Early 911 Batteries 101 - Help?

[Doug&Julie]

Probably dumb questions, but...

My car won't start and I'm fairly certain it's the batteries (again), so I need to charge them to at least get the car started. I also have a couple of "new" batteries that came from another car that may need charging, but might last longer than the ones currently in my car. So my questions are:

1) What's the safest way to "jump" an early 911? The two battery thing is a little new to me.

2) What's the proper proceedure to trickle charge an early car? (I'm assuming we can?) I have a typical 12v trickle charger purchased at an autoparts store. Can I use this? Which battery do I connect it to? Positive to positive, negative to...? ...negative? ..ground? The manual says to disconnect the positive terminal when charging...true? ..so I can't charge through the terminal?

3) Is there a way to "bench" charge my other batteries? Can I put them (one?) on the trickle charger w/o installing them in the car first?

4) In lieu of all of this, can new batteries be found at most auto parts stores or do I have to order through Pelican or other?

Thanks for your help on such "101" questions. (I never claimed to be a wrench!)

Edit: FWIW the car didn't start over the winter and I had it towed to my mechanics. He says the charging system is fine and the batteries should be good as long as I drive it every three - four days. I didn't get to it this weekend...

[304065]

1. Thou shalt not "jump" unless thou art stranded and have no other way to get home. If you are stranded, charge the 911's batteries off the running vehicle for as long as you possibly can before attempting a start.

The reason is, your old Motorola/Marchal alternator wasn't designed to bring two batteries back from the dead, it was designed to keep them at full charge. When you start the car off another vehicle and then disconnect the good battery, your alternator immediately goes to max output in an attempt to charge up two dead batteries. This causes heat which isn't good for it.

2. Thou shalt not use an unregulated "trickle" charger. Thou shalt buy a "Battery Tender Plus" from the Usual Suspects and connect the positive to the positive and the negative to the metal of the car a few inches distant from the battery terminal so that any Lurking Hydrogen Gas doesn't do a mini-homage to the Hindenberg (oh the humanity, the humanity!) , raising your unhappiness quotient to N where N is a large number. A good place on your '70 911T w/2.4 (Zenith Carbs) FOR SALE is on the wing nut that the negative strap is connected to.

3. You can bench charge your golf car, your Amigo mobility scooter, your electric clay pigeon thrower and your deep-cycle bass tracker trolling motor battery all using the Battery Tender Plus. Do not tell the car about this.

4. Pelican does not sell batteries. You should buy a pair of Sonnenscheins and read every post ever written by Warren Hall AKA Early_S_man that contains the word "vinegar" in order to ensure that your charging system is worthy to receive nearly $400 of German-made sealed-gel-cell batteries. Also, if you are not participating in a concours d'elegance anytime soon, you may consider the installation of a Transpo adjustable voltage regulator which will allow you to very precisely set the charging voltage to 14v to make the batteries very, very happy.

Good luck!

[Doug&Julie]

Originally posted by john_cramer
2. Thou shalt not use an unregulated "trickle" charger. Thou shalt buy a "Battery Tender Plus" from the Usual Suspects and connect the positive to the positive and the negative to the metal of the car a few inches distant from the battery terminal so that any Lurking Hydrogen Gas doesn't do a mini-homage to the Hindenberg (oh the humanity, the humanity!) , raising your unhappiness quotient to N where N is a large number. A good place on your '70 911T w/2.4 (Zenith Carbs) FOR SALE is on the wing nut that the negative strap is connected to.

Thanks John for the colorful reply!

Re: "unregulated 'trickle' charger"...I have a:

Schumacher 10/2 amp "Fully Automatic / Manual Battery Charger".
- 2amp trickle / maintenance charge turns on and off as needed
- 10 amp rate
- reverse polarity protection
"For 12 volt batteries"

Is this a no? Ignorant question...who are the "Usual Suspects" from which to buy a "Battery Tender Plus"?

On another note, it's interesting that of my four different 'how to' books, nothing really tells me exactly how to charge a battery? I suppose I should have taken auto shop in high school. (..to busy with all that advanced calculus and analytic geometry...see what good that has done for me..)

Thanks again!

[DW SD]

Originally posted by john_cramer
1. Thou shalt not "jump" unless thou art stranded and have no other way to get home. If you are stranded, charge the 911's batteries off the running vehicle for as long as you possibly can before attempting a start.

