30KWH Pack Charge Voltage

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DaveBlack

Member
Joined
Jun 3, 2020
Messages
15
Hi all, I have built an RX8 with a Mrk1 Leaf drivetrain (30KWH Battery Pack).

I am using the full stack (motor, inverter, charger / pdm) but am worried about my charging setup. I had hoped the Charger / PDM would auto stop when the batteries are full. However I am nervous that I set it going, and it just keeps charging until I stop it.

I get nervous when the per cell voltage starts to creep over 4.2v.

Has anyone got a 30KWH pack, with perhaps a LeafSpy on it - that gives the total High Voltage of the Pack whilst its charging. It should reach a 'peak' Voltage, then stop climbing as it finishes the constant current phase and enters the constant voltage phase.

If that voltage is above where I get scared, then I know I can continue and it will likely auto stop, if that voltage is below or around the 4.2v per cell, then I know I need to code the charging to stop myself...

Cheers all

Dave
 
DaveBlack said:
I get nervous when the per cell voltage starts to creep over 4.2v.

Has anyone got a 30KWH pack, with perhaps a LeafSpy on it - that gives the total High Voltage of the Pack whilst its charging. It should reach a 'peak' Voltage, then stop climbing as it finishes the constant current phase and enters the constant voltage phase.

Cheers all

Dave
Congrats on your conversion !

So far as I know, all the LEAF generations reach a max cell voltage of about 4.15v.
The constant voltage phase starts at ~ 40 - 50% SoC, and continues on till about 95% SoC. From then on, current flow is little more than a trickle charge in the neighborhood of 4 Amps.
 
Thanks Sage, agreed with the CV and CC analysis - but I think the 30kwh pack is slightly different. I have read that essentially it is the 24kwh pack but they just utilise more of the capacity available by pushing the batteries a bit harder (hence the higher full pack voltage).

No idea if that is true or not, hence wanting to see if there is someone out there with a 30kwh pack that can see what their packs HV is at full charge (whilst charging as it will settle lower).

I also find it hard to believe that the PDM will charge the batteries at a higher Voltage than they should be!

Dave
 
The high voltage charging system will charge to whatever voltage it's programmed to reach. Interesting idea about the 30kwh pack being a 24kwh pack with a wider utilization range. I'm not at all sure that they could get an additional 25% capacity this way, but if they could and did, then it goes a long way toward explaining why some of the packs are troublesome and lose capacity rapidly, and some seem to be perfectly good...

While waiting for the info you seek, you can probably find it yourself, by searching for LeafSpy screen shots from 30kwr cars.
 
Hay LeftieBiker - I totally agree, you would think the Leaf's own charger would charge to the correct Voltage. But as I say when it gets to 4.2v I get scared and turn it off! As I am controlling it - I am wondering if I am missing something in its configuration of can bus commands that tell it what V to charge at.

If that is true (that you can send it a voltage) - then the Leaf PDM is a versatile charger that could charge a range of packs. But I don't see people online using it all over the place so feel that is not true.

I have had a good look on this forum and online and just cannot see the Voltage at 99-100% SOC whilst being charged... Thats the key bit (whilst on charge), as the overall voltage will fall back after charging.

Dave
 
I never had a 30 kWh LEAF, but I see cell voltages up to 4.211 for my 62 kWh 2019; up to 4.12 for my 24 kWh 2015; and up to 4.106 for my 2011 (looking at screenshots from LEAF Spy after full charge). I just looked at a few screenshots from Android devices so there could be some higher values than those.
 
GerryAZ - that is awesome news, the 24kwh pack used LMO and the 30kwh onwards use NMC as the battery chemical structure. So I would expect my 30kwh pack to have the same top charging voltage as your 62kwh one. I just need to wait a little longer and the PDM will probably change to constant voltage mode, I got to 4.21 on some cells and bottled it again.

Few nuggets online for those that ever find this on the interweb...

Difference between 24-30kwh packs
https://pushevs.com/2015/09/28/new-30-kwh-nissan-leaf-battery/

Showing more information
https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/li_ion_ev.html

Dave
 
Yes, the different chemistry, with its higher energy density, is the source of the extra capacity, not a substantially higher SOC.

From that first site:

I would never recommend an electric car with a battery made with LMO cells, this is why I think the 30 kWh battery is great news. We will stop having people scared with losing battery capacity bars.

Ah well, such is the nature of prognostication...win a few, lose at least a few more.
 
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