First of all, where the H$LL did the search button go!? I haven't used the search feature for awhile. Did something happen to that feature here on the forum??
Anyway, I have one of these battery disconnects with the bypass circuitry. What exactly is the theory here? It looks as though the bypass circuit is nothing more than a fuse with pigtails that is suppose to be connected across the disconnect switch. I assume it is suppose to keep power to the computers so that you retain all of your settings when you have the main disconnect disconnected. But, doesn't this defeat the whole purpose here, to keep your battery from draining while the car is stored for extended periods of time? If the disconnect is disconnected, but yet you have a wire going across the post as shown in their diagram, what the h$ll?
Am I missing something here?
I have an indoor car show coming up and I thought I could use this, but I didn't want the car to set for three days and lose all of my settings, so when I saw this advertised, I assumed there was some sort of elaborate circuit that allowed power to go to the vital computers but not to things like the courtesy lights and other battery-draining devices. I'm going to have the doors, hood and back hatch open but I didn't want courtesy lights to come on. I know there is a timeout circuit, but it takes it forever to finally turn all the lights out.

 

Looking at

http://www.jegs.com/instructions/555...5-10320-21.pdf

this is what I understand:

This unit allows a quick disconnect by hand using a **** instead of a tool.

"It is available with a 15-amps bypass that retains computer settings, radio/clock ecetera while the battery is disconnected
"

this is not quite true, as in fact the battery is still connected by the bypass.

"Note: If you attempt to start the vehicle while the unit is disconnected, it will blow the fuse"

as the current drawn is too high for the 15-amps fuse.

IMO this bypass makes not much sense to me. If you leave the car in winter, it will empty the battery as much as it will without it.

It just makes sense if someone wants to start the car, but if one does, he will soon open the hood and connect back the batterypost.

Hope this helps.
Frederik

 

maybe it was designed as some kind of anti-theft device?

 

To make your idea work you would have to isolate everything you wanted to stay powered up from everything else. That would be very time consuming. The easiest thing to do would be to pull all the light bulbs. That would only take a few minutes and is easy to do.

 

Thanks guys. Thats what I was thinking. Not any good except maybe for a theft deterrent. I thought maybe the fused pigtail is suppose to be connected somewhere on the fuse panel that only supplies power to the vitals. What about those 9 volt battery connectors that plugs into the cigarette lighter that are claimed to save your settings, etc? What happens when you have your main battery disconnected and only this little 9 volt plugged in? Does it try to light up your courtesy lights when the doors are open?? My calculation is there should be about 5 amps draw when all the coutesy lights are on. A little much for a 9 volt.

 

I agree with you.
These 9 volt battery connectors via cigarette lighter may only be useful for a quick battery change, but not for a day at the car show.
Frederik