TheSamba.com :: View topic - Making interior lights run off aux batt question

Fri Apr 27, 2007 5:42 pm

So if you follow some of my posts I recently added a bunch of interior lights and now I want to make it so they run off the aux batt instead of the starting batt. I pulled down the fuse panel, see that fuse #3 (this is in an 87') is the interior lights, pulling it confirms. When I look at the back of the fuse panel, there is a clip that plugs into a set of pins that include the fuse for the interior lights. My question is I can't make sense of this mess, I tried figuring it out with the bentley to no avail. Now I'm pretty good with wiring (I did wire in all of the lights) but I'm wondering if anyone has done this and can tell me what I need to do to get just that interior light circut working (I know I need to run a wire from the aux batt to the fuse panel, but how do I tie it in?) any help appreciated, tencentlife perhaps, the resident samba electical genie?

Fri Apr 27, 2007 7:24 pm

Actually, I think your best bet would be to circumvent the fuse panel entirely. I'd cut the wire that is the power output to the interior (later on you might want to splice it back where it was originally. Also, you could even put a switch in there so you could change it from main to aux power.) Then connect the cut wire via an inline fuse to your wire coming from the auxilliarly battery.

Looking in the Bentley, it looks like just one wire, the one coming off of pin 12 of the B plug. If you bypass that, then the cigarette lighter will be the only item left running under fuse 3.

Another thing I notice in the bentley is that, it looks like the digital clock on the dashboard is also fed from fuse 3. So when you pulled your #3 fuse, did you notice if the clock shut off too?

Good luck!
-Andy

Fri Apr 27, 2007 7:48 pm

The clock has never worked, so I didn't notice!

Fri Apr 27, 2007 9:10 pm

Look up my old post, which I believe made the stickies, 'Winston Gets Wired.' The safest and wisest course is to rig in a new fuse box, and what I did was to splice in a section of sprinkler system control cable--very waterproof--and also run the new lights to the same circiut.

The clock for me wasn't a problem. I replaced it with a tachometer I can't imagine going without.

Best!

Fri Apr 27, 2007 11:41 pm

Remove the two fused panel behind , and long side the driver's seat, add a 4 or 5 fuse std. fuse block, and wire the lights into it.

This set up is easy, quick to get done, and you now have an accessory fuse panel to wire up all kinds of 12 volt gizmo's without wiring forward to the under dash fuse panel.

Tue May 01, 2007 1:26 pm

Well, since you asked.

I can see several ways to do this. Glutamodo's is the most straighforward and understandable: just clip the red wire from B12, B being the red multi-point connector on the back of the main panel. Leave a couple inches of wire in case you ever want to make it original again, and tape off the bare wire end. You can do the same with B11 if you want cig. lighter accessories to run off aux battery as well. B12 also powers the radio, so you pick that up as well, a good thing. I you leave B11 attached, the lighter will be the only load left on fuse 3.

Make sure that whatever feeder you run from your aux battery positive has fuse protection, as near the battery as is practical. Get a small fuse block from a FLAPS or Radio Crack, mount it near the aux battery, and you will have a new power center for other accessories you may want to power from the aux. You can also backfeed the charging current to the aux battery thru the new fuse panel, making sure that the new panel's maximum current rating is sufficient to handle your charging current. 30A should be fine for a 10AWG wire from the main battery and relay. Go higher if you use a larger wire so you can utilise the full charging potential. Always use a size fuse an increment smaller than the maximum load rating of the panel, particularly if you backfeed the charge input.

There are other ways you could feed the lighting/radio/cig lighter circuit:

Run a wire from your new aux fuse board to any hot lead at any of the OEM cabin lights and pull fuse 3. This will power all the other lights (they are all on a single positive bus wire), as well as backfeeding the main panel to power the cig lighter and radio. The problem with this approach is that current is limited. The small wires running from light to light are sufficient to power those small loads, but the OEM wiring to the cig. lighter is much larger, as it is a momentarily high-current draw, and it would be downstream on that circuit. You could do this and isolate the lighter by clipping B12 behind the main panel, and leave fuse 3 in place. If you did that, all the interior lights, radio,and clock would be on aux power, and the lighter would be the only circuit on fuse 3.

Or, run a 14AWG wire from the new fuse panel, and patch it into E3, in the black multi-point connector on the main panel. Remove fuse 3. This will feed the interior lights, clock, radio, and cig. lighter via the OEM wiring. Fuse 3 must be removed to isolate the batteries, and therefore you must have fuse protection on the feeder from the aux battery, i.e. your new aux fuse panel. I like this approach the best. If you can't handle the E3 patch, you could Skotchlock your feeder to B11 right behind the main panel. Electrically, this is exactly the same. You must still remove fuse 3 in this case to keep the batteries isolated.

Tue May 01, 2007 4:40 pm

Ten-cent

As always you are the electrial man! Thanks!

Tue May 01, 2007 5:15 pm

I'm just reading the map, man. Kind of like a human GPS, I guess.

Sat Mar 28, 2009 3:59 pm

Just wondering about the fuse numbers, I guess fuse #3 powers the cabin light for water cooled, or older than 81? But on my 81 Westy, when I pull #8, the cabin light goes off. I'm wondering how these instructions (clip B12, 11 etc) might be altered to accommodate an older fuse setup? Probably this is self evident, but I'm a electro-novice.

