I recently bought an 12v battery jumper pack. I wanted to make sure I could easily access the 12v battery before actually needing to. The space between the two terminals are so cramped that I can't get both cables to fully clamp around the terminal connectors. Would it be okay to connect it to the bolts/nuts as shown in the image instead of fully around the terminal connectors? Has anyone had to do this before and been able to jump start their prius C?
Why not just use the jump point under the hood; rather than rip out the access panel under the seat???
The cables are very short. I couldn't reach the spot that was recommended to connect the negative cable clamp to.
The car has a negative-ground electrical system, so pretty much any unpainted metal you can reach with the clamp will do the trick. I've never tried to jump a Prius c, but I also can't remember in any car ever having to look very hard for a place to clamp the ground.
^That or preemptively install a short ground jump wire and tuck it away. That's what I did for my old 2012 Prius C.
Early production c's didn't have a jump point; was a real design fail, considering the battery location. @pasta4breakfast doesn't disclose his year though,. If there's no under-hood jump point, maybe just wire in some sort of quick-connect??
I carry a 2 foot #6 home made jumper with good size alligator clips in our Rav4 hybrid to avoid the "easy" ecm frame ground which is known to blow the ecm on occasion. However it has seen more use when providing a jump to big pickup trucks.
clamping the nuts is fine, even though there's not as much contact area, it can still work. Wiggle it around if it doesn't work right away. Look in the owners manual, it may show a clamp point in the underhood fuse box. One of the big problems with a 2nd gen is if you stash your jumper cables in the trunk by the spare you can't get at them when the battery is dead, because the trunk only opens electrically. So I stash my cables under one of the front seats, because you can get at them with the mechanical key to open the door. Just another simple thing overlooked by the genius Japan engineers. They were so focused on building the most technologically advanced vehicle of it's time, they missed some of the small simple things.
As I recall; it was a very skinny jump point - those clamps pictured above won't clip-on. My solution was two quality alligator clips, then clip onto the alligator clips. It wasn't pretty, but it works. No getting on your knees and fighting the lower seat panel cover. Another idea is to run a couple of short jumper wires from the battery and drill a couple of holes in the plastic cover to put a bolt through. You can just clip onto the protruding bolt heads to jump. The bolts will need to be far enough apart so that there's no accidental bridging of the two points. As I recall; that access panel was a bit of a pain to remove; with my tool box next to me. I can only imagine the pain, in a parking lot or side of the road w/o tools. YMMV
Thanks for all of the ideas. It is a 2013 prius C. I believe there is a positive terminal in the fuse box under the hood. I didn't think to use it because the videos I saw showed people connecting the negative clamp to a point on the other side of the engine bay. I knew I wouldn't be able to reach that with my tiny cables/clamps. Looking at my engine bay below, I should be able to reach the bracket on the corner of the inverter assesmbly closest to the fuse box. Would that be safer or at least as safe as playing around with the battery in that cramped location?
Visual aid, for anyone wondering where the Prius c fuse box is: You can verify if an alternate ground point is indeed grounded, with a multimeter set to ohms or continuity, or with a test light:
Under the hood of every Prius model I've worked on, the fusebox with the positive jump point is within even a pretty short cable reach of the inverter assembly, which is a stout aluminum grounded case that also contains the source of the car's 12-volt power system. I generally just clamp on there and get on with things.
I just checked an owner's manuals for the prius C and it uses a spot on the inverter assembly case in the illustration below. Is there any reason why this part of the inverter assembly case would be safer than any of the other spots on the inverter assembly marked with a red x in my photo below? unfortunately my cables can't reach the bottom left corner of the inverter assembly case, but they can reach anything on the right side of the inverter assembly case. The spots I marked with an "x" are nicely shaped for my clips to grab. https://assets.sia.toyota.com/publications/en/om-s/OM52A87U/pdf/OM52A87U.pdf?_gl=1*v64f4f*_tmna_au*NTE5MjIxNjUyLjE3NzUxMDI3MTE.*_tmna_ga*NDUyMTk0MTUwLjE3NzUxMDI3MTE.*_tmna_ga_EP43E5EFVZ*czE3NzUxMDI3MTEkbzEkZzEkdDE3NzUxMDI4MzEkajYwJGwwJGgw
Either of your X spots should be ok. There are some bolt heads near your Xs, like holding down that bracket and that cover plate. I'd make an effort to place the clamp with some teeth right on the bolts if you can; those are threaded securely into the cast-aluminum case for excellent contact. Having the clamp only on the thin stamped bracket or cover plate is less excellent, but probably not enough less to stop you from jumping your car. (As long as the bracket or plate is bare metal; it kind of looks that way in your photo, or it could be some sort of finish. In my gen 3 they used black paint.) The inverter is the home of ruggedized power electronics that handle kilowatts routinely. Grounding your jump pack to its already-grounded case need not spook you.
Another thing I don't understand on the Toyota hybrid system, is how come the big battery can't trickle charge the small battery when it's going dead?
Well, they made the step-one engineering decision, to satisfy a safety goal, to have the big battery always fully isolated and out of the picture any time the car isn't READY. There isn't a technological reason they couldn't go back to that decision and add some exception like "or when the 12-volt battery needs charging." After all, gen 3 already added such an exception for "or when the key-fob remote A/C button is pressed." But I think they did that because "pressing the fob remote A/C button" is still something the owner has to knowingly do. Here, we'd be talking about the car, at some random time, deciding it should autonomously come online to recharge the 12-volt battery. What answer would you propose to the obvious follow-on question: after bringing the big battery online to recharge the 12-volt battery enough times that now the big battery needs charging, should the car autonomously start the engine? or no?
