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

Ok, It's time to stop jawin' and start doin'. I'm moving ahead with the combo of the Black & Decker BB7B Simple Start 12-Volt Battery Booster and
the Coastaletech Power Outlet Mod.

Today, I went to a local auto parts store and picked up the B&D booster. I figured that getting it from an internet vendor was senseless if there was a 50/50 chance of it not taking the initial charge.

When I mentioned the reported failure rate, the clerk checked the company's data base and said that in 30 sales since Dec '07, there has been only one return. Still, I asked him to plug it into 120 AC. He politely declined. "Ok," says I, "please write your whole name on the back of the receipt. Mr Bob Miller, the manager of this store, is a high school classmate of mine (which happens to be true). If this unit fails to charge, you can be sure I will be here tomorrow when the doors open, with your name on my foaming lips." (Fiendish Jack Nicholson grin followed)

I get home, very carefully follow the charging sequence... and get the smoke alarm screech. I see red and I'm looking for something or someone to hurt. Get cooled down, and force myself to think. The unit comes partially charged, how much so is anybody's guess as initial charge times of 5-15 hrs are reported. The manual says 15. I try the LCD light, its plenty bright.

The manual says that when you turn the unit on, the charging light is steady green. But when you start to charge, the light blinks. When the charging is complete the light goes solid again. The light is steady when the unit is screeching. Aha, thinks I, what if the circuitry sees sufficient charge so that in its weak little mind recharging isn't needed? So, I turn on the LED light and wait, and wait, and wait. Four hrs later its still burning brightly. But, when I try the charging sequence, the light starts blinking. Bingo!

Four hrs later, its still blinking/charging even as I write. Lets hear it for dumb luck.

My next step: Tomorrow I'll see if this little baby will boot the CPUs with the 12v battery disconnected. First, I'll disconnect the 12v battery. Then I'll go in through the underhood/bonnet charging posts. Yes, I'll need jumpers, but not really heavy ones. And yes, I'll be extremely careful to ensure there are no chances for even momentary shorts. The unit does not energize the charging leads until a switch is closed.

If anyone sees any thing that I've missed, or desperately need to know, please post ASAP.

 

Sparky, thanks for the quick come-back.

"...why don't you hook up the B&D unit through an ammeter to the car first? That way when you disconnect the main battery your car will still have power from the B&D. You won't lose your stereo presets and power window settings."

Good idea. I don't have, don't know how to use an ammeter. I plan to hook straight to the charging points. Can I do this before I unhook the 12v battery?

"I'd be interested to learn what the current draw is from the spare battery when you try to power up the car."

The specs say a 500mA 12v DC output. I've got an e-smart friend, and I'll see if at some later time he can get a reading.

"Did you look at the DJUMP-17 from Duracell? It looks like a nice unit although a bit larger and more expensive than the B&D unit:
Amazon.com: Duracell DJUMP-17 Instant Jumpstart... "

No, I either missed it or just got tired looking. The B&D unit does fit in the glovebox, just, if you slide it to the extreme left. Which was one of the initial goals.

"For those considering using primary cell (ie carbon-zinc, alkaline, or other non-rechargeable) batteries in series, you should put a Schottky diode of sufficient current rating in series with your battery pack. This will prevent it from blowing up when the inverter comes on-line and attempts to force a charge into your jump battery."

OK, lets back-up the technotalk bus; I haven't got the slightest idea what you're talking about. Since this unit has "high energy density, AGM, rechargeable, lead-acid cells," I take it that this Schottke diode business doesn't apply to this unit. Correct?

 

darelldd, you said:

"Just opening the door is going to cause more draw that that, I'm afraid!"

OK, I'm looking for some help here. Can I stop that draw by closing the door?

I think I'm beginning to tease some unspoken givens out of your little snippet.

Lets see. If I hook up the booster before I unhook the 12v battery, when I do then unhook the 12v batery, the booster will be seeing a steady state draw which it might be able to meet. On the other hand it possibly wouldn't meet any increasing demands from something as simple as activating the light in the door, which I'd have to do to get in the car to power-up the CPUs

I take it that in a real world scenario these larger demands would be met by first having the booster charge the 12v battery for some time before trying to power-up.

