Legitimate need for battery charging or ripoff?

Lead-acid batteries self discharge over time. An old, worn out battery discharges faster. so it is possible for a vehicle with a tired battery to be unable to start after a day or so. Or even over night :-(

You could check with a multi-meter. A fully charged battery will measure 12.7 volts D.C. Check the voltage after you shut down for the day. First thing next morning check again and see what the difference is. You can also check the charging rate hook up the multi-meter to the battery and read the voltage with the engine off. Start the engine and run the engine at about 1500 - 2000 RPM and watch the meter. The voltage should rise to something over 13 volts after a while.

Cheers,

John B.

This sounds like a normal case of Magic Test Equipment.

Technician who doesn't really understand the underlying technology of the system buys Magic Test Equipment which does some internal calculation and produces a derived value. Then the technician believes implicitly what the test equipment says, even when it is clearly incorrect or not relevant. Because it is Magic.

The more parameters that go into the derived value, the more parameters can be wrong or measured incorrectly....

--scott

In a daily driver there are only four reasons for a dead battery.

A bad battery - Internal damage or sulfation due to age/shock/damage Bad alternator - Internal problem (diodes, stator rings) regulator Bad wiring - main cables failing or corroded so a poor connection excessive draw - lights/stereo left on or a bad module causing high drain.

Sounds MUCH more likely.

Not uncommon. Newer vehicles with lots of electronics will draw them down if left connected and not charged. 3-4 weeks is about normal in that case.

For them to test to see if the battery is defective they'll need to attempt to charge your battery for X number of hours and see if it'll hold a load test.. If it passes you may have another issue causing the battery drain.

If your battery ran dead and you are just letting your alternator recharge the battery, your battery will never be fully charged.. You need to put it on a slow charge to maximize your batteries charge.. Only letting the car charge it is like giving it a quick charge.

well, the battery might be dead for a reason - you need to check and see there's no issues like a trunk light not switching off or some such.

for the battery though, once a starting battery has been allowed to discharge, it's pretty much shot. unless you want to sit there with the battery on a de-sulfating charger for weeks to try and revive it, and with no guarantee of success, you just need to get a new one. i'd say this is well known to the battery guy and this "charge" waffle is just an attempt to wriggle out of a warranty. pursue accordingly.

*******

Does everybody buy into this?

Sure a battery can run down even if it's driven every day. If you don't spin the alternator enough replace the electricity used in starting the battery will inevitably over time go dead. Batteries can also be marginal, but hold enough of a charge to get your car started in warm weather. When it turns cold - presto - discharged battery, or one that needs to be recharged.

I would never buy a battery from a roadside assistance company. Just get it jumped to start and have the battery tested and replaced by a real mechanic.

You can run the engine all night long on a marginal battery and you might have enough stored energy to start the engine if it catches right away.

buy into what???? Slow charging batteries has always been better than a quick charge.. Most cars alternators run 70-110amps.. Battery chargers on a slow charge are only 2-5 amps. Some a bit higher for a faster charge, but the lower the amps the longer it takes to charge and the better your battery will be.

If the battery is in good shape and the charging system is working as it should, it can adequately recharge a battery, although it will take some time... and maybe that is not always a bad thing. High rate chargers are not necessarily the best way to recharge a better.

buy into what???? Slow charging batteries has always been better than a quick charge.. Most cars alternators run 70-110amps.. Battery chargers on a slow charge are only 2-5 amps. Some a bit higher for a faster charge, but the lower the amps the longer it takes to charge and the better your battery will be.

********** Your statement about if you let the alternator charge the battery, you will never reach full charge.. Define full charge,maybe. Alternators have the ability to charge the battery, assuming the battery and charge system are okay, and to maintain it at optimum charge.

Slow charging IS better than fast charging, but it's not because the charge is "incomplete" in any way. It's because of the heating effects.

--scott

Monza,

do you have any idea how many Amps a 70 -110 Amp alternator actually puts into a battery that is already charged?

Mark

do you have any idea how many Amps a 70 -110 Amp alternator actually puts into a battery that is already charged?

Mark

****** I await the answer with bated breath.

"hls" wrote in news: snipped-for-privacy@giganews.com:

since the charging voltage is limited to appx 13.5 to 14.5 in most applications, almost none. Also realize the same charging systems are on over the road and farm tractors that can run for days without shutting off, and supprise, they don`t overcharge the bat. KB

it certainly doesn't trickle charge it.... depends on the accessories that are on and how low the battery is the more dead you batter is the more amps it'll use. Slow charging (off of the car) is still much better than letting your alternator do it.

From Edmunds.com

Here are a few tips to quickly restore a battery using this method.

1. Drive at a constant speed (highway driving) versus stop-and go (city driving). This will give the alternator an opportunity to charge more evenly. 2. Turn off all accessories (radio, air conditioner, etc.). 3. If possible, drive during the day. Even headlights use power. Having them off increases the amount of electricity going to the battery.

Remember, this does not replace charging the battery. A car's alternator is not designed to fully restore a depleted battery, but rather to maintain a healthy one. As soon as possible, put your battery on a battery charger such as the Battery Tender, and a give it a full charge for a day or two.

:P

"even" headlights? they're power hogs, close to 10A - more if you have four headlights on high beam

nate

it certainly doesn't trickle charge it.... depends on the accessories that are on and how low the battery is the more dead you batter is the more amps it'll use. Slow charging (off of the car) is still much better than letting your alternator do it.

****** With a healthy charging system and battery, you should almost \ NEVER have to resort to the use of an external battery charger.

The alternator will bring a good battery up to the charge level it can take.

I dont really care what Edmunds said.

If you have a car/truck, a good battery charger is handy to have in case you ever need to use it.No legitimate reason is needed. cuhulin