The reason is, your old Motorola/Marchal alternator wasn't designed to bring two batteries back from the dead, it was designed to keep them at full charge. When you start the car off another vehicle and then disconnect the good battery, your alternator immediately goes to max output in an attempt to charge up two dead batteries. This causes heat which isn't good for it.

2. Thou shalt not use an unregulated "trickle" charger. Thou shalt buy a "Battery Tender Plus" from the Usual Suspects and connect the positive to the positive and the negative to the metal of the car a few inches distant from the battery terminal so that any Lurking Hydrogen Gas doesn't do a mini-homage to the Hindenberg (oh the humanity, the humanity!) , raising your unhappiness quotient to N where N is a large number. A good place on your '70 911T w/2.4 (Zenith Carbs) FOR SALE is on the wing nut that the negative strap is connected to.

3. You can bench charge your golf car, your Amigo mobility scooter, your electric clay pigeon thrower and your deep-cycle bass tracker trolling motor battery all using the Battery Tender Plus. Do not tell the car about this.

4. Pelican does not sell batteries. You should buy a pair of Sonnenscheins and read every post ever written by Warren Hall AKA Early_S_man that contains the word "vinegar" in order to ensure that your charging system is worthy to receive nearly $400 of German-made sealed-gel-cell batteries. Also, if you are not participating in a concours d'elegance anytime soon, you may consider the installation of a Transpo adjustable voltage regulator which will allow you to very precisely set the charging voltage to 14v to make the batteries very, very happy.

Good luck!

WOW - great advice, better humor!
Laughing over here in Encinitas CA!

Doug

[304065]

Doug (#1):

From the looks of that Schumacher charger, I don't know if it's exactly what I would recommend. How long have you had it?

Recently, OK, since about 2003, there have come to market a new class of "chipped" battery maintainers that have a built-in algorithm that varies the charging voltage depending on the battery's state of charge. When you start off charging a low battery, say one that's discharged to 12.2v (50%) charge the charger initially goes into high-amperage mode to get the reaction going, then levels off, then tapers off, then goes into storage mode. A regular charger without that logic doesn't do that, and some of the modern ones do desulfating of lead-acid batteries (for the eleven guys in the USA who still use those)

Anyway, more good battery information can be found on the Deltran site here: http://batterytender.com/faqs.php

Deltran is, amazingly, the manufacturer of the aforesaid Battery Tender Plus, and you can buy it directly from them, or you can pick a friendly business whose P&L you want to enhance and those Deltran rascals will STILL get the revenue, albeit at an OEM discount I would guess. I bought mine from NLA Limited because WAYNE does NOT sell them.

I am not now, nor have I ever been, a shareholder of Deltran, Inc.

Dough (#2), thanks! One of these days I am going to only write like Harry Pellow.

[Doug&Julie]

I've had the Schumacher charger for a couple of years now. My neighbor is the only one who's used it ( ). I'm fairly certain it's one that adjusts it's charge to accomodate the battery. But I'm not 100%.

However, this dead battery problem has reared it's head earlier this year, so I'm thinking of just getting new batteries. Any help on sourcing those in the Cinci are would be greatly appreciated.

Oh, and did I mention that my car is for sale?!?!?!

[304065]

Doug,

If your car were a 964 resplendent with no fewer than 48 electrical motors for such niceties as power windows that "jump up like frogs in a dynamite pond*" I would consider it acceptable to have the battery drain in about THREE WEEKS. There is no, no, no reason to have to drive the car every "three or four days" so your mechanic can go ahead and put a bowling trophy in the spot on his mantelpiece reserved for the Nobel Prize in Physics.

Parasite current drain, that's what you got, just like an electrical tapeworm, sucking down electrons when you're not looking. It's not difficult to fix but it's time consuming. You should fix it before you sell the car, this will work wonders for your Porsche Karma. It's a twelve-step process:

1. Obtain a digital multimeter that measures voltage and amperage. Some, such as those made by John Fluke &C., will measure everything from capacitance to the internal temperature of Prime Rib, but one from your friendly local Radio Shack will do, be sure to compliment the salesman on his diamond-studded tie bar and short sleeve shirt.

2. Charge the batteries for three days nonstop. If they are the lead-acid type (red and white interstates) be sure to verify that there is in fact electrolyte in them. The electrolyte is excellent at burning holes in the car, your skin, and your Megadeth t-shirt, so avoid any two of these. That being done, the batteries should read 12.6 volts, not a penny less.

