Battery problems

Lincssailer · Post by **Lincssailer** » Sat Oct 02, 2021 12:55 pm

Normally no problems but if i leave my car stood for a couple of days she wont start, new battery installed, checked for anything staying on but cannot find anything, where do i go from here, and how do i do it please

Wayfarer · Post by **Wayfarer** » Sat Oct 02, 2021 1:30 pm

Was the new battery fully charged before fitting?
If not try putting it on an intelligent charger such as a CTEK or NOCO for a day and /or night and try again, as new batteryare often not fully charged.

Hopefully others will come along with other suggestions ideas shortly.

Leslie · Post by **Leslie** » Sat Oct 02, 2021 3:16 pm

I think the bonnet switch for the alarm is a common issue which I would bypass first plus the hedgehog for the heater can stop it shutting down, you will see mist on the windscreen in colder weather where it has put heating on sometimes , is the blower functioning correctly and not surging ?

X5Sport · Post by **X5Sport** » Sat Oct 02, 2021 3:42 pm

The ‘tell-tale’ that will show if the car is awake is the ‘P’ on the gearshift indicator staying on. It should go out after around 15 minutes. If it stays on then the car is being kept awake. As above, the ‘hedgehog’, a part of the heating system, is known to keep the car awake and drain the battery. Short journeys will also not charge the battery properly.

I would recommend charging any new battery for 24 hours.

Alan Gunn · Post by **Alan Gunn** » Sun Oct 03, 2021 6:57 am

Another sign of a failed hedgehog is the heater fan/blower playing up or not coming on at all.

Lincssailer · Post by **Lincssailer** » Tue Oct 05, 2021 3:51 pm

Hi ref my battery problem, yes the battery is fully charged, yes the car is going to sleep, could it be a charging problem and if so how do i go about checking it?

X5Sport · Post by **X5Sport** » Tue Oct 05, 2021 5:56 pm

With the engine running and using the under bonnet connections (jump start points) connect a multimeter and see what voltage is showing. It should be at least 13.8V (14.2 to 14.7V if you have an AGM type battery) with the revs at around 2,000. Worth checking what it is showing at normal idle as well.

After that you’re getting into more specialist tools such as a current clamp to see whether there is a parasitic drain when the car is asleep and to see what the actual current output from the alternator is. If the voltage is swinging widely at different rpm then the regulator is likely to be faulty with specialist tools a car electrician has being able to confirm..

Lincssailer · Post by **Lincssailer** » Sun Oct 10, 2021 3:25 pm

Thanks

henrym3 · Post by **henrym3** » Sun Oct 10, 2021 8:21 pm

I’ve just sent for an under bonnet switch, the new ibus module I have shows the bonnet open, I can piss about with the switch till it shows closed so new switch it is. Maybe I should have nicked the switch from the e46 to double check but didn’t think of that till just now.

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