number of days of standby (S3) time.

**greenman100** · 11-03-2005, 09:21 PM

Originally Posted by StrataG

So please explain to me how long his system will last. If he is even close to correct, why aren't more people doing it? Why do so many people end up with dead batteries who try this? I'd love to be able to use standby, but from what I understood, it was not viable for people who do not drive their car everyday.

He's good for 4-7 days, depending on how cold it is outside.

More people aren't doing this for a couple reasons.

Some motherboards don't have S3.
Some people have a ton of USB devices that draw on standby
and likely the biggest factor, most people just don't know about it.

I have a dual xeon system, 1.6ghz chips overclocked ot 3.2ghz, each. The chips cost me $120 total. a similar pair of chips that can run 3.2ghz stock, would have cost $600. WHy don't mroe people overclock? Not many know how.

**kbyrd** · 11-03-2005, 09:22 PM

Why don't most do it? Maybe they don't turn as much off on the mobo, maybe their car draws more than mine, who knows. Maybe 5 people posted that they drainer their battery and the rest of us just took it as gospel. Once I ran across the 60AH rating for my battery, I had to do the real test to know for sure. It's a daily driver for me, so I hope the overnight drain isn't too much. Combined with the kill switch (with relay thanks to greenman100's advice in another thread. Although I did find a 25A/12V "automotive" switch at RadioShack I might use, I'll need a relay for another thing.)

StrataG:
As for testing it yourself. I'm new to this, I just bought a multimeter a month or so ago (there's even a post about it, I needed advice), I just bought an "automotive test lead" kit a couple of nights ago. If I can figure it out, you can.

greenman100:
So, half discharge is about a volt drop, so that'll be about where the m1-atx cuts power. At 11V, can I start my car? I know constantly going to 11V would shorten the battery's life, but with my driving pattern, I don't see that happening.

**greenman100** · 11-03-2005, 09:22 PM

Originally Posted by StrataG

How old is your setup? I felt what happened to you is what typically happens. Any battery, even deep cycle will lose it's ability to hold a charge a lot faster if it's constantly drained. Obviously you are not completely draining it, but I know the lifecycle of a battery is longer if the discharges are very small and vice versa. If I needed to replace my battery every few years, it wouldn't be a big deal. If I'd have to replace it every year though, it would have me avoid this type of setup.

this is true. But how many of us go a week without using their cars? I use mine every day. And if you restart every 24 hours, that's only discharging about 15%

**greenman100** · 11-03-2005, 09:25 PM

Originally Posted by kbyrd

Why don't most do it? Maybe they don't turn as much off on the mobo, maybe their car draws more than mine, who knows. Maybe 5 people posted that they drainer their battery and the rest of us just took it as gospel. Once I ran across the 60AH rating for my battery, I had to do the real test to know for sure. It's a daily driver for me, so I hope the overnight drain isn't too much. Combined with the kill switch (with relay thanks to greenman100's advice in another thread. Although I did find a 25A/12V "automotive" switch at RadioShack I might use, I'll need a relay for another thing.)

StrataG:
As for testing it yourself. I'm new to this, I just bought a multimeter a month or so ago (there's even a post about it, I needed advice), I just bought an "automotive test lead" kit a couple of nights ago. If I can figure it out, you can.

greenman100:
So, half discharge is about a volt drop, so that'll be about where the m1-atx cuts power. At 11V, can I start my car? I know constantly going to 11V would shorten the battery's life, but with my driving pattern, I don't see that happening.

as for the 25amp switch, that'd work fine. I was worried about the 5 amp switch you'd proposed earlier.

half discharge is about a volt drop, yes, but this is all very rough. a lead acid battery is actually naturally at about 12.5v, fully charged, with no load. so, a volt drop....from 12.6 or 12? I hope you see I'm making generailzations - I don't know much about your setup or environment at all.

11volts should be okay as long as it is not too cold out. keep in mind, the colder the engine, that harder to start AND the less the battery can put out

**Cris** · 11-03-2005, 09:26 PM

Originally Posted by StrataG

How old is your setup? I felt what happened to you is what typically happens. Any battery, even deep cycle will lose it's ability to hold a charge a lot faster if it's constantly drained. Obviously you are not completely draining it, but I know the lifecycle of a battery is longer if the discharges are very small and vice versa. If I needed to replace my battery every few years, it wouldn't be a big deal. If I'd have to replace it every year though, it would have me avoid this type of setup.

The battery is almost a year old, as is the system. It's a chep battery I bought for something else, when my stock battery died, so it was a quik replacement. I never thought it would last this long.
I figure with a quality battery one should have no problem leaving the car for 6 days.

**StrataG** · 11-03-2005, 09:35 PM

Thanks for the info guys, and sorry to kbyrd for somewhat jacking the thread. I may just have to see for myself what kind of draw I have. I don't drive my car on a daily basis, which is why I've been reluctant to even attempt standby. Thanks for the hope that it may help speed up my time to music.

**kbyrd** · 11-03-2005, 09:46 PM

Originally Posted by greenman100

as for the 25amp switch, that'd work fine. I was worried about the 5 amp switch you'd proposed earlier.

Of course, I clearly didn't know jack about switch ratings, that's why posted. Not that I'm an expert now, but I think I get the problem. I have no problem using a relay (well, we'll see when I actually try), but I happened to run across this switch and I actually like its form factor better. Oh, I forgot... Thanks for your help and patience.

Originally Posted by greenman100

half discharge is about a volt drop, yes, but this is all very rough. a lead acid battery is actually naturally at about 12.5v, fully charged, with no load. so, a volt drop....from 12.6 or 12? I hope you see I'm making generailzations - I don't know much about your setup or environment at all.

Sure, sure. My mileage may vary, if I strand myself with a dead car battey it's clearly my fault. I don't want to mess with a secondary battery at this point, I've read some hype about Optima Yellow Top being both a cranking and a deep discharge battery. Is this crap? The spec sheet say it's got either 55AH or 48AH capacity (don't know which size would fit). It's a small 4 cylinder engine, it does't really get cold where I live, I don't really need more cranking amps, but if it holds up better in the face of my constant small discharging, I might be interested.

**greenman100** · 11-03-2005, 09:56 PM

.2A * 24hrs = 4.8 amp hours

that's like a 10% discharge

the yellow top is good as a deep cycle, but 10% is so little - you drain more leaving the headlights on for half an hour (10 amps *30 minutes = 5 amp hours)

**Ravin13** · 11-03-2005, 09:57 PM

i think when i attempt my setup i wanted to do this.. could their be a way (im sure their is) to just have a switch to turn the usb port off? and then when you go AFC (car) you would turn your usb devices off, sence you wouldnt need them anyway. and then it would work better.

**IntellaWorks** · 11-03-2005, 10:03 PM

like another member stated I'm going to say 4-7 days sounds right depending on the temp. Vehicle batteries are depended on quite a bit nowadays in the modern vehicles. For example, after I shut my truck off (05 taco) there is a ton of devices that are still drawing power (not including my carpc). In fact there is a fuel dissapation system that may kick on 15 minutes after the vehicle has been shutoff as it stats in the owners manual.

With that said the constant drain on your battery will kill it faster. How fast it dies really depends on the vehicle type. You could add another battery to the mix but then your alternator has to work harder to charge both batteries at the same time, killing that faster.

I've heard from a mechanic that most modern vehicles should replace the battery after 3 years of use, weather or not this is true it makes sense after reading that my truck, without the pc, draws power while the engine is off for its operation, no matter what the temp. is outside.