Preserve settings with a battery maintainer?

[jrustles]

This is why I have a huge, old school Mallory electrolytic capacitor (as well a small array of noise caps) tied into my electrical system. With the standard OFF load, it can keep the system powered for about a minute. Well, it's there for other reasons too, like stabilizing voltage and providing 'inrush' amperage, but a battery swap out is no issue.


Some people have huge 0.5 and 1.0 Farad caps for their stereo systems, but I think the resistance of those stereo caps may be slightly higher than those smaller ELCs- and I'm not a big stereo guy

 

[eljefino]

Originally Posted By: raytseng
man, i'd just reprogram my radio to save $4.50


You lose your emission monitors which sometimes take a while to come back. Rough if you have to pass an inspection soon.

 

[1kickbuttranger]

Here is what I use. Got the plug from Napa, batt holder from Radio Shack. It gives you a full 12 volts. Cheap dollar store batteries seem to work, better ones make the unit heavy and needs to be supported so all the weight isn't on the plug.

Has a red light on it, so you can tell if it receives power from the car before the battery pack is connected.

It did blow the 2A fuse on the Mustang, (don't know why???) so I put a 3A in there.

 

[Quattro Pete]

Nice! I like that battery holder.

 

[JHZR2]

Just get a little power supply without smarts. It's the open circuit, reverse polarity, dead battery protection type stuff that causes some to act funny.

I've used a 2A 12v power supply without issue.

The problem really is that fancier cars especially, that have various actuators and things that energize and de-energize during car shutdown. Those power supplies will current limit and then the actuating devices can act funny.

Also keep in mind that not all cars have 12v at all times at the plugs. In that case, you need to inject via some bussing at a fuse box or elsewhere so that the actual circuits remain hot. A relay controlled socket will not necessarily do this.

 

[SnowDrifter]

At work, we use these things called "Memory savers"

All it is, is a small 12v battery attached to a OBDII dongle to supply the vehicle's computer with power even if the battery is disconnected. I'm sure you could make your own with a little 9v battery and a diode that would suffice

The caveat is that even though your battery is disconnected, the positive terminal is still energized and needs to be treated as such. If it grounds out, it will blow your OBDII fuse. Not a big deal, but you lose your settings and need to replace said fuse