Bi-Directional DC-DC Confirmation

[Mike Dabrowski 2000]

I believe that the FEH button does charge the HV battery, and may run a heater as well(you measured it).The battery pack in the FEH is huge,and heavy. I have opened one up and carried one.
The 200 lbs+ of batteries(estimate) would take many minutes to heat up, with a large expenditure of the 12V battery capacity.
The Ford like the Prius, does not have the option of using the 12V to start the car like the Insight and Civics do, so my reading is that it charges the HV battery to the minimum SOC to crank and start the motor. A DC clamp on meter on one of the battery leads would confirm this.
The early Prius in Japan also had this type of 12V to HV battery charge system.
Here is one of the design advantages of the simpler IMA system with it's included 12V starter.

[gpsman1]

I think the battery "box" is ~200 pounds with most of this being fans, and electronics, and case.
I think the battery cells are ~50 pounds? What is your guess? Ford says 2 button press ( 16 minutes ) is typical to get the HV battery up to snuff. I'm not saying there is not a 330v step up. I am saying for sure this process heats the battery. -John

P.S. any SOC change is too small to register on the Ford SOC dash display... or like you say with grid-charging, maybe the electronics cannot keep track? But then again, personally, I have never had my car less than 20% SOC. ( and the dash is scaled to read 40-60% )


P.P.S. I have seen 31% SOC with a ScanGauge in my car, and others have had 24% SOC in their car, and the car would not change SOC with the "mystery button" in this range.

[gpsman1]

This turns out to be a good thought experiment.

Let's say you have a HV battery pack at -20'F.
Let's say you have 100Wh of 12v power to "spend".
Let's say you want to get your car started in the least amount of time, and must use the 330v pack.

Which will do the most good for you?
Which is easiest to do? ( may not be the same choice )

A) Step up the 12v to 330v and try to shove that into a -20 degree battery?

B) Use the 100Wh to externally heat up the HV pack so it becomes more useful at a warmer temperature?

I have all the questions.
I do not have all the answers!
-John

[gpsman1]

Originally Posted by Mike Dabrowski 2000

A DC clamp on meter on one of the battery leads would confirm this.

And I would love to be the first to try this... except... the HV battery needs to be critically low to test this. Not something any of us can just go out to the garage and test at will.

This is an "emergency" last resort button. The next step is calling a tow truck.
-John

[Mike Dabrowski 2000]

The ford uses "D" cells just like the Insight, but at 330VDC, there are about 250 of them. While the case does have fans, and cooling components, the majority of the weight is likely the cells them self and the supporting structure. No mater it is a heavy lift for 2 strong guys.
Don't spill any liquids in that rear area on top of the pack, as it would likely do some damage to the pack, as the seals do not look to be 100% water tight.

[IamIan]

Most D cell NiMH batteries are around ~160g each... at 250 cells... that is 40kg or ~88 pounds of batteries + the connections between the batteries + Enclosure + Electronics + Fans.... Sound like around at least 100 pounds of batteries to me.

[ElectricTroy]

Originally Posted by Armin

Caveat: In Insights the car can start off of the 12V starter, which it does at low temperatures, but has anybody ever seen this happen in warmer weather where it would presumably triggered by low charge in the 144V battery?

Yes. When the Insight's 12 volt battery goes dead, the insight's computer "forgets" how full the high voltage battery is. So rather than start off the HV battery, the computer assumes the HV == near-zero, and uses the 12V battery starter.

I have also seen the 12 volt battery used after a battery recalibration event (when the meter is reset to near-zero).

[joecvt]

Originally Posted by ElectricTroy

Yes. When the Insight's 12 volt battery goes dead, the insight's computer "forgets" how full the high voltage battery is. So rather than start off the HV battery, the computer assumes the HV == near-zero, and uses the 12V battery starter.

Maybe it has to do with different model types or years but if I disconnect my 12V then reconnect, my Insight still starts from the IMA even though the SOC shows zero bars. The only time I have seen it startup from the conventional starter motor is when it is like below zero degrees on the first startup in the morning.

JoeCVT = Just your average CVT owner

[IamIan]

Originally Posted by joecvt

Maybe it has to do with different model types or years but if I disconnect my 12V then reconnect, my Insight still starts from the IMA even though the SOC shows zero bars. The only time I have seen it startup from the conventional starter motor is when it is like below zero degrees on the first startup in the morning.

JoeCVT = Just your average CVT owner

I know when I had pulled the battery to rebalance it and the car did a recalibration that it still started with the IMA HV and not the 12V starter.... there are probably lots of little variables and who knows what the algorithm is in those control models... Still nice 12V starter back up feature... most HEV can not start or run without the HV battery.... The Insight can.