quick question regarding the battery charge/jump points under the bonnet. I have a trickle charger and I need to hook it up for the next few weeks as I probably won't be using my Prius that much and I don't want the battery to die. Only issue is, the distance between the positive terminal and the 'negative' point are quite far apart in the engine bay and my ctek charger lead with the crocodile clips won't extend that far between the two points. Possibly a stupid question but can the negative just be on any part of the chassis away from any electrical components? So I can just clamp on part of the metal frame around the front of the engine bay?
Yes, anywhere you can get a good ground point on a non-painted, metal frame surface or bolt should be OK.
Just checked, yeah the Owner's Manual shows a negative connection point way over on the other side: But there's nothing special about it. The main criteria is that it's substantial, easy to clamp to, and grounded to the engine or car body. This is my preference: (The day we test drove it, they used this point to jumpstart it, due to dead 12 volt, lol) This'll also work, but I'm a bit nervous about that point, since it's part of the inverter:
thanks! i wonder if that came from the old drawings/thought process where the battery is under the hood, and you connect the ground after the positive, and you don't want a spark near the battery? my father taught me that when jumping a car.
If I'm connecting directly to negative post (know you're not supposed to, but hey) I'll just blow across the top of the battery first, figure if there's any amount of hydrogen there it'll be outa there with a puff or two. Pretty much just whistling-as-you-walk-by-the-graveyard I suppose. It's a good idea to wear safety glasses, or mask, even better. Still usually don't, but I should.
If you have a multimeter you can sus out good ground points. Easiest is if it's got a continuity scale with audio feedback: beeps when you've made a circuit. Clamp one lead to a know ground, then go around touching possible ground points with the other lead.
There is no danger of any spark under the hood (bonnet) causing an explosion. The battery and hydrogen is in back. I connect to the largish piece of aluminum just to the left front of the fuse box. In fact I just did that a few minutes ago. Snow is getting deep enough on the side roads I hear it scraping on the undercover. A "real nice" snowstorm just hit. Rush hour this evening is going to be a "gong show". Glad I'm home! FJ time!
If you are charging or maintaining, you can also hook the negative clamp to the strut nut behind the fuse panel panel. For those who had a Gen II Prius, it would be the "same location" that was used for the negative terminal. I have done this several times on our Gen III with no problem. Will look for the aluminum David B just mentioned.
You can use pretty much any clean bare metal part of the body or engine that isn't electrically isolated from the body by being mounted in plastic. For "jumping" a conventional car, you need something fairly substantial to handle the high current, but for the low charging current you're dealing with, even skinny parts will work ok, as long as they're grounded.
FWIW, it's best to avoid using the bolts/brackets on or around the inverter assembly as ground points. Doing so may trigger the ubiquitous "Check Hybrid System" error, from the system detecting an unexpected ground current through the inverter electronics. FYI, this error can be cleared by going through several On/Off cycles of the vehicle, but it's much easier to avoid getting the error in the first place. I know this because I was probing some circuits under the hood for one of my wiring projects using the bracket on the inverter with some ground wires attached to it as my ground point. Now, I use the bolts on or near the firewall and strut tower for ground.
