98 Volvo: Weak/Failing Battery?

[sleddriver]

Timely post re: 2012 Battery Notes for the Volvofolk

Your batteries sure last longer than mine. Not near as hot though where you are as here in Tx.

I've been using InterState for more than a decade since that's what my mechanic sells, but I'm beginning to doubt them. They don't seem to last more than 3-4 years.

Yesterday, I'd been running a few errands. Pulled in the grocery, turned off the engine but left the radio & A/C fan blowing while I made up a list. Then the radio just quit! When I left the car, the remote door locks didn't work. I left it, went shopping, tried again: no joy. Got a jump, came home and checked each cell with a hygrometer. Two cells floated 3, the rest only 1.

I peered into each cell with a bright light and saw something odd. The main bar/buss the plates connect to on three of the cells looks new. However, on the remaining three, it looks moderately corroded.

So I put on the charger, set it for 6 amps, meter indicated a 4A draw, left it overnight and most of today and just turned it off..21 hrs later, to let it equalize before I check the gravity. The battery is slowly bubbling, the charger is barely warm and the meter shows current draw at 1A.

The sled's on its second alternator, which I installed about 5-6yrs ago. Had my indy check it with his load tester and DC current clamp meter. Said it was fine. He also tested the last Interstate battery with an electronic tester, which indicated it was good. But it would only float a couple of balls. He replaced it with this one in Sept 2009. Three years almost.

The battery is an Interstate MegaTron II, 75mo, MT-47 590cca/740ca, made in mexico.

I've noticed periodically the starter spinning slower-than-usual. So I'd put on the charger that evening and let it charge all night. The next day it would spin like usual. I've done this more than a few times.

I thought I might have a parasitic drain, so I put a DC ammeter in-line, first with nothing on, then started turning on the radio, the blower fan, opening doors, etc. in various combinations. I don't have the numbers at hand, but didn't notice anything excessive.

Perhaps batteries 'just aren't made like they used to be'? Perhaps the extreme heatwave we had in Tx last Summer took a few years off it's life? Unfortunately, I don't have a DC clamp ammeter to check the alternator.

This would happen late Fri at the beginning of Labor Day weekend! I'll be keeping my portable power pack in the car though. . . .

Could be a battery issue or alternator issue or batt/alt issue. It would be interesting to see the alt current waveform on my oscilloscope, but I don't have a shunt. A bad regulator/diode could also be at fault. Having replaced the alt once, I tried to disassemble it to get to the voltage regulator, but no joy.

What brand will go the distance in HOT Tx?


***************************************
UPDATE:
Just finished taking some measurements after allowing the battery to rest 3 hrs. after the long charge (see above post).

No load batt. V: 13.17v.
Turn on parking & interior lights: 12.93v. After one minute, drops to 12.72v. After 5 min: V=12.74v

Acc key on, a/c blower & radio: v=12.45v. After 4 min, it drops to 12.49; after 5 min. it reads 12.48v.

Add low-beams to above, v now 12.29v. After 5 min, v=12.23. After 10 min, v=12.13v.

Turn all off, v rises to 12.64v. After 5min, v=12.78v

Start engine: v=13.21v. After 2 min v=13.22v.

Increase rpms to 2000; v=13.24.
Back to idle (~950rpm); v=13.17.After 5min at idle: v=13.2v.

With engine running, turn on low-beams, a/c blower & radio. v=12.76v. Increase rpms to 2000; v now 12.78v. Wait for two min. v now at 12.84v

Turn off engine; v now 12.76. After 15min, v=12.85.

Not sure how much current was being fed into the battery from the alternator, but shouldn't there be around 14.7v at the battery terminals (instead of 13.2v) with the engine on?

Unfortunately I forgot to check the gravity after allowing it to rest for 3 hours before doing these tests. I'll do it tomorrow morning.

 

[JHZR2]

13.22V operating is pretty low to force appreciable current into the battery.

Remember Vt=Voc+IR on charge.

So the more current, the more voltage you need to drive it.

 

[Falken]

The hardest thing on a battery is Texas heat.

Pony up Big Boy, 3-4 years Interstate isn't swindling you at all.

From what I have read in your post you know what's up and what's down electrically.

Simply put, just re-check that your alternator is putting out 14+ Volts when the car is running. (Touch + - batt terminals with your multimeter set to DC Volts).

I'll blame Texas heat... If you want a battery to last an extra year can I recommend Chilly Montreal? NO? Well, I cry in my beer for you Texan. :_)

 

[NEOhio_Bob]

Based on what you've provided, I think your battery is probably fine. 13.2v after the long slow charge sounds about right, and all of your other readings make sense...EXCEPT the 13.2v with the engine running - you are absolutely correct that it should be 14+v. Sounds like your alternator voltage output is low (I believe there's an internal voltage regulator, so that can't be addressed separately?).

