Starting with dead battery

[olderbudwiser]

Noticed a thread about a Hybrid that wouldn't start at dealer.

So searched bit and could not find my answer. I really know nothing about Hybrids. But in olden times automatic transmissions had 2 pumps so you could push an automatic transmission car to about 25-30 mph put it in D and engine would turn over much like a manual transmission car.

Since a Hybrid has no torque converter I think, could these be pushed to a certain speed and turn the engine over?

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[clavicus]

Noticed a thread about a Hybrid that wouldn't start at dealer.

So searched bit and could not find my answer. I really know nothing about Hybrids. But in olden times automatic transmissions had 2 pumps so you could push an automatic transmission car to about 25-30 mph put it in D and engine would turn over much like a manual transmission car.

Since a Hybrid has no torque converter I think, could these be pushed to a certain speed and turn the engine over?

In the planetary gearset of the eCVT, the generator motor (sun gear) is has to have power supplied to it to turn it faster than the ring gear to turn the planet carrier (ICE crankshaft). The ring gear is tied to the wheel rotation, essentially. The sun gear rotates freely as fast as the ring gear, but without extra input to resist or propel it’s rotation, it will also stop with the ring gear if the the planetary carrier is also stopped. It’s hard to visualize the planetary gearset in your mind’s eye. At least for me, it took a long time for me to get a model of it correct in my brain.

Anyway, if the HVB cant do it from a stopped position, I don’t see how it would do it from a rolling position.

 

[olderbudwiser]

In the planetary gearset of the eCVT, the generator motor (sun gear) is has to have power supplied to it to turn it faster than the ring gear to turn the planet carrier (ICE crankshaft). The ring gear is tied to the wheel rotation, essentially. The sun gear rotates freely as fast as the ring gear, but without extra input to resist or propel it’s rotation, it will also stop with the ring gear if the the planetary carrier is also stopped. It’s hard to visualize the planetary gearset in your mind’s eye. At least for me, it took a long time for me to get a model of it correct in my brain.

Anyway, if the HVB cant do it from a stopped position, I don’t see how it would do it from a rolling position.

Kinda like how fast would a treadmill have to spin so an airplane the off?

Having a hard time trying to visualize all that.

 

[icegradner]

To put it in more simple terms, a hybrid cannot run without a functioning electric system. If the HV battery is dead, and you are on the side of the road, you'll need a tow truck.

 

[fbov]

No, you can't push-start a TRW PSD drivetrain. (Although you could...)

Remember that a hybrid's Li-ion batteries live between ~15% and 90% charge level. The control system will tell you the HVB is "dead" long before it's unusable. The critical bit is that 12v is mandatory to access the HVB. Once booted, the HVB will maintain the 12v battery.

And then there's this.... A 1.1kWh battery is also a 1100x3600 = 3,940kWs battery
Electrical energy is conventionally measured as "kilowatt-hours." But we use the HVB for fraction of a minute, so I find it useful to look at HVBs in terms of "kilowatt-second" capacity.

If it takes 10kW to turn the "starter" and we crank the ICE for 5 seconds, we use 50kWs.
At 15% charge, we have 594kWs of energy left. Starting needs less than 10% of that.

Push-start is possible, but greatly disadvantaged. You could use the control system to hold the charging motor at 0 RPM, so moving the car would turn the ICE, but electric motors are all current limited at 0 RPM, so that would take a lot more power than it seems. Far easier to spin the ICE with a big motor and battery.

 

[olderbudwiser]

No, you can't push-start a TRW PSD drivetrain. (Although you could...)

Remember that a hybrid's Li-ion batteries live between ~15% and 90% charge level. The control system will tell you the HVB is "dead" long before it's unusable. The critical bit is that 12v is mandatory to access the HVB. Once booted, the HVB will maintain the 12v battery.

And then there's this.... A 1.1kWh battery is also a 1100x3600 = 3,940kWs battery
Electrical energy is conventionally measured as "kilowatt-hours." But we use the HVB for fraction of a minute, so I find it useful to look at HVBs in terms of "kilowatt-second" capacity.

