More Cold Weather Questions
Hybrid and Ethanol Expert
Joined: Mar 2005
Posts: 3,616
From: All over the Central U.S.
Re: More Cold Weather Questions
M/E coolent is "allowed" to be as hot as the engine... but it usually is much cooler. In summer, with lots of use, I've had mine to 190-200 degrees.
I take that back, I've had my electric motors that hot, M/E coolent, 160'F.
The electric motors themselves can tolerate more heat than the combustion engine.... 400'F. That's right, 400'F. Unlikely your car will ever see that.
They are definately, "industrial strength"!
-John
I take that back, I've had my electric motors that hot, M/E coolent, 160'F.
The electric motors themselves can tolerate more heat than the combustion engine.... 400'F. That's right, 400'F. Unlikely your car will ever see that.
They are definately, "industrial strength"!
-John
Thread Starter
|
Ridiculously Active Enthusiast
Joined: Nov 2006
Posts: 773
From: Colorado Springs
Re: More Cold Weather Questions
I'm on Day 3 driving the MMH with the grill block and last night I plugged in the heater WITHOUT the timer so it was on all night. The coolant temp was 93 degrees vs the 85 on Monday. My batter temp (programed in the SG last night) was 44 degrees (same as the ambient temp in the garage) so it doesn't look like the '08s have a battery warmer.
Today, I went into EV about 2.5 miles from the house, although the ambient temp was 21 which is about 15 degrees warmer than yesterday. I was able go into EV several times actually and my mpg was 30.3--noticably better than the pair of 27s I had Mon-Tues.
Obviously, it doesn't make sense to keep the heater plugged in all night when I have a timer, but I wanted to see what a full night's heat did to the EV. It doesn't look like the 3.5 hours of heater that I gave it on Monday was enough to get things warm and toasty.
Today, I went into EV about 2.5 miles from the house, although the ambient temp was 21 which is about 15 degrees warmer than yesterday. I was able go into EV several times actually and my mpg was 30.3--noticably better than the pair of 27s I had Mon-Tues.
Obviously, it doesn't make sense to keep the heater plugged in all night when I have a timer, but I wanted to see what a full night's heat did to the EV. It doesn't look like the 3.5 hours of heater that I gave it on Monday was enough to get things warm and toasty.
Ridiculously Active Enthusiast
Joined: Nov 2007
Posts: 720
From: Southeast Coastline
Re: More Cold Weather Questions
I can't help but wonder if a small electric blanket placed on top of the HV battery case and ran in parallel with the EBH would work.
I don't get real cold weather (70degF and sunny here today), otherwise I'd try it myself.
I don't get real cold weather (70degF and sunny here today), otherwise I'd try it myself.
Ridiculously Active Enthusiast
Joined: Mar 2006
Posts: 1,401
Re: More Cold Weather Questions
M/E coolent is "allowed" to be as hot as the engine... but it usually is much cooler. In summer, with lots of use, I've had mine to 190-200 degrees.
I take that back, I've had my electric motors that hot, M/E coolent, 160'F.
The electric motors themselves can tolerate more heat than the combustion engine.... 400'F. That's right, 400'F. Unlikely your car will ever see that.
They are definately, "industrial strength"!
-John
I take that back, I've had my electric motors that hot, M/E coolent, 160'F.
The electric motors themselves can tolerate more heat than the combustion engine.... 400'F. That's right, 400'F. Unlikely your car will ever see that.
They are definately, "industrial strength"!
-JohnStill... I'd bet (as long as everyone is into pushing for 0.1-0.2MPG, that if you could somehow block your main ICE radiator, but allow the M/E coolant to get cold, you'd squeeze out a little TINY bit more. Considering the improvement in the motor winding resistance with temperature and the efficiency of the DC Converter. I'd bet you don't want the motors ICE cold because of bering friction, but somewhere there is probably a happy medium.
Ridiculously Active Enthusiast
Joined: Sep 2006
Posts: 1,678
From: Beautiful Pacific NW
Re: More Cold Weather Questions
Now... I agree with that, with the following observation. In stop and go driving you'll find that the Electronics temperatures go up pretty quickly with the grill fully blocked. I've never seen them over 100F... but how high should they go? AND is the an advantage to keeping them much lower?
