Key Off drain on Battery...



Key Off drain on Battery...

Postby DorianL » April 25th, 2012, 7:06 am

How much "key off" drain on a battery is acceptable if you drive once every 10 days?

How's that for a neat question? 8-)

D.
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Re: Key Off drain on Battery...

Postby grumpyvette » April 25th, 2012, 7:43 am

http://www.harborfreight.com/automatic- ... 42292.html
Image

REPLACING A C4 CORVETTE BATTERY VIDEO
http://www.youtube.com/watch?feature=pl ... 03-roWP2A#!

, finding your battery dead when you want to drive the cars a huge P.I.T.A., spend $6 and eliminate the problem, honestly I figured this was a waste of money and typical of most HF tools it would never work, well at $6 I had to try it and while it won,t charge a battery if its dead it will keep a battery charged thats fully charged, for weeks at a time, I only drive my 1996 corvette rather infrequently, so it was common to find the battery low or dead and needing a charge if it sat for a few weeks, plugging this in keeps it charged PROVIDED you start with a fully charged battery,
keep in mind the light stays on because the battery is constantly draining, the current flow the charger supplies is MINIMAL, but its enough to prevent the battery dying


If the battery drains after running the car in what you may feel is far less time than might be normal, youll want to check all your frame grounds and then try to isolate the problems source, You disconnect one battery lead , put a volt/amp multi meter between the negative cable and battery post and measure current draw while pulling fuses one by one to identify the circuit that has the excessive drain while the cars not in use.
don,t forget you'll to Need to duct tape over any door , hood or trunk contact switch thats open while testing so you don,t find in error, its the interior lights circuit causing the problem,I know corvettes have contacts that turn on under the hood and rear hatch lights and youll need to do it so you can have the door open as you access the fuse panel without interior light on
There are also other items fed directly off the battery ( through fusible links) that would have to be metered individually after removing wires from the post behind battery.
Headlight motors some accessories,, heater control module , etc have hot feed ;key off.


related thread

viewtopic.php?f=70&t=2133&p=19303&hilit=battery+charger#p19303

http://www.hotrod.com/techarticles/gene ... ewall.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: Key Off drain on Battery...

Postby Indycars » April 25th, 2012, 8:02 am


You can also make one from a wall wart, like this one!

http://autospeed.com/cms/A_110354/article.html

Wall Wart Charger.jpg


As to your question about how much drain for 10 days. Looks like you might be able to extrapolate from the "Reserve Capacity" specs for a battery.

The reserve capacity of a battery is defined as the number of minutes that it can support a
25 ampere load at 80°F until its terminal voltage drops to 1.75 volts per cell or 10.50 volts for
a 12V battery. Thus a 12V battery that has a reserve capacity rating of 100 signifies that it can
be discharged at 25 amps for 100 minutes at 80°F before its voltage drops to 10.75 volts.


http://www.odysseybattery.com/autospecs.html

BatterySpecs.JPG


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Re: Key Off drain on Battery...

Postby DorianL » April 25th, 2012, 8:32 am

Been meaning to get one of those - tired of disconneting the batt everytime I park. Mostly it is because my switch panel has LEDs - uses 3 amps/day if left on. The fear of leaving lights on I guess.

Image

So how does 3 amps/day translate to batt drain?
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Re: Key Off drain on Battery...

Postby DorianL » April 25th, 2012, 8:34 am

Hold on... there is math here!!! 100 min at 24 amp/hours so that figures too...
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Re: Key Off drain on Battery...

Postby DorianL » April 29th, 2012, 4:37 am

There:a connect and forget...

Image

Going to arrange for it to connect under the car so I don't have to open the trunk each time.

Oh and the car uses 140mA/h parked.
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Re: Key Off drain on Battery...

Postby DorianL » April 29th, 2012, 11:36 am

Lololol - I just killed the extension cable. I forgot the battery minder was still connected to the batt in the tunk. I drove away - felt a small clunk and drove on. Came back to discover cable snapped and fuses in house blown. Heheheh - gotta get used to this. 8-)
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Re: Key Off drain on Battery...

Postby DorianL » April 29th, 2012, 11:43 am

Oops.

Image
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Re: Key Off drain on Battery...

Postby DorianL » April 29th, 2012, 1:54 pm

Also added a neat little toggle to get rid of the switch panels ground. 8-)
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Re: Key Off drain on Battery...

Postby mathd » April 30th, 2012, 8:36 am

Lol, its best to unplug before you go, it wont charge once the car is gone :P

You should have less that 50 mA of parasitic drain(if it excess 100mA theres a problem).
Just set your multimeter to ammeter and measure current flow between a battery post and one of the cables.
If its too high pull fuses and relay 1 by 1 so you know what circuit is draining your battery.
My car can sit for week(even a month) and the battery have all the needed power when come time to start(its a brand new battery).
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Re: Key Off drain on Battery...

Postby Indycars » April 30th, 2012, 9:15 am

mathd wrote:Lol, its best to unplug before you go, it wont charge once the car is gone :P

LOL, I think you said it best. :lol: :lol:
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- Need a Dynamic Compression Ratio Calculator: viewtopic.php?f=99&t=4458
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