Battery Test Report: Input Needed

[gathermewool]

'08 Subaru WRX STI - purchased 12/08 with ~200 miles

Battery: OEM

Charging System: Alternator reads high 13's to 14V while running.

Battery Contacts: Last cleaned and corrosion-protected in September – some corrosion on the negative lead was noticed.

Oil: Rotella T6 (same as used last winter)

History: STI was only a weekend car up until this past spring, and would sometimes sit for a few weeks at a time. Started somewhat slowly during below-freezing conditions, but not as slowly as this winter. Early summer I noticed a lot of wetness along the top of the battery after an extended highway drive. I used some CRC cleaner with indicator, which immediately turned color, indicating acid. I cleaned everything up and sprayed CRC protection spray on. I also needed to add a few oz. of distilled water to bring the level up to full; the plates were all still covered.

This fall/winter, I noticed the slow starts as soon as temps dipped
Since the battery would be covered by warranty, I drove 5 miles over to the Subie dealer to have it tested, and these are the results 10 minutes after shutting down the car:

Voltage: 12.28 VDC

CCA (rated): 550 A

CCA (tested): 459 A

Temp: 39F

State of charge: 75%

Results: Good – Recharge

The 75% SOC is a little odd. The dealer thought so, too, but said that the battery would have to fail the test in order for him to replace it. He also mentioned that some batteries will pass when the customer comes in, but fail after being charged over night. He suggested I trickle charge it overnight (which would require me to remove the batter and charge it on the back porch) and bring it back tomorrow to test it again.

Any suggestions would be appreciated.

 

[Steve S]

Have you tried to call the 1800 Subaru help # in the manual and ask for help? Usually batteries should last longer and it seems the dealer isn't willing to make sure you are satisfied with your purchase. Heck that is the kind of service I would get from a G.M dealer. Remember batteries loose their volts as they get colder. How is it with the head lights on for 5 mins. and the engine not running? Caution it may kill the battery charge. The battery may be bad and the drive to the dealer may give it enough charge to barely pass the test. Again the dealer is not very good. Iam sure you spent $$$ for your car and the dealer was happy to get the sale now they are unhappy to make you happy. What I worked at the forklift dealership I tried to make the customer as happy with their purchase and the company was getting the sale.

 

[gathermewool]

Actually, this dealer is great. I called at 1530 to let him know about the slow starts and he said to pop on in before close and he would take care of me. I got there at 1630 and only had to wait 10 minutes before he walked out (between other customers) and performed the test.

 

[The_Jeff]

That voltage sounds a little low especially with a little underhood heat soak plus surface charge. That it was burping acid says to me you were overcharging and or you have a weak cell that is itself overcharging.

However under warranty they probably won't replace it unless it absolutely fails to start (and you have it towed in and it fails for them.) This happened at least to a bunch of early Pontiac Vibe owners who were shafted with dinky 350ish CCA rated batteries. Everyone knew the batteries were junk but the dealer wouldn't get reimbursed under warranty.

So you may have to "wreck" your battery.

Deep discharges and vibration are bad.

 

[gathermewool]

Haha. I'll keep that in mind. Would the battery sitting for extended periods and then being charged by the alternator at 14VDC overcharge it, by chance?

I just pulled the battery and hooked it up to a Batteryminder for a slow over-night charge.

I noticed some white corrosion toward the back of the battery - battery sits athwartship (parallel with the axis of the front CV shafts) - that I wasn't able to clean up back in September.

P.s. It's freaking cold out!

 

[bodeh6]

I just replaced the original OEM Subaru battery after 4.5 years on my 06 Legacy. The last week it would hardly crank then I had to replace it today.

 

[gathermewool]

Originally Posted By: bodeh6
I just replaced the original OEM Subaru battery after 4.5 years on my 06 Legacy. The last week it would hardly crank then I had to replace it today.


Was it a slow death or did it just begin this winter?

What'd you end up going with to replace it?

 

[gathermewool]

BatteryMinder went from charging mode to maintenance mode after only 30 minutes of use. I'm not sure what this means, exactly, but I'd assume it's good news for the battery.

 

[punisher]

If they used the electronic battery tester, which many dealerships are forced to for warranty work, then it won't generally condemn a battery unless it is charged fully. Agree to fully charge it, at least to 12.6V+, and perform another test. Once it starts with a battery that is above 12.5-12.6V, the tester is good at finding the duds.

 

[gathermewool]

Originally Posted By: punisher
If they used the electronic battery tester, which many dealerships are forced to for warranty work, then it won't generally condemn a battery unless it is charged fully. Agree to fully charge it, at least to 12.6V+, and perform another test. Once it starts with a battery that is above 12.5-12.6V, the tester is good at finding the duds.


The question I asked the dealer was whether my driving 7 miles to work, then 5 miles to the dealer would affect the SOC. He shrugged.

I guess we'll find out tomorrow. The corrosion, boil-over and slow starts aren't really instilling a whole lot of confidence, regardless of whether it passes. The fact that it was only 75% charged 36 hrs after a two hours highway stint is also disheartening.

I hate to be deceitful, but would you guys recommend intentially "killing" the battery? I guess I could always bite the bullet and pay out of pocket for a better battery...

 

[dwendt44]

Sounds like you aren't running the engine long enough to re-charge the battery.
Had a similar problem with a second car that wasn't driven much.
In town trips mostly-battery never got fully re-charged in those few minutes.

My 2¢

 

[SubLGT]

Check the specific gravity in each cell. They should match very closely. You may have one bad cell.