3. Temporarily disconnect the crossover cable that connects the starboard and port batteries. You would do this by undoing the clamp on the port battery at BOTH ENDS. If you only undo one end, the chances of you blowing up the car increase by 72% due to the likelihood that one end of the crossover cable will contact the fuel tank resulting in an instant Blue Oyster Cult video.

4. With that done, connect your handy multimeter between the PORT positive battery cable and the positive battery terminal. From this point on, do NOT operate any electrical equipment on the car; if you were to flip the lights on you will kill the meter which means another trip to Radio Shack to see the guy with the pencil-thin-moustache.

5. The multimeter should be reading some small value of milliamperes, which is a measure of the current being sucked by the tapeworm somewhere in the car.

6. Slowly and carefully remove every fuse on the upper and lower fuse blocks and note the milliampere reading. It will probably jump all over the place but settle down after the fuses are reinserted. While you are down there, check to be sure the fuses haven't overheated, the ends haven't corroded, the brass contacts aren't corroded and none of the screws holding the wires are loose.

7. Make sure you get the right fuses in the right slots, don't want a 25A in an 8A hole.

8. One of the circuits should result in a significant diminution in current drain. It is in this circuit that the tapeworm lives. Could be the clock, could be the tail lights, we don't know.

9. Print, from the Pelican Main page, the wiring diagram for the '70 911T w/2.4 (Zenith Carbs) FOR SALE or the closest equivalent, which I think is the '71. Use this to chase down all the components in the circuit to see where the short is. It's likely in a switch where the contacts have oxidized over and the oxidation forms a very weak bridge allowing current to flow, not much, but enough to kill the battery.

10. Verify also that the red light for the alternator is not faintly glowing with the engine running. This could be indicative of a blown diode (such as caused by "jump starting" which could also be draining the battery. The only way to really test that would be to pull the alternator and check the diodes, but check everything else first, you would probably see a shorted diode as a glowing alternator light WITH THE KEY OUT OF THE IGNITION.

11. Once you find the tapeworm's head, kill it with emery cloth and 9% pickling vinegar. Warren posted the recipe for this.

12. Achieve total consciousness.

Good luck!

*in homage to the Late, Great HST.

[Jim Sims]

"Thou shalt buy a "Battery Tender Plus" from the Usual Suspects and connect the positive to the positive and the negative to the metal of the car a few inches distant from the battery terminal"

These will not work with the dual battery system unless you separate the batteries electrically and use a "Battery Tender Plus" unit on each one.

New batteries of traditional construction and configuration and of the appropriate size and rating for the dual battery arrangement are available via other on-line/mail order catalog vendors. The batteries are shipped dry and one buys sulphuric acid locally (Autozone, etc.) to fill them initially.

Make sure the batteries are well secured and the hot side (positive) terminals and connections are well insulated electrically from grounding to the car body and other parts.

[oldE]

Doug,

I found out, a couple of years ago that a battery specified for a 1988 Chev 1/2 ton with a 305 cu in. V8 would fit into one of the battery compartments of the old E, if I installed it in end first. To take advantage of this, I had to change my cable ends over to the modern side-terminals and modify the hold-down strap.
As the old E sits, covered and alone in the garage from November to March, I remove the battery to a room which has heat and charge it fully. Then, when the weather turns nice, I hook up the charger again to top it off and re-install in the car. The sound of spring is the sound of the clock starting when I hook up the positive cable.
Do not leave the battery on a cold concrete floor. Place wood, cardboard or something else under it to insulate it from the cold floor. Failure to do this results in chemical aging in the bottom of the cells and shortens the life of the battery. Storing the battery without a full charge shortens the life of the battery. Double ditto on the above if the battery is in an environment which gets below freezing.
Preventative maintenance is the key to batteries (and, oddly enough, to many other devices.)
When you are charging, remember: Positive to Positive, Negative to Negative.

Have fun.
Les

[Doug&Julie]

Originally posted by john_cramer
10. Verify also that the red light for the alternator is not faintly glowing with the engine running. This could be indicative of a blown diode (such as caused by "jump starting" which could also be draining the battery. The only way to really test that would be to pull the alternator and check the diodes, but check everything else first, you would probably see a shorted diode as a glowing alternator light WITH THE KEY OUT OF THE IGNITION.

Hmm...we may have a cause right here. Since I get up early enough to see the sun rise, driving to work is in the dark, which means I see every little bit of light in my dash (..and we all know, there is only a little bit of light in the dash of an early 911). I'm fairly certain now that I've seen a faint glow from the alt light. I suppose it would be silly to suspect that it's glowing from other bulbs in the gauge?

