abrescia

So... i started my 86.5 car last Friday night and ran it for about 5 minutes. No problems. The car sat in my heated garage until last night (5 days) and my wife started it and backed it out of the garage to sweep out the floor. Then when trying to start it again, complete deadness. No click, no buzzing, no warning lights or dash lights or interior lights. The clock works! I put a battery charger on the posts and at first it read 67% but it also read 12.3 volts. I left it on the charger overnight and this morning it read over 90%. Still complete silence when turning the key. I recently had the car in the shop for some stupid little stuff and we tested the battery, ran a check on the charging system, and did a check for any draw. The draw was less than 0.5 or whatever the acceptable limit is. Everything checked out ok. We did this because ever since I got the car back from Classic9 (total interior redo, including dash pulled off and replaced) I’ve had some problems with the car needing boosted on the battery charger if I didn’t start it for 5 days. I never had a problem with this battery or with the car starting before that interior project. Any thoughts? I’m sure the word “relay” will be involved. Thanks for any consideration.

davek9

Do you keep the car on a battery maintainer when its not in use, if not, you need to do so,
Running a 928 for 5 mins (and or stop and starting it) and not bringing it up to temp is always a bad idea, it won't charge the battery and will load up the spark plugs as they all run rich when cold, mostly when in the white bar on the temp gauge.
Also short running doesn't burn off moisture inside the engine and trans.
Take the battery out and have it load tested, clean the connections, if you replace the battery, invest in a good battery maintainer (not one from HF

With a good/new battery if the same issue, then its Relay time

Dave K

jetson8859

If you have good power (once battery checked) then my guess would be starter not engaging, can tap it with a hammer while someone turns key and see if it engages.

Shark2626

Battery.

If you have a Walmart Superstore nearby get yours tested there, their equipment is far superior to Auto Zone or O’Reilys (parts stores).

davek9

I'd suggest the 14 pin connector first, it's easier to get to, and you can spin the starter from there bypassing the relay

Dave K

SeanR

Battery ground strap/connection there would be my first check.

abrescia

Thanks everybody!

linderpat

Aaron - all of the above, but I am also still bothered by your description of when the problem began. I am wondering that if upon reinstall, something got crimped causing a small short/parasitic draw. Or, a ground was left loose in the pod. Could be lots of things that may be a PIA to chase down, but getting a volt meter might make sense at this point too, and working through the wires, or pulling the pod and inspecting the connections. Pod pulls are not hard to do.

abrescia

yeah Ed that thought has been lurking in my head too, and that’s why we did that draw test when it was in the shop. We hooked up the meter and just watched it for 5 minutes- it just kept reading like 0.25 or 0.3 if I’m remembering correctly. We turned on the lights, watched the meter, turn on the new radio and new amp, watch the meter, it always went right back down to baseline when we turned things off.

Mrmerlin

Im with Sean here about a bad ground,

and agree with Dave about not running the engine for short periods
My suggested test procedure
without doing any battery terminal servicing
attach a battery jumper cable to the negative terminal of the battery
NOTE leave the car ground wire alone
attach the other end to one of the nuts for the rear shock
Go start the car it should start
NOTE if it starts cranking you may have to hold your foot to the floor till it fires.

If the car cranks then you have to look for a bad ground connection
Please report what you find

Also did you have a new radio installed in the car when the interior was done?

abrescia

ok Stan, let me see if I understand you correctly: pull up my daily driver car, and hook up a set of jumper cables to that battery just as though I’m jumping any other car. But I’ll take the negative cable and hook it to my dead car’s negative battery post, and take the positive jumper cable and put it on the rear shock nut (as in below pic?) Then start the car. (?)
the radio was not installed at the time of the interior.
Also I wasn’t relying on quick starts to keep the battery charged this winter- I was driving it on a reasonable regular basis since we’ve had nice weather- I just needed to reposition the car in the garage last Friday night. But in general, when I got it back from the leather shop, I’ve noticed that if I don’t start the car for about 5 days, the car wouldn’t start and I’d have to charge the battery- then it would start. That was never a problem before that 7-week stay at Classic9 and they had it on a battery tender the whole time. But like I said, my wrench guy and I went thru and couldn’t measure a significant draw and couldn’t necessarily show evidence that the battery was a problem. But thank you for the strategy and if I’ve interpreted it correctly I’ll try it tonight after work.

Tomkat80222

Your are not understanding Stan. He is saying to attach the ground of the battery to a different ground of the car. The shock tower is a large ground. Use one of the two jumper cable wires to make this connection. Got it. However, from what you just said above, the battery is dying from an unknown drain. To save yourself a lot of trouble you really need a battery charger and tender to own a shark. There are many low cost options on Amazon. I use a Battery Minder 1510 to maintain the battery. I just got one of these as an extra. This one is a charger and maintainer. I have used to top off my daily cars and it works fine. Make sure you attach the tender directly to the battery as the loss from the engine bay was too great to maintain the battery with the Battery Minder.

abrescia

ah....got it. I think. Thanks

dr bob

!!!NOT THIS!!!

Re-read Stan's suggestion. Connect positive to positive, then negative to the donor car battery, other negative to the 928 TOP shock tower bolt or other solid chassis ground. NOT the shock piston rod and nut in he middle, use one of the three nuts.studs that pass through the tower metal just above and forward of the battery and spare wheel. Ultimately positive-to-positive, negative-to-negative, but keeps the last connection point clear of the potentially explosive gasses from the charging battery.


Going to the "last things worked on" list, start with the idea that Classic9 had the battery disconnected while they worked on the car. Clean and secure the clamps at the battery posts, plus the smaller positive feeder wires that attach to the positive post terminal. Then the ground strap and bolt where it secures to the rear bulkhead. If the ground strap is the original, add one of the upgraded ones to your next 928 parts order.

Next would be wiring connections related to the dash and console if they were out for work. Clean the grounds in the foot well on either side, as others have suggested. Those would not normally have been disturbed by the upholstery work but there's never any downside to cleaning 928 ground points.

The connector for the ignition switch deserves a look. A couple screws secure the harness connector to the back of the switch, accessible with an angled/ratcheting screwdriver and tiny hands. The contacts are self-wiping on that, so if you can slide it on and off a couple times then tighten the screws it removes a possible cause of your symptoms.

After that, the diagnosis will be more detailed, using a DMM to find open circuits in the ignition and starter wiring and connections.

My dime (you'll have to send postage to collect it....) sez you'll find the problem at the battery connections.


After all that, you'll want to do some electrical sleuthing to find the parasitic draw that's running the battery down. The target number is 35mA or so, same as 0.035 Amps; That's about 10% of what you are reporting for parastic drain. Something is stealing power. A typical 60AH battery will be completely drained in 180 hours or less at the numbers you report. It will drain to the point of not being able to crank the starter in a lot less than that. Good reason to find and fix whatever it is that's draining the battery. Know that each time the battery suffers a deep discharge, it loses about 20% or its remaining capacity. Half a dozen of those deep discharges cycles will turn a new battery into an old one.

I've kept a maintainer attached to the car whenever it's going to sit more than a few days between drives, a habit that started the first time the battery drained while I was on an overseas project for a month. The 928 mob counseled me, and from then the maintainer has been a constant 928 companion. I lift the ground strap if I know it will be a few weeks or more of non-use, just to save the battery the mini charge cycles. Parasitic drain on my S4 is around 30mA, with stock everything except the radio head unit.

G8RB8

Sounds silly, but does the horn blow? They draw a surprising amount of power and is a good test to see if it's the starter.