Battery Charging Voltage

[BHopkins]

While charging a battery today with my Pro-Logix battery charger, I noticed that it is charging at 15 vdc. I verified the voltage with my Fluke, and it showed 14.97 - 14.98 vdc.

This raised the question, what is the maximum voltage that a 12 volt auto battery can be charged at, without damaging the battery?

My apologies if this subject has been asked and answered before. I thought I have seen a discussion on this topic before, but was unsuccessful in searching for anything.

 

[BrendanC]

was it in a “desulfation” mode?

 

[bdcardinal]

Is that the "nuclear" setting that Eric O refers to?

 

[BHopkins]

was it in a “desulfation” mode?

No. It was still in the charging mode, and had not yet started the "desulfation" mode. Now that you mention it, I think I've seen voltages as high as 15.5 vdc, when it is in the "desulfation" mode.

 

[BrendanC]

Is that the "nuclear" setting that Eric O refers to?

that’s that “START YOU POS” mode

 

[JavierH19]

That's too high for standard charge mode which is typically 14-14.5

 

[BrendanC]

No. It was still in the charging mode, and had not yet started the "desulfation" mode. Now that you mention it, I think I've seen voltages as high as 15.5 vdc, when it is in the "desulfation" mode.

what mode is the charger set to? AGM’s will require higher voltages to get to 100%

 

[BHopkins]

I've got it set for flooded (STD) and am charging at 10 amps.

I just did a few Google searches on the subject. From what I can see, 14.7 vdc is generally considered the maximum charge voltage. Does this seem right?

 

[Jetronic]

set it to a lower amperage. Apparently it needs 15V to reach 10 amps.

 

[Hirev]

Most of the better battery chargers I have run around 14.2 - 14.5 V max. Back in the early 1990s had a nissian car that would charge up to 15.1 V that thing was hard on batteries. Most cars I've checked in the last 25 years don't charge more than 14.4 V. So this should give you an idea of range.

 

[SubLGT]

While charging a battery today with my Pro-Logix battery charger, I noticed that it is charging at 15 vdc. I verified the voltage with my Fluke, and it showed 14.97 - 14.98 vdc.

If the ambient temperature is below 77F the charger has a temperature compensation algorithm that increases charge voltage. A typical compensation coefficient would be 12mV per degF deviation from 77F. I don't know what specific compensation value Pro-Logix uses, because they don't specify it in the owner's manual. But based on what I have observed with my 20A P-L charger (PL2320) it is around 13mV per degF.

 

[SubLGT]

...........From what I can see, 14.7 vdc is generally considered the maximum charge voltage. Does this seem right?

Yes, for a battery that is at 77F. Allowable max voltage is higher at colder temps, and lower at higher temps.
Google "lead acid battery charger temperature compensation" for more details.

 

[D1dad]

Which model? I have a pl2140 and even in winter cold and agm it doesn't get any higher than 14.7. I really can't stand the charger but its float voltage and auto restart if it loses power is why I have it hooked up right now. Its been on my wifes agm while we've been out of town for 2 weeks.

 

[nobb]

Depends on type of battery. Typically AGM don't like higher voltages because the excess gassing may pop the relief valve and you lose water over time. Flooded batteries are quite tolerant and the occasional high voltage is good for desulfating. Also known as an equalizing charge.

On batteries that I'm trying to rejuvenate from sulfation, a nice boiling of the plates by applying a 15.5 - 16.0V for up to half a day can do wonders that even pulse desultators cannot do. You can technically do this on AGMs too, just need to open up all the caps and ensure the media is water saturated.

14.5V is a very typical normal charging voltage, but it won't really be enough to knock out the stubborn sulfation. 14.0V and below, the battery likely won't be fully charged unless it's a very long trickle charge.

 

[meep]

I’d have no problem charging at 15V during absorption stage. Let ‘er rip. AGMs usually state suggested charge rates and 14.8 is not unusual. Once the current drops in it should taper down. I would not want to float at 15.

 

[John105]

15v sounds high. The alternator ideally can provide clean power, ie even if 140 A or maybe these days even more, ideally the voltage is nearly constant. Prolly would exceed 13.8 but not much more. My .02 with v = ir

Maybe battery aged and resistance is high

Ps reread and this is a charger not an alternator. So yes imho 15v is high and might mean the device cannot supply clean power and lets the voltage increase with demand. For example used to be a battery charger at Walmart is $80 and some crazy amps. Then a power supply like a shop would use is $600+. The difference is the latter provides clean power. Voltage doesn’t shoot up as load increases. Think of a RV power supply. A lot is riding on it (12v appliances).