So anyway...is an alternator diode something that can be fixed? ...or would it mean a whole new alternator?

[304065]

An alternator diode can be fixed, but it would be brightly glowing when the key is OFF and the battery would be flat in a couple days max.

If your alternator "genius light" (let's not call it an idiot light, it's one of the best diagnostic systems there is) is dimly glowing, then that would suggest that there's a weakness with the charging system, such as a slipping belt, oxidized terminals, bad voltage regulator or at worst a defective alternator. It looks like the mechanic who proclaimed the charging system "fine" spent too much time doing calculus and analytic geometry and not enough time staring at a voltmeter!

OK, forget the twelve-stepper. Take the multimeter's temperature probe out of the Prime Rib and measure the voltage AT THE BATTERY when the engine is running. If it's less than about 13.5 volts it's time to repossess the bowling trophy.

[Doug&Julie]

Hmm...well when Ken (let's put a name to the owner of the bowling trophy) had the car last time, I'm certain he checked the voltage. My receipt notes: "Towed in - won't start - charged batteries, started OK. Check charging system - 14.2v - OK" I'll have to talk to him about anything else he might have done/checked.

So I guess I have to chase down some of the other options...

[72doug2,2S]

3. Temporarily disconnect the crossover cable that connects the starboard and port batteries. You would do this by undoing the clamp on the port battery at BOTH ENDS. If you only undo one end, the chances of you blowing up the car increase by 72% due to the likelihood that one end of the crossover cable will contact the fuel tank resulting in an instant Blue Oyster Cult video.

This "crossover" cable is the positive cable on both battery +terminals? Then the Port (Battery closest to the passenger) is the only one producing current when the +cable and +terminal are connected with the tester.

Question 2 the PO had put large batteries in the box, they both stick out of the boxes with the +terminal facing out of the box.
I have had no problems with this set up, electronically speaking. Is there any unforeseen problems with this set up?

(Side note)I have tried my best to protect the + terminals but the Starboard (side near driver) still has some wide bits sticking out.

[SandyI]

I've jumped my 911E from my Blazer a few times by simply connecting the jumper cables to the Porsche's passenger side battery and turning the key. Simple.

And the 2 new Interstate batteries in my car work great.

You should be able to go more than four days without starting your car and not have to worry that your battery's dead. After an 18 day vacation, my car started right up.

[304065]

Originally posted by 72doug2,2S
This "crossover" cable is the positive cable on both battery +terminals? Then the Port (Battery closest to the passenger) is the only one producing current when the +cable and +terminal are connected with the tester.

Question 2 the PO had put large batteries in the box, they both stick out of the boxes with the +terminal facing out of the box.
I have had no problems with this set up, electronically speaking. Is there any unforeseen problems with this set up?

(Side note)I have tried my best to protect the + terminals but the Starboard (side near driver) still has some wide bits sticking out.

Yes, if you just disconnected the port battery by removing the positive clamp and the starboard battery were still hooked up in parallel, you couldn't connect the multimeter in series. Well, you could, but it would be in parallel with the other battery which would throw the readings off.

Thou shalt not drive around with too-large batteries in the box. That goes double for the "big optima sideways" deal-i-o too. The right size batteries are out there and they come in cheap (interstates) or dear (sonnenschens) but there is no reason to bolt a 38 pound optima on sideways and expect a 35 year old battery clamp or a piece of plumbing strap from Home Desparate to keep the positive terminal from shorting to the fuel tank when it comes unglued during a high-g turn. There are just more important things to worry about, like how to manage a 7-10 split. If the car burns down, would you pay $400 to have The Spirit of Ferry come down and return the smoldering mass to concours? Hell, I bet there'd be a seance convened faster than the Pelican Parts board would ask if the engine was for sale.

[72doug2,2S]

I guess the PO was thinking outside the box. I will heed thy words Cramer and put this on the official “on the list” list. Just out of curiosity, what does a 2,2S (MFI) go for? $$-$$$

[304065]

With fire damage? Or without?

Just kidding. I would think around $10k with low time and good compression, last time I thought about buying one that's kind of where they were. Probably more now that everything with "S" on it sells for an absurd premium, e.g. used "S" oil filter, contains original numbers matching copper bearing particles from "S" motor originally installed in the legendary 180 HP 2,2 "S" engine etc.

