Idiot light on (Battery Icon)

Mr. Detail · Post by **Mr. Detail** » 30 Apr 2018, 11:37

I plan to go to an "Auto Zone" store after work today as my co-worker has told me that they will check my electrical system for free and perhaps tell me if i need a new alternator or a battery.
When I went to one of my online Volvo parts stores, they listed both an 80 amp and a 100 amp alternator.
Which is the one i should be buying if necessary?

Post by **scot850** » 30 Apr 2018, 11:49

Your car should have a 100A alternator. There should be a plate on it stating that but it is hard to see.

Neil.

Post by **misha** » 30 Apr 2018, 12:35

100A.

Mr. Detail · Post by **Mr. Detail** » 30 Apr 2018, 17:02

Thanks guy, 100 amp it is I guess. Does this sound though like I need a new alternator or is it the battery. I just went to the AutoZone store and the guy brought out a meter. Hooked it up and said there wasn't enough juice in the battery (65%) to tell which was the cause. They told me to drive around for a few miles and then come back for a re-check. I drove 5 miles and went back to the store and they then read off the meter 40%! They said the only way to tell for sure which to replace is to run a charger to the battery to get it up to 100%. Not sure what to believe at this point.

Post by **FlyingVolvo** » 30 Apr 2018, 17:53

100 amps. Your alternator is probably fried. I replaced my original one around 200K with an Autozone Duralast because I was desperate and time was a factor. It lasted about 35K before dying. Replaced it with a Bosch unit.

You can try recharging the battery and going from there, but based on what you said, it sounds like it's getting no charge (which is what the light is supposed to indicate). Of course, check all cables and connections first.

Post by **scot850** » 30 Apr 2018, 19:32

Ed makes a very good point on checking the charging wires and connections to the battery from the alternator to the starter and then tho the battery +ve cable. Also check the negative cable and the 2 ends it has. One bolts to the inner fender just behind the LH headlight, and the other runs down to the front of the engine block. Also check all the other grounds.

There are usually 2 or 3 others.

1) First has a bolt into the LH shock tower between the tower and airbox.
2) There should be one on the rear corner of the engine cylinder head at the corner nearest the coolant header bottle.
3) Some cars have one from the middle rear of the cylinder head to the firewall near the alarm horn in the middle. Some do, some don't.

There maybe more but can't think of any.

The alternators can have a diode fail in them that can cause the alternator to drain the battery even with the engine switched off.

Does your battery have the 6 little access caps to the 6 cells? You can buy a cheap hydrometer from Harbor Frieght/Walmart or the like and check the quality of each cell after a good charge. Check the level of the electro-light is close to the max. Usually there is a plastic tab that indicates the max point if you look into each cell. If they are low you can add distilled water using the hydrometer to get it to the correct level, and then fully charge the battery. Then test each cell for charge condition. If they are all about the same and in the mid-point on the scale the battery is probably ok. If one is significantly lower than the others the battery is bad.

Neil.

Post by **BEJinFbk** » 30 Apr 2018, 20:44

As stated, there’s a really good chance that you’ve got
a charging system problem other than the alternator.
Cables, connectors, grounds and ground straps, maybe
even a bad battery. You can pull the battery, charge it
completey and get it checked out of the car if needed.
It’s well worth eliminating all of those possibilities before
giving up on the alternator that’s in there now.

If this is a stock alternator that’s factory original equipment,
it’s advisable to make sure that it really needs replacing.
Many “rebuilds” are a big step down from Volvo OEM.

Is it quiet? If the bearings are good, that's a great start.
With the engine running, does it produce at least 13.8 volts
when you measure the voltage output directly from the B+
post on the back of the alternator ( the BIG post ) and
reference the alternator’s case for a meter ground?
If yes, more good news. Hang on to that alternator!

If not, it may just be a failed internal regulator. It’s a
tight squeeze, but the regulator in your alternator may
have worn brushes or failed electrically and can be
replaced without removing the entire alternator.

If you do determine that you need a fresh regulator,
there a plenty of posts advising that you stick with
a real Bosch replacement. It may cost a couple bucks
more, but hey, no electricity and you’re not driving...

Keep digging around this site for more information
about your charging system. There’s a lot of great
information here! “voltage drop”, “charging system”,
“regulator” are some good search terms to start with.

Good Luck!

Mr. Detail · Post by **Mr. Detail** » 01 May 2018, 04:13

scot850: No, the battery has a sealed top and is a NAPA brand.

BEJinFbk: Yes, as far as I know the alternator s the original one. The car presently has 181k on it. Yes, the bearings are still quiet.

ecbsykes: I did not have a chance yet to check all the cables and connections. Will do that today hopefully.

Thanks to all here!

Mr. Detail · Post by **Mr. Detail** » 02 May 2018, 14:14

Ok, gentlemen, had a technician/mechanic determine today that my problem is a bad alternator. I now plan to order a Bosch rebuilt from FCP Euro but that part does not come with the pulley attached. If i take it to my regular mechanic who has worked on this car before will he have the necessary tool(s) to remove my old pulley and then re-attach it to the new re-built one? I read something about a 12 pt./star tool needed to properly re-install the old pulley. Just wasn't sure if all mechanics have this.

Post by **abscate** » 03 May 2018, 07:02

If your alternator has the free-wheeling pulley you need the tool, Im not sure if you need it on a solid pulley on your 1998. I have to tool here but am coming to Bryn Mawr either this week/early next week if thats close and you get your parts in line.

If your mechanic doesn't have the tool to do that job, s/he has to go buy it.

The ABN tool is about $30 on Amazon, when purchased through the MVS link -

KD tool is about twice that - better quality - Lowes I think

There used to be a cheap radioactive one at Harbor Freight which was ok if you used it quickly, but last time I was there was a half-life so it was half price for half the tool.