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Why is ELR charge time 5 hours on 240V?

7703 Views 26 Replies 19 Participants Last post by  petefoss
Is the usable battery portion 12KWH? Does it have a large vampire draw while charging? Anyone?

Thanks,
MrEnergyCzar
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Apparently to get the range they extended the charging window. Only GM knows for sure.
Odd, because the Volt battery is capable of a <30 minute charge based on my calcs. It will take over 60 kW during regen.
 

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Qinsp -- That is pure DC power. The transformer in the volt is only sized to take a 3.3kw AC charge, that is the limiting factor. When you see a Tesla and their 100kw charging stations, that is pure DC power being provided directly to the batteries no ac-dc conversion necessary.
 

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Apparently to get the range they extended the charging window. Only GM knows for sure.
Odd, because the Volt battery is capable of a <30 minute charge based on my calcs. It will take over 60 kW during regen.
There's a lot of difference (in terms of battery wear and cooling system sizing) between 60 kW for 10 seconds during hard braking and 60 kW for 15 minutes for DC quick charge. Surge ratings on batteries are routinely 4x the continuous rating. (But there's no charger in the car that can sustain 15kW, either.)
 

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elr-volt battery

I note the elr has 12% less epa mileage but only about 2.7% less electric range than the volt. Assuming that gas and electric efficiency losses for the heavier and bigger tired elr are proportional, this suggests that they may be getting about 8% more out of the "same" battery. This implies that a revised volt could get (1.08 x 38) equals 41 mile epa range. Very good for promotion. What am I missing?
 

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They have said the ELR uses a higher percentage of the same 16.5 kWh battery. Not sure I remember the exact number but 70% rings a bell. I'm sure it's on the net somewhere. Why they haven't allowed the Volt to do the same is something of a mystery, though. I strongly suspect there will be a mid-cycle enhancement with a powertrain upgrade for MY2015 (for both Volt and ELR), in part because I don't expect the next generation Volt until 2017. And I really don't think GM wants to get overshadowed in this game by newcomers arriving soon.
 

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Qinsp -- That is pure DC power. The transformer in the volt is only sized to take a 3.3kw AC charge, that is the limiting factor. When you see a Tesla and their 100kw charging stations, that is pure DC power being provided directly to the batteries no ac-dc conversion necessary.
OK, if the Volt battery will charge in 4 hours at 12a x 240vac, then it would take 400vdc at roughly 5 amps. AC power is not DC.

60 amps x 400vdc = 24 kw to charge in 20 minutes.

Someone smart check my math. 24 kW is a small fraction of the regen power, and the batteries are water-cooled, and the charge is 20 minutes duration.
 

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60 amps x 400vdc = 24 kw to charge in 20 minutes.
It's somewhat academic because the Volt isn't designed to allow for DC charging. As mentioned, AC and DC charging are different animals.

Assuming you could DC charge the Volt, you have to remember that you have to slow the charge at the bottom and top. But 15 - 20 minutes, which is your guess, is probably a good one for low power DC charging. The Leaf takes that long using CHAdeMO to take on 10 kWh. Note you could use much higher charging levels. I think the SAE Combo has an option for 100 KW charging.
 

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I asked the question on another thread....

Why is the charge time 5 hours on 240V? I thought the ELR has the same size battery as the 2013-14 Volt.

RobbertPatrison stated:
The ELR has the same battery but uses 11.8kWh instead of 10.5kWh in Volt, so it takes longer to charge. That was needed to avoid the drop in EV range due to the bigger tires, higher weight and worse wind resistance. In all, the ELR drives ~20% less efficient than its drivertrain-identical twin Volt, and its battery will wear out a little quicker due to the large charge window. That is the price of beauty.
 

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Assuming you could DC charge the Volt, you have to remember that you have to slow the charge at the bottom and top. But 15 - 20 minutes, which is your guess, is probably a good one for low power DC charging. The Leaf takes that long using CHAdeMO to take on 10 kWh. Note you could use much higher charging levels. I think the SAE Combo has an option for 100 KW charging.
The bottom and top are already buffered out of the equation due to the BMS. Presumably the key issue would be managing battery thermals while charging, which is something that the BMS should be able to handle fairly straightforwardly by engaging the AC and fans to pass cooled coolant thru the battery. Less efficient perhaps, but a faster charge.

Here's hoping the next Voltec vehicle gets a couple of motors derived from the Spark EV, along with a bigger, better battery that can take a direct charge via CCS and double or more charge rates via AC (gimme 60A!!)
 

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Discussion Starter · #11 · (Edited)
I asked the question on another thread....

Why is the charge time 5 hours on 240V? I thought the ELR has the same size battery as the 2013-14 Volt.

RobbertPatrison stated:
The ELR has the same battery but uses 11.8kWh instead of 10.5kWh in Volt, so it takes longer to charge. That was needed to avoid the drop in EV range due to the bigger tires, higher weight and worse wind resistance. In all, the ELR drives ~20% less efficient than its drivertrain-identical twin Volt, and its battery will wear out a little quicker due to the large charge window. That is the price of beauty.
Ok, that makes perfect sense. I forgot the ELR isn't getting 35 miles range but 37 and it weighs more. We might be looking at the next Volt battery window, 11.8 KWH.... still plenty of cushion on both ends... although he says the battery will wear out quicker, that could mean 50% faster or 5%, I'm sure there's some formula where they know how much shorter the battery will last etc...