Sat Mar 28, 2009 5:37 pm

All this stuff is about late vans, after late '85, with the new style fuse panel with plug-in blade-type fuses. Your van has the early panel with Bosch "stick-type" fuses, and the wiring system overall is different in many ways. Sorry, but most of the methods discussed in this thread don't apply to your wiring system. It's a bit more complicated to power interior lights, radio, clock, etc. from a second battery on your van than it is on the late system, where they are all on a single fused circuit.

Sat Mar 28, 2009 5:46 pm

Right then, clip the wire at the light and route it to the new aux. That's a schematic even I can understand :)

Sat Mar 28, 2009 5:54 pm

I would not do that. The method for 80-85 is not as simple as 86-91 but no need to just clip wires willy nilly.

Mark

KayAych wrote: Right then, clip the wire at the light and route it to the new aux. That's a schematic even I can understand :)

Sat Mar 28, 2009 6:44 pm

Any idea where I might find some info on the 80-85 non willy nilly method? Love to try to do it right.

Sat Mar 28, 2009 6:57 pm

This thread:

http://www.thesamba.com/vw/forum/viewtopic.php?t=309898&start=20

has a post by iiigoiii about midway down that has some details about which wires he tapped into. There have been other posts where details were discussed, but I'm not aware of a really comprehensive description anyone has written that spells it out for you. I'm not saying there isn't one, just that I'm not aware of one.

Of course it's hard to write up the real deal instructions for this, because different people want to transfer different circuits to their second battery. Suffice it to say that any of the laods you might want to transfer are fed off the back of the fuse panel, so doing all your patching and/or cutting there would at least make it easier for someone in the future (you, perhaps?) to be able to see what has been done in one location.

Sat Mar 28, 2009 7:06 pm

KayAych wrote: Just wondering about the fuse numbers, I guess fuse #3 powers the cabin light for water cooled, or older than 81? But on my 81 Westy, when I pull #8, the cabin light goes off. I'm wondering how these instructions (clip B12, 11 etc) might be altered to accommodate an older fuse setup? Probably this is self evident, but I'm a electro-novice.

On my '81, there was a #12 red wire running from 30 at fuse panel, (starter battery B+) through aux battery compartment, to sink pump, fridge etc. I cut it at aux battery area, installed aux battery, connected sink pump etc. end to to aux. battery. It is fused. Remaining end of wire that ran forward was prepared for connection to aux. battery. Other end of this wire at fuse panel got moved from 30 to backside of fuse S7 (decomissioned silver socket fuse). The #20 red wire for interior lights got moved from S8 to output of "new" S7 fuse. I also connected radio to it.

Now my kitchen stuff, interior lights and radio run off the aux battery.

Sat Mar 28, 2009 7:27 pm

Different early years have different options for doing this. Remove the negative terminal from all batteries while working on the wiring.

I don't have access to an early aircooled at the moment to check but it looks like fuse 7 is not used in your 81 van. If you look at the back of the fuse panel you should see a single big red wire to the bottom side of fuse 7 but nothing connected to the top side. If so, you can unplug the red wire, COVER IT, and then plug a power feed wire from your aux battery in where the red wire was. Then move the wires from the top of fuse 8 over to the top of fuse 7. Fuse 7 will now be your interior lights, cig lighter socket, and your brake lights. The wires on the top of 8 now should be 2 smaller reds and a red/yellow strip. The smaller of the reds is the interior light wire and the slightly larger one is the cig lighter wire. The red/yellow stripe wire is the brake lights.

You could cut the brake light wire free from the red one if it is combined in one end and then put a new end on it and put it back on top of fuse 8 so the brake lights won't be on the aux battery. This would leave the brake lights alone on fuse 8.

All power wires feeding from your aux battery should have a fuse on them right near the aux battery. Do not skip this! 15 amp should do.

Mark

KayAych wrote: Any idea where I might find some info on the 80-85 non willy nilly method? Love to try to do it right.

Sat Mar 28, 2009 7:37 pm

If what Neil says is true on your van, fuse 7 may have a wire to the top of it already. Make sure there is only one wire at the bottom, and none or one wire at the top. If the top feeds the silver socket on yours you can unplug it and tape it off unless you need the silver socket for something. Also unplug the big red on the bottom end of fuse 7. Then my earlier proceedure should work for moving the stuff from 8 over to 7.

Mark

Sat Mar 28, 2009 7:43 pm

Thanks a million you guys. Mark, in order to check to see if what Neil says IS true... which poster is Neil?

Sat Mar 28, 2009 8:03 pm

crazyvwvanman wrote: .... Then move the wires from the top of fuse 8 over to the top of fuse 7. Fuse 7 will now be your interior lights, cig lighter socket, and your brake lights. The wires on the top of 8 now should be 2 smaller reds and a red/yellow strip. The smaller of the reds is the interior light wire and the slightly larger one is the cig lighter wire. The red/yellow stripe wire is the brake lights.

Mark

I would actually have to go outside and physically double check on my Westy, but if memory serves me correctly, on my Canadian '81 Westy, I found that power to the interior lights/door buzzer ran on a separate #20 red wire from S8.

KayAych

"Neil" = "Vanagon Nut"

On my '81, and IIRC, S7 powered the silver socket. In Bentley, it shows the fuse. It takes power from the backside of S9 but it is not connected to anything.

Here's the AFC '80-'81 diagrams. Click on them. A new image may allow zooming (if browser supports it)

Neil.

Sat Mar 28, 2009 8:27 pm

And to be clear... (though Mark explained this)

I disconnected the power coming from backside of S9 to backside of S7.

Power to S7 (now my interior light/radio fuse) comes from aux battery.

S7 became available as I had no need for the silver socket.