Crank generator or other solution for death 12V

whoops, sorry, forgot you were gen I. any who, you can try to start it after making the connections.

 

If the 12 V is dead, you only need to address the 12 V battery.
I'm pretty sure there is only one but it might be located under the back seat with no easy access points up front.......depending on what model you have.

If the traction battery is also dead........you're pretty much screwed.

 

I guess I read the "on each battery" as being: on the car's 12V battery and on the donor 12V battery. But I see I was making assumptions....

-Chap

 

agreed. tat's what this thread is about.

 

Primus, I've been wondering if we could manually stimulate the DC-DC converter to transfer energy from the HV to the 12v battery.

 

That's what it does anyway whenever the system main relay is clicked in. And all you need to click the relay in is ... a supply of 12 V.

-Chap

 

...or a manual shunt?

 

I just returned after parking my 2003 for 2 months. My plan was to have a friend start the car periodically, of course that didn't happen... On return the 12v was reading about 2v. I put it on a charger for 4 hrs and got it to 11.4 or so. Of course this wasn't enough to start, but it did show signs of life. I had a new garden tractor battery in the garage and thought what the hell. I managed to get the clamps onto the terminals with some coaxing. The car started immediately. I was skeptical and ran the car for 2 days with no anomalies. Living in FL, 230 amps from this $25 WM battery seems perfectly adequate, so I made it a permanent install. Hope this helps with the discussion.

 

Eureka! Take out the trunk and back seat trim, pull the cover off the live HV battery, bring a hunk of wire and shunt it across the 300-volt-carrying system main relay (if you're feeling civilized, shunt it across the resistor-guarded contacts first for long enough to charge the inverter capacitors, then quickly shift it to the resistorless pair), and voilà, no need for all the bother of getting a perfectly ordinary jump for the 12 V battery like everybody's grandma knows how to do, but hardly ever has to in a Prius.

Should this whole thread be subtitled "risk analysis as performed in an alternate universe"?

-Chap

 

Where are you going to shunt it FROM ?
It is called "Jumper Cables".

 

It won't......without some more details.
What does Florida have to do with it ?

 

Ok, so I was a little amused by this thread until about 30 minutes ago. I was taking the trash bin to the curb but the NHW11 wheels were cocked at an angle blocking access. No problem, I'll just start the car, straighten the wheels and get the trash to curb. But I couldn't find one of two sets of keys I keep on the coffee table. I grabbed the spare and started wondering what pants I was last wearing when I sat in the car and found the primary key set . . . in the lock . . . turned to accessory . . . no cabin lights.

After getting the trash bin out to the curb by other means, I reached in the glove box and discovered my emergency flash light was also dead. No problem, I went to the closet where we keep our AAA batteries . . . Oh yea, I need to get some more.

Well I've got the 12V battery on a 2A rate, charger. I've also got to swap the rear tires with the Yokohamas. Dawn is breaking so I'll finish this note and swap the rear tires. Then I'll test wheel well clearance by driving over some speed bumps at high speed to see if there are any interference issues. If no problem, I'll order the second, identical sized set and have Firestone mount them on the front wheels.

Every time this happens, I start thinking about a low-voltage, isolation relay on the 12V battery. The idea is when the voltage reaches less than 11.9V, isolate the 12V battery to preserve enough charge to start the car. Done right, it can also be a reverse connection protector to prevent burning out the controllers.

Later,
Bob Wilson

 

That's totally a thing.

Not to rub salt in, but how many times does this happen? And what's your choice of battery? How long do you think the keys were in?

-Chap

 

And how much additional risk of vehicle failure will result from this addition to the electrical system? Suppose the relay control circuitry decides to open the relay while the battery voltage is actually still OK. Or the relay coil just decides to burn out.

The relay contacts also have to be rated for the maximum current flow to/from the battery, so this is going to be a pretty big relay.

 

Though temps drop in FL in the winter, it's not like you need 700CCA in the northland when the temps drop. A week in and performance is no different than with the Panasonic that was in the car. Sorry if I should have started a new thread on this.

 

you're only turning on the computers, it doesn't take much amperage. it always seems to be a voltage and longevity problem.

 

Frequency . . . it happened about three years ago with the 2010 Prius when I left a dome light on. I just don't remember it happening before except when the original 12V battery was starting to go in a cold winter.

It was probably in that state from about 1:30 AM Thursday morning until about 6:00 AM Friday when I discovered it. Thursday we used my wife's 2010 Prius to run her around for various medical appointments.

I like the low-voltage protector but the 4 ma overhead is a little high. If I remember correctly, reports are that the parasitic load is already ~35 ma. I'd want to understand that part a little more before getting one. But for my wife's electric wheel chair, this might be a winner!

My understanding is the caps for the brakes and possibly the airbag system have a heavy, initial load.

Bob Wilson

 

If the little battery is anywhere near to being healthy, cold weather should not be a factor........as it does NOT supply a big surge of current to turn the starter like a conventional car does.

 

Only thing that cold temperature will change is how much current battery can take. So if you drive short distances and drain battery in between them (like listening the radio with key on acc or not driving car for long time (especially gen2 with smart key)) and it’s cold outside then your battery will slowly drain. In that cause you should charge it with external charger cause empty battery won’t start computer and if battery isn’t fully charged its lifetime will be shortened.

 

Somewhat but it has a greater impact on how much it can give BACK.

Your advice is good regardless of temperature.

Where you live it might get cold enough to make a real difference but most places it doesn't.