circumvents this limitation. I suppose that for the Mux device to work correctly, the second battery must be connected after the current sensor, it needs to be checked.
 
jkenny23 said:
map40home said:
Thanks for the answer. I want one. If I understand correctly, I just need:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)
2) Connection to the power cables out of the battery to parallel the new pack (with a nice reseteable fuse in the middle for safety)
3) Relays to connect/disconnect the extender so there is no damage to the resistor in case you turn off the car and the extender is still connected. (By the way, is it possible that you could sell us the wiring diagram for those relays?)
4) CAN in the middle attack board

Am I missing something?

Once again, thanks Mux, looking forward for you to share with us your knowledge.

I really don't advise using LiFePO4 with an extender unless you expect your extender battery to be able to handle the full charging and discharging current (120A charging, 280A discharging). LiFePO4 is such a vastly different chemistry than LMO that I foresee a lot of problems trying to parallel the 2, not even getting into the different charging profile and termination characteristic.

What kind of resettable fuse have you found that can interrupt 400VDC at 300A? I would be interested in such a part.

I can provide the wiring diagram for the contactors, it will basically be identical to the ones already in the car main battery, sharing the same control lines also. If you're new to EVs, you need to use things called contactors which are specially designed to stop DC arcs and have a much higher rating than a typical AC relay, which can get away with less since there's a zero crossing in the waveform.

Got it, thanks. What batteries do you recommend?
I could use the wiring diagram if you have it handy
I’ll see if I get you the part number for the resettable fuse. If I recall, it was 250 amps
 
Irling said:
map40home said:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)


You need to use 114 elements. However, if you plan to install an additional battery in AZEO, then you will encounter the same problem as me. First, the COX will increase to 103% (if the second battery is connected correctly, transfer the current sensor), you will receive 285 energy GID for work. As soon as your battery is discharged to approximately 5 GIDs, you will get a turtle despite the fact that the voltage of your battery is still high and half of the energy reserve is left. This is the main problem that needs to be addressed ..
I thought the Mux solution circumvents this limitation. I suppose that for the Mux device to work correctly, the second battery must be connected after the current sensor, it needs to be checked.
I was assuming that the Mux device would address the turtle mode. As far as the battery, what do you recommend?
 
map40home said:
Irling said:
map40home said:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)


You need to use 114 elements. However, if you plan to install an additional battery in AZEO, then you will encounter the same problem as me. First, the COX will increase to 103% (if the second battery is connected correctly, transfer the current sensor), you will receive 285 energy GID for work. As soon as your battery is discharged to approximately 5 GIDs, you will get a turtle despite the fact that the voltage of your battery is still high and half of the energy reserve is left. This is the main problem that needs to be addressed ..
I thought the Mux solution circumvents this limitation. I suppose that for the Mux device to work correctly, the second battery must be connected after the current sensor, it needs to be checked.
I was assuming that the Mux device would address the turtle mode. As far as the battery, what do you recommend?

Use LiNMC battery elements (3.65V., for example LG Chem 60ah Chevrolet bolt)
We are waiting for a response from Mux, what will happen to his device when the LBS spends all 285 GIDs
 
map40home said:
jkenny23 said:
map40home said:
Thanks for the answer. I want one. If I understand correctly, I just need:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)
2) Connection to the power cables out of the battery to parallel the new pack (with a nice reseteable fuse in the middle for safety)
3) Relays to connect/disconnect the extender so there is no damage to the resistor in case you turn off the car and the extender is still connected. (By the way, is it possible that you could sell us the wiring diagram for those relays?)
4) CAN in the middle attack board

Am I missing something?

Once again, thanks Mux, looking forward for you to share with us your knowledge.

I really don't advise using LiFePO4 with an extender unless you expect your extender battery to be able to handle the full charging and discharging current (120A charging, 280A discharging). LiFePO4 is such a vastly different chemistry than LMO that I foresee a lot of problems trying to parallel the 2, not even getting into the different charging profile and termination characteristic.

What kind of resettable fuse have you found that can interrupt 400VDC at 300A? I would be interested in such a part.

I can provide the wiring diagram for the contactors, it will basically be identical to the ones already in the car main battery, sharing the same control lines also. If you're new to EVs, you need to use things called contactors which are specially designed to stop DC arcs and have a much higher rating than a typical AC relay, which can get away with less since there's a zero crossing in the waveform.

