GM's new Volt

Alternative energy sources
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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

Re: GM's new Volt

Postby Doug Coulter » Sat Nov 19, 2011 1:37 pm

Ah, picked up the terminology from Wiki. Here's the link you were too lazy to put in. The Volt just uses the normal cycle, but is highly optimized in other ways (variable cam timing separately for intake and exhaust, super high compression ratio, advanced generator with variable torque/speed/output electronically controlled) so it does a more than decent job - the thing gets better mileage on this engine, without the turbo, than the Cruze which weighs less due to that. I'll vote for the simpler engine myself - if I'm going to have weird linkages, I'd rather have them in the lower torque parts (cam drive).

I found the paper that describes the SAE standard for chargers. Well, charger is a misnomer - glorified extension cord is more to the point, there's very little in one of those, they could be made FAR cheaper than the $400-800 they are getting for them. If I can get one of the connector vendors on Alibaba to ship me a few, I'll start making them, one heck of a lot better and cheaper than the manufacturers do. I note on http://gm-volt.com/forum/index.php that a lot of the people who own these, like me, are running on solar PV systems and using them to charge their Volts.

Well, then - I'm no longer such a weirdo, or at least I have a lot of company at it. I'm using the Volt as a diversion load, as all my charge controllers have fried - at present all I have is this big knife switch to take the panels offline, not so great, and I'll be making something better soon, but till then it seems nicer to switch in the Volt than to switch out the panels. There's just one thing - the supplied GEC (glorified...) only has two draw settings, and in fact the standard says this is infinitely variable and in real time. Would it not be much nicer to have it adjust the charge current to maintain the battery voltage, when possible? Further, my 120v inverter can go a lot more amps than their max at the moment - they limited it to what a standard NEMA 120v outlet can do, and in the case of GM's thing - only use 16 ga wire, yuck.

The paper implies that I could use something like a PIC uP to generate the signals required to talk to the car. Looks darned easy - pics even have built in programmable PWM outputs which is how you talk to the thing. So a pic and a quad opamp, and if I go the safe route, a big relay - that's pretty much all that's needed other than a +/-15v power supply for the opamp to make the +/- 12v signals required for this (and 5v for the pic). If I should use the same board we use in the std counter - I'm almost done before I begin, and I get USB on top, so my home computer network can get involved to set settings (or use the RS232, whatever I feel like, and I could easily enable both). This would let me do charging at whatever current I want to hold the house batteries at whatever voltage I want to hold them at - at least until the Volt itself is charged and stops drawing current, which doesn't look like an end-of-the-world hard to solve problem.

So I guess I have a PIC project to do, a little fun one. The built in a/d can handle all the sensing with a feed from my house batteries to monitor those. It could send a signal to pull the panel switch too once the car is up to charge.

One thing I found out last night is that the Volt will draw power from its batteries when it gets cold enough outside (we had 20 F last night). So it wouldn't mind staying plugged in most of the time to make up for that. Also, if you remote start it with the climate control turned on, it will use house power to warm (or cool) the cabin for you so as not to use its battery up before you leave. A nice feature around here - I'm rarely in a super-rush to bolt out the door and go, I usually have a bit of warning, and getting into an already warm car is kind of nice. This will do that with a lot less energy waste than idling an IC engine as it stops drawing power when it gets to temperature.

Now to try and sucker some guy in China into sending me sample quantities of those fancy connectors. They usually only like to sell a shipping container of junk per (the type you can live in).
But we'll see - they can't be selling that many as there just aren't that many of these cars out there yet, they might be workable with.

finalsaej1772.doc
SAE spec on EVSE charging equipment - most of the work is in the car, this is pretty simple to do.
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Re: GM's new Volt

Postby chrismb » Sat Nov 19, 2011 2:43 pm

Doug Coulter wrote:Ah, picked up the terminology from Wiki. Here's the link you were too lazy to put in.


:? ?
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Re: GM's new Volt

Postby Doug Coulter » Sat Nov 19, 2011 3:43 pm

Atkinson vs Otto.
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Re: GM's new Volt

Postby Doug Coulter » Tue Dec 06, 2011 2:31 pm

One thing I'm not impressed with so far is the cheezy (but expensive) charger cords GM makes available - you get one free, but the rest, oh my god. It's nothing more than a glorified extension cord with some error detection and a series relay for safety. It generates a pilot signal to tell the car when and how much current to draw from the mains, and that's pretty much it.

