GM Volt Forum banner

1 - 20 of 98 Posts

·
Registered
Joined
·
630 Posts
Discussion Starter #1 (Edited)
Just curious, since I've been able to disable ERDTT on my Gen1 in the last week I've saved what I'd estimate to be in the range or 15-20L of gas in this one week alone given our extreme cold snap in the Ontario Canada area.

My driving pattern recently consists of a variety of reasonably short trips where ERDTT does mostly nothing except waste gas - some trips are so short that the coolant valve doesn't even open, so the gas is more o less wasted, and then I come home with tons of battery capacity left. On longer trips the grid heater does perfectly fine heating the cabin up and keeping windows clear.

It works just fine.

Recharge, repeat, sometimes 3-5 times a day. On average I'm probably going through 2 full charges a day spread out across multiple trips.

ERDTT is, in most of my drive situations, kinda useless to me, and serves little else except to burn gas that doesn't benefit me at all when I have a battery sitting beside me with a 50% or more state of charge remaining.

But, I got into a debate tonight with an older fellow on Facebook (who since had a hissy fit and threatened to block me) who's spouting off that my method is dumb. Using gas is normal, everyone needs to do it! Disabling ERDTT will harm your battery! ERDTT isn't inefficient at all!

All the logic in the world about why I don't NEED to burn gas in ERDTT mode, how inefficient the Volt's engine is at the lower coolant temps in ERDTT mode, and why it's a complete waste as often the coolant often never even heats up enough to have the coolant valve even open for some trips is completely lost on him.

He's running around telling people to "use gas!" more or less.

Anyhow, for those on the "Chevy Volt Owners" Facebook group, here's the thread in question. I think I've been tactful and factual in my responses despite his complete unwillingness to live outside his little box, and he's now stooped to calling me names, but whatever, I won't stoop back.

Find the "Check out this fuel economy. Worst yet" post and then read the comments under "Don't disconnect the ERDTT.... The car is designed for it."

https://www.facebook.com/groups/che...=1514935492605333&notif_t=group_comment_reply

Just wondering what the opinion is here, especially during this unprecedented cold snap where a huge number of Volt owners are experiencing ERDTT for the first time (some even in TX and FL!), and many others of us further north have been experiencing it for longer than ever before. For those of us who understand ERDTT better than this guy and have driving patterns that make disabling it a no brainer, why wouldn't you?
 

·
Administrator
Joined
·
20,351 Posts
ERDTT defeat has no affect of the battery. It uses its own temp senors, not the outside air temp sensor.

It's like debating which wax finish is the best. If he wants to burn gas instead, his call, doesn't bother me. If you don't, that's fine too.

It looks like the Volt uses about 9 ounces of gas per ERDTT. My fully charged battery cost $1.30 to fill.

I decided to test the resistor defeat because I did not need to use $0.90 - $1.87 of gasoline waste heat on my 5, 10, 15 minute drives to the store. I have plenty of inexpensive, electron-based heat, just like my Bolt. I arrive home never having ERDTT turn on 5-10 times during the drive.
 

·
Registered
Joined
·
3,521 Posts
ERDTT defeat has no affect of the battery. It uses its own temp senors, not the outside air temp sensor.

It's like debating which wax finish is the best. If he wants to burn gas instead, his call, doesn't bother me. If you don't, that's fine too.

It looks like the Volt uses about 9 ounces of gas per ERDTT. My fully charged battery cost $1.30 to fill.

I decided to test the resistor defeat because I did not need to use $0.90 - $1.87 of gasoline waste heat on my 5, 10, 15 minute drives to the store. I have plenty of inexpensive, electron-based heat, just like my Bolt. I arrive home never having ERDTT turn on 5-10 times during the drive.
Yeah, if I were to do it, it would be for the trips to the grocery store and for my wife's whopping 3 + 3 mile commute.

Right now longer trips are being done in EV mode. Good news, it's going to warm up a bit. Bad news, it's forecast to snow virtually every day where the temperatures get up to the 20s.
 

·
Registered
Joined
·
630 Posts
Discussion Starter #4
ERDTT defeat has no affect of the battery. It uses its own temp senors, not the outside air temp sensor.
I know that, you know that...people that actually understand the Volt in depth know that, but this guy wanted to argue up and down with me that the Volt was designed to burn gas during ERDTT, therefore not doing that was potentially harmful and silly.

