[Sean_R]

My understanding is that the Volt's battery is never fully charged to 100% or discharged to 0%, but is kept in a range of state of charge in-between.

Has anyone determined what the state of charge (SOC) range is that the onboard charging system maintains as hard minimums and maximums, and how this corresponds to the displayed charge level on the driver's display panel?

On a related note, I've read elsewhere on this forum that maintaining a SOC on the battery centered around the 50% level, with small deviation from this level, will significantly prolong battery life due to not fully exercising the limited number of charge cycles. I'm wondering if a charging strategy of keeping the SOC between 45 and 55% would accomplish extending the battery life.

While reviewing specs on the earlier Gen 1 Volts, the 2015 Volt, and now the newest Gen 2 model, the battery capacity has only increased a small amount (<10%), yet the Gen 2 models jumped in EV-only range from 35 to 53 miles (50%). Aerodynamics aside, this might imply that GM has opened up the available amount of capacity on the battery for driving use, while eating into the cycle life of the battery.

If this is so, perhaps it's because GM's had 5 years of history with Gen. 1 battery life to get more comfortable with meeting the battery life warranty requirements. But this claimed increased range might then come at a reduction in battery life, of which customers would be unaware. There would be nothing wrong with this per se, but it would be nice to know the approaches that owners could take to keep the battery best-cared for to promote maximum longevity. Any thoughts on this?

 

[telveer]

Based on OBDII readings, I have never seen it go below 20% and never over 85% .. I can't remember the exact numbers as I have not checked in a while. This ~65% SOC explains why we can only use ~10.5kwh even through the battery is 16.5kwh (2013MY)

 

[Jeff N]

The 1st generation Volt started with using 65% of the battery with an upper state of charge of around 85-87% and a lower state at around 20-22%. The 2nd generation Volt uses about 76% of its capacity (14.0 kWh out of 18.4). Presumably better experience, battery design improvements, and the benefits of larger capacity (less likely to be fully discharged of usable capacity each charge cycle) lead to the increased state of charge usage. GM has claimed that battery aging studies project that the 2nd generation packs should last at least as long as the 1st generation packs and perhaps a bit longer.

If you believe that the Bolt EV's nominal capacity is not much more than the published 60 kWh then it appears to allow nearly all of the battery to be used. It may well charge as high as 97% and allow discharge down to near 2-3% at reduced speeds before finally rolling to a stop. Those numbers are just guesses because GM has not released actual numbers and some people suspect that the battery may be noticeably larger than its claimed size of 60 kWh thus allowing a bit more of a buffer zone at the top and bottom.

 

[Dutch]

I don't know the details, but I frequently find myself wishing I could dial 2 more kWH out of the battery to cover my commute in bad weather <sigh>. Being SO CLOSE to work or home and having the REX kick in for the last 1-3 miles annoys me far more than I expected. (laughing at myself for my first world problems)

 

[canehdian]

These are fuzzy numbers, which can vary a little because of mismatches of charging levels, resting SOC levels, and computer estimation algorithms.
e.g. you could charge a hot battery to 83.5% ("Full"), which then cooled off overnight, resulting in a lower SOC (82%?) by the time you drive off. Conversely you could charge a cold battery to 83.5% and it warm up during the day and technically be "overcharged"
to 85%.
The computer will also recalculate SOC periodically while driving, and after being parked for about 1-2h. In-use estimates aren't as accurate as standby estimates.

Gen1.0:
87%-22%
Gen1.5:
83.5%-18.5%

Hard floor of 15% - propulsion power reduced if you hit this level

Gen2.0:
I don't have data. Someone's probably posted it here, somewhere. But the window has widened, as mentioned.
10% more battery is being used every charge, thus the larger jump in range.

 

[Sean_R]

Thanks canehdian - this is what I was looking for. Now we just need to find someone who has the Gen 2 data...