Moving Both Batteries Under the Rear Bench--'85 Wolfsburg

[joetiger]

I try to shy away from starting new threads on old topics, but I have a story to tell and no topics that I've found address specifically what I was doing here, so...

(cue the responder with links to ten threads that show exactly what I've done here.)

I wanted to move both batteries under the back bench. This was my setup at the time:

Group 41 Starting battery under passenger's seat
Duracell 44 AH AGM battery under driver's seat
Yandina C100 isolator
Blue Seas fuse panel under the driver's seat running stereo, lights, 12v plugs, and Norcold fridge

My initial plan was to add another 44ah AGM battery, but then I saw this:

http://www.yandina.com/mixedbattery.htm

And realized that I would need to buy a new isolator in order to charge the AGM batteries effectively. So it became a question of sacrificing the isolator, or sacrificing the AGM battery in favor of something else.

That lead me to thatvwbusguy's recommendation in several battery threads to get a Group 27 flooded deep cycle and put it under the rear seat. For $90 at Wal-mart, I could get this more powerful battery and keep my Yandina.

So, I decided on the deep cycle and to move the whole shebang to the back bench. I'd have a shorter run from the alternator/starter to the Group 41, and I could house both batteries together and free up the space under the front seat for tools and such.

So, away we go.

Here's an initial mock-up of the batteries under the seat. I used one long ratchet strap and three anchor points to tie both batteries down.

I found a pack of these in my garage to use as anchors:

Please disregard the crappy sound deadening installation from many years ago...

--Per thatvwbusguy's direction, I then drilled a hole through the back wall, added a grommet (home depot sells an assortment bag for a couple of bucks) and ran a 3 foot, 4 gauge battery cable (again lying around the garage from another project) for connection to the starter battery.

--The Yandina was run between the two batteries and grounded to the chassis.

--I wanted to keep the fuse panel under the front seat due to stereo, lighting, sub, and fridge wiring, so I ordered a 10 foot, 6 gauge tinned marine battery cable from https://gregsmarinewiresupply.com/Zen/. Great people to work with, the cable was to my house very quickly and is top-quality. I ran the wire through the existing grommet that originally linked the starter battery to the house battery in the weekender and connected to the fuse panel. (more on that exposed wire in a moment.)

--I then ran the 10-foot cable along the underside of the van, zip-tie'ing to an existing wiring run, then through another hole in the back wall of the bench area for connection to an inline 50a MIDI fuse, then to the house battery. I had just enough length; maybe six inches of cable remaining. I made sure that the cable was free and clear of all moving parts and that it was not stressed at any point along its journey.

This photo shows where the wire dropped down; I subsequently moved it to the other side of the receiver/dryer.

Now back to the back bench.

--I moved the 350w inverter from behind the jump seat to a new spot on the back of the bench's kick panel and connected it directly to the house battery.

--I added a dual USB charging port on the kick panel and added a 5 amp fuse. This was also wired directly to the house battery.

--I wired the connections for my little Black & Decker trickle charger to the house battery as well. This will be replaced eventually by a more robust charger, possibly this Powermax PM 35.

Here's the final setup back there:

And after adding the inline MIDI fuse against the back wall:

Here's the fuse panel setup under the driver's seat:

(Yes--that one power wire on the right is exposed. I shall clean that up poste haste.)

This panel powers the fridge, stereo, sub, interior lights, and passenger base & dash 12v receptacles. The former battery area now holds two canvas tool roll-up bags and various other necessary crap. The wires running through the storage area go to the subwoofer under the jumpseat.

After doing all of this, checking a double-checking, I connected all cables and wires and grounded it all to the chassis under the bench seat.

It was time to turn the key.
_________________
Joe T.

'86 NAHT Vanagon GL Syncro/ supercharged ABA 2.0 "Pigpen"
'04 GTI 1.8T
'04 Golf R32

"get metaphysical with it. if it's simply a means to get to and from places, it will let you down. if it becomes your zen, it can't fail you." -dabaron

"Still, it's good to be afield."--VWagabond

Available Now! Vanagon to Louisiana--A Two-Lane Reckoning Through Past and Present

www.josephtrussell.com

[joetiger]

So I turned the key, and nothing happened. Nothing. The interior lights worked, the 12v receptacles all worked, inverter, but nothing from the ignition. The stereo didn't work either, but that's because I have the GoWesty stereo on/off switch installed, and it was off.

Hmm...Oh, yeah, what about those red wires in the starter battery box under the passenger's seat?

