Parasitic Current Draw, Batteries and Battery Tenders

[forzasteve]

Note: Edited Dec 6, 2015 ... uploaded new version of paper


I have been doing some extensive personal research on the topic of parasitic current draw the effect that modem cars inflict on car batteries. I raise this topic here as there has been a lot of discussion about how long a car can sit unattended before the battery drains down.

A logical follow on topic to parasitic current draw is a discussion about batteries and battery tenders.

I have written a paper -- attached here -- where I discuss these topics in some detail and I offer it here for your use.

If you have any comments, I welcome your input.

Regards,

Steve

[GVA 45TH 2SS]

Thank you, some cool info in there

[JLSuperfly]

Nice read.

[myold88]

Well I asked for it and I got it. As far as I can tell forzastele came up with the answer I was
looking for. It explains that a car battery drains at a rate of about 3% a month if allowed to sit.
Plus battery life can be reduced if the battery is allowed to drain below 75% of a full charge. So
if your car sits for 6 months you would reduce battery charge by 18-20%. It seems to me that
cold weather would increase battery drain but I'm not sure.
I still don't think I'll ever spring for a battery tender. I've never had a problem or battery failure
from just recharging the battery in the spring.

[Jsafe17]

Originally Posted by myold88

Well I asked for it and I got it. As far as I can tell forzastele came up with the answer I was
looking for. It explains that a car battery drains at a rate of about 3% a month if allowed to sit.
Plus battery
life can be reduced if the battery is allowed to drain below 75% of a full charge.

[myold88]

Originally Posted by myold88

Well I asked for it and I got it. As far as I can tell forzastele came up with the answer I was
looking for. It explains that a car battery drains at a rate of about 3% a month if allowed to sit.
Plus battery life can be reduced if the battery is allowed to drain below 75% of a full charge. So
if your car sits for 6 months you would reduce battery charge by 18-20%. It seems to me that
cold weather would increase battery drain but I'm not sure.
I still don't think I'll ever spring for a battery tender. I've never had a problem or battery failure
from just recharging the battery in the spring.

Unedited Full reply.

[forzasteve]

Originally Posted by myold88

Well I asked for it and I got it. As far as I can tell forzastele came up with the answer I was
looking for. It explains that a car battery drains at a rate of about 3% a month if allowed to sit.
Plus battery life can be reduced if the battery is allowed to drain below 75% of a full charge. So
if your car sits for 6 months you would reduce battery charge by 18-20%. It seems to me that
cold weather would increase battery drain but I'm not sure.
I still don't think I'll ever spring for a battery tender. I've never had a problem or battery failure
from just recharging the battery in the spring.

Your strategy is perfectly good. Letting the battery sit for an extended period and then recharging after 3 or 4 months is probably fine. That would be considered a deep discharge cycle and if you have those kinds of cycles too frequently, it would likely adversely affect the the battery life. But once year? Probably no problem at all.

I would disconnect the battery from the car, though. If you do that you will take away the parasitic draw and you just may discover that the battery retains enough of a charge after 3 or 4 months to restart the car just fine.

Regards,

Steve

[myold88]

Originally Posted by forzasteve

Your strategy is perfectly good. Letting the battery sit for an extended period and then recharging after 3 or 4 months is probably fine. That would be considered a deep discharge cycle and if you have those kinds of cycles too frequently, it would likely adversely affect the the battery life. But once year? Probably no problem at all.

I would disconnect the battery from the car, though. If you do that you will take away the parasitic draw and you just may discover that the battery retains enough of a charge after 3 or 4 months to restart the car just fine.

Regards,

Steve

Thanks and yes I always disconnect the negative cable at the battery. Some guys
actually remove the battery but I've never understood doing this. Thanks again
for the great study on this subject.

[homewrecker]

Thanks steve, i started a thread a few days ago on exactly this. I had 2 camaros, a 2014 1LT and a 2015 1LE and they both can't sit for more than 2 weeks without the battery dying.

Sent from my SM-N920P using Tapatalk

[forzasteve]

I made some changes to the paper. Version 2 is uploaded and can be accessed at the original post.

Steve

[homewrecker]

Hey Steve I read that paper you sent. Really good stuff! but there's something definitely wrong with my battery. I drive a once a week and sometimes once every 2 weeks and the battery shouldn't be dead that fast. It happened to my other camaro too - which is a 2014. I'm thinking the battery might be bad before I got it because it was sitting in the parking lot before I bought it. Either way, I appreciate the research and the time and effort! Thank you! Btw did you email the first or second version?


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[Rock-It Man]

I can't imagine any reason for not using a battery tender for winter storage.

[hammdo]

The only reason I can see NOT to disconnect the battery is it resets all of the emission entries used for registration/emissions inspection. Some of those take weeks to reset so, if you intend to do that, try to give yourself a month to reset -- also, some wont reset until it gets above 40 to 50 degrees -- trust me, I went though this...

-Don

[BLU DUCE]

Originally Posted by homewrecker

Hey Steve I read that paper you sent. Really good stuff! but there's something definitely wrong with my battery. I drive a once a week and sometimes once every 2 weeks and the battery shouldn't be dead that fast. It happened to my other camaro too - which is a 2014. I'm thinking the battery might be bad before I got it because it was sitting in the parking lot before I bought it. Either way, I appreciate the research and the time and effort! Thank you! Btw did you email the first or second version?


Sent from my iPhone using Tapatalk

If you don't have the proper item to read a battery. Take the car to a car parts place like NAPA or Advanced Auto they will test your battery free and let you know if it has a bad cell or something else.