He doesn't seem to grasp any of the logic no matter how simply it's presented.
 

·
Registered
Joined
·
630 Posts
Discussion Starter #5
It looks like the Volt uses about 9 ounces of gas per ERDTT.
Just for the record, I've seen ERDTT cycles use twice or three times that much. On new years eve on our way home it was approaching -30 here and I was watching the coolant temps on MyGreenVolt - the engine started at 50c and struggled to get back to 60C (with the heat on full blast) in ERDTT mode.

Yes, I let ERDTT do it's thing as it made sense in that application. But, it doesn't for a trip to the corner store. Again, most of us here get that. ;)

So, how much it uses is also temperature dependent. We are expecting to see -35 here overnight later this week.
 

·
Moderator
Joined
·
4,868 Posts
I think there’s a couple important caveats on ERDTT...

It’s correct that disabling it has no effect on the battery health in terms of temperature monitoring and heating. However, you will draw more kW out of a cold battery when ERDTT isn’t in use. Shouldn’t have much effect on the battery, but that is an assumption.

The engine may like to be turned on occasionally, more often, in frigid weather. ERDTT May be as much for the engine as it is for the claimed passenger comfort. Not that it needs to run constantly on short trips but some lubrication by running may be a good thing.

To be clear I’m generally of the opinion that ERDTT should be able to be disabled by users and I generally think it’s rather pointless for short trips, though useful for trips where the distance travelled exceeds vehicle battery range.

Despite my pro “disable ERDTT” opinion, the reasons above are worth consideration as to why it may have been setup the way it is.
 

·
Moderator
Joined
·
4,868 Posts
One other note.. the 2011-2012 Gen 1 Volts would let you game ERDTT a bit. You could let it run, then crank up the climate temp setting but decrease the fan speed. This effectively kept the coolant hotter longer than the set point to turn the engine back on, delaying and reducing ERDTT runs.

The 2013-2015 seemed to change the mode again and they don’t really rely on the resistive heater once ERDTT starts, so there’s no way to game the coolant temperature. Ironically, this results in colder air heating the cabin than when there is no ERDTT.

Anyways, has anyone verified how the Gen 2 Volt handles ERDTT with the resistive heater? Any ability to game its coolant temperature like the 2011-2012 to reduce engine cycling?
 

·
Registered
Joined
·
2,089 Posts
The way I see it, for my driving I might as well burn a bit of gas and make use of the waste heat. If I didn't, that heat energy would come from the battery and I'd be running the engine to get home anyway.

It's a debate as old as the Volt and generates a lot of heat just on its own.
 

·
Administrator
Joined
·
20,351 Posts
The way I see it, for my driving I might as well burn a bit of gas and make use of the waste heat. If I didn't, that heat energy would come from the battery and I'd be running the engine to get home anyway.

It's a debate as old as the Volt and generates a lot of heat just on its own.
I totally agree. But now my Volt is almost exclusively used for trips under 35 miles, so I added the ERDTT defeat. The longer trips use the Bolt. And the very long trips use the Volt in EREV mode where we use gas anyway.
 

·
Registered
Joined
·
203 Posts
I just let the car work as the engineers designed it to. I’m not worried about burning some gas. In fact I feel it’s best to run the gas engine regularly.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
630 Posts
Discussion Starter #11
I think there’s a couple important caveats on ERDTT...

It’s correct that disabling it has no effect on the battery health in terms of temperature monitoring and heating. However, you will draw more kW out of a cold battery when ERDTT isn’t in use. Shouldn’t have much effect on the battery, but that is an assumption.
My thoughts on the health issue is this - GM eventually decided (after much public outcry) to allow ERDTT to be adjusted as low as as -10C, so is -11C, -15C...or even -20C or below going to be harmful? Yeah, probably not.

Further to that, BEV's like the Bolt, Leaf, etc don't even have an engine, therefore the argument that ERDTT is somehow essential or beneficial to battery health is even further weakened.

ERDTT was almost certainly mostly to do with customer perception in extreme cold - faster heat (efficiency be damned), and most importantly, less impact on electric range on a vehicle with an already small battery.

The engine may like to be turned on occasionally, more often, in frigid weather. ERDTT May be as much for the engine as it is for the claimed passenger comfort. Not that it needs to run constantly on short trips but some lubrication by running may be a good thing.
Starting an ICE in extremely cold weather is a high wear situation. Repeatedly having it start and stop in a constantly inefficient temperature range (lower than full CS mode) just muddies the water even more.

