| 928
Battery FAQ (Frequently Asked Questions)
compiled by www.rennlist.com from its archives database |
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SECTION 3: Memory Charger Electronics Electronics II Changing Battery Tips Changing Battery Sizes Burns Voltmeter Corrosion White Powder |
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In a question dated: 9/15/99
I've been reading a couple of recent threads......Let me see if I got this right... In a response dated: 9/15/99
Not exactly. The idle setting need only be reset on 928s that have the Bosch Hammer connections, and apparently, some folks have managed to do it without the Hammer.
YMMV. In a response dated: 9/15/99 Yup. It's like being in a strange place (a VERY strange place) and asking
someone for directions. They mumble this and that, point this way and that,
shake their head, and finally tell you: "You can't get there from here". |
In a question dated: 5/11/2000 I have... or had (!) a Varta 75Ah performance battery. Two years old. It worked perfectly until last monday. There was almost no power at all in the cells. No...i did not leave any power consumers on. Sure. But this is not the issue. ;) Normally one would find the battery capacity to gradually decrease until useless. But this battery completely died. I'm unable to charge it at all! It takes less than 0.5A when charging, which means... it's not even charging at all. It is a fairly new Quality battery. My question: what may have caused the battery to fail like this? Anyone? Thanks Theo Response(s) Theo, I think this is the way new batteries die. I have had three batteries in three different cars in oh, say the last three years, die like this. One day the car was fine, the next, it's like someone stole the battery. completely flat. Replace it with a new one and all is well. I do wonder about the two year thing though. Should be some kind of warranty on it, no? Mark Grasser Response(s) 85 > have an interior light relay 928 618 225 01 located second row next to last relay on the right , it has a time delay 25 seconds plus or minus 5 seconds it also keeps the red door edge warning lights on . They can fail to shut off Jim Bailey 928 International Response(s) My guess is that an internal cell bus bar connection has broken, limiting the amount of current that can flow thru the battery. Be careful! Placing a battery with a broken connector under load (charge or discharge) can result in a battery explosion! Wally Plumley |
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In a question dated: 10/31/00 Well, I went to start my car today and, after about 2 weeks of non use, it
is completely dead. It has been cold here in the north east but nothing
that I was worried about. The car is in my garage and I usually hook up a
battery maintainer while it sits there, but of course this time I didn't.
The car has no electrical power at all. I thought that I could just hook
up the maintainer for a little while and I should be all set. The problem
is that when I hook the maintainer up I usually get a yellow light that comes on indicating that the hook up is complete and the battery is
charging. Now, I get no indication at all. The charger wont even kick in
because it thinks it doesn't have a connection. Am I missing something?
Why won't the battery take any charge? I quickly tried to do this before
work this morning and I haven't had a chance to mess with it at all tonight. What should I check next? Any help would be appreciated. I hope In a response dated: 10/31/00 To be a true "battery maintainer" rather than a "battery charger", the unit
has to have some smarts. One of those smarts is that it doesn't turn on until it is hooked to a battery. If your battery is totally dead, then the
maintainer obviously can't tell that it is hooked to a battery, so it won't
turn on. |
Dead Battery III
In a question dated: 10/29/00 Now I have a mystery that I can't figure out. There is something that drains the battery after a few days. I measured the current with everything shut off and it is less than 10ma, so there must be something that turns on sometimes or?? Anybody have an idea as to what to look at first? In a response dated: 10/29/00 My educated SWAG is that the little red lights in the doors are still on because something is indicating that the doors are ajar. In my case it was the rear deck switch that was still making contact even though the rear hatch was closed. I repaired the broken plastic plunger that the ground wire was connected to and that solved the problem.
