'99 V70. No start condition MVSOLVED. New batt cables

[E Showell]

Ok -- No start again this morning. Wife reports nothing, not cranking. I put my Schumacher 2/10/50 plug-in charger on it (in lieu of calling AAA) and it fired right up with a 50 amp boost. Drove it down to my mechanic who load tested the battery -- fine -- and said the charging system appears OK.

With a digital multi-meter -- Battery at rest across the posts reads c. 12.5 V. With engine running at idle I'm at about 13.9 V and with engine running and all kids of goodies turned on, heater fan on max, high beams, radio, rear fog light, emergency flashers, it was reading c. 13.5V at idle.

The positive battery cable going to the starter was ever so slightly warm, but I could hold the cable all day long in my hand and not be troubled by the temperature. I popped the main fuse box cover off and the B+ connection looks like it just came off the show room floor.

The starter is a rebuilt, about 2 years old, but could be failing. I could also have a bad fuel pump relay (haven't checked). Has the feeling of an electrical gremlin. I have searched "Voltage Drop Test" on the forum, but not found the magic post. Guess I'll just have to keep looking.

It is a virtual certainty that we are working with the original battery cables -- both positive and negative, so I may opt for replacing them just as a form of preventive maintenance, but they aren't cheap. I got quoted $52 for pos. and $100+ for neg. I guess spot copper is up, eh?

Any thoughts?

[kahl]

So the car started since 21 December. Have you thought of a worn brushes on the alternator? Worn brushes will cause intermittent charging causing the car to run off battery with no replenishment from the alternator. Your voltage threshold seems to be just below starting voltage as shown with only a 50amp boost. I had similar issues with the S80 and a MB 420SEL years ago. replaced voltage regulator and problem was fixed. Cold weather seems to amplify voltage problems.

[draser]

I'd check alternator as well, you mention 13.5 volts but it should be 14.4. Losing 1 volt somewhere. Cables don't go bad just the end lugs, so look at the interface point for green oxide. If none present cable's good. Sounds like a flaky regulator if pulley's okay and it spins like it should.

[misha]

...Cables don't go bad just the end lugs, so look at the interface point for green oxide....

They GO bad and green oxide is not the only indicator.

E showell...something is draining your battery.Check for "parasitic drain" and perform the test.
Usual culprit on these cars is glovebox compartment light,but could be something else.

[E Showell]

So on Friday, I took off both battery clamps and cleaned the posts and clamps to a veritable shine. Dielectric grease on the posts as well. I also cleaned up one negative ground to the body in front of the battery tray and a ground in front of the fuse box/strut tower and smeared them with dielectric grease as well. Finally I cleaned up and greased the rear engine block grounds. Interestingly, the car practically leaps to life after the slightest touch of the key now, but the voltage values I checked the other day are pretty much unchanged.

Interestingly, when I fired it up after sitting overnight I heard a loud buzzing from under the hood and a loud click as well. Never heard those before. Any guesses as to what they might be?

[E Showell]

OK, so no start again this morning. It is about 25 degrees F out and went lower than that overnight. Voltage measured across battery terminals with a digital meter after start attempt was 12.09 volts. 50 amp boost did nothing to improve starting.

I can hear the fuel pump working in key position II so I don't think it is a fuel delivery issue.

Starter is a rebuilt as of about 2 years ago.

I haven't changed the voltage regulator in the alternator, but believe I do have the part. I've had the devil's own time removing the alternator cap with the alternator in situ and I don't want to remove belts. I guess I'm headed for the mechanic on Tuesday since I think we'll be iced in on Monday based on the current forecast.

Any other thoughts on possible problems?

P.S. I haven't been getting a battery light on the dash suggesting a problem with the charging system and while everybody says 14.4 volts is specification for a charging system in good shape, I've also read and heard plenty that these cars typically show somewhere in the mid-13s and exhibit no problems.

Could the battery have a bad cell and still load test OK?

[misha]

About charging output...
You MUST have at least 13.5v at idle with all consumers ON.Everything BELOW 13.5v is not enough to keep your battery charged.

I had a same problem few years ago when alt output on battery terminals on a HOT engine(after about 30min of driving)was 13.2 at idle with headlights and heater blower.On cold engine i had 13.9v.So...i had about 0.8v voltage drop at battery terminals and discharged battery in a week or two.Alternator output,when measured directly on it was normal 14.2-14.4v all the time.

After replacing B+ and negative cables i had constantly 14.0-14.2v with all consumers ON at idle.

Never had discharged battery again.

You must use 2 awg (u.s measure)or 25mm2 (eu measure)cables for battery terminals to match original ones.

Never put a thinner cable than original on this.

[abscate]

Evan , that 12.09 volts is really low..was that directly on battery terminals or positive to ground metal on engine ?

We did have a poster who had good looking connections but the actual wire was bad and caused starting difficulties. That was almost impossible to diagnose visually as it was under the insulation of course.

[E Showell]

Steve, that was voltmeter directly to the battery posts after two attempts at starting in 25 degree temps. Looks like I'll be laying in some new battery cables.

[E Showell]

My local Advance Auto Parts has battery cables. A new negative cable would be about $9.00. 4AWG wiring (I am advised). A new positive cable would be $15.00+ from the same source.

New cables from FCP are c. $50 for the positive and just shy of $100 for the negative cable. The negative cable from FCP is OEM Volvo, the positive is RAFAC.

Any reason I shouldn't go with the generic cables for c. $25 bucks if they are, in fact 4 AWG?