You might even be running a "deficit" on short trips with lights, heater fan, etc. all turned on, where the alternator is not supplying enough voltage/current to maintain the battery, and the battery is effectively slowly discharging while the car is running - that might explain the occasional slow cranking/partial discharge.

 

[JHZR2]

Keep in mind that for every 8 Celsius over 25 degrees, battery life is halved.

 

[sleddriver]

Originally Posted By: JHZR2
Keep in mind that for every 8 Celsius over 25 degrees, battery life is halved.

25°C = 77°F and 8°C = 46°F, adding gives 123°F. That's a regular solar heat index around here in the Summer. Underhood temps could easily be > 180°F

 

[sleddriver]

Originally Posted By: NEOhio_Bob
Based on what you've provided, I think your battery is probably fine. 13.2v after the long slow charge sounds about right, and all of your other readings make sense...EXCEPT the 13.2v with the engine running - you are absolutely correct that it should be 14+v. Sounds like your alternator voltage output is low (I believe there's an internal voltage regulator, so that can't be addressed separately?).

You might even be running a "deficit" on short trips with lights, heater fan, etc. all turned on, where the alternator is not supplying enough voltage/current to maintain the battery, and the battery is effectively slowly discharging while the car is running - that might explain the occasional slow cranking/partial discharge.


Yeah, I think alt output V ought to be higher. Amp output could be OK, but weak on Volts. Could be a weak regulator or weak field. Unfortunately, it's internal. When the OEM alt went, I replaced it with a Bosch. I asked the place I bought it from to test it first as it's a PITA to replace. They claimed they weren't able to because they didn't have the 'correct' harness. I looked at the guy and said WTH? You have a digital tester and you're unable to test the alts you're selling?

So I installed it. And evidently it had an internal short because the shiny aluminum case soon turned amber and smelt burnt! The case would get so hot within 2min of engine on you could no longer touch it.

I had my indy do a load test/alt check in the car and he said it was tango uniform. I went back to the manager, with the dead alt. he warranteed it and took the replacement to another shop to have it tested first before I bought it. (So much for Bosch would never ship a TU electrical part).

I'm going to have it verified by my mechanic. Could be the reason I'm going through batteries every 3-4yrs along with the Tx heat.

The gravity in all 6 cells indicates 75% charge, so it's back on the charger at the 6A rate.

BTW all voltage measurements were made with a Fluke 77 DVM.

 

[Volvohead]

Originally Posted By: sleddriver


What brand will go the distance in HOT Tx?


Just my take, but your Ah capacity is probably fading on that one to the marginal level for your car's load.

But the hot TX heat is also your friend in the winter -- you won't have the more severe starting loads and diminished cca capacity we have up here come February. So perhaps you don't quite need 90%+ capacity anyway, and can squeeze more out of it. OTOH, I've seen fading batteries take out overworked alternators if left in service too long, more typically with rebuilt ones.

Still, when the time comes, I'd drop a Deka AGM series into it. PA-made just up the road, and first-class all the way as batteries go.

http://www.dekabatteries.com/default.aspx?pageid=4

FWIW, the the original batt in our '06 (garage-kept, trunk mounted) is now in our '97, as it still tests over 90% of capacity, and the ancient Volvo-Varta battery in our '97 (which sits outside year-round) is finally starting to fade like yours. We'll keep that fading one on a trickle charger this winter as an emergency spare before retiring it next spring. We'll see how that '06 one (2005, Wk 30 build) holds up. But neither owes us anything at this point.

Our experience is that if we don't get at least 5 years of service out of a starting battery, we got a clunker. But after year 5, we keep a heavy eyeball on them. Alternators and road service can be a lot more costly.

 

[eljefino]

My 91 volvo owners manual literally says to charge the battery periodically, IIRC every six months.

I wonder if they design the alt/charging system to under charge slightly so as to not boil off water. A temperature compensated alt puts out less in the heat. I wonder if the voltage regulator comes off of your alt and can be mucked with.

But you have charged yours more than occasionally which is more than many people do.

FWIW after a cold start I get 14.2 volts at idle.

 

[andyd]

Yah, My same era BMWs are doing well to put out 14 V. They are designed that way. Bosch stuff. The alternators last forever as a result.

 

[The_Eric]

Depending on the conditions, an alternator won't always put out 14+ volts. Many will drop their voltage with heat, especially if the PCM controls the alternator.

I've seen many alternators putting out mid 13's in blazing temps with an otherwise charged battery.

Now if the temps were say 0* F, you might see it putting out 15-16 volts for a short time.

Now, that being said, I do tend to think that 13.2v may be a bit low and is worthy of investigation.

