Make sure you practice opening the jumper port in the fuse box

That's assuming that the battery is completely dead. In that case, you don't want to "shock" it with a high amp charge, anyway. That would likely shorten tle life of the battery.

I might be wrong, but I'm assuming that there will be enough power to unlock the doors including the hatch.

First chance, I'll wire battery tender leeds directly to the battery and have the connector under the rear bumper.

 

We now know how to open the jumper port. You are correct: it is not complex. Your video (and, perhaps some in-garage practice) is a valuable step forward in such understanding.

An additional concern, which I have described with particular clarity (in two posts) is a potential problem that may be encountered when using that port with standard jumper cables. That problem is the result of a slight design flaw in the jump point. As I've described, that design, when combined together the design of at least some jumper cables may result in a situation whereby a non-conductive portion of jumper cables contacts the jump point, while the conductive portion of the jumper cables contacts the non-conductive support backing behind the jump point.

My jump cables were bought (some years ago) at Sears, so I presume that their design may be employed in other cables.

 

Hi Mike,

In my case (the first time) - the battery was flat dead. I could not unlock the door. I had to use the metal key within the fob. (And, to make matters worse, it was 11:30PM, in an airport parking lot, and I had just returned, weary from a cross-country flight.)

Leads under the rear bumper would have been a big help in that situation. (But for those of us who don't have such leads - we're restricted to the battery or jump point). I've noticed with some fondness and admiration the structural frame stiffener you've designed and fabricated. Maybe this could be another project you would be willing to provide for other members?

In the second case - I was at home - so the door wasn't locked, and I can't say whether there was enough charge remaining to unlock the front or rear door.

In both cases: I don't really know how many amps the jump provided to the battery. Each jump was relatively short in duration (just enough to get the car started), and the remaining charge was provided via the Prius's charging system.

 

I have jumped my car before. You open the hood, open the small door, flip the red tab up, connect the red jumper cable, then connect the black cable to a metal spot on the car. Why is this hard?

I will post a video when I get home.

 

I looked at the vent on the side of the battery compartment. It would be hard at all to make a fused connection and to run the leads out of one of the large holes that has a plastic flap on it.

And, thanks for you nice comment on my frame brace. I am considering making a short harness for those who do not have the special crimpers and connctors that I can get ahhold of.

I'm thinking of at least 10 gauge with a 20 amp fuse.

Or, it might be good just to use a battery maintainer and for the user to keep it plugged in, if the car is not used for more than a week.

 

Hi Mike,

A few points:

1) As a question: Do you know what that electrical connector (about central to the picture) is? I've seen it on mine, and wondered what it did.

2) You're welcome: I enjoyed reading your analysis and fab process. Where I used to work, I was fortunate to be in the company of highly skilled toolmakers and machinists. They taught me a lot, and I now miss their vast experience for fixing just about anything, as well as the sounds of lathes, milling machines and press brakes.

3) I haven't done a parasitic current measurement, but I think the Prius (under ordinary circumstances) could survive a week of storage. (I'd hope it could survive a month - but I'd leave those calculations to the EE's on this board). In my case, the first time I had to jump was completely my fault for leaving a map light on. Can't really blame the car for that. The second time (I think) marks the beginning of the end of the battery. (It's the original and I've had the car for 36 months now.) It has had one complete discharge, which I believe these lead-acid batteries don't like. In my case, I parked the car on Thursday night (before the NE blizzard), and on Wednesday AM it was unable to start (or light the map lights). I've noticed a recent drop in MPGs, and am hoping that a new battery will also fix that. (Fingers crossed).

 

Yes,

It is clearly true that a standard lead acid car battery's life is appreciably shortend when fully discharged and then recharged by a 60 amp alternator.

The Prius system may recharge the battery at a lower amperage rate.

Personally, in a situation as your first complete discharge, I'd recharge it with a trickle charger at 1-1/2 amps. That would have been best for preserving the life of the battery.

 

What I think the OP's point is, before you actually have to get at the jumper connection, you should attempt to do it while you have light, etc., so that you can easily see what you are doing. Put another way, try to jump your Prius while blindfolded. If it were a normal battery jump, I could do it blindfolded. Luckily, when I had to jump my Prius, I had plenty of light, though it was at night.

Mike

 

I keep a small LED flashlight in the glove box and a bigger LED flashlight in the trunk. It is always good to be prepared.