I finally built a radiator block over the weekend and put it on the MMH. I made a "quilt" out of heavy denier nylon and batting that you would use to make a pot holder. It blocks the huge upper grill, the middle grill and it leaves the bottom grill open. It looks really nice, and it did a great job of keeping the temps up in the 160-180 range during the sub-zero temps this morning.

However, I was still really disappointed with the EV performance today! I plugged in the block heater so the timer started at 3:00am. When I left at 6:30, the coolant temp was 85 degrees and I quickly got into the 150+ range once under way. After hitting 180, I got about a half mile of EV before it went down to 160, and then I didn't get EV for the rest of the drive (about 2 miles of downhill).

I assume this is caused by a cool battery right? What is the best way to warm the battery up on a cold day? How would I confirm that my '08 block heater has a battery warmer? The block heater was installed after purchase by my dealer. Any other tips for driving in the frigid cold?

 

Wrap the ICE iself in an insulating blanket..??

I don't know how the ICE coling system works but allow me a couple of assumptions.

With a standard mechanical thermostat.....

So as to have a reasonable level of sensitivity most thermostats of this type have some level of bypass so some coolant flow, CONSTANT coolant flow, always exists. Otherwise the coolant within the engine block could get TOO hot due to the thermostat never opening.

If I were trying to do "this" I would modify the thermostat "circuit" such that it opened on a somewhat regular basis, say using an electric solenoid. Another approach might be to bypass the radiator flow via a solenoid bypass.

 

If you don't have a scanguage II, then obtaining this device can help share information on various hybrid items.

 

I am currently in NW Nebraska, and am in similar weather.

The daytime high was +1 degree, night time low was -16 degrees F.

I'm staying in a hotel, but lucky for me, there are outside 120v outlets.

I was plugged in for 12 hours, ( car outdoors ) since I didn't have a timer.
When I went out at noon ( +1 degree ) my engine water temp was 71 degrees and my HV battery pack was 57 degrees before I turned the key.

I was in EV mode in 2 miles, and using EV warmed the battery pack to the mid-60's. I could use the battery from 53% to 46% about 1 EV mile, then the engine came back on, because the cylinder head temperature dropped to the minimum allowed. A 30 second run with the gas on heated things up, and I could use EV again.

A cold battery does not turn off EV.

A) A cold engine ( cold cylinder head ) will turn off EV
B) A cold catalyitic converter will turn off EV

A usually happens before B even at zero degrees F.

A cold battery reduces the amount of amps, or EV power you get.
2 nights ago I forgot to use my plug-in heater.
My HV battery was 23 degrees, and my amps allowed were 33 amps.
A warm (85 to 95 degrees) battery pack will put out 70 amps.

HTH,
-John

 

I was going to post some of my cold weather observations, not that I have a SG this year so I guess I'll just add to this post.

I was in to big a rush to install my garage door opener while it was still 70 to work on a radiator block But at least I can finally ger Li'l out of the wet (insulated but non heated garage).

So the first thing that happened was the 2500 rpm no matter how hard you were pressing the gas. Even reaching 150-160, I was not able to get EV. I remember the rpms from last year, it took nearly 15-20min to get a hint of EV, then only twice for short bursts. My SG won't read Batt Temp.

Tonight I was amused. I forgot I shifted into L, and was coasting to a light. 2500 rpm, quickly droped to 1000, almost droped off, then 'danced' around up to 1500, 2200, 1800, finally came bak up to 2500 (as the light changed to green of course).

So cold has a funny effect on our FEH's. I don't have a plug in heater, and for the few days and short drives I make, it's not worth the investment.

I may try to find a way to block the radiator tho, but afraid to since it can be both 70 & 17 here in a few hours!


wwest: I think it's on this board, I can't remember, there's instructions for installing some sort of bypass for the coolant. I don't recall where, or what the resulting effects did, but i do recall reading it. It might be for summer and by passing the heater core tho.

kristian: Sorry don't have any advice on how to confirm a batt heater was included (I think I saw a post with some pics, under the back seat carpet are a few plugs, 1 is the heater, but think that's <07). One other thing to remember is, even dropping below EPA Mpg is still better than a non FEH!

 

After yesterday, I didn't plug in this morning for comparison sake (BTW, I park in a non heated garage and temps were in the low single digits today--about 7-10 degrees warmer). I got the same small segment of EV and that was it. Overall, I got 27.2mpg yesterday and 27.1 today, so it is hard to say if the block heater makes any difference for my 10 mile suburban commute.

I am happy about the radiator block though--it definitely helps keep the temps in the 160-180 degree range, and I don't feel as guilty about using the heat when I drive! I left the bottom grill open, and I'm hoping that will be enough air flow to safely drive in 60 degree temps at highway speed.

Like you, I can't tap the gas without the tach being at 2,500 rmps, and it idles about 1,400 which seems high to me. I have the same "L Dancing" and it is a litte weird to me too--I wish I understood what was going on there because it doesn't seem normal. I hardly use L anymore because of it.

I think I'll add in CHT and see if that is what's causing the EV to stop so fast--thanks for the tip gpsman1.

 

I think it's on this board, I can't remember, there's instructions for installing some sort of bypass for the coolant. I don't recall where, or what the resulting effects did, but i do recall reading it. It might be for summer and by passing the heater core tho.


You are referring to what GaryG created with his heater core bypass to allow the airconditioning to run cooler. There are photos here and at cleanmpg.com

 

In the past I have often recommended going to Home Depot and buying/installing a manual water flow shutoff valve to combat the effects of radiant heating within the HVAC plenum area.

Is that of which you refer...??

 

Gary G, who will no doubt, chime in at any moment, put a U shaped hose on his heater core, and looped the engine coolent over onto itself, ( or did he plug it, not sure, but has the same effect ) so no engine heat passed through the heater core assembly in mild Florida.

Why?
A) to keep more heat in the engine for long EV periods
B) to keep the cooling system, cooler, since the air blend door is not 100% air tight.... a little heat will slip into your A/C cooling during summer. This keeps the "recirc" mode cooler a little longer in EV mode.

P.S. I have my lower grille open, since I do a lot of highway driving where the engine is really working. If you drive at slow speeds and have lots of stop & go, you should block off 100% of the radiator for best results.

P.P.S. in sub-zero conditions, my RPM's will go down while decelerating to a stop. Then at a stop, it will idle at about 1700 RPM without my foot on the gas at all.... presumably... to keep the engine hot??? Or the computer is really confused with dense, -15'F air!!! ( I've seen this for 4 winters now )

 

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. 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.