 

[Donald]

I think one of the diodes in the diode bridge is gone in your alternator. There are 6 and if one or two are gone then it will put out a lower voltage than it should. The best place is to have a rebuild shop check it, second best is a place with a Midtronics tester that can pick up a bad diode. The rebuild shop will have an oscilloscope.

 

[sleddriver]

Found this but not sure if it represents mine. Shouldn't the common Y connection be grounded? May have been left out for clarity. 3-phase, 2 diodes/phase. I'll get out the o'scope and hook it up. Thanks for the replies.

Sure was more convienent when the regulators were external!

 

[Donald]

The oscilloscope is the right tool, thats what the rebuilders have, but unsure if there test setup has a car battery that acts as a capacitor. It needs something for the alternator to sense the charge needed however. If you have a scope you obviously know electronics and will figure it out.

Darn, my Dad would know this, bless his soul.

 

[Vikas]

Originally Posted By: eljefino
My 91 volvo owners manual literally says to charge the battery periodically, IIRC every six months.


I hope you meant 6 years!

 

[Volvohead]

sleddriver,

I just re-read your OP and checked into your battery.

That JC/Interstate MT-47 is undersized for that Volvo.

Interstate is hot to trumpet their CCA, but doesn't publish all its ah specs. If you dig around, some of its vendors have. CCA is for the causal consumer. But ah capacity is what matters most.

The MT-47 is only a 51ah G47/H5 battery. The OE Volvo is a 70ah G49/H6. 70ah should be your bare minimum on any replacement.

You've likely been cycling the MT-47 deeper than it was designed for, which is hard on the battery, and hard on the charging circuit. Add in your TX heat, and the result seems predictable to me.

But despite what others are saying about the alternator, and they may be right (although I tend to agree with the other gentleman about the low-floating Bosch units from that era), I'd get a new battery. Then double-check your charging circuit to make sure the undersized Interstates haven't overstressed anything.

Take a look at that Deka. Perhaps the mechanic that's been handing you the undersized Interstates should, too.

 

[eljefino]

Originally Posted By: Vikas
Originally Posted By: eljefino
My 91 volvo owners manual literally says to charge the battery periodically, IIRC every six months.


I hope you meant 6 years!


Charge, not change!

 

[Volvohead]

One other thing.

Be aware of the following Volvo TNN that affects your vehicle's battery/charging circuit:

Make / Models : Model/Build Years: VOLVO / C70 1998-2000
VOLVO / S70 1998-2000
VOLVO / V70 1998-2000
Service Bulletin Number : 0015 NHTSA Item Number : 627799 Summary Description : B+CABLE, BATTERY-TO-FUSE BOX, REPLACEMENT. *YD

After about 7-9 years, the B+ cables on ALL OF THEM need to be replaced, regardless of mileage.

If not replaced and it fails, it burns up batteries and alternators.

I'd check and see if your mechanic with the undersized batteries has addressed that little issue, too.

 

[sleddriver]

Originally Posted By: Volvohead
sleddriver,

I just re-read your OP and checked into your battery.

That JC/Interstate MT-47 is undersized for that Volvo.

Interstate is hot to trumpet their CCA, but doesn't publish all its ah specs. If you dig around, some of its vendors have. CCA is for the causal consumer. But ah capacity is what matters most.

The MT-47 is only a 51ah G47/H5 battery. The OE Volvo is a 70ah G49/H6. 70ah should be your bare minimum on any replacement.

You've likely been cycling the MT-47 deeper than it was designed for, which is hard on the battery, and hard on the charging circuit. Add in your TX heat, and the result seems predictable to me.

But despite what others are saying about the alternator, and they may be right (although I tend to agree with the other gentleman about the low-floating Bosch units from that era), I'd get a new battery. Then double-check your charging circuit to make sure the undersized Interstates haven't overstressed anything.

Take a look at that Deka. Perhaps the mechanic that's been handing you the undersized Interstates should, too.


Very interesting VH! Very interesting indeed. Just finished doing some research and I agree. Interstate shows two batts for my car: the MT-47 and a 47(H5). The later is a bit larger and has more Ah's (60 vs 51). I thought it curious why my batts never took up the whole tray length, now it makes sense.

Why don't they show an H6 at least?

So my indy shop has just been sticking these in there over & over again. I checked my manual but it didn't give a specific size (ie H6). Just a CA rating.

You're right about the 47's (measily) Ah rating: 51! Their H6 batt is 73, their H7 is 81 and their H8 is 106. Stepping up to an H6 is a 43% increase over the 47 in Ah ratings.

Found this interesting from Interstates site:

Quote:
Step 1: Determine how long to recharge a battery by calculating how much capacity your battery has. For example, an Interstate battery with the part number MT-34 has 120 minutes reserve capacity. In order to calculate the amount of amp-hours in a battery, the rule of thumb method is to multiply the reserve capacity by 0.6. In the case of a MT-34, 120 minutes reserve capacity multiplied by 0.6 = approximately 72 amp-hours (at the 20-hour rate).

