[DCFusor]

Had something interesting happen the other day. I was showing a friend the Volt (he has a Prius) and had the hood open. I turned on the car, which invokes maintenance mode, and of course the engine started. We could both hear the inverter singing. This appears to charge the main battery, even sitting still, in normal mode, and with the battery already over the MM engine cut-in threshold. We let it run for 15 min or so, and got another bar on the battery display, and more miles shown on the car (and of course, more gasoline usage).

After I got home, in MM I had the usual about 45% charge. I ran it some more in that mode and wound up with about 60% charge reported by the car itself. I didn't think to check MyVolt last night.

Trying it again this morning (cold out and I wanted some heat in the car) - same thing, more miles shown on battery display, more gas used - I shut it off after about 15 minutes and on closing the hood and restart, was showing about 70% charge - about another 10% from where the car reported before doing this. Curious about this, I came up here to the computer and checked with MyVolt.com - which showed not the number the car did, but the number it had when I parked it last night (44%) - the new charge didn't show up there at all. You therefore cannot use MyVolt (or presumably the smartphone apps) to monitor this at all, and I have no idea if now they will be out of sync permanently or will get back together if I drive the car, or fully charge it off home power.

This might be nice to know in an emergency for getting a full charge when there's no other way, or just to get the car warm of gas even if it's charged above where MM can kick in the gas engine. To me, that's relevant and potentially useful, as I'm fully off the grid and can't reasonably precondition the car early in the morning when my home system doesn't have the power to spare.

But one has to wonder - since there is a bug in reporting this to the outside world, could there also be a bug that would allow the battery to be ruined by overcharging it in this mode? Interesting hack at any rate.

 

[DCFusor]

To add a bit more data. I've now plugged in the car, in the lower power 120v mode. MyVolt has been failing to work at all for the last couple hours, but now updated - but is still wrong in an interesting way. It's showing charge from the cord, battery state based off the 44%, not the 70% the car itself was showing when I plugged in - but! The time to complete is similar to the car, as though the cord was providing power at a much higher rate than it actually is. It isn't, of course - I monitor power drain in my solar system with a good bit of detail at all times.

Not sure where this discrepancy lies, but that's gotta be the worst written website I've seen in a decade or more.

Actually, the jury has to be out on which is telling me a lie just now - but I'll go by the sound it made while the engine was running - inverter whine and engine obviously loaded - to surmise that yes, it really was charging - which is what the car display says too.
One wonders if MyVolt will attempt to report over 100% charge later today since it's not counting the roughly 20% charge I got off the ICE in maintenance mode!

 

[dwl]

That's actually really interesting. I think if what's happening can be explained, it'll provide some useful insight into the vehicle's reporting function. It'll also be interesting to see if/when/how it corrects itself. I'm betting the reporting mechanism isn't allowed to go below 0%. So when the battery is fully depleted, it'll be synced again.

 

[Bzzzt]

Fascinating observations, DC.

I'm sure you've noticed how it sounds more like a diesel at idle than a gas engine. I'm sure that has something to do with running it at WOT - how many people have really stood next to an auto engine running wide open, and for the most part, with a full (or heavy) load on the engine.

Neat to know that the engineers are not letting even the smallest bit of fuel be totally wasted.

BTW, some of us out here are counting on you to void your warranty and see if you can turn the Volt into a 60kw gen set. Maybe the engine cooling can't handle that with no air movement, but I'd settle for 10-15kw. Bet there's folks in hurricane or spring ice territory that would love that. No more stale gas or gunked up carbs.

 

[DCFusor]

Thanks for that, Bzzzt - in fact I'm in contact with GM now and trying to get an NDA and some info that would make the genset idea really practical from a business sense - for either me or them. I'm not worried about the warranty as long as I don't actually break the car. But my time is worth something, and reverse engineering this thing is not something I want to have to do, and shouldn't have to in this case. Frankly, in a complex system, RE'ing is much more work than designing a better one from scratch, though perhaps the resulting product isn't as inexpensive. It would not be very difficult to design and market a 20kw class inverter to run off 360v DC if the only info I had was how to tie it in and fully maintain the car's existing battery monitoring and control stuff. Which could be as simple as "hook here and ensure the car is on while using it". But I can't know that without a little help from GM.

