Charging and Battery Voltages

[chesjak]

Hi

Does anyone know what Honda say the following should be:

Battery Voltage when fully charged without engine running

Voltage across battery terminals when engine running

Voltage across battery terminals when under load say with headlights and drivers heated seat on.

Mine are 12.75v 13.9v and 12.75v respectively.

Battery is less that 1 yr old

I ask this question because I don't feel that my headlights are as bright as I feel they should be with latest Osram Night Breakers installed.

Any help appreciated.

 

[Jon_G]

Voltage without the engine running will depend upon temperature and/or how long the battery has been standing after being charged. But yours seem pretty reasonable @12.75V (although a bit odd that this voltage is the same whether under load or not?).

Voltage with the engine running will depend upon whether the engine is ticking over or at a more representative 'running' RPM. I would expect better than 13.9V... more like 14.4V at 1500RPM.

I'm not sure that Nightbreakers are ever particularly bright.

 

[freddofrog]

yeah there's several threads about those lights not being very bright on the Accord.

And those voltages look fine ....were you expecting more than 14 volts charging ?

If so, how much more ?

The wattage of a bulb is proportional to the square of the voltage, so 14 volts (a typical charging voltage) should give about 36% more wattage than 12 volts (***uming that the resistance doesn't change). But AFAIK the human eye won't notice 36% as being significant (***uming also that 36% change in wattage of a conventional bulb equates to 36% change in light output)
i.e. if you look at the lights' brightness against a wall with the engine running, and then turn the engine off, it won't look like the brightness has decreased by 36%.

So it has more to do with the lenses in the Accord, which IIRC did get mentioned as the problem in one particular thread somewhere

 

[jjmartin349571]

It might also be worth checking that all the earths are in good condition?

 

[freddofrog]

^ a possibility not to be diminished (see what I did there LOL) B)