12 Volt Lead Acid Battery Replacement

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mogur said:
Case in point: MWalsh who shows off his Leaf at gatherings.


I've showed my car quite a few times, but I don't leave the battery on !!! It's one thing for maintenance, or listening to the radio for a bit, or loading the navigation, but leave it on for hours/days at a time?

For me, a cigarette sized one would work, but then, I know that there's not much discharge between the 5 day top off from the traction battery.

So, how big do you think the battery should be?
 
mogur said:
No, because we still have to power all the accessories and lights for an extended period when it is in ACC mode, plus we have to power all the vampire systems for up to 5 days when the car is off since the car only charges the battery once every 5 days.

The LEAF's battery pack charges the aux if needed at any time while driving. IF you don't drive it for five days, then the battery pack will charge the aux.
 
TonyWilliams said:
I've showed my car quite a few times, but I don't leave the battery on !!! It's one thing for maintenance, or listening to the radio for a bit, or loading the navigation, but leave it on for hours/days at a time?

I do. I like people to get a feel for how the cool tech in the car works, and to play some tunes for the show attendees. The second accessory position (where the car is essentially on, but a drive mode can't be selected) is perfect for this, and my car will typically be in this mode anywhere from 2-6 hours.
 
I probably am the wrong person to ask that question of as I have no problem with the battery that is currently used. I simply don't see the ROI in changing it out for something else.

TonyWilliams said:
So, how big do you think the battery should be?
 
mwalsh said:
The second accessory position (where the car is essentially on, but a drive mode can't be selected) is perfect for this, and my car will typically be in this mode anywhere from 2-6 hours.

So what exactly is the difference between the first and second accessory position (what the manual calls "acc" and "on")?
 
I've been following this thread with some interest. As I see it, the current battery installation (25 pounds?) is well under 1% of the total vehicle weight. The performance gain in a lighter battery would be negligible at best... You've probably got that much weight with junk in the trunk anyways... If on the other hand you just wanna get the lead out...well...whatever... :cool:
 
TangoKilo said:
I've been following this thread with some interest. As I see it, the current battery installation (25 pounds?) is well under 1% of the total vehicle weight. The performance gain in a lighter battery would be negligible at best... You've probably got that much weight with junk in the trunk anyways... If on the other hand you just wanna get the lead out...well...whatever... :cool:

I've got that much extra weight on my belly! I would just go on a diet before I changed my battery out to save 25lbs!
 
mwalsh said:
my car will typically be in this mode anywhere from 2-6 hours.

We can agree, I hope, that this is not "normal" ops, and even the current AGM battery needs a little love during that load.

I don't know, but I presume, that the traction battery is using the DC-DC charger in ACC mode? And if the car is outside, that you're getting the mega-awesome solar charge, correct ?

I'll have to go hook up the Fluke 117 / i410 combo and measure that power consumption in ACC.

And for everybody who is not jump starting other cars, leaving the car on ACC for hours, or other "not exactly what the car was designed for" type activities (I guess throwing in some super-huge stereo system, Baja flame-thrower type spot lights, etc, would all apply).....

... a tiny A123 technology battery the size of a cigarette pack would replace the 1850's technology lead / acid. Is there a monetary payback? Sure, in 10-15 years.... maybe. I'm not sure you could even measure the mileage increase with a lighter battery, or put a value on the price of not being left stranded when the lead/acid fails to boot up the car in a few years (my 2010 Toyota Sienna lead/acid battery failed at less than a year... in my lifetime, I can't count how many lead / acids that I've replaced in cars, planes, and other equipment).

Are there other cool things you COULD do with NOT having a heavy, sometimes failure prone, relatively short lived (compared to the life of the car or a lithium) battery? Sure. How about if you put a simple, cheap, water/dust resistant plastic box in the same place as the existing dinosaur battery that can store all the charger accessories? I plan to do that. All the maintenance things under the hood.
 
TonyWilliams said:
We can agree, I hope, that this is not "normal" ops, and even the current AGM battery needs a little love during that load.

I don't know, but I presume, that the traction battery is using the DC-DC charger in ACC mode? And if the car is outside, that you're getting the mega-awesome solar charge, correct ?.

Agreed. Correct. Correct.
 
TangoKilo said:
I've been following this thread with some interest. As I see it, the current battery installation (25 pounds?) is well under 1% of the total vehicle weight. The performance gain in a lighter battery would be negligible at best... You've probably got that much weight with junk in the trunk anyways... If on the other hand you just wanna get the lead out...well...whatever... :cool:


How about if I took out the battery for a light one and swapped the wheels for lighter ones?

24 pound-ish battery savings
116 wheel savings (about 40-11 for a 29 pounds per wheel savings)

140 total, or almost 4% of 3600 pounds.

Would that make a difference? If not, what weight would?
 
TonyWilliams said:
How about if I took out the battery for a light one and swapped the wheels for lighter ones?

24 pound-ish battery savings
116 wheel savings (about 40-11 for a 29 pounds per wheel savings)

140 total, or almost 4% of 3600 pounds.

Would that make a difference? If not, what weight would?
The battery means nothing, but the wheels are a special case. They represent a lot of kinetic energy as they are spun up and slowed down. Even a modest decrease in weight there should pay dividends.
 
Not as much as you might think because, depending on how you drive, it is not lost energy per se... Regardless, I personally again see no ROI in changing them...

davewill said:
the wheels are a special case. They represent a lot of kinetic energy as they are spun up and slowed down. Even a modest decrease in weight there should pay dividends.
 
davewill said:
The battery means nothing, but the wheels are a special case.


Individually, any single small weight reduction is probably not measurable. But together (and not just wheels), lots of small changes do become measurable.

Some bolts used in aircraft are center drilled to lighten them. It would be impossible to measure the savings of a bolt, but when the same processes of lightest weight are applied throughout, it does add up to something measurable.

If I could find another 140 pounds of savings on the car, would that be "worth it"?
 
mogur said:
Not as much as you might think because, depending on how you drive, it is not lost energy per se... Regardless, I personally again see no ROI in changing them...
Unfortunate turn of phrase on my part. No, I don't think there's an ROI case to be made there, either, but comparing pound for pound, I would expect 40lbs saved there to actually make a measurable difference unlike 40lbs in general.
 
TonyWilliams said:
TangoKilo said:
I've been following this thread with some interest. As I see it, the current battery installation (25 pounds?) is well under 1% of the total vehicle weight. The performance gain in a lighter battery would be negligible at best... You've probably got that much weight with junk in the trunk anyways... If on the other hand you just wanna get the lead out...well...whatever... :cool:


How about if I took out the battery for a light one and swapped the wheels for lighter ones?

24 pound-ish battery savings
116 wheel savings (about 40-11 for a 29 pounds per wheel savings)

140 total, or almost 4% of 3600 pounds.

Would that make a difference? If not, what weight would?

I am not sure where you are going to save 29 lbs per wheel as the stock ones are 21 lbs each. The lightest aftermarket wheels in a similar size are in the 11 lb range; most are around 13-14 lbs. Plus you cannot factor wheel weight as static/dampened weight as it is un-dampened and rotational mass (inertial) as well. Your 140 lb loss estimate is not correct.
 
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