1999 V70 Alternator output

DML · Post by **DML** » 08 Sep 2014, 21:38

1999 V70 Base Auto 168,xxx miles.
What should the output be on these alternators ? I have read 13v - 14.8v.
My V70 stalled out (3) times today. Twice on my wife (1st time in am and 2nd in afternoon) and once with me this evening on a test drive. Let it sit 15-20 min and would restart again.
Before test drive I checked the battery voltage and it was 12.4v. Started and let idle in the driveway and checked the alternator output (at the alternator) and it was 13.6v. Checked at the battery and it was 13.0v with the A/C and daytime lights on. I left the meter on the battery and let run for 15 mins and the voltage fluctuated from 12.9v to 13.0v. I took it on a test drive and about 150 yrds down the hill it dyed. I quickly checked the battery and it was 12.5v. Just before it dyed the up arrow, battery and oil light came on. Let it sit 15mins it started right up and made it back up the hill. I left it running and put the meter back on the battery and it was 12.9v - 13.0v with A/C and lights on.The alternator was putting out 13.4v. I let it run and watched the meter and after 1 min the voltage started to drop slowly until it reached 12.6v and was about to stall out and it jumped back to 13.0v and stayed 12.9v - 13.0v. At this point I turned the high beams, A/C and emergency flashers on and let her run for 15mins
and voltage never dropped below 12.9v. Did a load test on the battery and voltage dropped to 11.4 (Twice).

Is the alternator output normal or is it on the way out ?

Thanks

Post by **jblackburn** » 08 Sep 2014, 21:45

12.9 is low, but you're seeing much higher output at the alternator and THAT voltage in within the acceptable range. The voltage slowly dropping off and the car dying out says to me that you need to investigate the battery cables themselves for corrosion or bad connections, or replace those. The battery to fusebox positive cable is a common one to go out; it will slowly choke off the voltage supply to the car, but it sounds like your alt to battery one has the same problem.

DML · Post by **DML** » 08 Sep 2014, 21:52

Ok thanks. I'll clean all the connections tomorrow and go from there.

Post by **precopster** » 08 Sep 2014, 22:02

The 1999 models suffer from the same fuel relay problems that all 850s and pre 2000 S70s/V70s suffer from. Try the fuel relay jumper trick pin 15 gets shorted to pin 87. The relay can be found under the cover behind the engine bay fuses near the wipers.

The voltages you describe could be better but are are ok as far as allowing the engine to run because 12.5 v while engine is stopped is quite normal.

Steve Ivins · Post by **Steve Ivins** » 09 Sep 2014, 04:25

A good alternator will supply 13.8 to 14.7 volt depending on the current load to the battery. Internal resistance in battery cables WILL change this. Resistance by corrosion affects the voltage and the available current. Here in Australia no salt and snow so cables last a lot longer. A battery when running in the car and engine stopped should indicate 12.6 to12.9 volt. Cheers Steve.

Post by **tryingbe** » 09 Sep 2014, 06:37

To test the battery cables, turn everything (light, a/c, rear defrost, etc) on, test the voltage between the POS end of the alternator and the POS end of the battery. You can do the same test to the negative cable by test the NEG end of the alternator and NEG end of the battery.

I upgraded my alternator to starter, starter to battery, battery to ground, and battery to chassis cables with thick 1/0 gauge welding cable. It's at least 70% thicker than stock.

With everything on, the voltage drop between the pos of the alternator and the pos end of the battery is now .07 V vs .7 V before.

Here are what you want to buy.

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And two battery terminal that you can get at your auto part store.

Post by **regent** » 09 Sep 2014, 08:33

This is a great mod, thanks for the nice write-up and links to material and tooling

Post by **timmybdaddyof3** » 09 Sep 2014, 11:04

just covered this....have a read

https://www.matthewsvolvosite.com/forums ... =1&t=65552

DML · Post by **DML** » 11 Sep 2014, 21:07

Update
I checked the resistance on the battery cables this evening.
Test was done with the car cold and not running.
The negative cables ohm at .2.
All of the positive cables were at .3 respectfully.
The cables appear to be in good shape. There not corroded.
I know you cant tell by looking...just saying.

Tomorrow I'm going to try to get to the welding shop and pick up some ground cable and make
up some new battery cables.

Post by **timmybdaddyof3** » 12 Sep 2014, 00:12

resistance will climb with both heat and load....i think you are on the right track