Dead 12v Battery --- A Glove Box Remedy?

If you are doing anything that requires your car to be jumped on any regular basis you are KILLING THE BATTERY!

While a small jump start device may be a good idea for those rare emergencies, goo battery care is a way better investment! If the car is going to sit for more than a couple of weeks, a small trickle charger, or a small solar charger will keep the 12vt battery at full float voltage.

The Hv battery will not be a problem if it goes down a bit over a few months. It will not sulphate like the flooded cell of the 12vdc battery.

Once again, I suggest all those with battery questions to read and UNDERSTAND some of the following: http://www.batteryfaq.org/


Icarus

 

Dead 12v - boosting how-to jumper cable story

Happened to me yesterday.

Rear parked against a snowbank on driver's side. Canada has Daytime Running Lights, that only turn off either :
- manually
- when auto, opening the driver's door when IG-OFF.

So, in this order :
1. Rear parked, tight spot, between snowbank and car
2. Opened driver door to see if I could get out.
3. Decided to stay put since my wife could get out on her side
4. Closed my door, then turned off car
5. Got out through front passenger door
6. Went to work
7. After work felt stupid

Got a lift home, went back armed with my wife's Yaris, booster cables, and the ***wonderful*** reference material found on PriusChat.com.
Like how to open the door when dead 12v battery, how to jumper - boost a dead 12 battery from the hood.

The hardest part was figuring out how to open the fuse box.
There's a damning -> arrow on the plastic pointing right - useless.

To open the fusebox, it's due south, or due north, to unclip. Not much force required.

Fun in -10c winter at nighttime with a poorly lit parking lot. Used my cellphone as a flashlight.

Connect Red & Black to the Yaris (with motor off) battery.

The 12v Positive screw is protected with a red plastic, lift, OMG a TINY screw. The cable booster pincer just barely attached.

The black pincers to the body of car, and then . . .


The car alarm went off !!!

Used the FOB to "open" the car.

Then started the car normally, the HV Battery was fine, hardly used.
Had to turn on the heat to start the ICE and have the ICE stay on.
Remove the cables from the Prius. Then the Yaris.

From then on, no problems. Including the Fuse Box Dilemma, Winter, -10c, this took less then 10 minutes to do.

No need to access directly the 12v battery in the rear of the car, which for me, would have been impossible.

[NOTE : Detailed story so that the PriusChat search engine can help others that fall in the same trap I did. Thanks for reading ]

Personally I don't think an extra on-board battery for "emergency" boost is a good idea. A taxi can boost you, CAA or AAA, a friend. Easy to do.

 

[Edit: Haven't found a human powered car battery booster/generator. Anyone?]
[Edit: Patent Opportunity?]

Any human force device, would have to produce at least 13.5 DCV to trickle charge a dead 12v battery.

For the Prius, if the main HV Battery is not dead, would not need many amps, just enough to boot the computer and quickly press the IG-ON & foot on brake. Then the HV battery takes over, the 12v is no longer necessary.

I've seen human powered pumps / cranks, but they do 5.5 DCV for cellphones. They work well, I've used them at camping.

So I'd see a human powered generator as a good solution for boosting a car, but as an added benefit could also do your cellphone with a volt redux adapter.

If such a thing exists over at Canadian Tire I'll check it out.

 

Makes sense. Actually the unit you linked looks pretty good to me. It runs 18V/3Ah internally and can put out 12V at 7A for 15 min. This is probably enough to start the Prius immediately, but certainly after a few minutes. I think the only unknown is the Coastal mod and whether this will give you a clear enough path back to the battery. I would expect so, but you would have to try it and find out. For a ~$50 investment, I'd say its probably worth trying. If the coastal mod doesn't seem to do it, you could always run a dedicated wire back to the battery and stick a female outlet plug on the end. Maybe run it into the center console? The only real trick with any of these battery boosters is that you have to remember to plug them in every so often to top up the internal battery. At least with this one you can also charge from the 12V aux outlet, rather than having to take it out and plug it in.

Rob

 

WEZA 12v FOOT CRANK PORTABLE POWER SOURCE

 

Hi all,
I don't have a prius (yet), but I enjoy the forums.

Back in the '60's when two-ways (and all radios) were valve models, a common issue was coming back to a flat battery. One solution that techies (read radio-tv serviceman) had was to have two 12 volt batteries: one to start the car and one to run everything else.

Early adoptees had two generators; later on heavy duty diodes were used.