Your comments and some others should help me push GM along into making some sort of deal so that genset thing can actually happen for us all. Personally, I'd not want to push it - 20kw class should be enough for all but the most extreme cases, same idea as them choosing a battery size that satisfies most, but not all - the old saying "get 80% of the results for 10% of the input" seems applicable here as well.

Haven't seen the schiz, but I sort of doubt one would want to mod the existing motor inverter for that. It's just a different class of problem than a VFD for a motor. The existing inverter/motor driver doesn't have to handle the slings and arrows of whatever weird load might be hooked to it - or suddenly removed - it works in a very well controlled set of circumstances, so if it's efficiently designed, will lack a bunch of things a home genset needs to survive, well....dumb home-owners who aren't EE's and who don't understand how to control things like inductive load dumps, lightning hits to the house - proper isolation from the power company, having every compressor in the house trying to start at once when power is re-applied after the grid went down...it's a long list.

This list is well taken care of by some of the professional home solar inverter companies, however. A possibility might be to simply broker a deal between one of them and GM to get something really good on the market, quickly and afford-ably. It's entered my mind as a ploy. While my own outfit would love to add a bunch of Volt related products - it's not the only way to get there from here.

FWIW, mine doesn't sound quite like WOT, in that condition (or when running in MM in the driveway before I turn it off) but it's definitely under a real decent load. I suspect they made a trade-off here between brutalizing the batteries and best BSFC.
IN fact, in genset use, this would be an issue where close collaboration with GM and the basic original plan for the car would be key - you'd want the engine to work harder when your "genset" was drawing power to be more efficient.

FWIW, I just bought a J1772 connector and am in touch with the open source project on this - my goal there compliments the above one - I'm making a controller that will integrate properly with my solar system - so as not to brutalize my house batteries when the sun goes behind a cloud - real time charge rate adaptation is the plan, based on information provided by the home system. This would be a huge step up from the abysmally dumb 120v cord - which you can't change the rates on without going down to unplug the car, and can't even turn on and off via the input AC without having the car go into conniptions and honking the horn. So in re Volt stuff - that one's my top priority till it's done, which should not take real long, the standard is pretty simple if I understand it right.

Maybe a GM engineer can chime in here and tell us whether you can destroy the battery in maintenance mode by letting it run too long, I'd love to know without having to find out the hard way. During that mode, in the other bug I've reported, of course you cannot find out where the battery level is, without turning it off, closing the hood, turning it back on again...

 

[mfennell]

FWIW, mine doesn't sound quite like WOT, in that condition (or when running in MM in the driveway before I turn it off) but it's definitely under a real decent load.

A standard OBDII scanner will give you throttle position if you have one handy.

 

[solar_dave]

Haven't seen the schiz, but I sort of doubt one would want to mod the existing motor inverter for that. It's just a different class of problem than a VFD for a motor. The existing inverter/motor driver doesn't have to handle the slings and arrows of whatever weird load might be hooked to it - or suddenly removed - it works in a very well controlled set of circumstances, so if it's efficiently designed, will lack a bunch of things a home genset needs to survive, well....dumb home-owners who aren't EE's and who don't understand how to control things like inductive load dumps, lightning hits to the house - proper isolation from the power company, having every compressor in the house trying to start at once when power is re-applied after the grid went down...it's a long list.

This list is well taken care of by some of the professional home solar inverter companies, however. A possibility might be to simply broker a deal between one of them and GM to get something really good on the market, quickly and afford-ably. It's entered my mind as a ploy. While my own outfit would love to add a bunch of Volt related products - it's not the only way to get there from here.

