Battery Not Charging... Any ideas?

[Suby Fan]

your going to want to do a wiring continuity test... just connect a volt meter from the output on the alternator to the battery positive (with the red lead connected to the alternator side) and if it says .3 volts or more then you have a problem in the wires some where... you can do this test only while the alternator is at ten amps or less though

[rallyingrob]

hmmmmmmm
ok
but how do i get the alt down to 10 amps or less?
when it was tested, it was producing 95 amps at about 2000 rpm (very rough approximation on rpm....)

<10 A would mean spinning it by hand......?
because even at idle, it would surely be 30 + A ?

(btw, my idle is messed up... its at approx 1300 rpm......the car SEEMS to run fine otherwise so THAT issue is pushed far far down the to-do list !!)

so for me at idle, the alternator is likely producing approx 50 A .........

no big deal to spin it by hand, or even a cordless drill and the old alt belt....

unless there is a better way.........?

[ItsPeteReally]

Don't worry, Suby Fan is proposing a wiring resistance test, not an alternator test.

If you have a fully charged battery then the alternator output will automatically be less than 10 amps. It's difficult and possibly dangerous to try to measure the alternator output current anyway.

If you can maintain 14.4 volts (or close) across the battery with the engine running, and the headlights on, then your charging system should be fine.

If you turn on more stuff, like the rear screen defroster and heated seats (if you've got them), etc. etc. you might see the voltage across the battery drop, but revving the engine a little more should bring it back up. If you turn on everything you can find you might just find that eventually the alternator can't keep up with the current demand and then the battery voltage will drop.

Really, if you find a significant voltage drop across any part of your wiring (not just the part that Suby Fan described, and I would certainly include the earthing (grounding) strap from the battery to the car body in this too) then it's a good plan to find out why.

The part that is under the most strain under this very severe test is the fusible link (mounted with the other main fuses next to the engine) which protects the alternator from delivering too much current. If your car is anything like mine you might see that the lid of the fuse box shows some pre-existing signs of heat damage from the current flowing through this link.

Do not bypass this link in an attempt to make things better, it's there specifically to protect your alternator from meltdown from supplying too much current.

[flyby]

sounds like you need a new altenator rallyingrob....if your disconnecting the battery while the engine is running and dies.

what i would do is take the battery and altenator to auto zone, checkers.. and get them tested for free. eliminate a couple of reasons.

[rallyingrob]

well , thats what i thought too but it seems that is a BIG no-no with the svx.

and also doesnt give an accurate reading of whats going on with the charging system...

the guy who checked my alternator is THE GUY to go to with automotive electrics....nearly 40 yrs experience..he is the guy that the dealers, military, and police/fire send stuff to for test and repair...(not to mention marine and industrial applications too..)

the alternator checked out perfect, no issues whatsoever and all readings were optimal, not just within spec, but perfect !!

i will admit, i havent delved too deep into things, i havent needed the car and its been too cold to work on things

it could simply be the battery crapped out.....or a wiring loom issue.i havent checked yet.....

but, long story short...the alternator itself is good.....
thanks for the input though!!

[dannmarr]

When I had this problem, all checked out (battery, alternator). An alternator rebuild shop replaced the plug that goes into the alternator and all went back to normal.

[rallyingrob]

i will check that out.i know the wiring loom is quite rough looking (old ,dry and missing some insulation (!!).....my parts svx loom is in little better shape and the legacy i have is different entirely...(although in good repair....dang!!)

i am thinking it is a wiring issue above all else..having recharged the battery, it holds loads just fine so at least IT is ok...
and the alt is good
so it must be somewhere between the two!!
easy-peasy!
lol

[michael]

Also check the post on top of the alternator in the back. Mine had cracked and the connection terminal was grounding on the alternator case.

[TheKoP]

I'm back again, sorry for the absence.

Lots of great ideas have been brought up and I thank you all for your input. Let me go through some with a little recap.

Originally Posted by Trevor

...Disconnect the ground lead from the battery and connect an ammeter from the lead to ground, so as to check for any stray current. Make sure all accessories etc are turned off and the doors are shut.

OK, I did this and nothing so I'll assume that I'm covered in this respect. I did disable the factory security system while I checked this since I figured that may show some drain.

Originally Posted by michael

Try opening the trunk and pulling down the plastic piece that covers the rear speakers. Left of center you will find the module for the power seatbelts. Try unplugging it overnight and see if that helps.

That is a great suggestion and one that I can see being easily overlooked. Unfortunately it doesn't apply in my situation sine I don't have power seatbelts.

Originally Posted by Trevor

If the alternator is not charging, the battery fault light should be illuminated. As a precaution, first check that it comes on at start up, as is provided as a test function for all fault lights.

No fault light in my situation, and yes it does come on when I start the car.

Originally Posted by Conn SVX

... I put a jumper battery on it still nothing I try to charge it it pops the breaker on a 5 amp charger. I said to the wife what did u do to my baby. NOTHING . Well turns out she used the rear wiper and it go stuck in the snow and never self parked. Did you guys know that until it parks it is using battery. I unstuck it from the window and as soon as I hooked up the jumper battery. (Car is shut off doors closed) the rear wipper self parked. All is back to normal now.

Also another good point, though I don't think it's my exact problem.

Anyway, to clear up a few things, this is my third battery since the problem has started. It hasn't happened since my original post about the issue (and I'm hoping it won't) but I'd like to be prepared. I will look into replacing the cables due to ease and to rule those out.