I want to understand using my Snap-On Super 550 Battery charger more. If I check the voltage across my battery with a digital multi-meter what should the voltage be? My charger book says 12.6V but my load tester book says 12.4V? My charger has 3 knobs. I understand the timer one. The other 2, the manual isn't that clear so I want to be sure I am using my charger correctly. The Coarse Rate Switch has 6 LO, 6HI 12 LO and 12 HI. The Fine Rate Switch has LO, Reg, Hybrid, and HI Main Free. Between the 2 switches I can get various combinations. I understand some of the combinations like Hi Main Free, Hybrid but was wondering when to use say 12V Hi and LO combination or 12V LO and LO? Thanks!!
Understand car battery charger
- Thread starter johninct
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scaron
Well-known member
the voltage on a lead-acid car battery in good working order should be always around 12-13 VDC or so. it's not a super precise thing; every battery will be a little bit different.
sasquatch12
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- Nov 6, 2013
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Fully charged 12 volt car battery should read 12.6 as you posted.
Hpozzuoli
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theoldwizard1
Well-known member
Actually, fresh off of a charger, it could be as high as 13.2V Left to sit for a few days, it still should be at least 12.6V.
If your battery voltage drops while at rest with no load, clean the outside of the case with baking soda, water and a brush. Rinse with clear water. Recharge.
jkwilson
Well-known member
Virtually all flooded cell batteries will measure 12.65V at full charge, and hundredths of a volt are important. Trojans usually go 12.72, and AGMs 12.8 to 13 depending on the manufacturer.
When charging, the voltage will normally rise to around 15V, but that depends on the particular battery technology.
On your charger, the 12hi and 12lo probably set the charge rate. The other switch may set maximum voltage.
When charging, the voltage will normally rise to around 15V, but that depends on the particular battery technology.
On your charger, the 12hi and 12lo probably set the charge rate. The other switch may set maximum voltage.
Hpozzuoli
Well-known member
I set the coarse rate at 12 lo. I set the fine rate at maintenance free. As far as time it charges super quick so I set it to 5 mins and it's usually good to start the vehicle in 2mins. I haven't charged something that has been dead for weeks and completely gone. I have done cars/trucks that died over night or have been dead for a day or so. It's a real good charger.
Hpozzuoli
Well-known member
I just caught the rest of your question. 12 hi would be for deep cycle stuff. 12lo would be car/truck batteries on the coarse rate side. Same theory applies for 6 volt stuff. Coarse rate basically determines the amount of charge needed for the application. The fine rate would be the type of battery. Typically maintenance free these days. Timer is pretty straight forward although this thing charges very fast.