I'd forgotten that I didn't know what was going on here when I started. I knew that one wire was for the 12v receptacle that ran to the house (driver's) side. One had to be for the relay to the driver's side. The last one, no clue. But obviously, it's important...

I found that if I connected all three and touched that exposed red wire (from my last post) to power on the fuse panel, I got power to the dash!

(I do not recommend this manner of testing. It is probably not safe.)

Then I tested each wire individually, and found that one of the red cables connected to another created power. OK, let's check the wire runs. I figured out that the exposed wire on the driver's side went back to a power wire on the passenger's side. I traced the power wire on the passenger's side, and found that it ran forward towards the dash.

I realized that this wire needs power from the starter battery, as it was originally connected to the starter battery terminal.

I then taped a 10 gauge run of wire to the now-unused starter cable and pulled the starter cable through the chassis to the back. The new 10-gauge wire followed effortlessly; I ran it through the hole for the accessory 6 gauge wire in the back and connected it directly to the starter battery. Then I zip-tied that wire up underneath the van in several spots.

Back up front, I added a 30 amp inline fuse and connected it to the wire running from the battery box to the dash.

Power everywhere. Rejoice. I checked all connections, tightened everything down, and started her up. Everything works, and I swear it starts with more vigor.

I put my tow strap, air compressor, extra fuel pump, and other odds and ends in the passenger battery box.

Done and done. If this was confusing, I'm somewhat confused myself. I took my time getting various parts, cables, and connectors purchased, thought long and hard about every single connection and how I wanted it to go, and feel confident in the work.

Next I'll add a solar panel and a real house charger. I also need to run a larger gauge wire from the alternator to the starter.

The subwoofer might be moving from the jump seat to the other underside of the back bench. Or I might just get a smaller sub (currently have a big tube.)

And, I need to sand and repaint the "former" battery boxes under the front seats.

It was a fun project with a few pitfalls and head-scratchers, but I feel like it's fused properly and everything's solid and where it should be.

Oh--venting. In this thread, thatvwbusguy discusses the rear bench and flooded battery venting:

http://www.thesamba.com/vw/forum/viewtopic.php?t=617754&highlight=vent

As far as ventilation is concerned, it is very rare that I see a Westfalia with the screws installed in the starting battery lid, and I have never once encountered a single person with a stock Vanagon charging system in good working order claiming any sort of hydrogen off-gassing problem with a battery installed under the rear seat or in one of the cabinets (where my dual Group 27's have lived for the last 5+ years). This is not to say that it couldn't ever possibly happen, just that it is incredibly unlikely unless you are dumping lots of current into a deeply discharged battery, which the stock alternator isn't really capable of doing.

The Vanagon is a pretty big box and most are not exactly hermetically sealed to say the least. I tend to err on the side of caution with most things that are potentially hazardous, but worrying about the potential for hydrogen off-gassing in my van is way down on my list of concerns.
_________________
Joe T.

'86 NAHT Vanagon GL Syncro/ supercharged ABA 2.0 "Pigpen"
'04 GTI 1.8T
'04 Golf R32

"get metaphysical with it. if it's simply a means to get to and from places, it will let you down. if it becomes your zen, it can't fail you." -dabaron

"Still, it's good to be afield."--VWagabond

Available Now! Vanagon to Louisiana--A Two-Lane Reckoning Through Past and Present

www.josephtrussell.com

[Ahwahnee]

[joetiger]

[crazyvwvanman]

So you have now weakened the power supplied to the dash loads. What was your objective here?

Mark

[joetiger]

[djkeev]

[joetiger]

[djkeev]

[joetiger]

I put the following numbers into the Bulkwire calculator for the original values:

4 feet
50 amps
13.85 volts

Recommended 14 AWG

Resistance for Length (ohms) .0103
Voltage Drop .515
Output Voltage (source less drop) 13.335
Percentage Loss 3.718%

Actual is a 10 AWG:

Resistance for Length (ohms) .00407
Voltage Drop .2035
Output Voltage (source less drop) 13.6465
Percentage Loss 1.469%


then, I put in the new numbers:

10 feet
50 Amps
13.85 Volts

Recommended 10 AWG
Resistance for Length (ohms) .01018
Voltage Drop .509
Output Voltage (source less drop) 13.341
Percentage Loss 3.675%

Forgive me, and I assure you I'm not trying to be argumentative, but I still don't understand what I've done wrong here. I definitely leave it to those of you with more electrical experience than me, but how is my 10 AWG wire not robust enough? And is a voltage drop of .3055 enough to cause problems, assuming 50 amps? Or should I be assuming a higher number?