MrEnergyCzar
 

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The bottom and top are already buffered out of the equation due to the BMS.

Here's hoping the next Voltec vehicle gets a couple of motors derived from the Spark EV, along with a bigger, better battery that can take a direct charge via CCS and double or more charge rates via AC (gimme 60A!!)
Charging is slow at 30% SOC and 60% SOC. It only motors in the middle.

I can't see the point of DC charging with the Volt actually. The electric range is too limited and you have the genset which will give you 40 miles on a gallon of gas. Rather than take half and hour and pay $5 for a fast charge it would be simpler and cheaper to just drive.

As for the time of charging and so forth, we'll know when we see the EPA sticker. Given that the car is shipping that should be real soon now.
 

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The ELR shows where I wish the Volt would go with regards to how much pack capacity is used. 1 more useable kWh would be a nice upgrade, as long as the corresponding shortening of the pack life doesn't bring it down too much. Which begs the question, what would be a satisfactory "life expectancy" (80% of original range) of the pack for the majority of Volt buyers? I would suspect that the Volt is not going to drop to 80% of the 38 mile AER for around 120k-150k miles for most Volt owners, judging from the results so far.
And whatever the limiting factor is, I REALLY wish GM would allow for a 6.6 kW rate of charge, AT THE LEAST, on the 2015MY Volt. I know some of you don't think it is needed, but it would be very useful for keeping the genset off, as much as possible, for a lot of us. 10-11 minutes of range per hour of charging is worse than pathetic, it looks like GM doesn't understand electric cars, or electric car drivers.
 

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The ELR shows where I wish the Volt would go with regards to how much pack capacity is used. 1 more useable kWh would be a nice upgrade, as long as the corresponding shortening of the pack life doesn't bring it down too much. Which begs the question, what would be a satisfactory "life expectancy" (80% of original range) of the pack for the majority of Volt buyers? I would suspect that the Volt is not going to drop to 80% of the 38 mile AER for around 120k-150k miles for most Volt owners, judging from the results so far.
And whatever the limiting factor is, I REALLY wish GM would allow for a 6.6 kW rate of charge, AT THE LEAST, on the 2015MY Volt. I know some of you don't think it is needed, but it would be very useful for keeping the genset off, as much as possible, for a lot of us. 10-11 minutes of range per hour of charging is worse than pathetic, it looks like GM doesn't understand electric cars, or electric car drivers.
100% agree about 6.6 kW charging. The Volt as an EREV doesn't need DC fast charging, but its lack of 6.6 kW at this point, and ESPECIALLY ON THE ELR is almost criminal. I hope they're not just trying to coddle their feeble Voltec 240V wall charger, which is only good for 3.3 kW. Another factor is that the slow charge rate makes using any pay-for-use public charger a non-starter, because even if it was only $1/hr. it's cheaper to use gasoline.
 

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Ok, that makes perfect sense. I forgot the ELR isn't getting 35 miles range but 37 and it weighs more. We might be looking at the next Volt battery window, 11.8 KWH.... still plenty of cushion on both ends... although he says the battery will wear out quicker, that could mean 50% faster or 5%, I'm sure there's some formula where they know how much shorter the battery will last etc...

MrEnergyCzar
This also is what I call the "ace in the hole" for the long term life of the Volt battery.

As the Volt battery gets old and loses some capacity, it would simply take a software change to allow the Volt to use more of the available capacity. This may accelerate the degradation, but it may extend the useful life of the battery for another couple years....
 

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100% agree about 6.6 kW charging. The Volt as an EREV doesn't need DC fast charging, but its lack of 6.6 kW at this point, and ESPECIALLY ON THE ELR is almost criminal. I hope they're not just trying to coddle their feeble Voltec 240V wall charger, which is only good for 3.3 kW. Another factor is that the slow charge rate makes using any pay-for-use public charger a non-starter, because even if it was only $1/hr. it's cheaper to use gasoline.
I was surprised the ELR did not offer 6.6KW charging. That is inexcusable...

Many in this forum have felt that the 6.6KW charging was a "nice to have" option but were concerned that it would lead to a higher price. With the ELR you already have that higher price so there is no excuse for not having it....
 

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Charging is slow at 30% SOC and 60% SOC. It only motors in the middle.

I can't see the point of DC charging with the Volt actually. The electric range is too limited and you have the genset which will give you 40 miles on a gallon of gas. Rather than take half and hour and pay $5 for a fast charge it would be simpler and cheaper to just drive.

As for the time of charging and so forth, we'll know when we see the EPA sticker. Given that the car is shipping that should be real soon now.
The point is 30-minute charging instead of 5 hours so you don't have to use the genset. The Mitsubishi i MiEV with its 16 kWh battery has a CHAdeMO plug for DC fast charging. Why can't the Volt have DCFC?
 
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