I was reading about the ability of some hybrids to "jump" themselves if the 12v battery dies using the traction pack. What is the exact procedure? Can a Honda do this?

Original thread:

http://www.greenhybrid.com/discuss/i...ion.10623.html

My 2007 FEH manual states you can re-charge the High Voltage battery by hitting a switch and taking amps from the low voltage battery. In order to jump the low voltage battery you need to use another vehicle for the jump. My question is which battery actually starts the car?

A Honda normally starts with the big "traction" battery and the IMA motor but can also start using a seperate 12v starter and the 12v battery if the big pack is drained.

I can't say for sure on HSD systems. I think the "traction" pack normally starts HSD equiped vehicles.

On the Prius, the traction battery is protected by three safety relays that are operated by the battery ECU. All of the ECUs require 12 VDC to run. However, once enabled, ICE operation is completely handled by the traction battery. The 12 VDC battery has only about 36 AH since all it has to handle are the ECUs and some 12 V. auxillaries.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

I don't have any idea what the answer is, but I'm posting because I'd be very curious to find out. How would you do it?

The procedure for jump-starting the TCH utilizing the 12 volt battery is given on page 305 of the owner's manual. It appears to be the same procedure used to jump start most cars.

For the Prius? Hummmm, let's make it a McGuyver challenge:

- 12 VDC battery is drained flat
- 273 VDC main battery pack is drained flat
- Swiss Army knife, metric tool box edition with VOM
- my Prius with 1 kW UPS

I would remove the main traction battery cover and rewire the batteries in parallel. Next, I would jack-up one front tire and wire the MG2 leads into a rectifier array using diodes from the disassembled inverter. I would turn the tire to generate the power needed to recharge the batteries to at least 45% SOC and reassemble the battery pack. Next, I would hook-up and recharge the 12 VDC auxillary battery to at least 12.5 VDC. Finally, I would let the car down and start it up.

Bob Wilson

ps. Alternatively, call AAA to tow the car to the Toyota service department and tell them, "It broke, fix it."

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Bob - cute. But in the post prior to yours I posted about jumping the 12 volt battery. I'm guessing the computers won't allow the hybrid batteries to drain down but don't know for sure. But if you leave some accessories going (radio, interior lights) perhaps its more likely to drain down the 12 volt battery.

Correct. The 12 VDC auxillary battery can be jumped like any other but take care about the polarity. I understand the NHW20 has a special, polarized plug but haven't seen it myself.

The one caution is to double check the polarity. All of the control computers are driven by the 12 VDC bus so reversal can be very expensive.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

I believe that running out of fuel typically preceeds HV battery discharge in Prius. We are supposed to be careful about travelling further in this EV mode.

Don't know if this applies to the other hybrid vehicle designs.

DAS