Variation in voltage at 100%

[FloridaSun]

This morning I charged to 100% as I'm going on a little road trip. So, I checked my cell and total voltage as also SoC BMS to prior to the update..

February 22, 2020:
408.1 Volts, SoC BMS 95.5%

June 20 2020
408.7 Volts, SoC BMS 96.5%

July 12 2020 post update:
408.0 Volts, SoC BMS 96.5%

Not sure if this is normal variation?

 

[KiwiME]

I responded on FB but as I noted, the resolution of SoC is not great. Temperature could affect this as could the method SoC is calculated while under charging power. The pack of course is under a slight load when you are using TP, via the LDC. I think though the SoC BMS is worth tracking over time because as you mentioned it's certainly expected to close in on SoC displayed as the pack deteriorates. I'm at 94.5% at 14,000 km.

 

[apu]

I think it's a normal variation depending how well balanced your individual cells are, I just finished a 100% charge today I'm reading 407.7 total voltage with few individual cells topped out a 4.14V and rest at 4.16. Next charge they will like even out more.

Sent from my SM-G955W using Inside EVs mobile app

 

[FloridaSun]

I think it's a normal variation depending how well balanced your individual cells are, I just finished a 100% charge today I'm reading 407.7 total voltage with few individual cells topped out a 4.14V and rest at 4.16. Next charge they will like even out more.

Sent from my SM-G955W using Inside EVs mobile app

Mine are all 4.16 at 100%. Looks like my battery is still very healthy..

 

[apu]

I'm usually all at 4.16 but the car has not been charged in over a week(until today's free charge at work )at a lower than typical SOC, pretty normal

Sent from my SM-G955W using Inside EVs mobile app

 

[KiwiME]

Yes, agreed, I wouldn't associate such minor cell voltage differences with pack health, it's just the result of miniscule variations in "cell" resistance while current is flowing, integrated over time. The resolution of the reading is only to the nearest 0.02 V so you know that's of little importance to Hyundai.

 

[electriceddy]

Yes, agreed, I wouldn't associate such minor cell voltage differences with pack health, it's just the result of miniscule variations in "cell" resistance while current is flowing, integrated over time. The resolution of the reading is only to the nearest 0.02 V so you know that's of little importance to Hyundai.

20 mV and below is a "happy differential" and for sure not cause any concern.
An example of concern would certainly be something like this:
https://mynissanleaf.com/viewtopic.php?f=30&t=26732&start=10#p540373
I know, different chemistry etc, but same principle.
Thankfully LG technology seems to have a positive handle on this 64 kWh pack. However I feel it is probably time for me to do a top end balance as I have never done it since purchase (about 16 months). Thanks for the reminder

 

[KiwiME]

This is what I see in those last two hours to 100% on 8A (actually 7.1 A). Once it hits 98.5% it just jumps to 100%. I gather balancing might extend that time a bit. The linear 2% per hour rate makes estimating charging time very easy.

 

[FloridaSun]

This is what I see in those last two hours to 100% on 8A (actually 7.1 A). Once it hits 98.5% it just jumps to 100%. I gather balancing might extend that time a bit. The linear 2% per hour rate makes estimating charging time very easy.

View attachment 8772

It has happened to me that it jumped from like 98.5% to 100%. I only observe it once as usually, if I charge to 100%, I'm sleeping while the car is charging to 100%

 

[electriceddy]

This is what I see in those last two hours to 100% on 8A (actually 7.1 A). Once it hits 98.5% it just jumps to 100%. I gather balancing might extend that time a bit. The linear 2% per hour rate makes estimating charging time very easy.

View attachment 8772

So maybe an hour after finish would do 100% balance, and then drive say 20 % off ? What do you think? I am going to try this on my vehicle but I don't have access to the software you guys do.

 

[KiwiME]

That's exactly what I did. You can only assume the balancing has taken place after it switches off, but there's no reason why it shouldn't.

