Battery Test Results - Replace?

[NYSteve]

Mother in law brought her 04 PT Cruiser to Firestone (I know that's another issue) and they said she needs a new battery. Current battery - mopar oem replacement -was replaced 3 years ago when she purchased vehicle at Chrysler dealership. Went to Advanced Auto tonight and here are the results:
Temp: 43f
Voltage: 12.54v
Measure CCA: 570 cca

Cranking voltage from starter: 10.72v
- voltage during start-up went from over 12 to right around 9v which stuck out to me

Charging was solid at 14.2 with high beams, blower motor and some
Lights on.

What do you guys think? I'm leaning toward telling her to get the best Costco battery she can as preventative care going into our cold winter.

 

[GMBoy]

If the car was just driven before the test (meaning a good charge just prior to the test) than the 12.54 volts bother me. With the battery being 3 yrs old it may have some more life so unless it is cranking slow or giving you other reasons to doubt it, I'd keep it. But for peace of mind, a new battery surely won't hurt...and you may have pro-rated warranty left.

 

[daman]

Is she having starting/cranking issues? 3 year old batt is not that old.

 

[JHZR2]

Vterminal=Vopencircuit-I*R

I dont know what your starting current is though.

If it is 570A (lets just say, based upon their determination of CCA), then the IR drop is 12.54 (which is low) - 10.72 = 1.82V

So IR=570*R=1.82V Thus, R=0.003 Ohm.

We'd have to look if this resistance aligns to new starting batteries.

A quick search shows 0.01 Ohm, so my numbers are a bit off. Let's say a starter test takes 60A instead. 1.82/60=0.03 Ohm.

If the battery resistance is 0.03 Ohm vs 0.01, then it has triple the resistance. Not bad, IMO.

You will see a good voltage drop under load, especially starting. What bothers me is that the battery is only 12.54V. If it was "fully charged", the surface charge removed and the battery settled, it should be more like 12.7V.

 

[JOD]

Originally Posted By: JHZR2

You will see a good voltage drop under load, especially starting. What bothers me is that the battery is only 12.54V. If it was "fully charged", the surface charge removed and the battery settled, it should be more like 12.7V.


Agreed on the drop in load at start-up; but would the voltage really be that high at 43 degrees? Keep in mind that voltage drops about .02V every 10 degrees F. 14.7 kinda sounds like "room temperature". This is from Exide's handbook:

Temperature: 57 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.258 12.59
75 1.203 12.26
50 1.153 11.96
25 1.113 11.72
0 1.093 11.60


I'd say he's well within acceptable range.

 

[oilstudent24]

Ive posted this before, but I Believe some manufacturers have done away with the pro-rated part of the warranty. The Everstart Battery comes to mind. 1,2 or 3 yr free replacement and no pro rating after that. I'm not sure about Costco, but thought that would be good information. Expect to pay around $100

 

[NYSteve]

Wow...quick replies guys! A little bit more info. This is a second vehicle for them and prior to today had not been driven in 2 weeks. First trip of the day was about 8-10 miles then a 3 mile trip to advanced auto about 3 hours later. So while it might be 43 outside, battery might be at room temp from engine heat.

I agree that 3 years is short for a battery and I usually run mine about 5 years. However they are older, not car buffs, and cannot get stuck as it is now my recommendation.

Thinking of Costco because they still have the full warranty and a great prorated as well.

Moving to more general battery question- what is the best 'metric' to evaluate battery health - voltage, cranking, etc? Thanks for the great insight

 

[crazyoildude]

i do not like the pro rated system i wont buy anything pro rated

 

[user52165]

Originally Posted By: daman
Is she having starting/cranking issues? 3 year old batt is not that old.


+1. OP - What about this........you never really answered. Or is Firestone just trying make their sales quota? You know those "women" customers............suckers?

BTW to other posters - many dealers still have pro rated warranty.

 

[JHZR2]

Originally Posted By: JOD
This is from Exide's handbook:

Temperature: 57 degrees Fahrenheit

Percent Hydrometer Unloaded
charge reading voltage
100 1.258 12.59
75 1.203 12.26
50 1.153 11.96
25 1.113 11.72
0 1.093 11.60


I'd say he's well within acceptable range.


Handbook > my top of the head conversation. Id tend to agree wrt voltage being OK with that basis.

