help pleas Re: renault scenic battery/alternator

spaceman5

This is going to be a bit long winded i am afraid, anyway 9 months ago i purchased a 2nd hand scenic, within first day battery had gone flat, so took it back to where purchased from, he diagnosed alternator was goosed, he got it repaired by local battery place, anyway about week later we took car out on its first longish journey, and about 2 miles from home the car just stopped with nothing electrical related working, battery goosed again, took it next day to the garage i normally use, who said it was alternator again, they took it to same battery place who told them there was nothing wrong with alternator as they had fixed it week before, so after more tests they decided it was battery terminals, and replaced them, all was fine for 3 months, then in summer 1 day, it would not start, so took it back to my local garage, who then fitted new battery, all was fine until 2 days ago, get in car, go to fire it up nothing, so charge battery take it to local garage, who do all the tests, check alternator working as it should, check the charge is getting to the battery it is, check the battery is holding the charge it is, so again diagnose battery terminals, and replace just the earth terminal, i thought the live 1 would have been more important but i am not a mechanic, when i get home i notice something unusual, for the past month when i lock the car you can hear a noise, like a motor in the door struggling to actually lock the door, but when i lock it after the battery had been fully charged no noise, when i lock it up, so today i take kids to school(only about 2 mile trip there), again when i lock car no noise, go home but this time when i lock the car noise has returned, check how fully charged the battery was, and my meter said 10%:eek:, this after it being fully charged yesterday morning and doing a maximum of 8 miles since then, so i can only presume that this noise when locking the car is somehow connected to the battery charge somehow, as when fully charged no noise, and when low charge, the noise returns if you see what i mean, anyway tonight i take it out to do shopping(2 miles) on way i put foot down a bit and heypresto when i get to shop and lock the car no noise, so i thought on way home i would make a detour and come home down the motorway(5 miles roughly) and put my foot down, get home and test battery, now it is showing as 50%, where as earlier it was 10%, so obviously putting foot down has charged the battery, so after all this my question is, does anybody know wwhat would cause a fully charged battery to drop down to only 10% after only doing 8 miles, so it is obviously not charging when doing normal driving, and then seem to work fine when i can get into open space and put foot down, as obviously it is not practical for me to take the car out down the motorway every day just to make sure it maintains its charge?

sorry for the long winded post, and thanks to anybody who manages to read it all and understand it, but i could not think of how to shorten it so you would be able to understand my predicament

TIA

Norman_Castle

obviously putting foot down has charged the battery,

No, doing extra miles has charged the battery.
Something may be draining the battery while the car is parked.

ginger_manx

Norman_Castle wrote: »

No, doing extra miles has charged the battery.
Something may be draining the battery while the car is parked.

Yes, sounds like an alarm fault...

spaceman5

Norman_Castle wrote: »

No, doing extra miles has charged the battery.
Something may be draining the battery while the car is parked.

thanks for that, but what i dont get then, is this morning i did 2 miles and it was very noticeable that the battery never charged, i,e the sound of the motor in the door for locking it came back, but when i did the 2 miles to the supermarket tonight it was noticeable that the battery had being charged at least a bit, i,e when i locked the car there was no sound from the motor in the door, so why in 1 trip the battery never seemed to charge, but in next trip of equal length(albeit a quicker speed) the battery did seem to charge

Rolandtheroadie

The initial start this morning would probably have juiced the battery more (colder during night, possibly sitting longer, harder to start).

Norman_Castle

The sound your central locking makes is possibly not the best guide to the level of charge in your battery.

thefishdude

deff sounds to me like something is draining the battery when the car is just parked that is why it can drop so fast over night. as to what that be is a diff matter.

Inactive

Sounds like the typical Renault, plagued with electrical faults.

epninety

spaceman5 wrote: »

so after all this my question is, does anybody know wwhat would cause a fully charged battery to drop down to only 10% after only doing 8 miles, so it is obviously not

OP, you have to be careful how you measure the charge level in a car battery. I'm guessing you measured the battery just after you parked up. Assuming you are using one of those cheap battery level meters, you wont get an accurate reading if you measure immediately after 'heavy' charging or discharging. The battery needs to return to its 'rest' state. Try measuring it after you've parked for an hour and you'll get a much more realistic answer.

If you have a meter that can read accurate voltages, you can probably work out where the problem lies, but otherwise it can be a long winded process, and you might be better off paying an auto electrician to give it the once over.

It's a process of elimination - first decide if the fault lies in Charging (alternator and wiring) / Storage (battery) / Discharge (something drawing excessive battery power) - then working through until the exact fault is found.

Your noisy lock may be cause or effect - it may be struggling because the battery voltage is low (or there's is a wiring problem), or it may be sticking and drawing power continuously, flattening the battery. Thats not going to flatten the battery quickly though, but might tip the balance if left overnight.

If you do call an auto-electrician, mention the lock noise

If your battery has repeatedly got down to 10% charge, it might need changing again anyway, even if it isn't the actual fault. Car battery don't like repeated deep discharge, it can really affect their performance.

jlrtech

do you have breakdown cover ?

most will be able to diagnose what the fault may be and fix it . it could also save the cost of an auto electrician and my i also say very sound advice from epninety :beer:

no-oneknowsme

I have owned two renault scenic and i have noticed the strange noise on locking in both cars .

never had any other trouble with either car though . Have to say i am fond of the scenic (the older ones anyhow...)