 

[FloridaSun]

just realized that I messed up my OP.. my 3rd picture was not at 100% charge.. here is the correct one..

 

[wizziwig]

Mine are all 4.16 at 100%. Looks like my battery is still very healthy.

What is your cell deviation at low SOC? That is usually more useful at detecting weaker cells than just looking at 100% SOC.

 

[FloridaSun]

What is your cell deviation at low SOC? That is usually more useful at detecting weaker cells than just looking at 100% SOC.

I usually don't run my battery below 40%.. The few times that I did run it lower, I didn't check my cell balance but the most I have seen was 0.02

 

[electriceddy]

That's exactly what I did. You can only assume the balancing has taken place after it switches off, but there's no reason why it shouldn't.

So I dusted off my EVSE (first time this year for usage)

I have probably used it less than 10 times since 2012
and charged my car to 100% for the first time.
I drove 100 km to get the SOC down a bit with these results:

I am amazed at the consumption, at 117 W / km there should be no issues accomplishing 500+ km even with our terrain. 90% hwy driving at 80-95 km per hour and 10% local, hot tire pressure about 44 psi ambient about 23 degrees C.
Thanks for the advice, next month I might do it again and maybe become a member of this:
https://insideevsforum.com/community/index.php?threads/kona-ev-300-mile-club.6098/

 

[KiwiME]

11.7 is very good even for that range of speed, much like ours. I'll usually get 13 to 16.

I miss the North American style of huge steel electrical panels. The power feed into the small commercial building I live in is 87 years old, 400V 3-ph wrapped in burlap! After equally ancient fuses, a later mid-century switch and more fuses, my flat gets one of the three phases (to N) and my panel (like many worldwide) is just a small plastic box, total 63 amps, which makes it impractical to install a 32 amp EVSE.

 

[electriceddy]

11.7 is very good even for that range of speed, much like ours. I'll usually get 13 to 16.

I miss the North American style of huge steel electrical panels. The power feed into the small commercial building I live in is 87 years old, 400V 3-ph wrapped in burlap! After equally ancient fuses, a later mid-century switch and more fuses, my flat gets one of the three phases (to N) and my panel (like many worldwide) is just a small plastic box, total 63 amps, which makes it impractical to install a 32 amp EVSE.

View attachment 8792 View attachment 8793

At least the burlap offers superior mechanical protection

 

[FloridaSun]

So I dusted off my EVSE (first time this year for usage)

I have probably used it less than 10 times since 2012
and charged my car to 100% for the first time.
I drove 100 km to get the SOC down a bit with these results:

I am amazed at the consumption, at 117 W / km there should be no issues accomplishing 500+ km even with our terrain. 90% hwy driving at 80-95 km per hour and 10% local, hot tire pressure about 44 psi ambient about 23 degrees C.
Thanks for the advice, next month I might do it again and maybe become a member of this:
https://insideevsforum.com/community/index.php?threads/kona-ev-300-mile-club.6098/

That's about 5.3 mi/kwh.. I just got 5.8 mi/kwh today on two 9 mile trips around town. (after increasing my tire pressure by 5 psi)
On the previous day with 5 psi less, I barely got over 5 mi/kwh... My 80% range is about 224 miles right now after a 3.7 mi/kwh 455 mile road trip..

 

[electriceddy]

That's about 5.3 mi/kwh.. I just got 5.8 mi/kwh today on two 9 mile trips around town. (after increasing my tire pressure by 5 psi)
On the previous day with 5 psi less, I barely got over 5 mi/kwh... My 80% range is about 224 miles right now after a 3.7 mi/kwh 455 mile road trip..
View attachment 8794

44 psi seems a favorable pressure when the tires are warmed up, an acceptable combination of comfort and efficiency. (at least with the Nexens)

 

[R P]

39 psi is the most I have run in mine. Maybe need to pump them up a bit more. Don't you get a rougher ride with that much pressure?