 

[gathermewool]

Originally Posted By: dwendt44
Sounds like you aren't running the engine long enough to re-charge the battery.
Had a similar problem with a second car that wasn't driven much.
In town trips mostly-battery never got fully re-charged in those few minutes.

My 2¢


I drive over 100 miles just about every weekend, and the 7 mile trip to work takes around 15 minutes usually. I can't imagine it being a short-trip issues.


Originally Posted By: SubLGT
Check the specific gravity in each cell. They should match very closely. You may have one bad cell.


I'll look into this. I'll have to google how exactly to do it, though. I've had the battery charging using my BatteryMinder for nearly 11 hours now, so hopefully the dealer's test will show something this afternoon.

Instead of driving 7 miles to work and then 5 miles to the dealer I might hop on I-95 and drive for a little extra time to make sure the short distance there doesn't affect the SOC.

 

[The_Jeff]

Remember alternators are temperature compensated so they put out more voltage when cold. Your battery will be very close to where it was before it turned your starter, 45 seconds after you start. The rest of your drive will charge, if necessary, any draws when the car is off... radio memory, alarm, loss from sitting, etc.

Battery minders might be too "smart" for this, it sounds like your battery reaches voltage and makes charging systems stop without "filling up" with amps. A manual 6 amp charger from walmart might be better for topping off the battery. As a diagnostic aid they're good with their cheezy ammeter on front.

 

[Donald]

Originally Posted By: gathermewool
BatteryMinder went from charging mode to maintenance mode after only 30 minutes of use. I'm not sure what this means, exactly, but I'd assume it's good news for the battery.


It means the battery is fully charged and the charger is now in "float" mode and will charge the battery as needed. It can stay this way for literally years.

 

[gathermewool]

Originally Posted By: eljefino
Remember alternators are temperature compensated so they put out more voltage when cold. Your battery will be very close to where it was before it turned your starter, 45 seconds after you start. The rest of your drive will charge, if necessary, any draws when the car is off... radio memory, alarm, loss from sitting, etc.

Battery minders might be too "smart" for this, it sounds like your battery reaches voltage and makes charging systems stop without "filling up" with amps. A manual 6 amp charger from walmart might be better for topping off the battery. As a diagnostic aid they're good with their cheezy ammeter on front.


Didn't know about the temp compensation; interesting. This morning, at a whopping 8F, the voltage reading at startup (after battery install, of course) was 14.6V. It didn't drop down to ~14.1-14.3 until I was almost to work.

I have a 2A/6A charger, and almost hooked that up in place of the BatteryMinder, but didn't think the 6A would be necessary, since there's really no reason for the battery to be anything other than fully charged. I also ended up charging the battery indoors overnight, and didn't want to have to worry about H2 formation - little to no H2 at around 1A after the BatteryMinder switched to Maintenance mode.

Originally Posted By: Donald
Originally Posted By: gathermewool
BatteryMinder went from charging mode to maintenance mode after only 30 minutes of use. I'm not sure what this means, exactly, but I'd assume it's good news for the battery.

It means the battery is fully charged and the charger is now in "float" mode and will charge the battery as needed. It can stay this way for literally years.


That's right, but it's a larger positive float than, say, a trickle charger, right? >1A if I read the literature correctly.

Regardless, I installed the battery this morning, let the car make some "wakeup" noises, and turned the key. The starting was maybe, maybe slightly faster than yesterday, but still very slow. The dealer mentioned that the Rotella T6 I'm using might also be the problem, but this issue didn't occur last year and 8F isn't really very cold as far as the T6 is concerned, IMO. I'll be switching over to AMSOIL Signature Series 0w30 before the holidays, so, if I don't get the battery replaced before then, I'll be able to determine whether it was a factor.

I'm going to take a break from work and drive over for another quick test this afternoon. What would you guys suggest if the test passes, but the SOC is still <100%? What if it's close to 100%, but I still experience slow starts? In the end, spending around $120 for a new battery would probably be better than having to buy a new alternator just after my warranty expires...

 

[Donald]

A plain trickle charger is normally around 2A, and left on for an extended period of time, it will ruin your battery.

If you charged you battery last night indoors, then they should make a BIG difference on how fast it turns over the engine. When I had a diesel Rabbit (before I got a block heater) I would just bring the battey into the cellar overnight (no charging) and then bring out a nice warm battery in the morning and the diesel would start like a charm.

 

[The_Jeff]

Head back to the dealer and tell them what you told us. If nothing else they might get you a battery at cost or something.

Though if you use a coupon to buy online advance auto's battery prices are better than wholesale, and you won't get stuck with something awful like an exide.

You could also hit a parts store that offers free battery testing and get the slip. I'd use Advance since you might see them again if you buy your own battery.

 

[rshaw125]

The battery is probably going to die this winter. I would make it happen on my schedule. Leave your a light on and drain the battery to zero. It'll kill at least one of the cells.

 

[edhackett]

I just replaced the battery in my '08 Legacy GT for slow cranking. It was a Subaru brand by Johnson controls. It was also showing signs of acid leakage at the terminals and vents. Apparently, not a great battery.

If you've got access to a VOM, check the voltage in the morning before driving. It should be a 12.5-12.6 volts. Then read the voltage while cranking. if it drops below 10V, the battery is on its way out.

New battery time at 3 years. These are the readings I got on mine:

Resting, connected- 12.58V
Dome lights on- 12.3V
Ignition on- 11.9V
Cranking 9.6-9.8V

Alternator charging cold- 14.5V

If you've got a group 85, replace it with the larger group 35.

Ed