Shumacher bat. charger

[browning300wsm]

the battery charger 2/12/75A ..fully auto starter charger ..when charging .
regular setting 12A = 10.42 V ..also on regular setting 2A = 10.70 V .. my question is am i getting the enough volts to charge my battery ..is my chargers output up to par ??

 

[901Memphis]

How are you testing the voltage output exactly and what device to measure? If you're numbers are accurate then no you'll never charge a battery at that voltage. Proper 12v flooded charging should bring the battery up to 14.6v before going to a float mode which will be closer to 13.6v. Flooded, agm, gel all have slightly different requirements.

Even at at a 12 amp setting you should quickly bring up a 12v flooded battery to at least 14 volts in short time. If the battery is extremely low if may take a few minutes before you see the voltage increase. If you are using the internal voltage meter there is a possibility the charger is charging at a higher voltage but the meter is faulty. I would verify the battery posts while charging with a good multi meter.

Some good information here.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

 

[901Memphis]

In my experience Schumacher chargers never work right, either cooking the battery or not charging correctly. Check out this thread if you need a good charger.

http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3810865/Finally_found_a_good_automatic

 

[wrcsixeight]

If you are putting this on a depleted battery, then those voltages you see are normal and it will take many many hours on the 2 amp setting for voltage to climb into the 14's and a few hours on the 12 amp setting. 10.5v is considered 100% discharged on a 12v battery.

Modern Automatic Schumachers in my experience and from other online reports indicate they are a little voltage happy.

Mine (sc2500a) will goto 16.4v at near 12 or 25 amps output which is too high and very abusive.

Generally the AGM setting prevents voltages over 15, but I do not trust the charger enough to leave it unattended on any battery I care about.

Do NOT trust the voltmeter or the percentage display on the schumacher. Mine can be over a volt off from true, when charging at higher amps and is 0.25v out at low charging amps.

I have increased the wire size on the output leads to the circuit board with no improvement in this regard. The % display is based solely on voltage when first hooked to a battery and has almost no basis in reality. Basically a useless 'feel good' feature to soothe the human observer, whilst actually mocking the human who believes it.

 

[browning300wsm]

i had the leads from the charger hooked up to my Mastercraft digital multimeter . setting on 20 volts ...

but after the response from members i went out side connected the 12 v charger onto battery and got a reading on my multimeter of 13.46 ..i should be ok ????

 

[wrcsixeight]

YOu can't test a modern smart charger voltage when it is not hooked to a battery, and on an old school charger unloaded one might see voltages way too high.

Voltage is only part of the equation when charging batteries. Knowing how many amps are flowing from source to load at that voltage is enlightening.

Voltage alone reveals little.

 

[4wheeldog]

Originally Posted By: browning300wsm
i had the leads from the charger hooked up to my Mastercraft digital multimeter . setting on 20 volts ...

but after the response from members i went out side connected the 12 v charger onto battery and got a reading on my multimeter of 13.46 ..i should be ok ????


At least that voltage is about what you should expect, on either a dead battery, or one nearly fully charged. In between, the voltage should go up to just under 15V.

It is not possible to test the output of a decent modern charger without it being hooked up to a battery.

 

[901Memphis]

I would hook it up to a known good battery that's hopefully near fully charged and keep the meter on it and watch it charge with the 12 amp setting for a vehicle battery. Watch the voltage and make sure it climbs near 14.7v but doesn't go over. (it probably will hopefully not too far)

I'm not aware of any of the Schumacher chargers using the correct charging algorithm but they will usually charge a low battery even if they do so with abusive high voltage. My old 2/10/15 Schumacher would take it up to 16.2v at 10 amps

 

[browning300wsm]

901 Memphis that is what i did [I would hook it up to a known good battery that's hopefully near fully charged and keep the meter on it and watch it charge with the 12 amp setting for a vehicle battery. Watch the voltage and make sure it climbs near 14.7v ]

and i got a 13.6 reading on my multimeter .

 

[901Memphis]

If the battery is completely full that's good for a float voltage

 

[JHZR2]

13.6 is good for float... Was the 10.x due to a fully dead battery?

Schumacher seems to try to do an equalization charge every time, where it takes the voltage to around 16v. The high cells will gas, but the low cells will be brought up fully.

I woukdnt want that to happen every time though.

 

[901Memphis]

Originally Posted By: JHZR2
13.6 is good for float... Was the 10.x due to a fully dead battery?

Schumacher seems to try to do an equalization charge every time, where it takes the voltage to around 16v. The high cells will gas, but the low cells will be brought up fully.

I woukdnt want that to happen every time though.





I think the 10v reading was with no battery connected just a meter to the charger if I understand

 

[browning300wsm]

I think the 10v reading was with no battery connected just a meter to the charger if I understand

yes that is correct ..meter to charger

 

[901Memphis]

Originally Posted By: browning300wsm
I think the 10v reading was with no battery connected just a meter to the charger if I understand

yes that is correct ..meter to charger


I'm actually very surprised it output any voltage with nothing connected

 

[browning300wsm]

ok thank u for all the positive feed-back ..everything seems ok ..

 

[JHZR2]

Originally Posted By: 901Memphis
Originally Posted By: browning300wsm
I think the 10v reading was with no battery connected just a meter to the charger if I understand

yes that is correct ..meter to charger


I'm actually very surprised it output any voltage with nothing connected


+1 me too. Do we know the actual model and setting where this was encountered?

 

[wrcsixeight]

I will test my Schumacher sc2500a that I bought in 2007 for voltage at the clamps, plugged in, but no battery attached, and report back.

 

[JHZR2]

Use a low impedance meter if you can. I suspect there may be stray ghost voltages...

 

[Rylan]

My Schumacher SE8, produced in 2012, automatically floats voltage at 14.68v (according to my multimeter) at 8Amp setting. It then will go into maintenance mode at 2Amp and will activate if voltage goes below 12.48v.

The 8Amp can quickly revive discharged batteries within a few hours and also desulfates at the same time.

 

[wrcsixeight]

My sc2500a showed no Dc output voltage plugged into 120vAC, and pressing buttons did nothing to change this.

If I pulled a cable when charging, and tried to measure DC voltage, nothing.

If I set the DMM to auto range I was able to read 18 Millivolts, but the leads in my hands I was able to read 65 or more. But in the 20 range, 00.00v.

After this, I used it on the 12 amp AGM setting to charge an old abused flooded group31 "deep cycle" battery. It went upto 14.89 volts then dropped to 13.61 after a period of time.

I then plugged in my Meanwell power supply and the battery took another 8AH at 14.7v before amps into battery tapered to under 1.5. I did not bother with the hydrometer, I knew the schumacher quit absorption voltage early, I knew I could stuff more juice into it with my MeanWell power supply at 14.7v, as I always can.

I know one cell on this battery will never go higher than 1.250 when the other five likely still can be brought upto 1.275