Anyhow, I do find it beneficial for trips outside the battery range - it DOES help, sure, but for a trip to the corner store, it's dumb.

As for gaming ERDTT in 2011's and 12's, it works well in moderate cold, but it doesn't stop that initial cycle, and in some extreme (nearly -30) temps we got here a few days ago ERDTT cycled on about a 2-3 minute off/on cycle even with the grid heater running at 100% simply because the outside air temp was sapping heat away from the engine so quickly every time it stopped. ERDTT sucked in that scenario as well as the engine was constantly running in a very poor temperature range while not actually cycling off long enough for the car to use any appreciable battery in between cycles. I should probably have hit the ERDTT disable until it was depleted and then let it run in CS mode in that extreme temperature example, even thought the grid heater would have been woefully inadequate.
 

·
Registered
Joined
·
902 Posts
On single-digit mornings, I have begun to use "Hold" to allow the engine to run for a few miles on my downhill to work. I think it helps with defrosting the windshield. When I return from work, I use more energy to climb up to my home and the weather is warmer, so the battery charge is primarily used for most of the trip. Using the engine generator reduces my wait for the charging station at night and still allows me over 100 MPG on the commute. Using 3 to 5 miles for gasoline burning, I drive about 15 miles on battery, including a 500-foot vertical climb in the afternoon. The single-digit mornings are not so much of the winter that I am running on generator. A greater waste of fuel are the long-distance trips without a charging station, 4,000 to 5,000 miles annually.
 

·
Registered
Joined
·
2,634 Posts
The Volt has a very slow electric heater, my wife's Clarity PHEV is blowing warm electric heater air by the time I put it in drive after backing out of my driveway. The problem with it is there is no battery heater so it basically runs in hybrid mode in very cold temps around 0F or less.

However, my own experience with the Volt is I find the cost of running ERDTT is high, it isn't fuel efficient and doesn't extend the range much, and the car gets almost comfortable (never really warm in ERDTT), and I still burn half a gallon a day and a full charge to drive 19 miles with around 0 F highs. You can precondition and forgo heat, but preconditioning has cost associated with it too. As bad as efficiency is in ERDTT mode in very cold weather, the cost still probably breaks even with gas only.

However, after driving the Clarity I would do away with ERDTT, don't use any gas until around 0F, then run hybrid mode all the time (more like deep cold ERDTT). This works in the Clarity since the electric heat is so much better than the Volt, at least above 0F. I just wish the Clarity had a battery heater in the US model.

ERDTT seems like a software fix for a bad heater, it really seems to work best around freezing temps when a heat pump would do better and not require gas. Just put the better heater in.
 

·
Registered
Joined
·
695 Posts
How I've learned to stop worrying and love ERDTT.

Note, I have my Volt programmed to the 15 F setpoint for ERDTT, as I find on a sunny day, even though it may only be 35 F, the interior temperature of the Volt is acceptable. Very little heat is required, and I even crack the front window from time to time in lieu of using the MAX defrost control, which seems to draw large amounts of electrical power.

Unlike some, I didn't buy the Volt in spite of its ICE, I bought it because it has an ICE! What great flexibility this vehicle has! I can utilize either gas or electric, depending on fuel costs, range requirements, or even cabin heat. If you live in a northern climate where temperatures get cold, I find the Volt offers something that a pure EV doesn't, and that is cabin comfort at an affordable cost.

Perhaps some of you live in an area where electricity is cheap, but here in New England, I am paying about 17 cents per kWh (and I have a competitive supplier for the energy portion of my bill, otherwise it would be closer to 20 cents per kWh). When I look at propulsion, my Volt has probably averaged about 125 MPGe on electricity. With an 85% charging efficiency, this equates to 3.7 miles per kWh from the wall, or about 4.6 cents/mile. On gasoline, I estimate that I am about 45 mpg average. Using gas at $2.50 per gallon, this calculates to 5.6 cents/mile. Here, electricity is the clear winner.

But now let's consider a cold day when cabin heat/defrost is required. The heat needs to come from somewhere. So when I look at thermal energy, a kWh of electrical energy costs me 17 cents. However, a gallon of gasoline contains the energy equivalent of 33.7 kWh, so the thermal energy in gasoline only costs 7.4 cents. Here, gasoline is the clear winner.

