DougWantsALeaf
Posts: 1051
Joined: Fri May 10, 2013 8:21 pm
Delivery Date: 18 May 2013
Leaf Number: 407811
Location: Chicago North Side

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

Wed Nov 13, 2019 11:55 am

Do the 40 and 62 packs have a maximum GID setting? If so, what are they?

Any reason to believe that the SOH or GIDS work differently in the larger packs?
2019 SV Plus Silver
2013 Leaf SV
100 Mile Club Member (Number 87)
Max distance on 13 Leaf: 120 miles
Max distance on 19 Leaf: 242 Highway 4.5 miles/kWh (4.9 KWh remaining)

Irling
Posts: 23
Joined: Tue Jul 16, 2019 10:38 pm
Delivery Date: 17 Jul 2019

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

Wed Nov 13, 2019 7:02 pm

mux wrote:
Wed Nov 13, 2019 10:19 am
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.

lorenfb
Posts: 2272
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

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

Wed Nov 13, 2019 8:23 pm

Irling wrote:
Wed Nov 13, 2019 8:10 am
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.
#1 Leaf SL MY 9/13: 74K miles, 48 Ahrs, 5.2 miles/kWh (average), Hx=70, SOH=78, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 4.5K miles, 115 Ahrs, 5.5 miles/kWh (average), Hx=98, SOH=99, DOD > 20%, temp < 105F

Irling
Posts: 23
Joined: Tue Jul 16, 2019 10:38 pm
Delivery Date: 17 Jul 2019

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

Wed Nov 13, 2019 10:29 pm

lorenfb wrote:
Wed Nov 13, 2019 8:23 pm
Irling wrote:
Wed Nov 13, 2019 8:10 am
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

mux
Posts: 233
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

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

Thu Nov 14, 2019 12:54 am

Irling wrote:
Wed Nov 13, 2019 7:02 pm
mux wrote:
Wed Nov 13, 2019 10:19 am
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.

Irling
Posts: 23
Joined: Tue Jul 16, 2019 10:38 pm
Delivery Date: 17 Jul 2019

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

Thu Nov 14, 2019 1:36 am

mux wrote:
Thu Nov 14, 2019 12:54 am


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 :)

lorenfb
Posts: 2272
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

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

Thu Nov 14, 2019 9:35 am

Irling wrote:
Wed Nov 13, 2019 10:29 pm
lorenfb wrote:
Wed Nov 13, 2019 8:23 pm
Irling wrote:
Wed Nov 13, 2019 8:10 am
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.
#1 Leaf SL MY 9/13: 74K miles, 48 Ahrs, 5.2 miles/kWh (average), Hx=70, SOH=78, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 4.5K miles, 115 Ahrs, 5.5 miles/kWh (average), Hx=98, SOH=99, DOD > 20%, temp < 105F

map40home
Posts: 18
Joined: Sat Oct 26, 2019 11:41 am
Delivery Date: 26 Oct 2019
Leaf Number: 009238

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

Thu Nov 14, 2019 12:04 pm

mux wrote:
Wed Nov 13, 2019 2:57 am
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.

jkenny23
Posts: 97
Joined: Sat Aug 19, 2017 12:49 pm
Delivery Date: 19 Sep 2017
Leaf Number: 009318

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

Thu Nov 14, 2019 12:59 pm

map40home wrote:
Thu Nov 14, 2019 12:04 pm

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.

Irling
Posts: 23
Joined: Tue Jul 16, 2019 10:38 pm
Delivery Date: 17 Jul 2019

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

Thu Nov 14, 2019 5:22 pm

map40home wrote:
Thu Nov 14, 2019 12:04 pm
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.

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