Float Charger

Chris Jones · Feb 5, 2015

I have 2 lawn tractors and a compact diesel here that I have float charger on to prevent the batteries from going down while not being used. I removed the leads today from one battery and tested across the leads with a volt meter. 9.6 volts. The manual says it should be putting out 13.2. I checked the others and they say 12.6 and 12.4 volts. All they have is an led on them that stays on when they are connected to the battery or plugged in.

Do these things go bad with age?

Do you reckon 12.4 or 12.6 is enough to be helping those batteries?

Ted in NE-OH · Feb 5, 2015

Maybe the 9.6 V one is for a 6V battery?

Greg_Ky · Feb 5, 2015

A float charger will not keep an inactive battery from sulfating and going bad, you need one that will also desulfate. I use BatteryMinder's myself. FWIW

JMOR · Feb 5, 2015

Measuring some/maybe most without being connected to a battery is just about meaningless. Why? Because you are measuring with a DC meter & the unit's output is not a clean DC voltage, but rather a pulsating waveform. 13.2 battery float voltage is a good number (measured on a 100% fully charged battery and after a day or so on float, so as to stabilize).

guido · Feb 5, 2015

Hello Chris Jones,

The charger that shows 9.6 volts is probably bad. Just swap it out with one of the other chargers, and you'll know for sure. Your other chargers appear to be working, although the output voltage
seems a bit low,

Guido.

JMOR · Feb 5, 2015

Chris, unless all 3 are the same model, then they are probably all good, just different designs/filtering/waveforms. Read my response above.

Chris Jones · Feb 5, 2015

They're all identical units. One is a year or so older but which I don't know as they are identical.

Chris Jones · Feb 5, 2015

Thanks folks,

I decided to throw the one reading 9 volts away so I cracked it open. I tested the transformer output which says is 18 volts AC. It tests correct so it must be something in the small circuit board that turns that into what the instructions say should be 13 volt DC output to the battery clamps.

I saved the clamps for future projects.

farmboy48 · Feb 5, 2015

I just checked the voltage on the one I have on the Suzuki four wheeler. It reads 13.8 output when not on battery, and 13.2 when connected to the batt. Batt also reads 13.2 but I just used it pushing snow with the electric winch on blade getting used a lot. Will check again in morning to see if it comes up to 13.6.

Dick ND

Den N Ms · Feb 5, 2015

Chris,Like JMOR said,The charger won't give a good reading of like 13.6volts if you test the leads of the charger.Test it with the leads hooked to the battery after being hooked up for a day or two.Then check the voltage hooked up at the battery posts.

Motorcraftman · Feb 5, 2015

Well... To give things a Different Twist... If a Battery is FULLY Charged... A Simple Solar panel Will Doa great job, Got it from Northern ita a 1.8 MA and will keep it Fully charged, granted, it wont Charge a Weak Battery, But will KEEP it up to Speed .. I have several on a Van tractor Mowers etc: they are Ready when You are... never had a problem,You just have to have them in the Sun/Window etc; Just cant Beat that FREE Charging... just My 90cents worth, Larry

Geo-TH,In · Feb 6, 2015

No float charger, even a batteryminder, can fix a junk battery. People need to invest in a good battery conductivity tester to determine condition of battery.

I too have a batteryminder 12248. Had it for 4 years now and saved a lot of batteries from the recyclers. It does help prevent, but can't help a shorted or dead cell.

John T · Feb 6, 2015

A good fully charged flooded lead acid battery at rest and stabilized and disconnected should read around 12.6 to 12.7 volts (subject to charge state, battery and temperature and other factors)...A typical float charge level of many somewhat "smart" battery chargers is around 13.2 volts....However, the open circuit unloaded voltage of a battery charger can vary by design and construction and it doesn't near tell the entire story, its to what voltage it can raise a battery to and maintain that matters most, i.e. it may Bulk and Absorption charge at higher levels (say 14.4 or 14.8 then 13.6 or so) and settle in and maintain a float level charge of around 13.2 typically.

If you charge a battery and then let it settle then use a Hydrometer and subject it to a load test you can come more near to ascertaining its true condition.

"Do these things go bad with age?"

YES that's possible

"Do you reckon 12.4 or 12.6 is enough to be helping those batteries?"

The 12.4 is NOT helping, its somewhat discharged (but may eventually climb over time???) and 12.6 is close to a typical full charge state subject to battery and temperature. My "smart" chargers maintain a float level of around 13.2 volts. Still, if its at 12.6 and stays there it should do okay, that's better then it setting in a discharge state for sure even if its not at 13+

John T

JMOR · Feb 6, 2015

(quoted from post at 10:20:57 02/06/15) A good fully charged flooded lead acid battery at rest and stabilized and disconnected should read around 12.6 to 12.7 volts (subject to charge state, battery and temperature and other factors)...A typical float charge level of many somewhat "smart" battery chargers is around 13.2 volts....However, the open circuit unloaded voltage of a battery charger can vary by design and construction and it doesn't near tell the entire story, its to what voltage it can raise a battery to and maintain that matters most, i.e. it may Bulk and Absorption charge at higher levels (say 14.4 or 14.8 then 13.6 or so) and settle in and maintain a float level charge of around 13.2 typically.

If you charge a battery and then let it settle then use a Hydrometer and subject it to a load test you can come more near to ascertaining its true condition.

"Do these things go bad with age?"

YES that's possible

"Do you reckon 12.4 or 12.6 is enough to be helping those batteries?"

The 12.4 is NOT helping, its somewhat discharged (but may eventually climb over time???) and 12.6 is close to a typical full charge state subject to battery and temperature. My "smart" chargers maintain a float level of around 13.2 volts. Still, if its at 12.6 and stays there it should do okay, that's better then it setting in a discharge state for sure even if its not at 13+

John T

ust can't get the concept, I guess? Told him that those disconnected readings were meaningless! Measure the battery while on float & stable!!!! He most likely already broke open & trashed a perfectly good unit as a result of not understanding what he is messing with. A 'little' knowledge is dangerous!

John T · Feb 6, 2015

Yep, unfiltered rectified AC (especially if only half wave) creates an AWFUL LOOKING CURVE on a scope and depending on the meter type and quality, no telling what voltage it may register. However as you point out hang a big electron bank battery buffer on then its voltage once stabilized tells you something meaningful.

John T

Float Charger

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