flat vehicle battery (1 Viewer)

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mjltigger

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Nov 12, 2014
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We are off on our long weekend tomorrow and to give us a fighting chance of getting to the ferry in time after work I decided to go tank up tonight. Good job I did as the vehicle battery is flat.

I tried jumping off the mondeo but no joy.... left mondog running for a few minutes and the engine turned over but didn't get up enough speed to catch.

I've left it with the mains plugged in and the built in charger connected to just the vehicle battery via jump leads (disconnected leisure battery and clamped jump leads to the terminals then out the drivers window into the engine bay) so it's open to the elements right now.

Question 1... Is there any chance it will start like this now and if so will it fry anything

Question 2... Assuming the answer to q1 is a no (my guess hence I haven't tried it) how long will the charger take to give the vehicle battery enough juice to start up

I know any answers you give me will be guesses .. and I have no numbers or anything off the charger (can't even see a make or model) but any better educated guesses than mine would be useful please
 

pappajohn

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Q1....no it wont start now.

DONT try to start it with the charger attached, the starter needs between 200 and 400 amps and will overload the charger.

Q2.....1/2 hr should see enough charge if its a good starter.

But....once it running what you going to do ?....you cant leave it running unattended and it may need a good hour or more to fully charge from the engine alternator.
 
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mjltigger

mjltigger

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Q1....no it wont start now.

DONT try to start it with the charger attached, the starter needs between 200 and 400 amps and will overload the charger.

Q2.....1/2 hr should see enough charge if its a good starter.

But....once it running what you going to do ?....you cant leave it running unattended and it may need a good hour or more to fully charge from the engine alternator.

Thank you pappajohn. If it starts tonight I'm going to have a bit of a drive, tank up and then park up again with aims hook up to run the fridge and a heater overnight. If I need to hook the charger up again tomorrow then at least I will know it's going to work. I'm home all day (working from home) but if I can't get it to go tonight I'm going to ring round and get the best price possible on a new battery anyway so nothing lost there.

I've had it on and off the drive the past few weeks so wasn't totally surprised by the flat, just the fact that it wouldn't jump which makes me wonder if the battery is a deadun
 

pappajohn

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If the battery has been ok i doubt it will be beyond help and as you say......start and stop will take it out of the battery.

Jump start ( leads) doesnt alway work.
the leads may be too thin or a poor connection
 
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mjltigger

mjltigger

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If the battery has been ok i doubt it will be beyond help and as you say......start and stop will take it out of the battery.

Jump start ( leads) doesnt alway work.
the leads may be too thin or a poor connection

Well having replied to your post I realised it had probably been connected for nearly and hour so went and had a go. Still not catching but an improvement as it had got to the clicking starter motor stage before and is turning over again now. I've secured it all as best I can and locked up so will have another look in the morning. At least then places will be open if I do need a new battery.

Thanks for your help..

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Baggers53

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Cut your losses and fit a new battery......batteries should be changed every 5 yrs according
to the "techie" that sold me my new one yesterday...my old one was 7 yrs old, it had not completely failed but
enough for me to change it!!!
 

ukbill

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my battery went in france and took a age to start with heavy duty jump leads took it for a drive around 1 hr stopped at supermarket and nothing battery totally dead cost me 250e for new battery which wouls have been around 100quid here so change the battery dont take a chance with it :)
 
Apr 29, 2009
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I would be very careful jump starting the Motorhome - we bought an Elddis which had a speedo fault and the diagnosis from the Peugeot garage was that it had been fried by the seller jump starting the Motorhome. A lesson costing £650.
 
Apr 13, 2012
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..........

Winter will always show up a 'dying' battery - an 'iffy' battery will cope alright with Summer conditions.

Winter- cold starts, heater motor, wipers, lights will take the charge from the alternator

If you think or know the battery is old, change it - you can guarantee that it will be wet and cold and inconvenient when it finally lets you down - and buying one now will take away the worry


(y)
 

irnbru

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Snap. Mines flat too. Turned up at the MH yesterday to take it for its mot and it was as flat as a pancake. Had been parked up with just the immobiliser flashing for last 3 weeks. Despite AA saying battery was still a good one, maybe we have the same symptoms.

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eddie

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Once you do start it check that the 12 volt operation of the fridge and more important that the leisure battery is still charging correctly.

One of the most electrical faults we fix is a blown fuse due to jump starting.

Imagine that as soon as the alternator is producing current the engine and leisure batteries are in parallel (directly linked together)

Now further imagine that you have for arguments sake. 100 amps in the leisure battery and 20amps in the engine battery, and these amps are all desperate to get together. The amps rush through the wire that joins them together, and blows the fuse, typically 20 or 25 amp

As the Motorhome has been on charge, the leisure battery is charged anyway, the engine is running so all appears well.

It's normally a few days later that problems actually see to raise their ugly head, often without the owners making any connection between them
 

ukbill

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i suppose the best is the battery thingy that eddie sells which keeps your engine battery charged ?
 

ukbill

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yes but i doubt Jim would give the after sales service you would i hate calls not being answered :whistle::whistle::whistle:

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