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Hey guys, im having an issue keeping my CarPC in standby.
I have a M2 ATX psu running an Intel board with a 3.0ghz p4 chip on it, 1gb ram, 160gb 2.5" ide hdd along with a usb hdd. The m2atx connects to a small plastic tool box behind my seat which has 4 x 12v sla batteries inside it, each rated to 7.1Ah. I have wired it so the load is split between the first and last battery in the parallel array to ensure equal discharge and recharge, when the car is on a 50A relay allows charging current from the main battery.
My issue is that when in standby, the CarPC draws 0.5a which should be fine for a good 10-15 hours. However the voltage is dropping below 11.5v so the M2atx is cutting power causing me to lose the saved state. Is there a way around this safety feature? Perhaps a voltage regulator rated to 8A for when the PC powers up? I don’t care about a flat battery as the CarPM is isolated. Any help is appreciated.
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AFAIK, you cannot disable the M2-ATX's automatic shutdown (deep discharge prevention). even if you set the 'hardoff delay' to 'never', it will still cut power to the +5vSB rail when the battery voltage drops below 11v. it may be possible to disable the feature if you know electronics really well and can somehow modify the M2. otherwise, you'll have to come up with another solution.
one way you might be able to get around that problem is to use a separate +5v POL regulator to provide +5vSB power to the motherboard. you would basically disconnect the M2's +5vSB wire (pin#9/purple) from the M2 and splice in a wire from the POL regulator instead. this way the motherboard will always receive +5v on pin#9 even when the PSU completely shuts off due to excessive voltage drop.
I have never tried this before so I don't know for sure that it will work, but I don't see why not. the only reason I can think of that would prevent it from working is if the PSU somehow requires a load on the +5vSB rail. I don't believe that is the case (but even if it was then you should be able to put a 'dummy load' on it).
good luck
Well you probably shouldnt be disabling the low voltage protection. Deep discharging your lead acid regularly below 11v is going to shorten the lifespan alot. You only have about 4x7.1 = 28.4AHr worth of battery...which isnt alot. Your best option would be to get a bigger deep cycle battery, unless you really dont care about prematurely killing your current SLAs.
Thanks fusion, i was thinking along the lines of something like that. Perhaps a voltage regulator connected to the storage batteries however I’m worried what will happen when the batteries die and the regulator is no longer able to provide that stable voltage? If the voltage starts to drop, will this damage components... i would think the system would shutdown completely but I’m not 100% sure.
Nobb, i have been though 4 sla’s already but this was due to having them wired parallel to my car battery permanently so they were discharging each other (so i believe). I can get these batteries for $15 a piece and am now thinking that another 4 will help my situation, or do you think i would be better off with a car battery?
Unless these are heavy duty wheelchair, forklift, or industrial grade batteries you are going to ruin your batteries by deeply discharging them regularly.
http://www.windsun.com/Batteries/Battery_FAQ.htm
It would work out to be cheaper in the long run if you just invested in a bigger true deep cycle battery, rather than having to replace your SLAs all the time. Or just use hibernation.
when the batteries die and the regulator can no longer supply +5v, then it will do the same thing that's happening already. it will abruptly lose power without properly shutting down. I'm not really sure how bad that is for the system, I would imagine it could cause corrupt data, etc but I don't think it would cause any physical damage to your hardware.
a band-aid to this problem would be to hook up a changeover relay to the POL regulator. this way the POL reg could draw power from the SLA's until they reach a certain [lower] voltage, then the relay would switch the power source from the SLAs over to the regular car battery (but there would be nothing stopping the POL reg from continually discharging the car battery if you left your car unattended for a couple days).
you have already spent $120 on SLAa, and you're about to spend another $60 on 4 more of them. is it really worth spending another $60 just to have the ability to leave your carputer in standby all night? is it really that torturous to wait a few extra seconds for the system to boot up from hibernation?
yeah it is that annoying becuase i have to load all the programs again. Im starting to think that the issue is related to charging, when i give the batterys a charge from a 240v charger they will last for about 14 hours on standby. is there perhaps a mobo that will use less current? the board i have atm will use 0.5a?
Basically i just want it to last over night so when i get in the car it starts where i left off rather than having to wait for it to power up, turn it off and then start it again.
Hmm ok, this is becomming an issue even when shutdown. Perhaps the standby voltage of these SLA batterys is lower than a common car battery. can anyone confirm this?
I appreciate all the help so far guys, as small as this issue is its still verry annoying (more so when you dont have a touch screen :P).
hibernation basically does the same thing as standby, but instead of loading the current windows state into RAM, it stores it on the HDD instead. it takes a little longer than standby, but its still faster than a cold bootup.Originally Posted by Seth_jxl
and you can always add programs to the 'startup' folder to have them launch automatically when windows boots up
why would it have to power up, then turn off, then start again? it should just power up and stay on
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