We tend to group "the brakes" to include the friction brakes on the wheels and the regenerative braking coming from the traction motor. They operate in concert so it's hard to think about them individually.

What scares me is the 12V to 300V jump start proceedure in the owners manaual.

I can't believe that would actually work.

Anyone want to test it for the group?

Chris Brown

Chris, I don't think anyone would let there FEH sit for months to drain the high voltage battery to test the jump start system. If the high voltage battery suddenly went bad, a jump start with the 12 volt battery would only be temporary to get to the Ford dealership.

I agree, this is a feature to give Ford credit for. I would try it in a minute.

I am so impressed with my FEH and I can't believe I got it at the price I paid. I pay more for my kid a to attend MIT for one year ($43,000). I wish I could afford to buy him one, but soon he may be able to afford to buy his own. Hats off to our gifted engineers. This is rocket science used in the automobile finally.

Lets make OPEC understand we have the brains and don't forget it!

From what I've read in the service manual it doesn't actually charge at 300V. There's additional wiring in the battery that allows the low-voltage charger to charge the groups of cells in parallel which allows a lower voltage to be used.

Thats not what I read in the service manual steve. I understand that the 12 volt battery dumps its charge in the High voltage battery as a one time attempt to start the FEH engine. Jump starts from other vehicles to the 12 volt battery system can be made also to charge the high voltage battery to FEH for a start up.

Actually, you get two tries...there's enough capacity in the 12v battery to run two cycles of the jump-start system.

Of course I can't find the detailed info on the HV battery I got this detail from, but from what I recall inside the battery each tube of cells (I think it's 5 cells to a tube) is individually monitored and wired to the jump-start charger. When you push the jump-start button it charges all of the tubes (I don't know if it does them simultaneously or sequentially) to a pre-determined value, which is just enough to start the engine. It also provides heat inside the battery pack to get the cells closer to optimal operating temperature.

So for normal operation, the battery cells are wired in series, but for the jump-start operation it's parallel. If you think about it this makes sense as the system can reduce the change of reverse charging a cell, which is especially likely when the battery is nearly flat.

I know one person on the Yahoo board has experimented with the jump-starter trying to use it to boost his battery for extended EV use. Of course, it doesn't put enough power into the HV battery to make a significant contribution.