 

Sparky, thanks again, you're being a great help.

If I might, I'd ask for your forbearance on a few more questions,

First, a quick review. The purpose of this whole exercise is to find a way to power-up the CPUs, get the HV battery and ICE on the line, and drive away, even if the puny 12v is completely kaput, wholly unable to take/hold a charge.

The procedure will be: (Fob will be in my pocket at all times,)
1. Take the covers off the 12v battery and the positive charge point under the hood.
2. Hook the booster to the charge points under the hood.
3. Unhook the positive lead from the 12v battery.
4. Close the rear hatch.
5. Get in the car.
6. Switch the "ignition" to the ACC mode and see what happens.
If any alarms or trouble lights, hit power button, abort test, unhook booster, restore 12v,
If no alarms or trouble lights, then
7. Step on brake pedal and press the POWER button, confirm Ready light.
8. Hold breath until ICE starts; 8-10 seconds.
If no ICE start, abort test.
If ICE starts,
9. Get out of car, unhook booster.
10. Get back in, take short drive on neighborhood streets.
11. On return, reattach booster.
12. Hook up 12v battery.
13 Remove booster.
14. Recharge booster.

Do you see any problems here?

 

An Update: Good News, News, and Not-So-Good News.

The good news is, I got through my test sequence as far as unhooking the 12v battery. And later hooked it back up, and the car started with no alarms or flashing lights. I didn't loose radio presets or Nav destinations.

The all-the-way-down-with one-touch feature on the drivers window is now inop however. Somewhere in the Owner's Manual or a thread there's info on how to re-enable this. I'll get on that next.

Now, before the news; this whole procedure had me very nervous. I felt like I was was the Sorcerer's Apprentice doing recombinant DNA on the kitchen table. As I'm working there were various beepings from the car -- door open, seat belt not on, etc -- and from the booster -- turned on, ready to boost, continuous beeping for what it thinks is successfully completed boosting. I proceeded slowly so that I could identify and address each signal in turn. Nonetheless, throughout this whole exercise, I was as skittery as a pig on ice.

The news is, I couldn't get the battery booster into the circuit. The problem seems to be that it needs a depleted battery to work against/into. I don't think this means that this arrangement won't ultimately work. It's just that without a dead or nearly so battery I can't prove it, at least to myself.

Both the car and the booster have circuitry designed to protect itself, and itself alone. Each is oblivious to the other. And, at least for this test, the protections seem to create a dead zone if you will.

When I hooked up the booster to the under charge points with the 12v stilll connected, it would "boost" for about 5 sec and report boost complete. (All the while, ScanGuage showed 13.8v.)

Despite several attempts to unhook the 12v battery in those 5 sec, I wasn't able to get the booster to continue boosting. So, I need to think the test procedure through again.

With the 12v battery disconnected, it wouldn't boost at all. This was a bit of a surprise. Once again, I think the not having a dead battery in the circuit was outside the boosters operating envelope.

Additional news: After the test, I put the booster back on 120v charge which it accepted without complaint. So it looks like I finessed the initial charge rejection issue.

What a drag -- bummer.

I'm now going to order the power port mod from Coastaletech. Wish me luck!

 

Sparky, thanks again for your input. I was about send a "HELLO? ... Anybody home?" posting.

"I would eliminate steps 9 to 11 in that sequence, and shut down the ICE before going to step 12. I wouldn't drive around with no battery connected..."

I reviewed the procedure before the test and came to the same conclusion.

"I think you might have better luck connecting the B&D unit to the car through the 12v accessory adapter on the unit. According to the specs that can deliver 5 amps and is protected by a resettable circuit breaker. It's probably a direct connection through a circuit breaker to the internal battery on the unit and would operate in a manner more suited to what you are trying to accomplish."

That's where I'm going next. I've ordered the power port mod.

