9 replies to this topic

[Incredible Hulk]

I want to get a smaller sized battery, like a 12v Lead Acid battery to use for my CarPC so that I can put it into sleep mode while the car is turned off without having the main battery go flat.

I'm not sure what would be required to do this though, the battery I want to use is a standard 12v 7.2Ah battery, which with the draw of between 50-150mAh from going to sleep, should last more than a day.

At the moment, it goes into hibernation, which OK, but the resume times can be annoying sometimes. So I want to set it up so that it will go to sleep for about 24 hours, and then it will automatically go into hibernation to save power again.

I drive the car everyday, usually for 30mins per trip to and from work. Plus the occasional spurt around town on the weekends/afternoons.

I was thinking of getting a relay and setting it up between the positive run between the two batteries, so that the relay is only engaged when the IGN is on. That way it will only see charge when the car is running.
Is this OK to do?

Thoughts, suggestions?

[Big_Valven]

A proper dual battery system would be even better but the relay you suggested would work just fine.

Laptops can monitor battery level and sleep / hibernate accordingly. Is there any hardware you can get to do this in-car?

[Incredible Hulk]

Big_Valven, on 20 June 2011 - 09:25 PM, said:

A proper dual battery system would be even better but the relay you suggested would work just fine.

Laptops can monitor battery level and sleep / hibernate accordingly. Is there any hardware you can get to do this in-car?

Due to space constraints of my boot install, a proper dual battery system wont fit.

I'm not sure about the monitoring, I'll have to have a look into it, but I figured a second smaller battery would be easier and then I wouldn't have to worry about not being able to start my car if it goes flat.
Having the computer cold boot is much more convenient than a dead battery.

[atmo]

If you're using a regular hard drive, have you considered switching to an SSD? From hibernate/suspend to disk it still won't be as quick as resuming from standby/suspend to ram, but it should be a big improvement.

[Big_Valven]

Incredible Hulk, on 20 June 2011 - 09:39 PM, said:

Due to space constraints of my boot install, a proper dual battery system wont fit.

I'm not sure about the monitoring, I'll have to have a look into it, but I figured a second smaller battery would be easier and then I wouldn't have to worry about not being able to start my car if it goes flat.
Having the computer cold boot is much more convenient than a dead battery.

I meant a proper dual battery isolator system to use with the SLA, not the actual batteries.

[268669♫]

Jaycar sell some small SLA batteries that would be good for this, and just use an isolator relay from a 4x4 shop. I use the SSD method in my carpc as it's cold boots from hibernation/deep sleep in about 7 seconds.

Ant

[Incredible Hulk]

Yeah, I'm running an Asus E35M1-I MiniITX board with an OCZ Vertex 3 SSD drive.
But I still want to have it go to sleep.

Whats the average price on an isolator if anyone knows?

[Spudley]

we sell the matson voltage sentative relays (http://www.matson.co...lay_140Amp_12V/) at my work for $129 all day every day.

I know the 140A is overkill for the low charge current going to a 12v/7Ah sealed lead acid battery, but I don't know any other companies that make a lower current one that will be much cheaper. At the end of the day, these are designed to isolate 4x4 batteries, but it won't make any difference with a smaller battery.

hope this helps.

Spudley.

Edited by Spudley, 24 June 2011 - 02:03 PM.

[Captn_Awesome]

Redarc $85 delivered on ebay.
But for what your wanting to do a simple 40 amp relay would suffice - ignition on relay clased, ignition off relay open.

[Incredible Hulk]

Cheers for the info.

I'm probably just going to get a fused relay and do it that way.
Won't be doing it for a while though.