What's an acceptable battery drain?

[VR6 Gar 10]

Got a problem where if I don't start the car for a week the battery has lost enough power for it to not start.

Just did a test and it is drawing 0.09 amps. Before I lock it on the central locking it is only 0.03, but afterwards stays at 0.09 whether the car is locked/unlocked.

Is this an acceptable level, wouldn't have thought 0.09 is enough to drain the battery in a week unless the battery is duff.

Alt is putting out 14.31v at the batt.

TIA.

[Sean_Jaymo 0]

That's a healthy Level of drain, I think mine is closer to 0.15 when I last checked. It's probably your battery wearing out. Most are only rated to 4 years or so although they can often go much longer (my wife's golf battery lasted over 7 years before it started to loose it's cranking ability)

 

What amp hours is your battery rated to? I think mine is something like 80ah. That means is can put out 80 amps for 1 hour, 40 for 2 hours, 20 for 4 hours etc.

 

0.09 drawn should last nearly 900 hours which is nearly 40 days or 5 and a bit weeks. Your battery has probably passed it's best if it can't muster enough cranking power after a week.

Edited January 19, 2014 by Sean_Jaymo

[VR6 Gar 10]

Thought that was probably the case, cheers for the explanation on drain.

Think the battery is the same one that James fitted when he built the car and put it under the arm rest, circa 4-5 years ago.

[Sean_Jaymo 0]

No problems Gar, If it's under the armrest, it's probably got a lower ah rating and max cranking amps anyway due to its size. But being in the car, insulated from the life under the bonnet has helped keep it healthy for longer. If you have a trickle charger for when it's not being used, that will help but you obviously need to have the car close to a power source which isn't always possible :-(

[VR6 Gar 10]

Had a look and it is lower at 60ah @ 20 hour rate, more than enough to crank the car when charged properly.

Ordered another @ £52.50 delivered. (Yuasa 075)

Trickle charge is a no go so the new battery should solve the issue.

Thanks again Sean.

[VR6 Gar 10]

Fitted the new battery today and it cranks over with such purpose now, way better than it ever has in my ownership. Must have been on its last legs for some time.

[easypops 8]

Nothing like a new battery, i had to buy one yesterday for my old sharan, massive big thing, same issue as you, leave it a couple of days and wouldn't start, new battery in and i swear it even runs better :lol:

[Sean_Jaymo 0]

Glad that got it sorted :-)

[Jim Bowen 1]

How do you test battery drain?, am having a small issue with mine, but it was new a couple of months ago.

[Roger Blassberg 0]

Put an ammeter in series between the earth strap and the frame of the car with everything switched off. Theoretically all it will see is the power to the alarm arming system, so 90 mA is reasonable. DO NOT switch anything on with the ammeter in the circuit, most multi meters have a very low current tolerance.

 

RB

[VR6 Gar 10]

How do you test battery drain?, am having a small issue with mine, but it was new a couple of months ago.

The way I do it is to disconnect the negative cable from the battery and make up the circuit using the multimeter.

Set the MM to Amps obviously, which on some, like mine, means swapping the red cable across a hole.

[Sean_Jaymo 0]

The way I do it is to disconnect the negative cable from the battery and make up the circuit using the multimeter.

Set the MM to Amps obviously, which on some, like mine, means swapping the red cable across a hole.

 

Exactly how I do it. Most multi meters have a 10amp rating so switching on low current stuff won't harm but as said above, not worth risking the fuse in the multi meter unless you have spare.

[VR6 Gar 10]

They are pretty resilient in my experience. Only got a cheap one and had smoke pouring out of it once a few years back from doing something I obviously shouldn't have been, still works perfectly :lol:

[Sean_Jaymo 0]

Aye, I bought a 10 quid eBay job and it's been fine for years, only have just replaced the original battery. Mine has an optical and USB port but never use that!