While an engine is more efficient at warmer temps, electronics for the most part (the DC converter, and the electric motors) would like it as cold as possible.
"like it as cold as possible..."
Semi-conductors increase "parasitic" leakage resistance as they get cooler, get them TOO warm and the current leakage gets so great as to make the semi-conductor aspects non-functional. POWER control/switching solid state components, power transistors, will often FAIL at elevated temperatures. The upper temperature limit is more likely "set" by the electrolytic filter capacitors more than any other component.
It's not likely the electronics will get cold enough here on planet "huston" to be a problem.
The battery needs to be warm, but not the electronics, hot electronics have increased resistance and losses.
It brings two questions:
- Is 100F too darn hot for the MeC (motor electronics coolant)?
- If its okay...If one were to block the radiator for the ICE but somehow NOT block the heat exchanger for the motor and electronics could one squeeze a bit more MPG out of the system?
I'm presuming there are two radiators for the systems, they operate at different temps and pressures so there would have to be. I think a full size radiator for the ICE and probably a small heat exchanger (a transmission cooler repurposed for it?) for the electronics. Its too darn cold tonight to take a look but I'm curious.
While an engine is more efficient at warmer temps, electronics for the most part (the DC converter, and the electric motors) would like it as cold as possible.
"like it as cold as possible..."
Semi-conductors increase "parasitic" leakage resistance as they get cooler, get them TOO warm and the current leakage gets so great as to make the semi-conductor aspects non-functional. POWER control/switching solid state components, power transistors, will often FAIL at elevated temperatures. The upper temperature limit is more likely "set" by the electrolytic filter capacitors more than any other component.
It's not likely the electronics will get cold enough here on planet "huston" to be a problem.
The battery needs to be warm, but not the electronics, hot electronics have increased resistance and losses.
It brings two questions:
- Is 100F too darn hot for the MeC (motor electronics coolant)?
- If its okay...If one were to block the radiator for the ICE but somehow NOT block the heat exchanger for the motor and electronics could one squeeze a bit more MPG out of the system?
I'm presuming there are two radiators for the systems, they operate at different temps and pressures so there would have to be. I think a full size radiator for the ICE and probably a small heat exchanger (a transmission cooler repurposed for it?) for the electronics. Its too darn cold tonight to take a look but I'm curious.
Hybrid and Ethanol Expert
Joined: Mar 2005
Posts: 3,616
From: All over the Central U.S.
Re: More Cold Weather Questions
The outside case is well insulated from the batteries.
Think 'Thermos' bottle.
This was never more apparent then when my A/C freon escaped this July.
My battery pack was getting hot, like 110'F and my EV was disabled.
I tried to get EV back ( as an experiment, totally impractical ) by placing 16 pounds of Dry Ice onto the battery case. Watching my ScanGauge for temperatures, the temperature didn't change by more than 1 degree in 1 hour.
And that's with a 200 degree temperature change on the case!
HTH,
-John
P.S. the good news is, it works the other way too.
If you get your battery warm from driving the car, and park for only a few hours, the battery will stay warm.
I drove and got my battery to about 60 degrees, then parked it at zero degrees for 12 hours. Upon my return, the gatoraide in my car was frozen solid, the inside of the car was zero degrees, but the battery pack was still 33 degrees.
Last edited by gpsman1; Dec 17, 2008 at 08:43 PM. Reason: P.S.
Ridiculously Active Enthusiast
Joined: Nov 2006
Posts: 1,747
From: Southwestern Pa
Re: More Cold Weather Questions
[quote=kristian;193705] so it doesn't look like the '08s have a battery warmer.
quote]
This is what has been seen on this site: Some 2008 models have the wire to the hybrid battery heater and some do not.
quote]
This is what has been seen on this site: Some 2008 models have the wire to the hybrid battery heater and some do not.
Active Enthusiast
Joined: Jun 2008
Posts: 239
From: O.C. Ca.
Re: More Cold Weather Questions
If I was not one week and 5000 miles away from my FEH... I would take a pic right now for you... If in that time no one does... I'll do it for u....