Most of the Grid Tie inverters operate in that kind of DC Voltage range. I suspect it would not be to big a deal to get one to bypass the anti-islanding stuff and add a 60 Hz freq source to keep it synced to to get some decent output. Most are less than 10Kw in the standard residential class so a pair of them might be required. The MPPT tracking stuff would make little sense as well as a Volt would not have cloud effect or much voltage variation. The issue would be on controlling the output side to match the draw.

The off grid stuff is generally limited to 48 V input but even those manufacturers might be willing to look at a higher voltage input side. Like Outback or SMA sunny island inverters. Of course they would have to know there is a market for the product to get production quantities.

Perhaps it could be as simple as making a buck converter to lower the output voltage to 48-50 V and then using off the shelf inverter technology. I am no EE but that seems to make sense.

 

[DonC]

Great post. Very interesting. It may explain why my voltstats/myvolt MPG numbers are off. By the gas consumption reported by the car and the miles driven the MPG should be 700-800 MPG. But voltstats/myvolt shows 550 or something. I wonder if when testing before delivery the dealer ran it with the hood open and that changed the numbers. I haven't used that much gas, not even a tank, so being off a gallon or so would make a big difference.

 

[Bzzzt]

I'll certainly admit that if you give the average home owner a gen set, all manner of stupidity could result. So, there would have to be various failsafes involved, mainly to protect the Volt (and probably the homeowner too), really, at all costs.

My business does a fair number of events that require non-grid power for various reasons - because the grid ain't there. We currently have a terribly loud (but reliable) air cooled diesel gen set that's heavy and clumsy too. It would be nice to drive up with your gen set, plug in the 220v, and go right to work.

I imagine that the inverter would have to be fairly smart, but if designed right, it could use the battery for a 'buffer' and communicate with the Volt brain for engine speed / demand / current supply.

For the future, a VoltVan or S10 VoltUp would be a contractors dream- show up for work, plug in and go. Small gen sets tend to scurry off in the night if left unattended at job sites.

Maybe the question should be, what would the homeowner pay for this option, what would the business person pay for this option.

I think for something around 15kw, $1000 would be pretty easy to get for a business reason. Esp. if its one of those fancy sine-wave inverters.

 

[ctmaverick]

check out via motors. It's a Bob Lutz endorsed company. Only problem is the vehicle they have engineered cost 90k

 

[saghost]

For the future, a VoltVan or S10 VoltUp would be a contractors dream- show up for work, plug in and go. Small gen sets tend to scurry off in the night if left unattended at job sites.

Maybe the question should be, what would the homeowner pay for this option, what would the business person pay for this option.

I think for something around 15kw, $1000 would be pretty easy to get for a business reason. Esp. if its one of those fancy sine-wave inverters.

I was waiting until I got home, looks like someone beat me to the punch. Yes, VIA motors has your VoltSilverado this year, and VoltVan and VoltTahoe next year, for a price. They have a 300kW!! main drive motor, so even with all the weight they should be pretty sprightly. It probably isn't quite as efficient as Voltec in CS mode - even aside from weight, drag coefficient, and frontal area (pure series drivetrain like we thought the Volt would be,) and they definitely aren't cheap. It would make an awesome toy, though.

http://www.viamotors.com/

 

[DCFusor]

I knew about the VIA, but that doesn't do a thing for Volt owners - or help justify Volt sales...when it could if done right.

 

[tboult]

A standard OBDII scanner will give you throttle position if you have one handy.

I'm using a generic OBDII bluetooth + torque on an android phone and use it to measure not jsut throttle, but temps and battery SOC. (Still looking for other stuff). But with the SOC should be easy to tell if you are over charging. I may do some tests on trying to replicate/measure based on your post (if noone with a dash-daq does it sooner).

(Actually also want to do it so I can find that darn thermostat so I can disable "engine running due to temp")