Help with my Battery / Alternator / ECU issue

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Josh999
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Help with my Battery / Alternator / ECU issue

Post by Josh999 » Wed Jun 14, 2017 11:58 pm

Hi guys,

This forum has helped me more times than it should, and I'm really hoping for some help with solving my dead battery issue.

I'm quite sure they battery is fine, however when I fully charge the battery it runs out within a 10 minute drive. It doesn't die over night and seems to hold its charge for a while. This leads me more into the area of the alternator, I've removed it and no concerning noises are there. Belts are fine, and all fuses are still intact. When I replaced my hydrogas spheres I removed my ECU, when I installed it back, the car revved a little higher. I reset the ECU and it corrected the problem, could the ECU not be cooperating with the alternator? How would I check that? Unfortunately, I don't have any multi mentors, I took the negative lead off the battery while the car was running, and it stalled. All wires look okay too.

Everything was fine before it was stored away in a barn for winter, just got it out to replace the hydrogas and ended up with this problem. Open to theories on all components.

Thank you for reading and any help would be appreciated

Geoff.F
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Re: Help with my Battery / Alternator / ECU issue

Post by Geoff.F » Thu Jun 15, 2017 8:41 am

I would suggest that you invest £10 in a Multimeter to check battery voltage across the terminals and clamps with and without the engine running. Clean all the connections specially the earth terminals.
NEVER run an alternator without it connected to a battery. It will damage the circuit.
Geoff.F

BodgeItAndScarper
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Re: Help with my Battery / Alternator / ECU issue

Post by BodgeItAndScarper » Thu Jun 15, 2017 12:03 pm

A tenner? Spendthrift! :)

http://www.ebay.co.uk/itm/191921991924

Got one of those the other day as a spare, seems to work fine and it's reasonably accurate.

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Steve White
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Re: Help with my Battery / Alternator / ECU issue

Post by Steve White » Thu Jun 15, 2017 12:31 pm

If the alternator isn't charging the battery, the electronic power steering (assuming the car has it) will flatten the battery very quickly when driving.
If the rectifier on the alternator has failed its unlikely you will be able to tell from looking at it.
As Goeff has said, a quick measure of the battery voltage with/without engine running will show if its charging, not charging or overcharging (will can damage the battery).
Its unlikely the issue is anything to do with the ECU.

FWIW we recently completed 35 miles/1hr journey in a TF with a fully charged battery (and a spare in the boot JIC) and an alternator that wasn't charging, just by removing the EPAS fuse and turning off anything electrical not essential (radio, cabin fan etc) :-o

willyphixitt
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Re: Help with my Battery / Alternator / ECU issue

Post by willyphixitt » Thu Jun 15, 2017 1:33 pm

Disconnecting the negative lead while the engine is running will toast the alternator.

willyphixitt

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RobboMC
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Re: Help with my Battery / Alternator / ECU issue

Post by RobboMC » Fri Jun 16, 2017 3:28 am

Steve White wrote:
FWIW we recently completed 35 miles/1hr journey in a TF with a fully charged battery (and a spare in the boot JIC) and an alternator that wasn't charging, just by removing the EPAS fuse and turning off anything electrical not essential (radio, cabin fan etc) :-o

Steve that is worth a huge amount for me to know. If an alternator belt ever breaks Step One is to remove the EPAS fuse.
Like a lot of things, obvious when you know but not so obvious until you sit and think about it.

In this great wide land down under help could be a lot more than 35 miles away, though most of the F's don't leave the populated areas
there are still some big empty stretches..

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talkingcars
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Re: Help with my Battery / Alternator / ECU issue

Post by talkingcars » Fri Jun 16, 2017 9:29 am

If the battery has gone flat several times it will stop holding charge unless you get it reconditioned, I got a Ring battery reclonditioner for under £50 and have saved several seamingly dead batteries with it.
Home to black Alfa 159 3.2 V6 Q4, blue MGZR160, green MGF VVC and grey MGF 1.8i, and red MG Maestro T16.

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Josh999
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Re: Help with my Battery / Alternator / ECU issue

Post by Josh999 » Fri Jun 16, 2017 3:03 pm

Thank you so much for your help so far, the Epas fuse is a very interesting thing to know!

I've put the battery on a different car and drove two hours without fault, so I can eliminate that.

I'll buy myself a multi meter today, is there a way of checking the alternator off the car? Or ECU?

Thanks again!!

Josh999
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Joined: Wed Jun 14, 2017 11:22 pm
MGF Register Region: South East

Re: Help with my Battery / Alternator / ECU issue

Post by Josh999 » Tue Jun 20, 2017 6:25 pm

All fixed!

So it was my alternator all along, I took it off to be tested at an auto electricians to which he comfirmed that it was no longer charging the battery. I have a donor mg, so I took the alternator off that swapped some bits between them and put it on the good mg. £25 well spent.

Always good to have a donor when you own an mg haha

Thanks for all your help guys!

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