would you replace a good battery?
The first step is to measure the battery voltage, but the "surface charge" needs to be removed to get an accurate reading. If the truck has been recently driven it might read over 13 volts. With the engine off turn the headlights on for 5 minutes, turn them off, and wait at least 10 minutes before measuring the votlage right at the battery posts.
There is a correction factor applied for the ambient temperature, but a standard lead-acid battery - the kind with filler caps to add water - are fully charged when they measure 12.65 volts. A sealed "maintenance free" battery is fully charged at 12.80 volts volts. Some of the high speed AGM and other batts may float a little higher or lower. Charge it up if necessary (most likely ... yes) and repeat the test. Note that while the voltage might be reading 100%, it still needs a bit of time on the charger - amperes - to replace the capacity.
If the OCV won't "bounce back" after charging, it might sulfated up a bit. Light sulfation can be removed by running the battery down (leave the lights on for maybe an hour and run it down to about a 50% charge to maybe 12.2 volts or so and re-charge for 24 to 48 hours at a low current rate. This works good. "Dumb" chargers have their place for things like this, the Shumacher 2/6 amp units that were sold for years.
The Battery Tenders are real good too, if a charged battery is "floated" at 13.2 in the off season it will take a very thorough deep charge over the course of weeks and months. Keep in mind if there is a heavy parasitic load a float charger is not enough to compensate this. Always disconnect the battery completely from the truck for long term storage when possible.
Check your Operator's Manual for any special jiggery-pokery or contortions that may be required as a result of disconnecting the battery and follow it exactly as described. In years past losing the radio presets was about the worst that could happen when disconnecting a battery. Not necessarily the case anymore. In certain luxury models a trip to the dealer is necessary, scan tool is required. A/C inop, windows won't roll down, crazy stuff.
I suspect that my 4 1/2 year old Motorcraft battery needs replacing - I was waxing the truck about a month ago with the stereo playing (like I usually do) and the battery completely discharged - I had to get a jump start to get things running again (this is on my 2013, F250, 6.2L gasser).
I haven't gotten around to getting a new battery - everything has been running fine ever since the jump start. However, today the "Service Engine Soon" idiot light came on. I just had oil & filter change and the Ford dealer's once over inspection a couple of weeks ago - so, all the fluid levels are good and the oil is new. My question is, does the onboard engine monitor that trips the SES light keep track of the strength of the battery? Can it tell if a battery is about to fail?
The alternator in practice can't really effectively charge a battery thoroughly. A bicycle pump for a tractor tire. (OK, not that bad, but you get the idea) Armed with a voltmeter and a few simple tests it is possible to gauge battery health pretty effectively without special equipment. A cranking voltage test isn't as torturous as a carbon pile load tester but if the battery fails this test in your truck, it's time to break out the bagpipes for that battery.
When you are certain the battery is serviceable and charged, then test the alternator output when it is energized and under load with lights and accessories on, AC, heater running etc. Run the engine RPM up to around 2000 or so and hold it there, and measure voltage directly at the battery posts.
I suspect that my 4 1/2 year old Motorcraft battery needs replacing - I was waxing the truck about a month ago with the stereo playing (like I usually do) and the battery completely discharged - I had to get a jump start to get things running again (this is on my 2013, F250, 6.2L gasser).
I haven't gotten around to getting a new battery - everything has been running fine ever since the jump start. However, today the "Service Engine Soon" idiot light came on. I just had oil & filter change and the Ford dealer's once over inspection a couple of weeks ago - so, all the fluid levels are good and the oil is new. My question is, does the onboard engine monitor that trips the SES light keep track of the strength of the battery? Can it tell if a battery is about to fail?
Steve
Regarding my SES light coming on, I dug out my SCT X4 tuner/DTIC code reader and hooked it up - it showed code P0442 : "Evaporative Emissions Control System leak", which turned out to be a loose gas cap. I cleared the code with the X4 and everything is behaving OK now.
Dang, you sure have to get high tech to clear the warning lights these days. About 25 years ago I had a little Chevy S10 and it had a "Gas Cap" light that would display if it was loose - you would tighten the cap and drive a couple of miles and the light would turn off.
Ford Trucks for Ford Truck Enthusiasts
I just thought I would let you know how nice it was to check my oil today and not see a slimy layer of oily battery residue or green and white crap growing all over the neg clamp and hold down
was it because the Motorcraft batteries were overfilled at the factory and all that crap seeped out when they warmed up etc
or they just plain leaked like a seive
or both
was it because the Motorcraft batteries were overfilled at the factory and all that crap seeped out when they warmed up etc
or they just plain leaked like a seive
or both
Denny
In fact a battery will never even approach a full charge without gassing. It does need to be minimized, however. This is one reason why a battery charger or the charging amp rate should always be "sized" to the capacity of the battery being charged. A small micro-amp wall wart can fully charge a 950 CCA battery, but it takes a week and a half to do it, and it will be outgassing excessively the whole time and lose water. Those large 50 amp chargers on the other hand, will provide a boost charge very quickly but they can cause the plates to buckle and heat damage.
A 12 volt dual battery system, connected in parallel is just a single large battery electrically speaking. The voltage is the same, the current capacity is doubled. When they become mismatched for whatever reason they won't accept current at the same rate, one battery will tend to hog all the current, and the other will see a higher voltage.
Both batteries need to be equalized in sort of the same way all the individual series cells in a single battery need to be equalized. The only way to do that is to use a charger with some serious current. A wall wart isn't going to cut it, about 20 amps would be a slow "trickle" charge. Either that, or charge them up one at a time.
In fact a battery will never even approach a full charge without gassing. It does need to be minimized, however. This is one reason why a battery charger or the charging amp rate should always be "sized" to the capacity of the battery being charged. A small micro-amp wall wart can fully charge a 950 CCA battery, but it takes a week and a half to do it, and it will be outgassing excessively the whole time and lose water. Those large 50 amp chargers on the other hand, will provide a boost charge very quickly but they can cause the plates to buckle and heat damage.
A 12 volt dual battery system, connected in parallel is just a single large battery electrically speaking. The voltage is the same, the current capacity is doubled. When they become mismatched for whatever reason they won't accept current at the same rate, one battery will tend to hog all the current, and the other will see a higher voltage.
Both batteries need to be equalized in sort of the same way all the individual series cells in a single battery need to be equalized. The only way to do that is to use a charger with some serious current. A wall wart isn't going to cut it, about 20 amps would be a slow "trickle" charge. Either that, or charge them up one at a time.
Denny