After thinking on it, I now believe that even going in through the power port may not prove anything. I expect the same results as with the under-hood jump points. The only way to know how the HSD and CPU will react is to have a dead or nearly so battery to try to boost. I wonder how much a shot Prius 12v battery would cost on eBay... (a joke) I know it's typical to turn in the old battery to recover the core fee when you get a new battery. But this may be worth a try:

Does anyone living within 150 miles of Baltimore have an old 12v battery that they'd like to donate to this effort? I'll come and get it.

(Mileage exceptions: My daughter lives on the north Jersey shore, and my son down near Bristol, VA. I'd have no problem diverting for pick up on a trip to visit either.)

For now, any further progress on this pends my getting the power port mod. With luck in a week or so,

In the interim, comments from the Peanut Gallery are welcomed.

 

Another tread has opened which may deal with a dead 12v battery:

http://priuschat.com/forums/care-ma...rius-died-while-driving-towed.html#post566759

In thinking about what has been posted there, I see some additional considerations that I will have to work through to get to a successful conclusion here.

Right now I'm waiting for the power plug mod so I can plug in the booster. It's due this week.

I'm no electrical expert, and I don't understand the workings of the HV-12v charging process.

I don't know yet if the combination of the various CPUs will even let the ICE run even though the booster is providing adequate power.

Could the HV tryng to charge the dead 12v do damage to the booster?

Does anybody know of a case where a Prius with a dead 12v battery was restarted with a booster, hot start, jump, whatever, and actually got home?

I mean a dead, d-e-d, not just seriously discharged, battery.

 

Hmm, all quiet on the western front. Press on regardless.

The power outlet mod arrived yesterday, the day Coastaletech said it would. The installation instructions are really simple. They are in a different format than those at the website, but essentially agree:


To do the install you have to get up-behind the lower dash panel which involves lying on your back in the driver side foot well. I hope to get to the installation this weekend.

I was referred to this site, Hobbit's massive collection of technical material, for another matter:
Prius links

Imbedded in the site is this reference:
Prius Startup Current

This is the first hard data I've seen on the smallest capacity battery that might start a Prius. In summary, 7 amps should be enough, with the possibility of 30 amps needed for a short time. There was an unconfirmed story that someone was able to start a Prius with a 7 amp-hour gel-cell battery, mine is lead-acid. According to the data plate on the B&D booster, it is rated for 7 amps, maybe just enough.

This article answers the third question in my original post which none of the subsequent responders addressed:
" Will the start-up of the 'accumulator pump' ---whatever that is and does --- negate this whole approach? " The answer is an emphatic, "Maybe."

The accumulator is an electric brake-pressure pump. In one start up sequence it drew 15 amps for three seconds. It is pointed out that to ensure that this load is not imposed during a start up, the pump fuse must be disconnected. Where is it located? Is it easy to remove in the dark?

Can you minimize the probability that this load will occur during the start up sequence by pumping the brakes really hard a few times before shutting the system down?

 

Project Update.

First, so it doesn't get lost in the clutter, my thanks go out to posters who have provided meaningful info as this project has developed. I am most appreciative to Evan for that very first encouragement. I am especially beholden to SparkyAZ for his repeated, patient posts in the face of my near total lack of electrical savvy.

This weekend I got the Coastaletech 'Continuously Powered Socket Mod' installed.

Although the mod has been described as simple, it is not necessarily easy. The idea of simply applying two power taps to two wires and connecting them with a jumper is conceptually simple. The execution of that ideal was not easy. Here are some thoughts on my experience.

The parts for the mod came in a plastic bag. After reading the instructions, it was apparent that there were more bits in the bag than were strictly necessary. In addition to the required jumper wire and two wire taps, there were an additional tap, and what turned out to be an example of a tap properly attached to a wire with the jumper end connector put in place. A nice gesture; a physical example of what the final arrangement should be.

But what of the extra tap? It suggested that maybe it could be needed. Such as in the event of tapping into the wrong wire and blowing the fuse... or maybe worse? To me that extra tap screamed, "Danger Will Rodgers! Danger! Danger!"