Step 2: Use a voltmeter to measure the remaining voltage in the battery. For example, if the voltmeter shows a voltage reading of 12.4 volts then the battery is approximately only 50% charged. Since the battery is 50% charged, then this means that there are approximately half of the 72 amp-hours in the battery. Therefore it is necessary to put about 36 amp hours plus 15% more to compensate for the internal resistance in the battery for a total of 36 amps + 36 x 0.15 = around 42 amp-hours back into the battery.

Step 3: Charge the battery at a 10-amp rate. 42 amp-hours needed by the battery divided by 10 amp charge = it will take around 4-1/2 hours to recharge the battery. (The best charger to use in order to charge a car battery is a 3-stage automatic 12 volt /10amp charger.) However, the charger really doesn't output the entire 10 amps during the charge cycle because it automatically limits the voltage and the amperage during the charge cycle. You may actually only see about 1/2 the output over the time period that you are actually charging the battery. For that reason, it can easily take 9 hours or more to fully recharge the battery. Even after 9 hours, because of the reduced voltage, the battery may require more charging to get it 100% charged.

Step 4: Use a voltmeter or, better, check the cells with a hydrometer to make sure the battery is fully charged.


And this:

Quote:
Note: Battery buying strategy for use in Canada, for example, is different than hot climates that you find in Texas. In the colder climates, higher CCA ratings are more important, whereas, in a hot climate, higher RC ratings are more important once the CCA rating has satisfied the OEM’s vehicle cranking amp requirement.


Well, well. . they recommend more RC for a batt in a hot climate, yet they recommend a 47. Must be biased towards the Northern climates! Yet I have gotten 3 yrs out of it. Interesting to dive into this as I've just trusted my indy's advice and it's been so long since the OEM battery was in there, I don't remember if it completely filled the tray or not.

So in summary, the Bosch alt could be low-floating and/or compensating for the heat and my battery is undersized, particularly for the heat in Tx. I need a H6 at a min.

Re: Deka. No dealers here according to their site.

Re: Cables. Interesting bulletin. Where did you find that? I did check mine the other night. Found no melted insulation, and bright shiny copper inside. When I replaced the alt some years ago, I did a V-drop test on all major cables. I did replace the battery to starter cable or maybe the alt to starter with a factory one...can't remember. Royal PITA to check with the engine on and cramped conditions, not to mention the heat. Turns out the cable didn't need replacing as the OEM alt was toes up.

Diagnose first THEN prescribe.

Finally, given Interstates charging rec's above and the fact my little charger is only 6A at max, the battery may need more charging time if it's to get to 100%.

51Ah capacity. Presently 75% charged. Which is 38Ah needed from the charger + 15% to overcome internal resistance = 49Ah. At a 6A rate, this is 8hrs. min. But that rate will not remain constant over that time interval, so it'll likely be overnight. . . or more with the small charger I have.

 

[Volvohead]

Well, I think we've figured out why your batts aren't lasting as long as ours.

I've seen other instances where Interstate's recommendations have been sub-optimal, so don't feel bad about it. But your mechanic should know better, especially if he's been around Volvos.

And you're not the first to put an H5 in an V70/850.

But the FWD white block models really need no less than an G49/H6 with 70ah for good long-term performance and longevity. A T5 is usually option-laden, and benefits even more from the added capacity. The more ah you can buy, the better. If you take care of it, you're usually buying more lifespan the bigger you go. That extra reserve margin gives you extra years. IMO, it's cheaper in the long run.

Although the tray may seem to hold one, I'm not sure an H8 will fit in the typical V70/850 engine compartment. You'll have to pre-measure yours to know.

As far as finding a Deka, they have an office in Texas:

East Penn Manufacturing Co., Inc.
1724 Trinity Valley Drive
Carrollton, TX 75006
Phone: 972-616-0682

They may refer you to the nearest distributor, or sell you one directly.

Of course, the other option is your local Volvo dealer when there is a service/parts special, or if you have some credit/discount with them. I've gotten my last two from the dealer in the $100 range, the last one an H8 for under $100 after discounts just a few days ago. FWIW, Volvo's standard H6 is a JC/Interstate. But it's the correct one, and the fill caps aren't stickered over with all the circus tags like Interstate's retail ones.

A 6A charger is enough to charge that battery to 100%, provided you give it the time, and provided the battery can accept the charge. If fact, a long slow charge is better for the battery than a fast, high current one. You don't want to boil off the electrolyte.

I'd check your electrolyte levels again if need be before doing any more charging.

Another option if battery health is an issue for you is one of the smart chargers such as a Ctek. It will gently desulphate and recondition some marginal batts, fully recharge them, and keep those in service fully charged if the car sits around. And they're Swedish, just like your car.