Battery Gauge and power issue

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Historicalgasman

Historicalgasman

Member
Posts
73
Location
Glasgow
Hi all, another problem I Ned some help with. My battery gauge, is running at half, when I have lights blower and wipers on the rear windscreen heater won't come on, when I switch stuff off it comes on. Just fitted a brand new 110ah battery today and the problem is still the same, battery gauge used to run at 3/4 and drop to above half until recently. Any ideas all? Cheers.
 
No no no, check don't assume!
Got a multimeter? If not. Buy or borrow one. Lots of YouTube vids on how to check alternator output.
 
With engine running and nothing on I have a steady 14v when everything is switched on this drops to 12.3v measurements taken across the battery posts.
 
Brand spanking new battery....I've seen a few vids on drop testing, how do you do it on a Defender with the battery being half a mile from the alternator. Gotta love a Defender! I'm going to see if I have any shorts tomorrow......I'm sure I will have!
 
Drop testing is done with the battery off the vehicle.
Charge the battery 24hrs and retry the alty outputs and battery voltage after leaving it overnight.
Didn't notice the new battery sorry.
Does sound like weak alty but not that weak? Wonder if your mm is inaccurate?
 
Tried with mine and my mates MM both almost identical readings....Alty looks the obvious but Landys always have that Little habit of throwing in the un-obvious! Cheers for the comments!
 
Check the voltage on the terminal post on the back of the alternator with loads on and off, if it can hold 14v on load then it is a wiring fault and not the alternator.
 
Both my alternators don't put our 14V highest they do is around 13.6V but they still manage to maintain my two batteries and cope with two winches, light bar electric fan and any other bits and bobs that are on at once.
 
So did some digging around today, I have no parasitic draw but I do have a short somewhere pulled all the fuses one by one but couldn't isolate the problem so got some further digging to do there. Got the multimeter in the back of the Alternator unloaded I get a maximum of 13.9v and with it fully loaded I am getting 12.5v maximum but the reading fluctuated between 0.8-12.5v. Seems a little weak to me. Is the alternator on its way?
 
Historicalgasman said:
So did some digging around today, I have no parasitic draw but I do have a short somewhere pulled all the fuses one by one but couldn't isolate the problem so got some further digging to do there. Got the multimeter in the back of the Alternator unloaded I get a maximum of 13.9v and with it fully loaded I am getting 12.5v maximum but the reading fluctuated between 0.8-12.5v. Seems a little weak to me. Is the alternator on its way?
Click to expand...
Are you sure it is fluctuating down to 0.8 v or is that a typo, the alternator output should be tied to the battery +ve terminal and I cant see the battery dropping to 0.8v from 12.5v without a lot of smoke and fire!
 
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