2010 Gen III Completely dead

Could it be the jumper cables are only "hot" on one side of the jaw? Some are like that. The jumpstart terminal in the underhood fuse box is plastic on one side, copper on the other. So look closely at your jumper cable, make sure the side the wire runs to is touching the copper side of the terminal.

And you have a solid ground point, bare, substantial metal on the engine or body? I like a point relatively close to the fuse box:



The jumper cables are solid too? And the Accord starts ok?

It's actually odd that jumpstart is not working, sympomatic of problems beyond the 12 volt. But I would try one more time anyway, with the above, unless you've already cover all of it, are sure it's not an issue.

 

This is a multi part problem that can get complicated with a Prius. Perhaps the simplest thing to consider is putting a battery charger on the 12volt battery for 24 hours and then see what happens.

 

I suspect your jumper cables is not making a good negative ground contact. You only need a little power to get the Prius started.

If the cables are connected properly, your lights would be working. So turn on your headlights while you're connecting the cables. If you see the lights go on, then it's connected properly.

 

12v might be fried. if that's the case, you'll have to climb in back and disconnect the neg lead to take it out of the circuit, then try jumping again.

 

If it's your original 12v battery you're due for a new one. Driving 10 miles won't charge a dead battery that showed zero life previously. Be prepared to jump it again.

FYI, the Prius takes very little power to "jump" since there's no starter motor. You don't need to run your donor car when jumping the Prius.

 

Yeah until you thoroughly recharge with a charger and/or replace the battery, it'll be low on charge, keep the booster cables in the car. A jump pack even better.

 

At the least, I'd recommend a day or so on a trickle charger. Mine has a pair of little LEDs that change color when it's done. As others mentioned, the 12V battery could be done for, but it's worth a try to get it charged back up as long as you're not concerned with getting stranded.

 

Most trickle chargers don't have enough amps to charge a dead battery. They're meant to top up batteries, not save them from a very low charge state.

 

Something in 3~4 amp range, and smart charging: what you need.

 

True. But that battery isn't dead anymore. It's already been partly recharged.

 

Check the date manufactured label on your 12v battery. If it's the original battery, it's time to look for a new one. We've replaced the battery on our 2011 after being stranded while doing errands one day.

 

Are there date codes, I mean: directly readable? IIRC Yuasa (at least) uses a coded number. And if you contact them they might translate it. Maybe just assume it's original, go from there.