Lying on my back and looking up behind the lower dash was not comfortable. [If you have lower back or neck issues, it might just be out of the question.] All the work would take place within 12 inches of my face, closer than my glasses allow me to focus. I pressed on despite the slight fuzziness.

When I first looked up, I saw a connection block right over my head with a green wire right in front of my nose. STOP! This was not the right block. Although it is not said in the instructions, the block I was looking for was way over on the left, against the side of the car, above the emergency break. Yes, the one that's nearly impossible to reach with one hand, my right, never mind two, which in fact I would need to do.

The necessary green wire was easy to identify. The idea was to fully close the wire tap over the wire at a 90 deg. angle. The operative words here are 'fully close.' I work with my hands every day; turning, twisting, pinching, squeezing. I have to be careful when I shake hands. Nonetheless, it was very difficult to get the tap folded in half, in the right position, and fully closed so the little clasp locked closed. I mean, really difficult, and ultimately involved a finger from my left hand to push against so as not to stress any existing wire connections. Oh, did I mention I had a small LED flashlight held in my teeth so I could hazily see what I was doing?

After a half an hour of dogged persistence I prevailed. To ensure full closure, after I got the tap to stay closed I squeezed the tap with a pair of needle nosed pliers.

Next, it was off to the other end of the mod, at the under-dash power socket.

The instructions call for removing a friction fit pin, and show a screwdriver being used. Forget that, I would most likely gouge the plastic panel. I just slipped my fingers behind the panel on both sides of the pin and gently but firmly pulled and the pin popped out.

The picture in the instructions shows the back of the power socket fully exposed. To get that you have to unhook the top of the panel the plug is in. This was my first partial dash disassembly, and this was very intimidating. With heart in throat I pulled gently, but insistently, on the corner of the panel below the plug, and wiggled the panel somewhat. Shortly, the panel disengaged along its upper edge. It was secured with two squarish pins. Now the back of the plug was fully accessible. At this point, I pulled the connector off the back of the plug. Attaching the tap and the jumper was much easier. Again, I set the tap with needle nosed pliers, hooked up the jumper, and reatttached the connector.

Now all that was necessary was to secure the jumper at unspecified numerous places behind the lower dash with tape, wire ties, whatever, so it didn't put any pressure on the tapped wires and was well out of the way of the emergency brake, brake, and go-pedal mechanisms. It needs to be well up out of the way so there is no chance of it being caught by a shoe. When this was done, I remounted the lower dash piece and reinserted the little plastic pin.

Did it work? I plugged my Belkin iPod charger in and the little green LED on its top came on. Yes! Next, I plugged in the B&D booster unit. I activated the 12v charging circuit and its confirmation light started blinking. BINGO!

Where am I now?

I've got the gear in place to overcome a dead 12v battery from inside the car.

Will it activate the CPU with a weakened or fully discharged 12v battery?

The indications are that it will. But I can't be 100% sure until I can try to boost a much discharged 12v battery. That is a condition that I am not willing to induce in my nearly-new OEM battery given its replacement cost. So, God willing, I'm ready should the car not start. If it does, I'll start another thread. My fervent hope is that that never happens.

Now, one last bit. I wonder if the info in this thread, properly summarized and meaningfully extended, would have broad enough application to warrant designation as a Sticky. Perhaps a humble supplication will work. Here goes:

O Existentially Beneficent Grand High Poobah in the Virtual Ether.
I entreat that you forgive this unforgivable intrusion on your Elysian existence.
Were I, through heroic yet unworthy efforts, able to bring together additional information such as symptoms of a weak 12v battery, access to 12v battery voltage through the MSD, with 8 by 10 photos of the parts and installation, and a summation of the desired conditions of this arrangement, would the resulting work, insignificant as it would have to appear in your blazing eyes, have a chance, even a miserable, paltry one reflecting my pitiable status as a Newbie, of rising to the level of consideration of Stickyhoodedness?