Voltage reading.

[80Sprint]

I have a fan issue on a separate thread but have notice a possible voltage issue. With the battery on a trickle charge I am showing 13v . If I leave it on ignition to check the fan I am only getting 11.7 bolts at the fan. No difference with an earth to the battery. Back to the fuse box and I still have 11.7 volts.
What should it be at the fuse and if mine is too low, why ? The battery is only a year old and higher spec than standard and the vision panel shows it as good.

[Mad Mart]

Your battery should normally show 12.6V but as you have the charger on a higher voltage would show. Check the Voltage across the battery terminals, this Voltage should be the same at the fuse. Check the Voltage between the +ve terminal and the +ve terminal clamp, it should be 0V. Do the same on the -ve terminal.

[marshman]

As Madmart says a good charged battery should show around 12.6V off charge. Trickle charging I would expect to see around 13.7V, are you sure the battery is fully charged? If it was completely discharged it could take several days to be fully recharged using a trickle charger.

The "11.7V" at the fan, is that with the fan running? if so it is probably voltage drop across the wires. Check all the connections and and as Madmart says measure the volts at the battery end while it is running as well. If the battery end is OK and you are dropping (losing) the voltage along the wires then maybe fit thicker wire. Depending on the type of fan they can draw quite a hefty current when running.

The "green" indicator in the battery is just a crude hydrometer, a coloured floating ball which gives a rough indication of the state of charge of the battery, or to get technical the specific gravity of the electrolyte. On some batteries it only indicates the charge of one of the six cells in the battery, so it is possible to have a duff cell, although the battery "appears" to be good.

Roger