Member Since: 27 Aug 2018
Location: Cheshire
Posts: 228
Hi not sure if this helps but my 2009 D4 has a regular wet battery which is getting a bit tired! Its not it’s original battery but I have no idea how long it’s been in there.
I note (from a cheapo Chinese fag lighter voltage reader) that when I get in the car but before ignition is on it’s just above 12v but when it’s running it’s usually between 14.5to14.8v
So from above that would indicate that it thinks it has an AGM battery in and may well be trying to overcharge it and hence leading to a premature battery death??
21st Feb 2019 5:48 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8073
You have got the last paragraph the wrong way round, a wet cell battery will take a higher voltage charge than an AGM, this is where the controversy is about damaging AGM batteries by putting a higher charge (voltage) into them than they are capable of accepting, in winter conditions and the CCF set to wet cell a Disco 3/4 Will charge at 15.5+volts for several minutes after start up, the maximum a AGM battery can accept is nearer 14.5volts.
Theory is in cold weather and for a few minutes they can cope with this rate of charge, but in summer on a long journey although the rate of charge will be lower it will still be above their capability and overheating can distort the cells and lead to the battery failing.
Yours appears to be set for AGM judging by your charging figures.It can when others can't,
It will when others won't,
It goes where others don't.
21st Feb 2019 8:17 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8073
or the alternator is getting tired.It can when others can't,
It will when others won't,
It goes where others don't.
21st Feb 2019 8:20 pm
Andy500
Member Since: 27 Aug 2018
Location: Cheshire
Posts: 228
Ahh ok good info thanks. I need to get some things changed on the CCf so will have that checked at the same time👍
21st Feb 2019 8:35 pm
TwoSheds
Member Since: 11 Sep 2018
Location: Royal Deeside, in a cottage on a hill
Posts: 25
M3DPO wrote:
You have got the last paragraph the wrong way round, a wet cell battery will take a higher voltage charge than an AGM, this is where the controversy is about damaging AGM batteries by putting a higher charge (voltage) into them than they are capable of accepting, in winter conditions and the CCF set to wet cell a Disco 3/4 Will charge at 15.5+volts for several minutes after start up, the maximum a AGM battery can accept is nearer 14.5volts.
Theory is in cold weather and for a few minutes they can cope with this rate of charge, but in summer on a long journey although the rate of charge will be lower it will still be above their capability and overheating can distort the cells and lead to the battery failing.
Yours appears to be set for AGM judging by your charging figures.
I was basing my numbers on the CTEK charger manual - here is a screenshot of the relevant page:
I wonder if the numbers you quote for the wet battery above might be a short 'Recond' cycle being run by the car?
I did check the voltages of a wet and an AGM while charging and both were a smidgen under the values quoted in the manual.
RogDisco4, Disco2, R1200R, CBX600FX, multiple Ham radios, and several bicycles...
All that lot and a tool fetish means that I seldom have more than two brass farthings to rub together.
22nd Feb 2019 9:32 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8073
Some interesting reading here for you from the real experts who have far more knowledge than I will ever have, for instance did you know the D4 has regenerative charging , which means it charges less when accelerating to reduce load on the engine and full charge when braking.
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who have far more knowledge than I will ever have, for instance did you know the D4 has regenerative charging 
, which means it charges less when accelerating to reduce load on the engine and full charge when braking.
