Battery Warning Indicator

[Lakeuk]

This week the Battery warning indicator on my aygo has started coming on for a short period at the start off my journey's, majority of my car use is long motorway drives, from multi meter reading the Battery and alternator look to be ok, the belt also feels tight, car always starts with no issues straight away - a couple of weeks back the clutch was changed on the car and the stations on the radio were reset so assume the Battery had been disconnected then, wondered whether a wire maybe loose.

These are the points the warning light has been on so far.

Thurs - Leaving work, light flashing as I leave multi story car park, 50 metres from setting of I notice it and pull over, turn of engine, when I start engine again no more lights for rest of journey

Fri - No issue going into work, leaving work start car in multi story and light is flashing, look under the bonnet, check wires to battery are secure, in that 30secs I get back into the car and the light is no longer flashing

Sat - At home check if the light comes on, it does in various states from solid to regular blinking. I get the multimeter out to check the voltage, with engine off the battery reads 12.7v, with engine on are running idle the battery reads 12.0v - I take the car for a short run, within 200metres light goes from solid to blinking and then after another 200metres it goes out and stays out for the rest of the days driving which short stop start journeys.

[Uncle Bob]

Checking the voltage across the Battery with the engine running, should give a reading around 14.5v, any less and it would indicate the alternator is not topping up the Battery.

If you have had work done on the car, I would first check all connection that they may have disturbed, ie connectors , earth to gearbox, maybe engine loom to alternator.

[MikeSh]

As Bob says, that 12V at idle is not right. However, as the light subsequently goes out and you haven't yet been stranded with a flat Battery it is obviously charging after a while.

The hardest work for the alternator is often after starting because that takes a chunk out of the Battery, so that's when a loose belt or iffy connection might cause a problem. Once a bit of charge is back in the demand drops and things charge normally. You've already checked the obvious stuff, so you're probably left with one of these:

- A poor connection you haven't found.

- Loose pulley (either crankshaft or alternator).

- Faulty alternator.

- Faulty Battery.

Given the cost of getting garages to check stuff like this (and the variable success rates they offer), then if the car is the 2008 in your sig and it's the original battery I'd replace that first and see what happens. It's probably due for it anyway, it's not a huge cost and if you do have to pay a professional in the end it's reduced that bill a bit.

[Lakeuk]

My synonyms moved on today to the light staying on constantly, back home got the multi meter out to test power under load with no increase in voltage, looks like alternator total given up the ghost not sending a charge to the Battery with the condition indication on Battery gone from green to dark. Job for tomorrow - organise appointment with mr toyota to fix