YMMV. In a response dated: 10/31/00 It's about 10:30 p.m. EST - so I trust those who've been out
Hob-gobling have returned home. I was doing a bit of trick-or-treating myself earlier today....and it relates to Gary Casey's question about possible "slow drain-downs on the battery", and also the "1/2 tooth off" T-belt discussion within the last day or so. When I would "shut the car off" for more than 24 hours - I would have to disconnect the negative battery cable. That would shut off the little red indicator light....located on the pod display in lower right corner - the "bottom" of the amperage guage, which would otherwise stay on until the battery disconnect. The car would re-start immediately with the ground reconnected. Without any time to deal with this annoyance because of a hell of a travel schedule this Fall, I put up with it. Then - 10-12 days ago - I lost my rear deck latch electric-release function. Now I ask you, how convenient do you suppose it is for a 6' 0 240-ish, late 40's type of guy to squeeze into the rear half of the car, move out all the assorted cargo items (not including the spare, jack, and elect. pump - which I'd already taken out? Even without need of wrench or vice-grips (I had it arranged for slide on, slide off - with just a proverbial twist of the wrist) it was getting to be damned inconvenient. When the bleedin' door swung to onto my right foot and ankle while I was stretched out in "disconnect maneuvers" one time - I said that's &$#*-ing IT!! SO - Gary...it seems that the round pull-type release switch may not have had a clean contact with the driver's door light, so the hatch release wouldn't activate. In other words - it didn't know the door was open - won't open if the door is "shut" ; safety design and all that crap. We did a temporary "clean and lube" fix - but will take it up more thoroughly during this winter's hibernation. What I didn't realize then - but I think this is what Ed Ruiz is suggesting - is that this door-light, or the door-is-open red indicator light - may also be what is the low and slow - but sure - parasite draining down the battery. A "vicious circle" as it were - in my case. HOWEVER - don't ask me why that passenger side release would still work
for a few days after the other side stopped. Then it ceased as well. My brain hurts too much to ponder that one. (This was the "Trick" part) |
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In a question dated: 11/2/00 Has anyone replaced the long 12V battery with a shorter
(lighter) version? How do you secure this type of battery. I believe Kim Crumb has made some type of mod
to fit the smaller battery. In a response dated: 11/2/00 Gary - As for some possible causes of the "slow drain down"....go back to the
List entries in the last 2 days - look for input from Ed Ruiz and my own
"drain down" discovery - in response to Gary Casey's similar inquiry. Heading is "mystery" or "mysterious". In a response dated: 11/2/00 I installed a battery switch in my gt. I used one of the simple 2-pole on/off track type
switches from automotion. I made a right angle bracket about 2" on each leg, mounted it on
the battery ground mount, behind the tool kit cover, then mounted the switch with one terminal
right onto this bracket. Then the ground strap goes to the other switch terminal. I cut a
small slot in the tool cover so that you could remove that without removing the switch key.
Very handy when working on the electrics or leaving the car for a couple of weeks or longer.
Mount a wire lanyard out through the drivers side of the rear hatch if you race the car,
remove that lanyard when you are not on the track. Works good, very handy. |
In a question dated: 5/22/99 After marvelling at my nice clean carpets, I decided I was done for the night and tried to roll the windows up. Nothing happened. I glanced at the
clock and radio - no lights. ^*&$^! Dead battery again. I had my doors open for several hours today, but flipped the switches on both of the door lights so that they wouldn't turn on. The other cabin lights need new bulbs, so I haven't bothered to see what position they are set in. Do the lights in the trunk come on when the doors are open? (I didn't set those off) The car has been sitting for about 6 days anyway (seat renovation), but it had power this morning (enough to get the windows down:). I wouldn't think the regular clock and the clock on the radio (aftermarket) would be enough to drain my 2 year old battery, so what else
could be doing it? In a response dated: 5/22/99 |
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| Section 2: Recommendations Recommendations II Recommendations III |
