I realize that this is old hat to most people but it may help a few.
---- What the ammeter reading means, a brief explanation ---
1- The ammeter is connected between the generator/alternator & the battery. It measures how much current is going into or out of the battery. Charge or discharge.
2- The amount of charging current is determined by battery state of charge & generator output capability.
3- How various loads affect the ammeter reading depends on whether the particular load is connected to the generator side of the ammeter or to the battery side. - See 7 below.
4- If a 10 amp load were conected to the generator side of the meter, the meter would not directly see this 10 amps. Eg. If the battery was receiving a 10 amp charge & a 10 amp load were connected, the meter would still show 10 amps flowing into the battery & the additional 10 amp load would not show, provided that the generator was capable of putting out 20 amps.
5- If the generator was only capable of putting out 10 amps, it's output would go to the 10 amp load & the meter would show zero going to the battery. If a 20 amp load were connected to this same 10 amp generator, 10 amps would come from the generator & 10 amps from the battery. The meter would show a 10 amp discharge.
6- Most older Lucas type generators are capable of putting out around 28 amps if they are in good condition & the belt is not slipping.
7- There are a few situations where a load may be connected to the battery side of the ammeter. Usually an intermittant high current load. In this case the meter will read the total generator output, not just the battery charging current. For this example, the battery is receiving a 10 amp charge & a 10 amp load is connected. The meter will now read the total charging plus load current of 20 amps.
8- For either connection, a fully charged battery will show no charging current on the meter. For the first case (connection type) (4) a load of 10 amps will not change the meter reading. In the second case (connection type) the meter would show the 10 amp load as an additional 10 amp charge. Provided that the generator is capable of putting out the required current.
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