GM Volt Forum banner

2013 Power output / regen not as much as others

10K views 102 replies 19 participants last post by  scottf200 
My biggest question out of all of that is why did you have to have the brakes replaced? It sounds like the brakes are engaged in some fashioned even without any pedal used. Your regen rate should be far higher than your getting. I usually see a max regen rate in the 50kw range when stopping from freeway speeds, and maximum power reaches 114kw when accelerating. This is also on a '13.

Mountain mode should build the battery from a minimum SOC to 50% or so in about 20 minutes. Having had to run yours for 45 should have been more than sufficient to climb any grade. 30 minutes on MM at idle should have had you returning with the 5 bars or so to indicate half of a battery on the GOM, and an engine off since it won't charge more than about 45%.

As for the mismatched pump/trip fuel calculations, I would definitely keep an eye on those. You mentioned it's a CPO, did you also get the onstar set up with a smart phone? If so, I would look at the car status page that shows battery and fuel range. If I recall, the fuel range shows gallons remaining. I have the free basic package so don't remember offhand since I lost that functionality. I would check to see how many gallons it's reporting at fill up, and again at the next fill up and see if it jives with what the car shows.

Sounds like there are a number of issues at play with this vehicle, and with the CPO warranty in effect as well as remaining Voltec/Powertrain I would definitely have it checked out. If nothing else, the very low regen and low acceleration power output are definitely a concern, with the lower power output possibly putting the car into a safety risk since it will have difficulty maneuvering in an emergency situation at this point should you need max power for some reason.
 
Definitely something wrong. in MM, you should see the yellow bar indicating engine operation, usually about 1/3 or so filled, but you should also see green in the regen indicating that it's adding to the battery to build the SOC.

When braking, friction brakes should only be applied when hard braking or speeds below 5mph. This was why I questioned the need for brakes so early. My '13 has over 100K miles and they look almost new. It seems to be that if you needed brakes, its likely been an issue for a while (possibly since new?) that the blended brake system isn't working as designed. I'm curious to add though, when accelerating at max power, what is the yellow bar reading? It should be near or at the max but I suspect you're only seeing it go to about 2/3 or maybe 3/4 since you indicated it's only applying about 60-70kw of power.

In response, you should see regen to about a complete stop when braking. Even light braking should give 10kw of regen with harder braking upwards of 30 to 40+. I probably don't brake as gently as I could, but I still begin to brake within a reasonable distance (4-500 feet from a stop) and even from 45-50 can frequently see regen in the 15+ range when coming down from 50mph or so.

Strictly speaking from my own personal experience, the electric portion of the car should take care of pretty much any driving conditions including braking to such a low speed the mechanical friction brakes are only needed to come to a final stop. It sounds like you definitely need to have a service tech see the car, and if necessary go on a ride along so you can demonstrate these odd behaviors. Definitely something not right!
 
I never noticed the brakes felt any different from a regular car. In fact, it's difficult for me to even tell the difference between regen and friction brakes in the Volt. By your description of "nothing for 25% of brake pedal" that tells me that regen is definitely not working right. I notice definite regen at the top of the brake pedal with progressively more regen the more I press. The sudden grabbing indicates the friction brakes are engaging, though not sure on why they release until you hit 50% brake travel other than that would be about where they would normally start to engage under harder braking. I suspect once this is all situated and working properly you will be very pleased with how the brakes work when operating correctly.

I don't really want to speculate anything just yet, but it almost sounds like something in the inverter went wonky but I'd think that should set a SES light. If that's the case, it's definitely covered by the Voltec warranty. I can sympathize with your dealership option. I'm in somewhat the same situation as there is only one Chevy dealership in town with a Volt tech, and my experience with them (as well as others with non Volt vehicles) is less than even mediocre. Unfortunately my next option involves a drive to LA which is about 100 miles south. I guess they know they're the only game in town and use that to their advantage. Definitely keep us posted on what the outcome of this situation is.
 
If it's a bad tune, that should easily be picked up when an MDI is connected. My understanding is that all modern GM ECU's maintain a record of all flashes performed. This has been a huge topic of concern since some people were flashing a tune, screwed something up, reflashed the GM approved tune and took in for warranty repair which was denied since a record of past tunes was present and indicated a non-approved flash.
 
I'd bet it's just something with the existing tune that went wonky. Unfortunately it seems even though a reflash frequently just writes the same program that was there before, it seems to take care of a lot of issues when done unless it's a hardware failure of some sort. I always question how something thats been burned to a ROM can get corrupt or altered to cause undesired operation but apparently it happens as several members have had control modules reprogrammed with the same programming that was present before and problems cleared up.

It's like trying to wrap my head around a CD/DVD going bad because the written portion somehow became corrupt. It doesn't work in my head how that can happen, but plenty of evidence on here suggests otherwise.
 
