Megane Dci 1.5 problem battery/electrics ? UPDATE

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Megane Dci 1.5 problem battery/electrics ? UPDATE

Postby ljames555 » Sun Oct 03, 2010 8:55 pm

Gf went to start the car thursday and it started but with all dashboard lights flashing on/off in no order.

As I was away working I charged the battery up saturday and after a 4hr charge It started and it was fine no faults but I turned off and restarted and then the faults came back. I checked the volt readings sunday and it was 9.6 ( ive heard any less and thats bad ) Got a bloke I know to check with diagnostic machine and he said its the battery because it wouldnt power his machine and blamed battery end of. ( very blunt )

I jump started the car off my van and took it for a spin down the road and during driving I got all type of faults/lights again at least once.
Checked battery and it was reading 11.6 and 2 hrs later it was 11.38. I decided to try a battery out a mates ford probe 2.0 which read 12.6 and I still got the same faults/lights also getting asif the doors are locking noise ( got before) now Ive seen and been told my car needs a heavy duty style battery being a diesel so maybe this test wouldnt give me a sign for a new battery.

The sunday before it happens I took the passenger mirror glass off as was cracked and put a bag over to top water getting in but this had blown off and the misses didnt replace so I was also thinking water getting into electrics ?

I am thinking maybe she has left lights/radio on as car wasnt used since wednesday night til thursday afternoon and I dont want to go for a big run because dont want to break down but if I do maybe this will recharge battery fully heard our batteries run at 13v-14 this right ?

bit of a essay apologise.
Last edited by ljames555 on Fri Oct 08, 2010 3:52 pm, edited 1 time in total.

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Re: Megane Dci 1.5 problem battery/electrics ?

Postby davelowe » Sun Oct 03, 2010 10:16 pm

If the battery has been discharged to 9.6V then it's had it - anything less than 11.5V will have killed it permanently no matter how many times you try to charge it. You might get an engine running voltage of 13.8V - 14.2V, but that is the normal regulated voltage of the alternator. Any no load voltage of less than 12.45V with the engine off having left the car overnight is further proof of its demise.

I suggest you get a new battery. Then, remove the negative connector, and hook up a 10A (minimum) DC meter between the terminal and the connector. Lock the car and if there is a bonnet sensor, tape it down to fool the car that the bonnet is closed. Observe the current drain for 30 minutes. It should read maybe an amp or so for about 20 minutes then fade to nearly unmeasurable. If it still drains by more than 250mA after 30 minutes, you have a problem with the electronics.

You are correct that the diesel batteries have both a higher amp/hour capacity and also a higher peak current output (because of the higher starting load due to glow plugs and compression ratio).
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Re: Megane Dci 1.5 problem battery/electrics ?

Postby ljames555 » Mon Oct 04, 2010 8:18 am

So a dead battery would give me all this irregular lights/dashboard lights/fans coming and going off?

Even though I tried using a battery off the ford probe which had full 12.6volts I'd still get all the electronic faults ? Because that's what happened.

Seen battery for about £50 that about right?

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Re: Megane Dci 1.5 problem battery/electrics ?

Postby ljames555 » Fri Oct 08, 2010 3:51 pm

Right charged the battery up to full power and not a problem car ran perfect so I got the battery tested and the Cold cranking amp reading was 359 should be 600 on my battery so went for a good drive and retested and was down to 337.

The fella at the shop said it'll need a new battery so I bought one and all is ok.

Checked the volts todays on the old battery been off for 2 days and its held its power.

Would the low CCA mean battery is dead ?

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Re: Megane Dci 1.5 problem battery/electrics ? UPDATE

Postby AlexB » Fri Oct 08, 2010 5:06 pm

Yes, the low cold cranking current means that half of each electrode is not working. The batteries serve 4-7 years depending on the make. The best are Bosch S5 and Varta Silver.

The voltage without load will stay at 12V until the battery is almost empty.

These cars depend on reliable battery. BOSCH SILVER PLUS S5008 (780A) is under £100 inc. VAT from a Bosch garage (probably cheaper on Internet).
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Re: Megane Dci 1.5 problem battery/electrics ? UPDATE

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