Earlier this year, when the temps were between 15 F and 35 F, and I needed heat/defrost, I would drive some sections of road (up and down hills) in NORMAL mode, and utilize HOLD mode on the flatter stretches of road. This lets the ICE run at a more constant speed and setting, which from my observations, increases fuel economy. When the coolant temperature gets to 145 F, I turn on the heat and normal defrost (but I don't use either ECO or MAX). I usually set the cabin temp to 80+, and use RECIRC if the windshield will stay defrosted. I found this to be the best method to heat the cabin quickly.

Lately, the temps have dropped below 15 F. Since I keep the Volt in a heated garage, I can usually drive a mile or so before the temperature sensor realizes it's colder than 15 F. Then ERDTT kicks in. However, I noticed that the coolant temperature seemed to rise faster than when I am in HOLD mode. It is my belief, that GM has programmed the ICE to utilize the external exhaust gas recirculation in this mode of operation to more rapidly heat the coolant (exhaust gas is cooled by the coolant prior to its supply to the intake). Thus, both the engine and the exhaust gases are heating the coolant. Pretty nifty concept, don't you think?

But ERDTT controls seem to heat the coolant to 145 F, and then let it cool to 125 F, at which point the ICE is started again. My preference, after ERDTT brings the coolant to 145 F, is to switch to HOLD mode and let the coolant reach upwards of 180 to 190 F (more optimal temperature for efficient ICE operation). Then, if conditions warrant, return to NORMAL and use the stored heat in the coolant for a period of time. When the coolant gets back near 125 F, I again engage HOLD mode to get more heat.

So for those of you that have low cost electric rates, I can understand your disdain for ERDTT. Also, for those with just a short drive, I'm sure that it has an effect on your mileage. But for me, most of my trips are at least 6 miles long, and I have come to embrace ERDTT for its quick and efficient warmup time.
 

·
Registered
Joined
·
630 Posts
Discussion Starter #15
I often wonder if you guys understand how cheap your gas is compared to much of the rest of the world.

Yesterday I paid $1.31/L (Just short of $5.00/gallon in CDN funds, so about $4.00/gallon equivalent after the exchange) for premium.

Our electricity on the other hand, off peak, is $0.06/kwh. Even on peak is only $0.16/kwh.

This is why I detest ERDTT when I have perfectly functional battery capacity remaining.
 

·
Registered
Joined
·
3,790 Posts
....This is why I detest ERDTT when I have perfectly functional battery capacity remaining.
And I detest that it is tough on the engine, or at least the engine oil.

Putzing along as a 'Gas-burning water-heater' the engine oil never gets thoroughly warmed to evaporate the moisture build up in the oil.
Check for 'Milkshake' on your oil fill cap after a season of nothing but ERDDT.
 

·
Registered
Joined
·
630 Posts
Discussion Starter #17
Check for 'Milkshake' on your oil fill cap after a season of nothing but ERDDT.
Those who are experiencing a lot of short-commute ERDTT's in the last 2-3 weeks since Antarctica settled on us here are now starting to report EMM's, so it appears that the ECM takes this into consideration and decides a burn off is necessary more frequently than what might otherwise be normal.
 

·
Registered
Joined
·
2,621 Posts
Ridiculous argument. "Designed to burn gas"??? So I guess all the SoCal Volts are damaging their vehicles since someone there with a short commute will never burn gas except on maintenance cycles. Isn't that why they have these cycles in the first place? It's to make the arguments the FB guy is presenting moot. As most have expressed here, ERDTT value is dependent on trip length. Otherwise the resistance heater works just fine. The only thing I'd like to see is a direct on/off switch for ERDTT that doesn't need a restart to activate.
 

·
Registered
Joined
·
5,782 Posts
In Texas, we have cold weather so seldom that ERDTT doesn't bother me. Besides, my commute is beyond the AER of my ELR in this cold weather (wow, a whole 25F). So, I just let it run.

I does bother me that the engine is firing up for no reason to go to the grocery though. I own this car and want the engine to last as long as possible.

With my '13 Volt, the electric heat was poor, so, I just used hold mode or mountain mode to make the engine run longer. ELR doesn't have any issues with electric heating, so, I just drive and don't obsess over ERDTT.

And yes @Taser54, my next car will be a BEV. Probably a Buick unless XT4 has an all-electric version. No ERDTT to talk about then. :)
 
1 - 20 of 98 Posts
Top