battery drain

[oldnick]

having had problems with the battery draining when my D2 A8 was left standing for any length of time I checked the parasitic drain in the approved manner using a 1ohm 10watt resistor
it seems to be running at about 100mA
is that about normal for an A8 ? seems a bit on the high side to me

[Delboy]

Originally Posted by oldnick

having had problems with the battery draining when my D2 A8 was left standing for any length of time I checked the parasitic drain in the approved manner using a 1ohm 10watt resistor
it seems to be running at about 100mA
is that about normal for an A8 ? seems a bit on the high side to me

How does one check with a resistor, would love to know your technique

[Goran]

for comparison, my current D2 S8 draws around 0.18A (using Maplin clamp Amp meter) and has very few options, my previous D2 S8 drew over 0.2A

A simple calculation, 0.1A over 24 hours is 2.4Ah capacity per day
If you have the standard 85Ah battery, and if it was fully charged, at your current rate of discharge it would take roughly 18 days to drain down to 50%
If your reading is correct, I suspect your battery is either discharged, or heavily sulfated and wont hold a charge.

Check your open circuit battery voltage. When fully charged, check its open circuit voltage, then leave disconnected for 24 hours and check voltage again, or connect a 12V bulb or something that draws a decent current accross the battery briefly, leave to rest for 10mins and check the voltage again. If the open circuit voltage after standing or brief load drops significantly from fully charged voltage, lets say from 12.7V to 12.3V or less, then your battery is heavily sulfated and hasn't got much of the original capacity remaining. On the web there are articles which reference open circuit voltage to state of charge. From memory, 12.0V or below is pretty much fully discharged.

[oldnick]

Originally Posted by Goran

for comparison, my current D2 S8 draws around 0.18A (using Maplin clamp Amp meter) and has very few options, my previous D2 S8 drew over 0.2A

A simple calculation, 0.1A over 24 hours is 2.4Ah capacity per day
If you have the standard 85Ah battery, and if it was fully charged, at your current rate of discharge it would take roughly 18 days to drain down to 50%
If your reading is correct, I suspect your battery is either discharged, or heavily sulfated and wont hold a charge.

Check your open circuit battery voltage. When fully charged, check its open circuit voltage, then leave disconnected for 24 hours and check voltage again, or connect a 12V bulb or something that draws a decent current accross the battery briefly, leave to rest for 10mins and check the voltage again. If the open circuit voltage after standing or brief load drops significantly from fully charged voltage, lets say from 12.7V to 12.3V or less, then your battery is heavily sulfated and hasn't got much of the original capacity remaining. On the web there are articles which reference open circuit voltage to state of charge. From memory, 12.0V or below is pretty much fully discharged.

well , as your's is running at about 180mA seems mine isn't bad at all !
my battery is excellent but , as you know know , this 100mA drain will half discharge a standard battery in a month [ pretty common when I am away in my motorhome ] at which point the voltage will be down to maybe 12.3 volts and there isn't enough to start the engine if it is at all cold

delboy , presuming you have a meter and a couple of spare crocodile clips £1 at maplin's will produce what you need


https://www.youtube.com/watch?v=B__DqK90IIc

[Goran]

Ah, yes, a month will kill it.
According to the interweb, if you leave your lead-acid battery sitting below 50% charge state for a significant lenght of time, it will form lead crystals reducing its capacity.
So going by the web, I doubt your battery is in a excellent state if you left it drain to zero for a month.
Also depends on the electical systems of the car, on my current S8 the old 110Ah battery could still just about start the car even when it was fully drained down to 11.9V

[ainarssems]

I have not measured drain current on mine but I have 6 years old 88Ah 730CCA battery which according to conductance tester have 61% capacity left and 630CCA and it recommends to replace the battery. If car is left alone for 2 weeks battery voltage will drop from 12.6V to 12.2V but it does start just fine at this voltage. I have had battery to drop to 11.5V in the past and it still started car but engine was barely turning over.