I have a 3 amp DieHard Battery Charger/Maintainer that I’ve hardly used. I recently connected it to 3 batteries: 1) an old battery, 2) and older battery that still seemed to work well in my car, and 3) a new battery that I installed yesterday (that works perfectly in my car). When I’ve connect the Charger/Maintainer to the 3 batteries, I get the same reading – It initially shows “CHARGING 6v 2%” and after about 45 minutes says “CHARGING 6 v 5%.” I’ve disconnected the Charger/Maintainer because I don’t want the seemingly very good batteries recharged to 6 volts instead of 12 volts. Is this a defect in the Charger/Maintainer or do all similar charging devices initially show them charging at only 6 volts? (Also, my new battery shouldn’t need ANY charge – I only connected it to the Charger/Maintainer to see what it said. I assumed it would have charged for a few minutes at 12 volts and then turned off due to it being fully charged). The instructions say nothing about this issue and Sears customer support says the batteries must be dead (and I know all 3 work perfectly and start up my car every time). In addition, the older battery was tested by a much larger and more sophisticated machine by my mechanic and was shown to be in perfect working order. I’m guessing the microprocessor or computer in the Charger/Maintainer is defective. Any thoughts or advice is appreciated.
The funny thing about electronics. They can fail. How long have you had it? If it’s past the warranty period, chances are that is is bad. And if you cannot find any obvious damage, like corroded clamps or damaged wires, you may just want to replace it. But it almost sounds like you don’t even need it.
I agree with BN, the charger is broke, toss it. They initially check for a 6v versus 12v battery and then select the correct charging voltage. This one can’t do that first step correctly. Probably not repairable.
Why do you have 3 batteries for one car? seems like overkill…
b
Look on the front of the charger. Does it have a voltage selector or a switch for manual and automatic? Try using the manual setting if you have it on automatic or vice versa.
Does your charger/maintainer have a manual switch to toggle between 6V and 12V?
Thanks for your replies everyone. The charger is like new, was kept in its box and hardly ever used (but probably just over the warranty period which I think was 3 years). There are no switches on it whatsoever - it’s completely automatic (not even an on/off switch). It chooses the proper voltage and lets you know if you got the +/- wrong. It did work when I first got it - but unfortunately now seems to only want to charge at 6 volts. Here it is: http://www.sears.com/diehard-platinum-6v-12v-battery-charger-and-maintainer/p-02871239000P On a side note…the reason for having 3 batteries - The 1st battery (old) was from another car which was totalled after the mechanic accidently dropped it off a lift. The 2nd battery was just over 5 years old and I tried checking it with the charger/maintainer after I got a new alternator for the car this week. When the 2nd battery showed it was being charged by the charger/maintainer at 6 volts (despite a mechanic saying the battery was fine), I decided to get a new battery (the 3rd).
Throw it out and get one of these:
The “junior” model is for very slow trickle charging and maintaining, so it’s only a 0.75 amp output, but it works like a charm. If you want faster charging rate, you can get one of the larger units in the “Battery Tender” family.
If you want to be careful with your money, before you throw the charger out you might want to connect it to a 12v battery, turn it on and then check the battery voltage right away and then again after a few minutes. It might be possible that the voltage readout function has failed but otherwise the charger is working correctly. Look for voltages around 13.6 to 14.5 for a charged battery. My battery maintainers, two different brands, do not have a voltage readout. You can do without that feature. Harbor freight has very inexpensive digital voltmeters for about 6 dollars that are surprisingly accurate. Otherwise a friend might lend you a voltmeter.
If the charge percentage indicator was rising, it may be that the charger was working as intended.
Automotive lead-acid batteries will take some charge at any time as they are self-discharging due to internal conduction even when disconnected externally. A fully charged battery in a running car will be absorbing around 2 amps of input current.
Either the logic in the charger isn’t recognizing the battery voltage or an electrical component has failed.
Just like an alternator, there’s rectifiers that convert the AC voltage to DC voltage and diodes that allow that voltage to flow only in one direction.
So if your charger is able to charge both 6 volt and 12 volt batteries, there has to be at least 2 different rectifiers and diodes. 6 volts passes thru one set of rectifiers/diodes and 12 volts passes thru 2 sets of rectifiers/diodes.
So, it looks like you’re going to need a new battery charger.
Here’s the one I use and recommend.
http://www.eham.net/reviews/detail/6024
What I like the most about this charger is, it tests the battery before it attempts to charge it to see if the battery is worth charging. And if it isn’t, the LED will display REPLACE.
Tester
Hey, @99novice99, time to trade in your '51 Packard.
;-]
"…connected it to 3 batteries."
The charger cannot charge 3 batteries at the same time because it does not know which battery to read to determine a state of charge.
Does the charger function correctly when connected to 1 battery at a time?
I’m assuming OP hooked the charger up to only 1 battery at a time
Just like an alternator, there’s rectifiers that convert the AC voltage to DC voltage and diodes that allow that voltage to flow only in one direction
Errrt! First, a rectifier is an arrangement of diodes that rectifies the AC into DC. In a charger, a full wave rectifier is used which is 4 diodes arranged in a pattern to produce the rectified DC. You don’t need or want any more diodes than what constitutes the rectifier.
Secondly, voltage doesn’t flow, current flows. Voltage is just potential to do work, current is the actual work being done.
6 volts passes thru one set of rectifiers/diodes and 12 volts passes thru 2 sets of rectifiers/diodes
No, that is not going to work either. A second rectifier wouldn’t serve any purpose since it’s already a pulsating DC after the first rectifier. Putting another set of diodes in will DROP more voltage across them. You can’t go from 6 to 12 by adding more diodes.
In a cheap charger what they do is use a multi-tap transformer that has a tap for “full output” and a tap that produces half of that full output. The 6-12 switch selects which tap feeds to the DC rectification circuit. They rectify the AC tap voltage to produce 12 volts or 6 volts respectively. That way, there are fewer parts involved and it costs less and is more reliable.
Is it set to 6V because the voltage selector switch is faulty? Try unplugging the charger from both the 120 volts AC and the battery, work the switch back and forth about 20 times, and see if the unit works right. If it doesn’t, then repeat, unplug it again, only pour some alcohol into the switch first. Let the alcohol dry throughly before plugging in the 120 volts AC again.
It’s possible the wiring from the voltage selector switch to the circuit board is faulty, maybe just a solder joint is bad.
I think he said there is no switch, all electronic. So time to toss and get a new one.