The free one has two speeds - that's it. You can't change speeds without physical plugging and unplugging the car plug (not just switch the AC to the whole mess, that results in horn beeps).
The SAE spec doesn't require that at all - it's supposed to be continuously variable, and that's what I want for a diversion load. So I've ordered one of those expensive (for now, they're not sold retail easily) plugs and will do my own. I mentioned this on the Volt forums, and some guy came back with this link right off:

http://code.google.com/p/open-evse/

Hey, open source rules again! Even his code makes sense. This one doesn't do what I want, which is to vary the drain based on the status of my excess power input from the solar panels, but our little PIC board from the standard counter could do this, and that's what I'll be doing. Very cool - most of the work is done in the car, this just tells the car what to do.

Here's a link to the SAE spec too (I'm doing this so I can find it all again easily).
finalsaej1772.doc
SAE EV charging spec
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Re: GM's new Volt

Postby Doug Coulter » Thu Jan 05, 2012 9:26 pm

I now know more about the heating situation. It could be an issue, but for me it's not making trouble. In full blast heating in "comfort" mode, it uses 7kw which is way too doggone much. However, in that mode the cabin gets nice quick, and the draw goes way back down quick, so not really that bad - but it might take a couple miles off the all-electric range.

The heated seats draw diddly (under 50w) but will blister your butt. Good (and you can adjust how hot they'll get). I'd kill for a heated wheel. It's not my butt that gets numb in the cold!

If outdoor temps get below 25F, it will command the IC engine to run to help heat the batteries, rather than run them down to heat themselves. Some on the Volt forums complain about this, but I like it, as the IC engine heat can also feed the cabin heater and it's frigging glorious - and it only runs a couple of minutes. In fact, since I don't always get to fully charge the car off spare solar in the winter, more often than not I can command the IC engine to run a little bit right out of the driveway in mountain mode, enough to heat the cabin quick, then go back to pure-electric mode with 15 miles or so range before it has to run again. This works well for me, and typically only uses a couple of cups of gasoline - not worth worrying about except to a real purist. This cabin is much better insulated than most other cars, so it stays pretty warm in there for a long time - so when the IC engine cuts out, I just turn off the heat.

I almost got caught up in the hypermiling fringe that surrounds this thing, but a little driving in sport mode cured me - this thing eats that river road even better than the Camaro, except of course on the straights. Doggone it, yes, you can really stretch the range if you drive super slow in cruise and max regen mode. But that's excruciating for a car guy. My best range so far is 45 miles in granny mode. It goes down to around 30 if I drive it like the sports car it is - worth it! Especially since 3/4 of the year my fuel cost will be precisely zero, and no heat will be needed anyway.

Looks like I'll be needing a new avatar - this is in, the Camaro is out, and I'm very happy this way.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: GM's new Volt

Postby Jerry » Fri Jan 06, 2012 12:46 am

Something, somewhat related to all of this is a patent a friend of mine has going though. A few years ago he designed a board that attaches to the LiPo cells they are using in vehicles and bikes. It directly controls the charging of each cell individually in real time. Where the charge controllers in vehicles now charge the pack and then level the cells, his device levels the cells as they charge. This cuts the charge time down significantly and also has increased the useful life of the pack of something like 3 or 4 times. The circuit also only draws on the order of microamps so there is almost no bleed down like conventional monitoring circuits.

The application:

http://www.google.com/patents?id=wG3NAA ... &q&f=false
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Re: GM's new Volt

Postby johnf » Fri Jan 06, 2012 3:53 am

Hey Doug
I saw a clip in our local newspaper about the GM volt battery packs not being crash safe.
GM says they are halting production until their Korean battery supplier modifies the packs ( hyundai I think) Lost the paper snippet during xmas cleanup.
Could be a case of letting them put a new battery pack in and saying you will dispose of the original for them
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Re: GM's new Volt

Postby Jerry » Fri Jan 06, 2012 6:55 am

I think two spontaneously caught fire something like two week after a crash test. Thats the problem with lithium.

I don't know how they will modify the packs. Maybe more padding around the cells.

My friend has also had pretty good luck rebuilding prius battery packs. Usually just one cell is bad to kill a pack.
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Re: GM's new Volt

Postby chrismb » Fri Jan 06, 2012 8:40 am

http://www.examiner.com/green-transport ... an-akerson

The problem was discovered in crash testing earlier this year when a Volt caught fire 3 weeks after its crash test. In November NHTSA did further tests of just the battery packs and were able to replicate fire conditions. The test reports indicate the test conditions involved extreme damage to the car (enough to damage pack's structural integrity) and involve the car rolling over.


The advice being - don't go rolling your car over.... :?
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Re: GM's new Volt

Postby chrismb » Fri Jan 06, 2012 8:47 am

Doug Coulter wrote:In full blast heating in "comfort" mode, it uses 7kw which is way too doggone much. ... I'd kill for a heated wheel. It's not my butt that gets numb in the cold!

Figured...

Go look at motorcycle accessories. You can get yourself 12V heated gloves, battery powered or wired (up your arms!).
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