Got it, thanks. What batteries do you recommend?
I could use the wiring diagram if you have it handy
I’ll see if I get you the part number for the resettable fuse. If I recall, it was 250 amps

I mentioned previously, but batteries from a plug-in hybrid make a good candidate for the high drain/high rate charging that the Leaf experiences. Examples are Hyundai Sonata PHEV (what I am using), Chevy Volt, Ford Energi PHEV, etc.
 
map40home said:
Irling said:
map40home said:
1) Batteries to produce 384V nominal (for me, 8 sets of 48V nominal LifoPo4 with their own BMS, in series)


You need to use 114 elements. However, if you plan to install an additional battery in AZEO, then you will encounter the same problem as me. First, the COX will increase to 103% (if the second battery is connected correctly, transfer the current sensor), you will receive 285 energy GID for work. As soon as your battery is discharged to approximately 5 GIDs, you will get a turtle despite the fact that the voltage of your battery is still high and half of the energy reserve is left. This is the main problem that needs to be addressed ..
I thought the Mux solution circumvents this limitation. I suppose that for the Mux device to work correctly, the second battery must be connected after the current sensor, it needs to be checked.
I was assuming that the Mux device would address the turtle mode. As far as the battery, what do you recommend?

We cannot currently address this type of turtle mode. It's technically possible with some work, but this is not something we've made so far. The big issue is that it's not a straight 'add main and extender battery capacity'-calculation. You have to actually interrogate the battery to make sure it's not overdischarging (or overcharging), essentially completely replacing the discharge and charge algorithms, something that may be quite dangerous if done improperly.
 
mux said:
We cannot currently address this type of turtle mode. It's technically possible with some work, but this is not something we've made so far. The big issue is that it's not a straight 'add main and extender battery capacity'-calculation. You have to actually interrogate the battery to make sure it's not overdischarging (or overcharging), essentially completely replacing the discharge and charge algorithms, something that may be quite dangerous if done improperly.

Do you planning to develop a technical solution to the turtle problem after the 285 gids in the azeo? Is it possible to develop alternative BMS firmware?
 
We're not making any solutions for the behind-the-current-sensor-extenders or direct cell swaps. But it's not too hard to code it yourself. We're still in the process of open sourcing the boards, so it's something you can likely do yourself pretty soon.
 
OK Mux, I just bought a used Leaf battery (I decided that the best chimestry to use would be the same that I already have). I just need one of your boards. We are ready to burn electricity!!!!!!
 
@map40home, I thought it was better to just share the information here in case anyone else wants it (it's all publicly available knowledge anyways, but I put it together for my own reference):

You want to use 3 contactors with your extender pack; 2 need to be full current capable, I recommend Tyco Gigavac EV200 which you can buy for a very reasonable price from EVWEST for the main contactor pair (negative and positive): https://www.evwest.com/catalog/product_info.php?products_id=387
And you can use the smaller LEV100 for the pre-charge contactor (positive only): https://www.evwest.com/catalog/product_info.php?products_id=388

The main LEAF VCM has 3 control lines that control the 3 contactors in the pack, labeled RLY N, RLY P, and PRE CHG:
Chg-seq.PNG


The pre-charge resistor is 30 ohm, 40W. I would suggest to use the same value and rating in the extender pack.
LeafBattery1.jpg


So you want to intercept the 3 control signals from the BCM (behind the glovebox), run those signals to the trunk area, then buffer, and use these buffered signals to control the contactors for your extender pack in exactly the same manner as the main pack, as Mux has mentioned in this video:
https://youtu.be/k3jaGtkyxvA?t=524

The only change I would make is to add an AND gate between the signals coming from the BCM to your contactors, to allow your own E-stop/limit signal to kill your pack connection in case things go bad (e.g. over temp, cell under/over voltage, etc.), from the BMS you are using in the extender pack.
 
jkenny23 said:
@map40home, I thought it was better to just share the information here in case anyone else wants it (it's all publicly available knowledge anyways, but I put it together for my own reference):

THANK YOU! It is greatly appreciated! I got a fully assembled Leaf 24KW battery comming, and I am planning to get this hooked up and running as soon as I get everything. Eventually I will get the Mux board and get the right GOM.
Once again, Thnaks!
 
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