Hold state of charge, question

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125mph

Member
Joined
Mar 15, 2021
Messages
20
I just coded my car and tested the HSC feature. I drove and hit the button at 50% and it seem work fine.. Then I turned it off...

WHen I got close to home, the battery was below 10% and I assumed the regular hold state of charge would kick in but it didnt.. So I manually turned it back on again.

When I "check" that box to hold state of charge, am I telling it to hold state of charge starting right now, or what is actually going on. If I dont have that check box checked, will the HSC never kick in?
 
The REx engine typically turns on when the battery pack's charge level drops to 6.5%, so your 10% charge level was too high. This should occur when the HSOC checkbox isn't checked.
 
125mph said:
Ahh perfect.. I thought the default % REX kicks in was 15%.

Alohart is right. Whether you have your Hold State of Charge ACTIVATED or not (not coded, LOL! I am going to make sure we stop saying coded...no one is coding anything)..REX kicks on yes, between 6-7%. I think 10% would be better, but obviously BMW thought not ;)
 
Deutsch100 said:
I think 10% would be better, but obviously BMW thought not ;)
The firmware gives you a choice in 1/2% intervals. It's the California Air Resources Board that said "The APU (REx) must not be capable of switching on until the battery charge has been depleted". BMW interpreted 'depleted' as 6%. Note: CARB is also why a 64 Ah REx can only access 1.9 of the 2.4 gallons in the gas tank: gas range can't be more than battery range.

Instrument Cluster (KOMBI_I01_F56)
3000/
SOC_HOLD_POSITION werte = hex value xx
Units are 0.5% -- default = 0C

0C = 6%
14 = 10%
28 = 20%
3C = 30%
50 = 40%
64 = 50%
78 = 60%
8C = 70%
 
JohnWasser said:
The firmware gives you a choice in 1/2% intervals. It's the California Air Resources Board that said "The APU (REx) must not be capable of switching on until the battery charge has been depleted". BMW interpreted 'depleted' as 6%. Note: CARB is also why a 64 Ah REx can only access 1.9 of the 2.4 gallons in the gas tank: gas range can't be more than battery range.

Instrument Cluster (KOMBI_I01_F56)
3000/
SOC_HOLD_POSITION werte = hex value xx
Units are 0.5% -- default = 0C

0C = 6%
14 = 10%
28 = 20%
3C = 30%
50 = 40%
64 = 50%
78 = 60%
8C = 70%
Has anyone actually been able to change at what charge level the REx engine automatically starts? I believe that SOC_HOLD_POSITION merely changes the location above the charge level gauge of the white triangle that indicates the charge level at which the REx engine automatically starts..
 
Would be interested in finding out as well. I tried setting it before but it did not take. At least I got manual HSOC to work.

Also, I found that that it typically takes around 6 mins for the REx to warm up for the catalytic converter to reach optimal temps so that REx can operate at higher RPMs. Max RPM, and resulting higher electrical output from REx is also not achieved until around 85kph. So those combined made me conclude that I should just rely on HSOC only when I have a stretch of highway travel ahead. So no point in having HSOC automatically trigger at 70%; just rely on my read of the current driving conditions and manually turn it on.
 
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