Battery Recommendations In a question dated 3/23/00: Hello All, My 87 will soon be needing a new battery, and I want to get the best battery that will fit. So, do any of you have any recommendations? Thanks, In a response dated: 3/23/00 Interstate
MTP91 Wk In a response dated: 3/24/00 An authentic Porsche battery. Let your car know you care enough to give it OEM!!! $125 plus tax (from the dealer) ---
Andrew In a response dated: 3/24/00 Be sure to put Porsche electricity in the battery --- I prefer the interstate battery -- more distributors for warranty - A much higher volume of sales -- potentially shorter storage on the shelf - I have had Porsche batteries fail in less than one year - Jim Bailey 928
International In a question dated: 5/21/1999 I need a new battery for the shark. Any opinions/suggestions on a good aftermarket battery (brand/model #). What are you guys using? In a response dated: 5/1/1999 "Interstate MTP-91." Response(s) In a message dated: 5/1/1999 I can tell you what NOT to use...the Optima that is supposed to fit the 928 is too tall and the posts will touch the top of your battery box cover. In a response dated: 5/1/1999 I use Porsche Batteries personally, but you can get as good or maybe even better one at Sears or NTB. It is the Sears Diehard Part # 22836249, retail is $106.99 , but mention a trade discount and you can get it for around $89. Fits all 78-86(early) 928s. In a response dated: 5/21/1999 Dana, |
Recommendations III In a message dated: 10/13/00 A while back, I proclaimed my great satisfaction with a Champion battery I bought at Sam's Club for my '85 928 for less than half the cost of Interstate/Excide/Porsche etc. batteries. Well, that was January, 1998 and my Champion battery is now kaput. So it didn't quite make it 3 yrs. Not very good, though it was an excellent performer while it lasted. I'm now testing a Dura-Last from Auto-Zone ($60). I has a 2 yr free replacement warranty and a 7 yr prorated warranty. Something tells me I'll be collecting a partial refund at the end of this one's life. I'll report on it's demise when it happens. Ed Croasdale In a response dated: 10/13/00 Ed, Your experience is the same that I have had with Champion batteries. GNB (Gould National Battery) makes the Champion along with a host of others , you can usually find "GNB" on the label or molded into the plastic. If I find those letters I won't buy it. -mark In a response dated: 10/13/00 As mentioned at the last Frenzy, the consensus was that maintenence -free batteries are not very reliable. I use Interstate (non-maintenence free) batteries in all my cars and have only had one go bad. (It was replaced at no charge.) They tend to last 5+ years and (so long as the fluid levels are kept above the plates) provide consistent voltage and enough CCAs to start the car, even on very cold (sub 15 degree F.) days. My advice is to pay the extra few bucks for an Interstate battery and save yourself the potential aggrevation you may get from a maintenence-free battery. YMMV. ~ Merry motoring ~ |
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| SECTION 3: Memory Charger Electronics Electronics II Changing Battery Tips Changing Battery Sizes Burns Voltmeter Corrosion White Powder |
Battery
and Memory In a question dated: 7/9/00 Is there any way you can unhook the battery/power yet still keep power to the "brains". Im heading to Hotlanta for training today and will either have the car parked at the airport or at home here for an extended time. I just don’t want the hassle of unhooking the battery terminals..hooking them up all the time then having the car run rough for a while as the brains remap everything. I would like to take all the items i can "off line" except the brains memory as to preserve the battery over an extend storage time? can it be done..and if so..could a switch be wired in so it could be done from the inside? Thanks Tony In a response dated: 7/9/00 Tony, I've seen a gizmo that uses a 9 volt battery hooked up to the cigarette lighter to maintain the computer settings. Don't know if you have to connect the battery posts together for it to work. Believe I saw it at JC Whitneys. Dennis Response(s) Spend a little extra money and buy a Schumacher battery tender for $30. Anything else is junk compared to these things. Get them at Wal-Mart or from Schumacher direct. The link is on my web pages links page. Brian Brian
E. Buxton |
In a question dated: 2/3/99 Could anyone suggest good battery chargeres for my shark sitting in the garage? In a response dated: 2/3/99
one of those automatic trickle/shut off kind?
