Does your battery measure up?

[vernj4]

To check a battery, first remove the surface charge; This can be done by leaving lights on for 5 minutes (engine off). Than determine the voltage across the terminals, should be as follows:

12.60 volts - 100% charge
12.40 volts - 75% charge
12.24 volts - 50% charge
12.08 volts - 25% charge
11.90 volts - 0% charge

In other words, .70 volts separates a good battery from a bad battery.

[whatnot]

Can you leave them connected together or does the cable need to be pulled between them first? (or one of the grounds)

[vernj4]

Check one battery at a time. If you went to a battery shop, they would remove one battery and perform "load test" on the bench, You are trying to simulate this procedure.

[moondoggie]

Good Day!

Thanks for putting this extremely useful info here. It

[vernj4]

Dunno about the high amp draw test; sounds reasonable though. Any idea how long the discharge time was? Was there any published criteria given to the operator?

Have added specific gravity to the original chart.

12.60 volts - 100% charge - 1.260
12.40 volts - 75% charge - 1.225
12.24 volts - 50% charge - 1.190
12.08 volts - 25% charge - 1.155
11.90 volts - 0% charge - 1.120

Chatted with an old timer recently; 50 years ago he worked in a service station where they did a lot of AAA work. If the customer was in need of a new battery, they would keep the old one on a shelf in the back room. Every few months, the owner would use the following procedure to try de-sulphate the batteries.

"To de-sulphate battery, fill each cell with water and add 1 teaspoon baking soda to each cell; charge on highest setting....let it bubble and churn vigorously. Dump out and fill cells with fresh battery acid. Charge on normal setting. Check voltage per the original criteria or with hydrometer."

According to the old-timer, this worked about half the time. If plates are warped and touching, the battery could not be revived. The owner would sell these refurbished batteries for 1/2 price of a new one with a 6 months warranty.

Would imagine the EPA would not think highly of this procedure.......would probabily impose a lot of restrictions!

[moondoggie]

Good Day!

I've never had it done, but if Batteries Plus is doing their job, that should be what they do when they roll out their cart & test your car battery. I know the tester they use sure looks like the load tester my brother (a mechanic) showed me once. I'm unaware of any other test that would adequately tell you what capacity a given battery had (assuming full charge at the start of the test).

Another way to do this would be to fully charge the battery, load the battery to 1/10 its amp/hour rating for 10 hours, & see how the voltage held up, but I doubt you'd find anyone willing to wait that long for a result.

Blessings!

Brian Johnson, #5044

[CleviteKid]

The free battery check at Sears Auto Centers is a timed load test to see how well the battery responds. The computer takes the voltage drop vs. time a some high load (maybe 200 amps for a minute) and chimes in good or bad.

With our diesels, a good tech will know to isolate the dual batteries for a test. If the tech does not want to, chase him away from your truck and don't let him touch it. He is a BAD TECH :mad: .

I have been pleased with the techs that I have encountered at Sears. The quality of their batteries is another issue, because to keep costs (as opposed to prices) down, they keep switching between Exide, Delco, and Johnson Controls, the three manufacturers who make 90% of the country's batteries under about 97 different brand names.

Dr. Lee :cool:

[Beedee]

The Proper way to test a battery with a load tester is to apply 3x the amp hour rating for 15 seconds, the battey voltage should not drop below 9.6 volts. If it fails this test, try to recharge and load test again, if it fails again get a new battery. Another quick test is to pop the caps off of the battery (can't do this on maint free), check the specific gravity and if it is good (see post above), hit the starter and see if 1 (one) cell is gassing worse then the others, if it is you most likely have a shorted cell and once again time for new.
There is a new generation of testers out there that will test a battery with out the load, but they are pretty pricey for the average guy. I had a salesman come by a couple of years ago, threw the fancy new meter onto several batts, compared with our results using the old method, got the same result in 20 seconds for each battery, took us several min. the old way.
Average life of an automotive battery is about 5 years, if you are doing a lot of off road driving it can be quit a bit less, the plates get shook up and break free inside.
One other point to mention, if you are using a hydrometer to check your electrolyte levels, you either need a temperature compensated hydrometer or most have a chart on the box or on the meter itself. The specifig gravity will go up the colder it is and down with the heat. I you check a fully charged battery at 40 below it will be a totally different reading from 100 above. :confused:
AND PLEASE, PLEASE, PLEASE wear some form of eye protection when working with batteries. I've had a couple blow on me. :eek:
Thats enough from me. ;)
Brian.

[moondoggie]

Good Day!

Beedee said,

[moondoggie]

Good Day!

To expand my previous thought: As my trucks have glow plugs that draw considerable current, I believe that by measuring battery voltage while activating the glow plugs, I have a crude load tester built-in. Simply test one battery at a time. It's not nearly as good as 1/3 amp/hr rating for 15 sec. & voltage ≥ 9.6V, but I figure I might get usable data from a known-good truck vs. one that doesn't seem to crank as well. Some day

[CleviteKid]

Good thinking, Brian !! I like the creativity. You should actually disconnect one battery at a time, fire up the glow plugs for a set period of time (15 or 20 seconds, but only with AC 60G's or Kennedy's super plugs) and report the voltage at the end of that time to us. If you do it at Kennedy's next get-together with all the trucks there, you could get a good baseline. Then write it up as an article and procedure for www.TheDieselPage.com. (http://www.TheDieselPage.com.) MorePower has a standing offer to all members that if you have an article published, your next years renewal is free.

Dr. Lee :cool:

[charliepeterson]

If you live in the snow belt you know how hard this is on our batteries. We need lots of cranking power. The battery is good for five years according to the battery guy's. I have a rule of thumb where I will keep it for three years. If I forget and go to four the first time it cranks slower than it should, then it's coming out.
Don't forget to check the alternator.

[moondoggie]

Good Day!

CleviteKid: You

[Beedee]

Glad I could be of some assistance Moondoggie. I've gotten so much out of the DP's. Nice to know I helped some one else out.
From the other Brian ;)