Opening the rear hatch with a dead battery

Remove the folding hatch floor. Look at the rear of the black plastic tray covering the tire and note a small rectangular panel. Remove that panel. Then you can reach the mechanical hatch release lever with a finger.

 

Will have to try this later today. My friend just called to say his Prius is dead. It's been sitting in his garage for months since his wife died.

Q: do you turn off SKS by depressing the button under the dash, or by releasing it?

 

It's easier to jump from under the hood, even with a Prius head into a garage. Remember that you don't need heavy gauge jumper cables with a Prius.

Tom

 

True. Friend just called to say he's bought a long jumper cable. But he'll still need help figuring out where the darn post is under the hood...

 

OK. So the jumper cable was long enough, but the clip was too large for the little post. So I ended up having to go through the hatch anyway.

Got the car jump started. All electrical systems looked fine (radio, nav, etc.)

Let it run on its own for awhile. After hearing the engine shut off, I figured the battery was recharged so I turned the car off. Tried to start it again: nothing. Dead as a doorknob. Does this mean the 12V battery has gone bad? (Hope not, since the rear hatch light was on but very dimly.)

Guess I'll have to bring a scan gauge over and try everything again to see if there's something else going on. Any troubleshooting tips would be appreciated.

 

I'm sure that the 12V battery is the problem.

You should not underestimate the time needed to recharge the 12V battery. The gasoline engine shut off because the engine ECU thought the catalytic converter was sufficiently heated. This has nothing to do with the 12V battery.

If it can be recharged, you'll have to either connect it to a battery charger or plan to leave the car READY for most of one day to recharge the battery. (Obviously, if you pursue the latter approach, make sure the fuel tank has sufficient gasoline to run the engine when it decides to turn on, and ensure the car is parked where the exhaust fumes will not endanger anyone and the car cannot be stolen.)

 

Thanks Patrick. I didn't realize it'd take that long to recharge the 12V battery. Would it recharge faster if you drive the car around instead of sitting in the driveway?

What is the minimum voltage the battery has to have in order to be able to start the car? I can use the ScanGauge to monitor while charging.

 

The DC/DC converter maintains voltage on the DC bus at ~13.8VDC when the Prius is READY. It doesn't matter whether the car is being driven or is just sitting on the driveway in P. This is unlike a traditional automobile where the alternator voltage tends to increase as engine speed increases above idle.

It's unclear what voltage the battery has to produce in order to reliably start the Prius. Regardless, the ScanGauge will just show ~13.8VDC while the car is READY. The battery voltage can't be measured reliably until the car has been IG-OFF for several hours, to allow surface charge to be dissipated.

 

After some maneuvering, I was able to get my charger clamp onto the little rectangular positive connection post.

But note that Patrick Wong had a great suggestion in another thread:

Clamp an electrical alligator clip onto the positive connection post. Then clamp your jumper clamp onto the electrical alligator clip.

Seems that it would be a good idea to keep an electrical alligator clamp in the car somewhere (e.g., tape it onto the red door covering the positive connection point or tape it onto the fuse box cover), or keep an alligator clip with your jump charger or jumper cables.

 

Great suggestions all. Many thanks. We did try looking for something to clip/clamp onto the post but couldn't find any. Will definitely get some alligator clamps (for my car too).

I've told my friend to invest in a battery charger that can also be used to trickle charge since the car isn't driven too often. A battery charger should be able to top off the 12V battery in about 2-3 hours, I've read.

 

If you take a look at the warning label on top of the 12V battery you will note that the maximum recommended charging current is 4A. Therefore if you use a battery charger I suggest you set that to the 2A setting (typically you'll have a choice of 2A/10A/50A).

Plan on the recharge taking overnight if the battery is as dead as your friend's.

 

I've not noticed that and would probably have used the 10A setting instead, as is typical for regular cars. Good thing you mentioned it.

An overnight charge should work out well for my friend. Thanks again!

 

I find the name of this thread misleading. To me, "Opening the rear hatch with a dead battery" would involve throwing the battery through the rear window. I suppose you could also use a dead battery to lift the hatch handle, but it would be hard to maneuver a dead battery into that position.

Tom

 

Har har.

I've had to kick myself twice now because I closed the hatch while I had the battery disconnected. I'll probably do it again.

- D

 

Does the Gen3 have a mechanical lock for the hatch?

 

Are you getting good at crawling through?

Tom

 

Yep, crawling through and unlatching is the easy part. Unlatching and actually lifting the hatch in that position is tough! It needs to pop open a bit more on it's own.

- D

 

Trying to open the hatch with a dead battery. I'm 80 years old and am unable to crawl back there to open the hatch. Is there another way to do it?

 

Is your 12v battery dead? If that is the problem it would be better to use jumper cables, a jump pack, or a battery charger to apply 12 volts to the under hood jump point (making sure that you hook positive to positive and negative to ground). This should allow you to open the hatch normally if the hatch switch/latch are working normally.