Member Since: 10 Apr 2017
Location: Hampshire
Posts: 401
Mat,
Taking your example of a 75A/hr battery with a draw of 1 amp continuous, it will take 75 hours to drain the battery.
You then go on to use the 550mA or 0.55A (just over half the previous example) draw that Pete is experiencing. This would give a battery life of 75 * 0.55 = 41.25 hours.
Surely it should be 75 / 0.55 = 136.36 hours.
If I'm wrong, please don't shout, I'm just using basic logic. Half the drain will take twice as long to flatten the battery.
Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
my bad.... lol, you're exactly right !!
Too many things going on to even think about basic sanity/arithmetic checks ..oops
75A/0.55A = 136hrs to flat (in theory)
Mat2005 TDV6 SE Auto
Cairns Blue
23rd Apr 2020 10:47 am
Trucks
Member Since: 30 Nov 2019
Location: south newton
Posts: 375
Started again with bonnet link out and car locked with one press no beeps from the horn see you in a while
23rd Apr 2020 10:54 am
matgriff
Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
I have that exact same link in mine....2005 TDV6 SE Auto
Cairns Blue
23rd Apr 2020 11:25 am
Davethegeo
Member Since: 01 Oct 2015
Location: Edinburgh
Posts: 879
matgriff wrote:
my bad.... lol, you're exactly right !!
Too many things going on to even think about basic sanity/arithmetic checks ..oops
75A/0.55A = 136hrs to flat (in theory)
Mat
Except...that at low discharge rates, then Peukert's Law comes into play and you get more run time that you bargained for. At high discharge rates you get less runtime (capacity) than you might reasonably calculate. Thanks to Robbie for this heads up when I was working out how long my D4 might sit in a car park and still be happy to start.D1 300Tdi - gone
D2 Td5 ES (Alive remapped...mmm) - sadly gone
D4 2012 SDV6 XS - Stolen
D4 2014 SDV6 HSE - Shiny
23rd Apr 2020 11:30 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Trucks wrote:
Started again with bonnet link out and car locked with one press no beeps from the horn see you in a while
Got fingers crossed that the problem with the alarm
23rd Apr 2020 11:30 am
Trucks
Member Since: 30 Nov 2019
Location: south newton
Posts: 375
Started with a 13.35v battery on ctek overnight
45 minutes later clamp meter reading anything from 00.38 to 0046 see picture .
Good news is I have had no alarm go off as it certainly would have normally with just one press of the fob so I guess I said guess that the alarm problem is the bonnet sensor switch.
Going to wait a bit longer the do a system check on the fuses under the hood.
I apologise to the person advising me to do this first and then to do the same when testing the internal fuse box i never read your post correctly.
23rd Apr 2020 11:38 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Just in case, here the part number for genuine new switch
Member Since: 30 Nov 2019
Location: south newton
Posts: 375
Just up loaded some pics thanks for the link will order one
Pete
23rd Apr 2020 11:43 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Trucks wrote:
Started with a 13.35v battery on ctek overnight
45 minutes later clamp meter reading anything from 00.38 to 0046 see picture .
Good news is I have had no alarm go off as it certainly would have normally with just one press of the fob so I guess I said guess that the alarm problem is the bonnet sensor switch.
Going to wait a bit longer the do a system check on the fuses under the hood.
I apologise to the person advising me to do this first and then to do the same when testing the internal fuse box i never read your post correctly.
Click image to enlarge
Hopefully that’s one issue out the way
Apologises if I’ve asked before, do u have anything plugged in or added/ wired anything extra to ur disco plse
Thks and brilliant with the updates
23rd Apr 2020 11:45 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Trucks wrote:
Just up loaded some pics thanks for the link will order one
Pete
That was the best deal I could find for a genuine switch, many were around £40 , so ref that link that works out around £26
Last edited by gstuart on 23rd Apr 2020 11:53 am. Edited 1 time in total
23rd Apr 2020 11:52 am
Trucks
Member Since: 30 Nov 2019
Location: south newton
Posts: 375
No nothing will be late posting back as I need to run someone to hospital for emergency dental extraxextraction just when things were going well to .
Pete
23rd Apr 2020 11:53 am
matgriff
Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
Quote:
Except...that at low discharge rates, then Peukert's Law comes into play and you get more run time that you bargained for. At high discharge rates you get less runtime (capacity) than you might reasonably calculate. Thanks to Robbie for this heads up when I was working out how long my D4 might sit in a car park and still be happy to start.
Yeah, there's a few reasons why it's not just a straight linear relationship... age of the battery, internal resistance of the battery, which varies with the state of starting charge and age etc, plus the load isn't a constant current, it's more like a constant resistance, which means the current will fall as the battery voltage starts to fall.
Additionally, what you would describe as "flat" in terms of being able to start the car and fully discharged are two completely different things
Mat2005 TDV6 SE Auto
Cairns Blue
23rd Apr 2020 1:40 pm
Trucks
Member Since: 30 Nov 2019
Location: south newton
Posts: 375
Ok I am back I have checked all the under hood fuses and sussed how to remove the glass on the cartridge fuses and tested them all read ok zero
I have uploaded some pictures of the clamp meter reading and boy do they vary the lowest reading was when I put the clamp on after being away for a couple of hours the other readings have been taken over a thirty minute period.
Removing the clamp back to zero and puting it back on again this I done 4/5 times to help get a good percentage of what is actually being drawn.
The battery is still at 12.99v but the Sun is on the engine compartment and it's a bloody hot day here
I know the battery voltage can change over the temperature changes.
Do you think it also will affect the meter readings on the clamp as the Sun is also hitting the battery cable to the fuse Box.
Pete
23rd Apr 2020 2:29 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13635
Hiya
Plse Try and see what readings u get on ur passenger fuse box with ur multimeter
Same as before , you’ve already got the bonnet latch bypassed, click the passenger door latch, press remote twice and then wait ur 30 x minutes and then see what u have
Apologises as I must sound like A broken record, lol, have u added / wired anything in , inc anything extra Into the cig lighter connections , since owning the disco plse
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