If it takes 10kW to turn the "starter" and we crank the ICE for 5 seconds, we use 50kWs.
At 15% charge, we have 594kWs of energy left. Starting needs less than 10% of that.

Push-start is possible, but greatly disadvantaged. You could use the control system to hold the charging motor at 0 RPM, so moving the car would turn the ICE, but electric motors are all current limited at 0 RPM, so that would take a lot more power than it seems. Far easier to spin the ICE with a big motor and battery.

I was just curious if one finds themselves in a desperate situation. Not something to do for fun.

 

[BILLNOROVILLE]

My wife's Prius died at a school parking lot. The 12volt battery was dead. A set of jumper cables would have probably got it going but I did not bother. In less than 10 minutes on the phone, I located a suitable quality replacement, took it 30 miles to her car (25 minutes) and changed out the batter (10 minutes). Fixed. I would have never tried to push start her Prius. Too much to break if you are wrong.

 

[olderbudwiser]

My wife's Prius died at a school parking lot. The 12volt battery was dead. A set of jumper cables would have probably got it going but I did not bother. In less than 10 minutes on the phone, I located a suitable quality replacement, took it 30 miles to her car (25 minutes) and changed out the batter (10 minutes). Fixed. I would have never tried to push start her Prius. Too much to break if you are wrong.

I don't know enough its why I asked. There are some pretty smart people on this forum.

Back in the olden days two of us could push a manual transmission car fast enough (bad battery) you jumped Put it in 3rd popped the clutch motor starts shift down to first and off you go. At 16 who had money for a battery!

 

[taralon]

Although I do not currently have a Maverick (awaiting a AWD hybrid version and doing research), my family does own 2 Ford Fusion Hybrids, a 2010, and a 2018.

One thing to keep in mind that is different from a convention car vs a Hybrid, is that although both do have a 12 volt battery, in the Hybrid, this is not used to start the motor.

The 12 volt battery in the hybrid is used to power accessories when the vehicle is in the accessory mode, and to close the relay that connects the HVB (high voltage battery) to the HVB power system. When the car is 'off' or in 'accessory' mode the HVB is disconnected. This is to protect it from being drained.

If the hybrid did not start on the lot, then likely the issue is that the 12v battery did not have enough power to cause the relay to close, or very unlikely, someone ran the HVB charge down too low and left it in accessory mode for way too long. A bad 12v battery causing starting issues is actually a fairly common problem in hybrids, especially older ones as it is possible to have a battery that would have long failed in a normal car continue to be used in a hybrid. My 2010 Fusion Hybrid when purchased had a 12v battery that was 7 years old and failed a battery check test. It still worked ok as long as you immediately turned the key from 'off' to 'on'. If you let it sit in accessory for even 10-20 seconds it would fail to close the relay, resulting in a car that failed to start until you turned it 'off' for 15-20 minutes. I recommend that with a Hybrid you get your 12v battery tested every couple years, to make sure it stays in good shape, as unlike a normal car there is not a lot of indication that the 12v battery is on the way out (slow cranking, hard starting/etc).

A small jump battery (including those that plug into the cigarette plug) will easily give you enough power to 'start' a hybrid, as long as the HVB even has a minimal charge in it. It is highly unlikely that you will ever encounter a situation that results in a dead/flat drained HVB and if you do, unfortunately towing is the only option.

Additionally, you don't really have to worry much about leaving the car parked for long periods of time. During the initial 'shutdown' due to covid in 2020, our 2018 Fusion Hybrid sat without running for 3 months, and had no issues with starting when we finally got around to driving it.

 

[Davidc83]

As I tell non-hybrid owners, you don't start a hybrid, you turn it on. The 12v battery turns on the electrical system, the electrical system connects the traction battery to the electrical motor which starts the gas motor when needed...by the way, never jump start a non-hybrid with a hybrid.....the electrical system of a hybrid was never designed to turn over a starter of a gas only car.

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