really I think the key is to disconnect the ground cable during In a response dated: 2/4/99 Chihiro: In a response dated: 2/4/99 I'd recommend the Schumacher SE-5212A. It's fully automatic so
you can't overcharge and has 50/10/2amp output for starting, fast
charging, and trickle charging. I bought mine at Wal-Mart for ~$50,
or you can buy them online at Schumacher's web site. In a response dated: 2/5/99 Chihiro: |
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Battery and Electronics
In a message dated: 9/13/199 Dear fellow sharksters: In a message dated: 9/13/00 Response(s) Ed, if your GT still has it's owner's
manual go take a look at it - or take a closer look. I will dig my owner's manual out tonight and double check but I'm almost certain that mine clearly states that the system will re-adapt after 10 minutes of driving once the battery is disconnected. Response(s) In a message dated: 9/14/00 Dear Daves: |
Battery and Electronics
Cont'd In a message dated: 9/14/99 As promised earlier today, I dug out my owner's manual. On page 95 it
states: I think Ed is possibly speaking of the "System Adaptation" (calibration)
concerning the Electronic Idle Control in the LH computer, see Vol 1,
section 03, page 15 of the Workshop Manuals. |
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In a message dated: 6/12/99 When changing your battery, it is preferable if you can keep 12V supplied to the car so that electronic brain settings and radio memories are maintained. Here are two ways of doing this. ____________ In a question dated: 7/3/00 I want to change the battery of my 93 GTS. The task seems to be fairly simple but...with so many electronics on board I am afraid of messing up anything. Any precaution to take before disconnecting the battery (apart from having the engine off of course)? Regards In a response dated: 7/3/00: 1) If your radio needs a code to operate, be sure that you have it. 2) Always disconnect the ground (earth) connection first, and connect it last. 3) Be careful in lifting the battery out - they are heavy and the box is quite a stretch. You can strain your back, spill acid on the carpet, or drag it on the carpet. You might consider protecting the carpet, and possibly climbing inside to get the battery out of the box. 4) Clean all of the connections inside the battery box. Earlier cars have the speedometer/odometer connections inside - yours doesn't, since the speedo drive is off of the left front ABS sensor. 5) It will take a few minutes for your computer to reprogram itself afterward. You will lsoe all of your radio station settings, etc. Wally
Plumley In a question dated: 1/XX/99 The 928 uses a "group 49" battery, I believe. Or maybe its a "group 48"? The difference is which end has what terminal. Only this battery size will fit right. In a response dated: 1/XX/99 Yes and no, the 78-early 86 uses a group 49 (the long battery) and the 86.5-95 uses a group 48 (standard size battery) . The change from the long (49) to the shorter (48) was due to the re-routing of the dual exhaust in between the differential and the battery box on the 86.5 and newer 928s. David Roberts |
In a message dated 5/22/99 Listen to what Marc says, he know for what he
speaketh. Response(s) In a message dated: 5/23/1999 I'll second that. I have two characteristic "burn" spots on my battery compartment lid that indicate one of the PO's had a similar "exciting" incident. The advice about choosing the correct battery is warranted. In a response dated: 5/23/1999 FYI, if you look on the Porsche battery and most of the other good batteries you will notice 2 small holes on the outside edge of the recessed area near the positive terminal. These are receptacles for the hinged "Positive Pole Cover" that came on your 928 originally and is still available from Porsche. It will keep the positive connector from hitting the battery compartment lid even if you don 't have it properly secured with the battery hold down bracket. _____________________ In a question dated: 3/29/2000 Jason D Wheeler wrote: Could this be a problem caused by the impending failure of my alternator, or is there a regulator in the system somewhere that is no longer monitoring the charge shooting through the components? It's nice having supercharged components, but I'm afraid at this voltage, many components are doomed for failure, or even worse, could I be sitting on a timebomb (potential battery explosion)? Fortunately, the surge in electricity only last a few seconds at a time, but I noticed it getting longer in duration Good job of observation and reporting, and a good guess on the problem. In a response dated: 3/29/2000 The alternator sounds fine. Yes, there is a voltage regulator mounted on the alternator. Either that regulator is failing, or it is not accurately measuring battery voltage due to a wiring problem. The regulator/alternator uses the battery as a reference voltage and voltage stabilizer, and having the battery come disconnected while the alternator is charging the system can cause serious voltage spikes that can damage almost any of the electrical components on the vehicle. Murphy's Law assures that the damage components will be either the most expensive (such as a computer) or most difficult to replace (such as a major wire harness). |
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In a message dated: 8/3/99
Marc White shared his story of wire corrosion at the underhood
jump-start terminal - everyone should be aware that there should be a
plastic cover over this terminal connection block, as well as a plastic
cap covering the jump terminal itself. If you can see the wires
connecting to the terminal, your cover is missing! |
In a question dated: 11/10/00 Big surprise, my Walmart battery died today after 3 years(that's good
for WM batteries). Decided it was time to get a quality battery. I remembered
reading good things about Interstate here on the list. Found a dealer and
the Interstate book called for a MTP-93 for an 86 928. It was way to long
but I found that the MTP-91 fit well. In a response dated: 11/10/00 The powder is corrosive residue from your dirty and discharging battery
(bad boy). Mix up a batch of baking soda and water to remove and neutralize
the gook, then paint the box with bituminous paint. A battery mat is not
a |
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