I think I see where you are going with that wordptom. However, the OP has stated that reduced power is also demonstrated with a fully charged battery. Something that SHOULD NEVER happen except I understand only when "engine not available, please add fuel" is present. Everything the OP has stated seems to indicate a definite software issue, or possible hardware failure of some sort without the presence of a MIL. It almost seems to me that either full power is not available to the MG for whatever reason, or perhaps only 2 of the AC phases are actually making it into the MGB/A which would explain the lower performance as well as the poor MM buffer build time. The lack of codes or MIL seems to indicate the system isn't aware of a problem though.
 
The only way I can describe the sound when running is it's quiet. As for RPM, definitely just above a normal idle. I believe I read 1400 is "idle" but I haven't confirmed with any diagnostic equipment. Even in park the accelerator causes an engine response though not to a terribly high RPM, my guess would be just under 3K.

I notice your description of MM when climbing and find it's somewhat different than my experience in that in MM with battery buffer built to the set point and climbing (6-7% grade), I find that my engine actually revs to the max RPM as indicated by the graph on the right. I will admit though I tend to maintain 65-70 to keep with the flow of traffic which may indicate a difference in driving style from you, and again possibly indicating the difference in MM RPM level.

I know we're all curious what the verdict is on the diagnosis so please keep us informed.
 
Glad you have everything working properly, though the "no fault found" seems strange. But like every other car out there, it never acts up for the mechanic. As for your lifetime mpg, that doesn't generally get reset since it reflects the lifetime mpg for the car. There are ways to have it done, including an app that will do it, but really it's a great indicator to show off how much better the Volt is than the Prius. :D

If you have L2 access at work, there really isn't much need for L2 at home, so the L1 EVSE should be sufficient for your needs. If you later upgrade to a full BEV, that might be the time to look into something that charges at a more substantial rate.
 
LOL. Well, each has their purpose, but I admit, I am biased, as well. I just need to quit taking it on long road trips and get my lifetime value back up to the 130 MPG from when I bought it.
Your ahead of the curve from me. When I bought mine it had 37.7mpg lifetime. I've managed to build that to 43.5 since September last year and thats included a couple trips to Vegas (300 miles away) and several trips to LA. I doubt I'll ever see 60+ since I do use the ICE on a semi-regular basis. I did contemplate resetting my lifetime mpg, but settled instead on resetting one of my trip meters at the beginning of the year and thus far I'm just a shade over 100mpg with ~4500 miles so far this year.
 
yeah, those little hills do cause my efficiency to dip just a tad when climbing. LOL On the plus side though, when I'm at the top of Tejon and driving back home I get enough regen to get me about 5 miles from home on battery alone. Not too bad seeing as I'm about 45 miles from the top of the Tejon pass. Being able to manage ~40 miles at 70 or so is quite nice.

And you did get the spelling of both correct. :)
 
Historically I have only used Mountain Mode like three times, all when the battery indicator showed no bars and I had large hills to climb.
I would suggest that you engage MM several miles before approaching large climbs. This allows the buffer to build sufficiently. Engaging MM at the base of a climb does rev the engine higher, but also doesn't give you enough wiggle room to maintain over about 55kW to the drive motor since that's roughly the limit that it can generate from the engine. That's what the buffer allows (full 111-114kW) since it has that additional reserve of power.

I found that unless the engine has run a good 20 minutes or so, it can still be cold enough that my mpg is still slightly low. I know during winter I tend to drive in hold to build up cabin heat faster than the electric heater can produce and I know that on average with my 6 mile commute to work I would average about 16-18 mpg due to the cold engine. Long trips with sustained engine operation seem to show 40+ however (43-44 on my last LA trip).

Depending on how long MM was engaged and building the buffer, it's very likely that contributed to your lower mpg since it's not only doing the job it would do in CS, but also running hard enough to provide an additional 6-9kW+ (mygreenvolt rough calculation in my experience) to building the buffer.

I find too that although the trip meter is pretty close, if you go with what is on the energy usage screen, that tends to be slightly more accurate especially if you haven't had a chance to charge and reset the numbers.
 
If you had a lot of regen from descending those hills, that can throw the GOM off since most recent average kW/mile is significantly higher. Although it generally takes a few charge/discharge cycles to calibrate, it also takes into account immediate history and weighs that most heavily. I know coming down into the valley it's about 45 miles to my apartment from the top of the grade. Descending will allow me to build the battery to about 3/4 full from the MM level and indicate 60 miles of range which is obviously not possible in a Gen 1 at 70+. I do however manage about 40 of those miles electric only and usually shows 3-4 miles at zero bars remaining. Unfortunately about 1-2 miles later the ICE kicks on since at that point I'm mostly level or perhaps a very slight climb into the city.

I think all in all you're really starting to see how capable in both performance, which you were previously lacking, and range the Volt really does have. I do wish it was better equipped as far as carrying ability and seating (think uber!) but overall it's definitely a winner over similar competing models.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top