..and its fully charged,where does the excess charge go?

In a car that is.

 

Into the flux capacitor, you need the excess charge stored ready for when you hit 88mph

John.

 

Or more seriously, if the battery's not charging, the alternator will just supply less current, and will put less of a load on the engine, so you get fractionally better mpg.

John.

 

If you had 2 batteries could you safely charge them both?

 

2 batteries isn't uncommon. It's usually done with a split charge unit, which i believe ensures the main battery is charged first, then switches over to start charging the 2nd battery.

That set up is often used so high-draw auxilliary items (eg. ICE, hefty driving lights, caravan, etc) won't flatten the main battery that's used for starting the car.

John.

 

yep like camper van leisure batteries, split chargers real cheap, very effective

 

 

 

PMSL at Flux Capacitor, WARP 9 Engage.....

 

 

I have two batteries connected in parallel in my boat and they charge perfectly well at the same time and have given no trouble for 5 years now.

Once the battery is fully charged Paul, the feedback from the battery voltage shuts the charging rate from the charger down, that is for a regulated charger which is normal. Unregulated overcharging could cause the battery to overheat if the charge was high enough.

Les