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Old 3 Days Ago   #1
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Battery voltage drop during startup

Hi All,

Got a tester off a friend, turning ignition on the battery drops to around 7.5v - is this likely the reason for start stop failing?

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Old 3 Days Ago   #2
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Re: Battery voltage drop during startup

Hi

Looking like a failing battery..

Is that JUST the starter.. or are you still running the fuel pump at that point?
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Old 3 Days Ago   #3
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Re: Battery voltage drop during startup

I’m not sure if I posted this twice as I posted, it displayed and after a refresh was gone.

I insert the tester with the engine and car off. It registers 12.87v. I then started the engine fully and it drops to 7.25v. Once started it then jumped back up. I didn’t turn the car off, so that’s with it on from the drop onwards. As far as I know that means the fuel pump started running from the point where it turned on (ie after the 7.25v was registered).

I did a few tests the worst was 6.5v, issues are the vehicle stalls when start stop is turned on at junctions eg traffic lights and it states “start stop is unavailable.”

I have some other intermittent messages eg “check glow plugs” which is not always showing but just some of the time. I have suspected a poor battery for a while, around 1.5 years ago I called breakdown as when I tried to start the car it wouldn’t and the lights / battery was showing. I eventually got it going by disabling the AC, removing dash cam, turning all lights off, setting the radio to not turn on at start up and tried it a few times.

This has happened once or twice since, but 99.9999% of the time it starts perfectly first time so I was a little dubious as to whether it was a battery issue. It’s nice to finally have this graph and be able to say it seems like a problem, Halfords had a look and said my car wasn’t reporting any data and told me to go Fiat, which I had been avoiding as I suspect the diagnostic charges were high.
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Old 3 Days Ago   #4
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Re: Battery voltage drop during startup

If battery fully charged before attempted start then definately looks like a very poor battery.
Replace battery. Make sure to get a correct replacement type especially if a stop start vehicle.
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Old 3 Days Ago   #5
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Fully charged yes, definitely, been doing a lot of motorway driving this week alone. Ok will get it swapped out and it is the start stop type. Recommendations of batteries / where to go? Halfords seems competitive online but are they installing junk
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Old 3 Days Ago   #6
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Re: Battery voltage drop during startup

Another one I randomly get “check glow plugs” coming up.

It’s not always showing it’s a 50/50.

Do we know of cases where a poor battery can cause this? OR is it more likely the glow plug issue has ruined the battery?

I leave my AC on 247, as my old car cost a fortune of get it recharged (like £200 or so). Also in this Fiat it really stops any condensation amazingly well. I have a dash cam connected and sometimes 2 iPhones also, so the drain is quite a lot on the battery. Should I try to cut this down in future?

The cars got 38000 miles, didn’t expect the battery to fail quite just yet.
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Old 2 Days Ago   #7
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Re: Battery voltage drop during startup

Buy a good brand from Tayna

Delivered to your door
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Old 2 Days Ago   #8
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Re: Battery voltage drop during startup

38,000 miles but how many years?
I bought a motorcycle battery from Tayna a month ago and it arrived next day- Very good service.
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