"Thinking outside the box," good one. Took me long enough to get it.

[Doug&Julie]

Originally posted by john_cramer
Anyway, more good battery information can be found on the Deltran site here: http://batterytender.com/faqs.php

Deltran is, amazingly, the manufacturer of the aforesaid Battery Tender Plus, and you can buy it directly from them, or you can pick a friendly business whose P&L you want to enhance and those Deltran rascals will STILL get the revenue, albeit at an OEM discount I would guess. I bought mine from NLA Limited because WAYNE does NOT sell them.

OK, I'm going to buy one of these. Now here's a stupid question...I'm buying a 12v charger, right? Am I correct to understand that this will charge both batteries in the car (with your instructions above)? Is it safe to charge on battery on the bench with a 12v charger? (I have extra battaries, I'd like to keep them charged...just in case!) Or do I need a 6v charger for bench charging?

Can you tell when it comes to electronics, I'm quite the...er...idiot?

Thanks.

[304065]

Doug, your 911 has two 12v batteries wired in parallel. Only the early 356's had 6v batteries.

Jim Sims, who is a brilliant person in general (seriously), says that using a Battery Tender Plus will not work on dual batteries in parallel. Perhaps he will post his experience with this. However, the Deltran web site says the following:

14. Can the Battery Tender Plus battery charger be used to charge more than 1 battery simultaneously if the batteries are connected in parallel?

Yes, the Battery Tender Plus battery charger can be used to charge more than 1 battery simultaneously when those batteries are connected in parallel. Theoretically, there is no reason that you cannot recharge your batteries in parallel, or that you can’t use a larger battery. HOWEVER, you must recognize that the amount of time required to recharge may be much longer than you would normally expect. Effectively, by charging more than 1 battery in parallel, the charger behaves as if one larger battery is connected to its output terminals.

The Battery Tender Plus only puts out 1.25 Amperes. That means it will take over 24 hours to recharge a 32 Ah battery to 80%, assuming that is fully discharged. It will take another 12 to 24 hours on top of that to recharge the last 20%. If you put an even larger battery in parallel with it, then the total times may double or triple. That is not a reason for concern.

The real concern is that the Battery Tender Plus will only switch over from 14.4 VDC absorption voltage when the current draw from the battery drops below 0.1 amps or after an 8-hour period in absorption mode. Under normal circumstances, with battery capacities up to 32 Ah, this is a good thing and the Battery Tender Plus will switch over to the long-term storage voltage of 13.2 VDC with no problem. In fact, it usually turns out that the amount of time spent at the constant voltage of 14.4 VDC, typically a few hours, is good for the battery, especially the newer AGM style batteries. There is a maximum time limit of 8 hours at 14.4 VDC. As long as the charger switches over to 13.2 VDC before the 8-hour timeout, then the battery will be 100% recharged. However, the larger the battery that you try to recharge, the higher likelihood that the charger current will never drop below 0.1 amps with 14.4 VDC applied, no matter how long the charger is connected. That means that the charger output will remain at 14.4 VDC for the maximum time period of 8 hours. This is also not a problem for the battery in terms of "dry-out", but again with the larger batteries if the charge current has not been reduced to a maximum of a few tenths of amps, then there is a good possibility that the battery will not be 100% recharged before the switchover to 13.2 VDC. This will result in even more time required before 100% recharge is achieved.

Our recommendation is that you not charge batteries in parallel, again assuming that the batteries are 100% discharged. If the batteries are only partially discharged, then it is probably OK to charge them in parallel.

So, bring them back from the dead one at a time, but for maintenance, in parallel is fine.

You aren't going to use this Battery Tender as a crutch to avoid finding the tapeworm, are you?

[Doug&Julie]

I'm just reading all of the FAQs on the site, thanks.

So if I understand this, I'm ok hooking this up to the car (per your directions above) right now since the batteries are not fully discharged (I still get lights, fuel pump, etc...just not enough power to crank the starter). But for the two batteries on my shelf, I'll need to power them up one at a time on the bench. Correct?

Re: crutch v tapeworm...Fear not, I'm just trying to get this thing started so I can enjoy the car while I find time to a) hunt down this tapeworm, as you describe it, or b) find time to get the car into my mechanics so he can do the hunting. (..did I mention I hate electronics?!?) At the very least, I'll be sure to notify to a potential purchaser this condition and adjust the pricing accordingly.

Am ordering 12v Battery Tender Plus right now. Thanks for all the help!