Hey folks

Will unplugging the 3-pin connector from the alternator damage the car in anyway? I'm told this makes it revert to a standard alternator but you'll always have the battery light on the dash.

I've had a charging issue. Garage has replaced the battery as it was ruined and have traced the wires as far as they can and they're in decent nick and everything is as normal. They've said when the alternator 3-pin plug is in, the car is doing everything it can to maintain a charge, idling at 1200+ and even revving to 2,500 at a standstill. This completely goes away when it is unplugged.

I'm thinking of making the alternator go back to be a standard one so I can drive it back to the place I bought it from.

42 minutes ago, YorkyPuds said:

Hey folks

Will unplugging the 3-pin connector from the alternator damage the car in anyway? I'm told this makes it revert to a standard alternator but you'll always have the battery light on the dash.

I've had a charging issue. Garage has replaced the battery as it was ruined and have traced the wires as far as they can and they're in decent nick and everything is as normal. They've said when the alternator 3-pin plug is in, the car is doing everything it can to maintain a charge, idling at 1200+ and even revving to 2,500 at a standstill. This completely goes away when it is unplugged.

I'm thinking of making the alternator go back to be a standard one so I can drive it back to the place I bought it from.

I didn't think a MK2 Focus had Smart Charging.

Mk2 does have SmartCharge - you're probably thinking of variable charging which didn't start until Mk3.

SmartCharge only increases charge voltage briefly after cold start, as a cold battery accepts charge more easily than a hot one.  Leaving it unplugged won't do any harm, just means it'll take a bit longer to recharge the battery after each start.

I've got the garage that did the investigative work to disconnect the 3-pin plug. Battery light is on the dash but everything seems OK.

Will get the place I bought it from, which has a three-month warranty, to find out the source of the problem.

Thank you.

45 minutes ago, TomsFocus said:

... as a cold battery accepts charge more easily than a hot one.

Actually, a COLD battery NEVER accepts charge more easily. The higher charge voltage is NEEDED in a cold battery, because it would NOT accept charge so easily otherwise.

https://www.victronenergy.com/blog/2019/01/09/lead-acid-battery-charging-in-cold-weather/