I did not do anything to the run that goes back to the positive post on the junction box.

I posted this project knowing it would require defense of my thesis, so to speak, and I appreciate any and all guidance that you can provide. I would never intentionally do any modifications that would create unnecessary risk. (unless it leads to more horsepower. )
_________________
Joe T.

'86 NAHT Vanagon GL Syncro/ supercharged ABA 2.0 "Pigpen"
'04 GTI 1.8T
'04 Golf R32

"get metaphysical with it. if it's simply a means to get to and from places, it will let you down. if it becomes your zen, it can't fail you." -dabaron

"Still, it's good to be afield."--VWagabond

Available Now! Vanagon to Louisiana--A Two-Lane Reckoning Through Past and Present

www.josephtrussell.com

[Ahwahnee]

I, for one, don't see where that 50 amp figure came from for what I think we're talking about (line from battery to the front).

Yes, you could see 50 amps from the alternator to a very low battery but for the loads in the dash I don't envision a draw that high.

IOW - I don't think you have a problem.

[joetiger]

[Ahwahnee]

I see - but it wasn't your use of 50 amps that I did not understand, it was this reference:

[djkeev]

I don't know what you are running, The 50 amp is the fuse bar for the cooling fan on my Van. Add to that the draw for the entire fuse panel....... I don't know what that amperage is.

Im only pointing out that an additional four feet can indeed change the wire size needed for safe operation.

You Have at least two wires on your positive terminal, one for the cooling fan, one for the fuse panel right?

My calculation I did was from 10' to 14' and the wire size jumped up a size. Both using a 30amp and a 50amp, a wire size increase was noted. Based upon that, I'd for sure run a larger wire to the original feed wires to safely handle the load.

I'm no expert but I do know that longer runs require bigger wires or higher voltage to utilize a smaller wire. You can't do the higher voltage trick so you are stuck with the larger wire answer.

You've got minor draws like turn signals, major draws like headlights and blower fans.
Don't go melting wires. Size it properly.

30amps for 10' requires a 12ga
30amps for 14' requires a 10ga

50amps for 10' requires a 10ga
50amps for 14' requires a 8ga

80amps for 14' requires a 6ga

If I were running a 30amp and a 50amp from one feed wire, that four foot feed wire would be a 6ga in my Van.

But again, find your draw needs..... Build accordingly.

I see three red wires......

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[joetiger]

[joetiger]

[djkeev]

My cooling fan..... Early 86 with AC...... Has a 6.0mm direct feed from the battery to the high speed fan relay..... A 50amp bar fuse
It has a 4.0mm feed to the two AC fuses 24amp and 20amp
It has 6.0mm feed to the fuse panel


Your system will vary, determine what amps you require, size accordingly.
Oversize to err on the side of caution, too big never hurts...... Too small? Well........ Many burned down houses attest to the hazards of undersized wiring.

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[djkeev]

You can't just ignore a wire.......

I was looking at the Bentley..... 1985.....

A 4.0mm Red wire If you have AC there a direct wire feeding the 20amp and 25amp fuses for the AC to the battery.

A 6.0mm Red feeds the fuse panel. This does your cooling fan via fuse #7 16 amps. This 6.0mm wire feeds the entire fuse panel. (6mm is between an 8 and a 10 gauge wire)

A 2.5mm Red wire feeds your camper set up.

85 does not have the high speed blower relay feed.

AddIng up your fuses that COULD be energized at the same time..... I come up with 88 amps. Unlikely, but possible. VW might have deemed it unlikely too and only fed the panel with a 6.0mm wire.... At 10' long a 50-60 amp draw...... But, I am guessing at a 10' wire length too.... A shorter run gives your wire more capacity.

http://www.thesamba.com/vw/archives/info/wireconversion.php


Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[joetiger]

[Westified]

Looking at your setup, I would recommend sealed and vented to the outside battery boxes, since these are flooded batteries and not AGM. They will off gas when charging. You can get sealed battery boxes fairly cheaply from JEGS, JC Whitney, Summit racing, and Speedway motors. It will also protect the under seat cabinet from acid spills and in an accident. Just a thought for health and safety.
_________________
1984 Westy Wolfsburg, owned since 1987. FAS 2.0 NA engine conversion in 2022.