Question:
How much current and voltage does it take to boot the computer and drive the relays that actuate the HV battery? Most CPU's run on 5volts or less, so I guess the issue is the relays.

I was thinking along the lines of some AA NiMh batteries trickle charged from the standard battery - with diode isolation so that the AA's wouldn't discharge along with the 12v system.

Then provide a switch that would allow the AA's to boot the car.

Would this kind of mod be feasible for the prius?

Cheers
Warwick
and thanks for a great forum

 

The first way I can think of to try and address this issue is with an isolator:
Powerline Multi-Battery Isolator
Add a second battery, and then a switch to parallel the two. The second battery gets automatically charged up every time the car runs, but is protected from being run down. My only concern is how much voltage will be dropped across the unit. The dc:dc converter output voltage is already a little on the low side (so as not to cook the sealed battery I presume).

You could accomplish the same thing with the OPs aux power unit, if you could modify the coastal mod to give a push button mode switch (assuming it doesn't do that already). You would leave the small booster battery in the center console plugged into the outlet, so it would always charge up each time the car ran. In the default mode, the booster battery would be isolated every time you turn the car off. If you accidentally run your main battery down, you close the switch to activate the aux power port which then ties in the booster battery and away you go.

The other way to address the problem is with an auto-disconnect switch like this one:
PriorityStart - Stop Dead Batteries on Cars & Boats [Priority Start! Battery Protector]
That way, any time your battery voltage falls to a certain point it will just disconnect it. This would have the added benefit of protecting the battery, which on the above method would still be over discharged and damaged. My only concern with a product like this is whether it will work as advertised with the voltages and small current demands of the Prius. It would have been nice if Toyota had built in something like this.

Of course, there is also a pretty good chance you will hardly ever (if ever) need this. There are certainly a number of people who have had battery trouble, but there are a lot more who haven't. Of course you watch, tomorrow my battery will be dead

Rob

 

I REALLY think this is a solution in search of a problem. While you can series the two batteries together, install a cheap blocking diode so that the "AUX" battery won't be run down, it does present another whole set of problems.

Mixing battery types and sizes is very detrimental to both batteries, but more so for the BIGGER of the two. (For attribution look here: http://www.batteryfaq.org/

The smaller battery will tend to equal the capacity of the larger. The charge rate of the alternator will tend to be too large for the small battery as well.

For all the trouble of all these idea, good battery maintenence and care, and a AAA membership would be money well spent.

Icarus

 

I still believe, the Prius is jumpable by 8 size D batteries through the aux port.
Even if the car appeared dead, in my case the bat still had a couple of Volts that were enough to switch on all the relays and I believe the glovebox aux port would have taken the extra battery energy supply back to the car circuits. Didn't have the chance yet to test that. My Prius is 8month, replacment bat is about 4 month old.

If the battery is dead-dead, surely only a jump at the charge points would help.

My repeated issue is, that if the car isn't locked overnight I might have an empty battery next morning.

frosh

 

The Prius has a feature that on my '95 Chevy Lumina was called a "Battery Saver" (at least my 07 Prius does). If any door, including the hatch, is not totally closed the interior lights will automatically go out in 15 to 20 minutes thus "saving your 12V battery". This feature does not apply to any manually switched on lights, like the reading lights in front or the trunk light. Therefore, if you manually switch the reading light on and forget it, the battery will drain. Also, if your trunk light switch is in the ON position, and the trunk is not fully closed, the battery will drain. Therefore, the thing to do is to leave your trunk light switch in the OFF position until you really need it, and immediately turn it off when it's no longer needed. Also, don't leave the reading lights on. I have tested this feature with the door and trunk lid activated passenger compartment lights on, and it works every time.

 

The Prius has a feature that on my '95 Chevy Lumina was called a "Battery Saver" (at least my 07 Prius does). If any door, including the hatch, is not totally closed the interior lights will automatically go out in 15 to 20 minutes thus "saving your 12V battery". This feature does not apply to any manually switched on lights, like the reading lights in front or the trunk light. Therefore, if you manually switch the reading light on and forget it, the battery will drain. Also, if your trunk light switch is in the ON position, and the trunk is not fully closed, the battery will drain. Therefore, the thing to do is to leave your trunk light switch in the OFF position until you really need it, and immediately turn it off when it's no longer needed. Also, don't leave the reading lights on. I have tested this feature with the door and trunk lid activated passenger compartment lights on, and it works every time.