 

[user52165]

Originally Posted By: crazyoildude
i do not like the pro rated system i wont buy anything pro rated


Why not? For example, Costco 3 years 100%, after that sliding scale out to 100 months - that's 8+ years. Yes, they will adjust for increase in new battery price, but still a good deal. Amazing how many batteries fail to hold a charge at 35 months!!

 

[JimPghPA]

Temp: 43f
Voltage: 12.54v
Measure CCA: 570 cca

Cranking voltage from starter: 10.72v
- voltage during start-up went from over 12 to right around 9v which stuck out to me

Charging was solid at 14.2 with high beams, blower motor and some
Lights on.






With the data you show I do not see any problem yet, however another piece of information is missing.

What is the CCA rating of the battery?

IF the battery shows 75 percent or less of its rated CCA then you might want to replace it. So if the CCA of the battery is less than 760 then a CCA of 570 would still be a good battery.

If it were a vehicle of someone in my family, I would look at how many miles are on it. At 60K miles I have the starter and alternator rebuilt by a good shop. For the alternator it gets new bearings, and new brushes. The starter gets new bendix, new brushes, the commutator cleaned including cleaning down into the groves, the field coils tested, and the shaft and the hole it goes into cleaned and greased. I have found that the first rebuild should be at 60K and then every 50K after that to keep a vehicle reliable.

Also replace serpentine belts and idler with tensioner about every 30 K. It use to be every 25 K but they last longer now.

BTW, I think I read something about the timing chain on those PT cruisers being a big job when they go. You might want to look into how many miles they are normally good for, and how many miles are on the vehicle they have.

 

[HTSS_TR]

Originally Posted By: user52165
Originally Posted By: crazyoildude
i do not like the pro rated system i wont buy anything pro rated


Why not? For example, Costco 3 years 100%, after that sliding scale out to 100 months - that's 8+ years. Yes, they will adjust for increase in new battery price, but still a good deal. Amazing how many batteries fail to hold a charge at 35 months!!

I agree. If pro-rated costs extra then it's another story, but at no cost it's a good warranty.

 

[NYSteve]

Originally Posted By: user52165
Originally Posted By: daman
Is she having starting/cranking issues? 3 year old batt is not that old.


+1. OP - What about this........you never really answered. Or is Firestone just trying make their sales quota? You know those "women" customers............suckers?

BTW to other posters - many dealers still have pro rated warranty.


No cranking issues or any other clues that point to a bad battery. She has dropped about $1k-$1.5k at this Firestone in the last two months. First $500 or more was new tires even though I repeatedly told her to go to Discount Tire. Somehow she needed new tires and a new rim that was allegedly cracked. Wasn't consulted before and am never brought along so who knows what was going on.

Second $500 was a legitimate front wheel bearing although again told her to find a real Indy mechanic. Even reco'd a couple for her but I think his battery 'issue' will kill he golden goose for Firestone. Yeah they see her as a loyal sucker coming back for more until she doesn't

 

[NYSteve]

Originally Posted By: JimPghPA

Temp: 43f
Voltage: 12.54v
Measure CCA: 570 cca

Cranking voltage from starter: 10.72v
- voltage during start-up went from over 12 to right around 9v which stuck out to me

Charging was solid at 14.2 with high beams, blower motor and some
Lights on.






With the data you show I do not see any problem yet, however another piece of information is missing.

What is the CCA rating of the battery?

IF the battery shows 75 percent or less of its rated CCA then you might want to replace it. So if the CCA of the battery is less than 760 then a CCA of 570 would still be a good battery.

If it were a vehicle of someone in my family, I would look at how many miles are on it. At 60K miles I have the starter and alternator rebuilt by a good shop. For the alternator it gets new bearings, and new brushes. The starter gets new bendix, new brushes, the commutator cleaned including cleaning down into the groves, the field coils tested, and the shaft and the hole it goes into cleaned and greased. I have found that the first rebuild should be at 60K and then every 50K after that to keep a vehicle reliable.

Also replace serpentine belts and idler with tensioner about every 30 K. It use to be every 25 K but they last longer now.

BTW, I think I read something about the timing chain on those PT cruisers being a big job when they go. You might want to look into how many miles they are normally good for, and how many miles are on the vehicle they have.


Jim I'll check what the CCA is when I get a chance.

Also that is amazingly proactive maintenance in the best way I can convey. I honestly thought those types of shops we dead and gone. Do the ones you use accept mail-ins? Starter is fine except a well known issue with the solenoid going out early. Will check into the timing job as well. Thanks for the headsup on that one!