Short Circuit 300tdi

So during the recent heavy rain when the trains to gatwick and the M23 were closed I shoe horned the family into the defender and ploughed through flooded backroads to gatwick... Defender saved the day... ish

On the way we hit lots of water, some deeper than I thought and sent spray way over the truck...

It then spent 3 weeks in an open car park... and thought it strange that the battery went flat after two weeks (normally lasts about 6) but put it down to cold and wet.

drove back from shatwick ok.. Its been fine for a week or so, but today I went to start and pre-heat and

1) all lights, radio, etc came on and engine preheat started

2) suddenly as I went to start the engine it all went dead, at first with the clicking of a flat battery but then

3) not even clicking or any signs of life when trying ignition

4) the battery has a voltage check which was not working, showing nothing, but that could be cut-off (its a lithium one)

5) I went to use the spare battery which I have been meaning to add as a leisure battery for a while, was at a healthy 13.2, however when I went to parallel them it arc'd like mad

Any thoughts? Is there a fusebox in the engine bay somewhere?

The battery box is all dry and was never wet

theres some large fuses under the bonnet on passenger footwell side,but you need to find the short first

Ok thanks, I was assuming there maybe blown fuses to give me a hint? or not?

Sounds like your battery has gone bad. Preheat uses what is left in the battery and nothing left to turn over engine, all goes dead giving everything to the starter.

Gmacz said:

Sounds like your battery has gone bad. Preheat uses what is left in the battery and nothing left to turn over engine, all goes dead giving everything to the starter.

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actually that’s made me think I will bring it in and charge, but the arcs when trying to put batteries together?

the battery sounds knackered and jumping from your spare is being drained by the knackered battery try starting with spare battery full charged and with the original battery removed

When you connect a fully charged battery to a flat battery there will be some arcing as current wants to flow from one to the other.

tottot said:

When you connect a fully charged battery to a flat battery there will be some arcing as current wants to flow from one to the other.

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there will ,its the amount of arcing that tells

this was not healthy amounts of arcing lol.. but then a lifepo4 shuts itself down so could be culprit ... put it on slow charge but 2.36v is not good!

I am reluctant to try the other battery until I see its not knackered this one... as lifepo4 not cheap!

phew back up to 12.7v already...

Thanks for all your help chaps, don’t know if its dried out or not (the previous night it rained hard and blew a hooley) but charged overnight to a worrying high of 14.6v, put the battery in with no arcs, started on the button so fingers crossed! it went down to 13.8v after first start and 13.9v after a drive round block... I will keep an eye on it as occurred to me the alternator amy not be charging as it has done ???

cborrman said:

however when I went to parallel them it arc'd like mad

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That could simply be an indication that your main battery was so flat that a large current was being drawn by it from the second one like a charger.

If you took two similar batteries, one discharged and one fully charged and connected them the net result would be the 2 batteries would equalise themselves, so the charged one would try and charge the flat one until they both equalised, net result would be 2 batteries sitting at say about 6-8V and neither very well charged.