Battery Issue?

[Eric1971]

I searched the forum but didn't find the answer.

Went to go to work yesterday and my 1995 EB cranked slowly but did turn over and start. Thought maybe I left something on overnight but couldn't find anything. 3 mile drive to work, then home for lunch about 4 hours later. Again cranked slowly but started. When I got home I let it run for 30 minutes, then back to work again and made it home OK. Tested with multimeter: alternator seems fine, showing 14.0 V with engine on. Tested the battery, 12.5V but it dropped to 8.5 V on engine start, but it did start. Just to be sure, I put my Battery Tender on it overnight. This morning it showed fully charged and 12.5 V. The minute I turned the key to ON, the voltage started dropping and when I tried to start the engine, it just clicked.

Battery is from the previous owner. Interstate MT-65, appears to be from September 2013.

Question 1: Does this seem like I've tested everything properly and it's definitely the battery?

Question 2: I see Costco has a great price on an Interstate battery with 850CCA, about $50 cheaper than a Motorcraft with the same capacity. Any recommendations/warnings on the Costco/Interstate batteries?

Thanks!

 

[BruceExploder]

Take the battery by auto parts place or Walmart to load test it?

 

[fastpakr]

At six years old, I'd change the battery first and ask questions later. That's the extent of any reasonable lifespan for a battery IMO.

 

[koda2000]

In my experience you usually don't get more than about 5 years out of a 12V battery. 12.6V is considered fully charged and you should see more than 14.0V at the battery with the engine running (around 14.6V). I've heard people say they have gotten over 9 years out of a car battery, but if (if) this is true, they're living on borrowed time. Old lead-acid batteries only last so long before the short out internally.

Volts to not start your engine, amps do. My guess is your battery is shot after 6-7 years. Replace it. There are only a couple of battery manufactures in the U.S.. That's not to say all batteries are of equal quality, but buy cheap, get cheap. If you're concerned about the cost of a new battery, many salvage yards sell used batteries for around $20. Look for one that is only a year or two old in the size/configuration you need. Gen II Explorers use a Group 65 battery. I got 7 years out of a Walmart Group 65 battery for around $75. I consider this price good value for the money.

 

[imp]

In my experience you usually don't get more than about 5 years out of a 12V battery. (1)

Volts to not start your engine, amps do.

@koda2000
1) Agreed. Have gotten more, but realistically, borrowed time is a good way to describe old batteries.

Voltage and Amperage are really both important, but the amps capability falls off as a batttery ages, even though it's kept "fully charged". Charged only describes the chemical quality of the acid inside, stronger acid, higher the "charge".

A battery is a source of voltage, all of which exhibit a concept thought of as "internal resistance". Remember in a series circuit, the voltages found across components add up to the source voltage, but the internal resistance is commonly overlooked. It's actually in series with the stuff connected to the battery, like a starter motor.

Let's say a starter is drawing 300 amps, cranking the engine. Voltmeter across the battery terminals showed 12.5 V before cranking, 9 volts while cranking. That means the starter is only receiving 9 volts, while 3-1/2 volts is being "eaten" across the battery's internal resistance. By Ohm's Law, the internal resistance in that case would be R = E / I or 3.5 / 300 = 0.012 Ohms. That's pretty good. But, so what?

As the battery ages, it's internal resistance increases; let's say it increases to 0.02 Ohms. Now, that 300 amps will cause more voltage to be lost in the battery: 6 V lost, only 6.5 left for the starter. 6.5 V will likely not crank the engine.

Before wailing about the assumptions made: It's hypothetical, largely, since battery internal resistance is dynamic, it's not always the same. But serves to illustrate what's going on. imp

 

[koda2000]

My point was that just because you leave a 12V battery on a charger overnight and that it shows 12.5V the following morning does not indicate your battery is good enough to start your car. You can take two 9V radio batteries and wire them together to produce 18 volts on a VOM, but that doesn't mean you can start your car with them.

Having a car battery "load tested" will tell the real story about its condition..

 

[J_C]

Gen II Explorers use a Group 65 battery. I got 7 years out of a Walmart Group 65 battery for around $75. I consider this price good value for the money.

Yes that or the Costco are the two best values out there, but assuming the WM was the Everstart Maxx, they're now $94.

Funny thing is, my '14 Explorer came from the factory with a group 59 or something... smaller battery, lower CCA, but costs ~$25 more, yet a group 65 will fit so that is what I bought. Only thing is the factory battery insulator does not fit a group 65, but the weather is not that extreme here to feel the need for it.

 

[koda2000]

Yes that or the Costco are the two best values out there, but assuming the WM was the Everstart Maxx, they're now $94.

Funny thing is, my '14 Explorer came from the factory with a group 59 or something... smaller battery, lower CCA, but costs ~$25 more, yet a group 65 will fit so that is what I bought. Only thing is the factory battery insulator does not fit a group 65, but the weather is not that extreme here to feel the need for it.

No, the WM battery for $75 is not the Maxx (see below). Still $94 is a pretty good price for a battery these days. I'd guess the Cosco battery for $50 doesn't have much of a replacement warranty, but IDK.

 

[J_C]

^ I took the post to mean the Costco battery is also around $100, $50 less than Motorcraft wants for essentially the same thing. It might be exactly the same battery. Johnson Controls and Exide both seem to be suppliers for all three brands, Costco, Everstart Maxx, and Motorcraft.

One thing the Maxx line has, and probably the Costco too, is a 3 year replace, + 2 year pro-rated warranty, but either way I figured the extra CCA would come in handy here as it gets colder in winter. IIRC the Motorcraft has the same 3 yr replace but (their high end line) has a longer prorated warranty than 5 years.

 

[Eric1971]

Thanks all. I got the Costco/Interstate for $95. 42 month replacement, 850CCA. All is right with my Explorer for the moment.

 

[CDW6212R]

Thanks all. I got the Costco/Interstate for $95. 42 month replacement, 850CCA. All is right with my Explorer for the moment.

Well done, that is a good deal for a new battery. Most higher rated batteries run $140 or more I've noticed the last few years. So $95 is great if it lasts a few years.

I just bought a Bosch AGM last month for $145ish from Pep Boys, that was a good sale then. Hmm, it's still on sale; Bosch Platinum Series AGM Battery Group, Size 65 | 838869 | Pep Boys

 

[Cowboytrukr]

The load test suggestion is great to determine intra-cell condition. Yes, time spent on a six year old battery is usually a waste, but if one has a newer one, it’s an easy check to confirm cell integrity. Battery can register 12.6V and fall flat immediately. That’s indicative of a dead cell and thus, time for a new unit.

 

[imp]

The load test suggestion is great to determine intra-cell condition. Yes, time spent on a six year old battery is usually a waste, but if one has a newer one, it’s an easy check to confirm cell integrity. Battery can register 12.6V and fall flat immediately. That’s indicative of a dead cell and thus, time for a new unit.

@Cowboytrukr

As said before, I believe having a ten-dollar battery hydrometer handy provides one of the most useful tools for checking battery condition.

A 'dead" or dying cell is readily located; all cells should "read" reasonably close to one another, and their state of charge is also shown, individually, as an added benefit. imp