Aux Battery Final Wiring Diagram For Review

[tuanis]

Hi all, sorry for yet another thread on an auxiliary battery. I have an 89 full westy, with a 2.5 swap done by the previous owner. They installed an auxiliary battery under the rear bench seat that has never worked very well, and I'm getting ready to redo and clean everything up. Here's the current set up:

First off the wiring and connections were done very poorly. I'm hoping that by removing everything and cleaning it up I solve some of the issues I'm having. Most of the connections are cheap plastic crimp connectors, and some of the wiring is solid copper house wiring. I've got an idea of how I want to redo things, but before I draw up the next diagram I've got a few questions:

1. The radio and lights don't work consistently. There doesn't seem to be enough power going to them - the lights are dim and the radio will turn on momentarily then back off. Most other setups I've seen involve pulling fuse #3 and tapping into it, but the PO did a cheap inline splice and removed the fuse. Could that be causing me issues?
   
2. Is 14 ga wire sufficient for that length of run? It's going from the rear bench all the way up to the dash.
   
3. Related, all the wire in this set up (besides the 8 ga wires connecting batteries) is 14 ga, are there any that should need sized up or down?
   
4. The 80 amp fuses on the 8ga wires off the positive side of each battery are this style of inline fuse usually used for car audio. Are those sufficient or should they be replaced?
   
5. There is currently a Stinger SGP38 battery isolator in use to combine the batteries. I'm not sure if that's appropriate for this application, but I already picked up a Blue Seas SI-ACR to replace it. It is my understanding the signal wire isn't required on the Blue Seas ACR, so I believe I can eliminate that section?
   
6. Any other glaring issues that should be addressed when I draw up my replacement diagram?
   

Thanks in advance for any advice!
_________________
1989 Westfalia - 2.5L Subie
1988 VW Westfalia - Stolen

[shagginwagon83]

1. Yes a bad connection can cause those issues. Or even improper size wire.
2. 14ga wire to handle how many amps? What will that wire power
3. 14ga is on the low side, but if you keep the cables short then yeah it could work out. A 12v outlet can support 10-15 amps. We need estimates of wire length (including ground cable) before we can confirm.
4. It should be fine. Not ideal but should work. I don't buy that style because just a little set screw is keeping your cable in.
5. I've used the SI-ACR before, but I don't really see a need for you to make a change as the Stinger should function the same. But yes you don't need a signal wire for the SI-ACR
6. It's typically best to fuse both sides of your large relay.

Thanks for making a wiring diagram to show these issues. I think we need to know wire length estimates before we can recommend upgrading wire size.
_________________
"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
Instagram: @joannthevan

[DanHoug]

[jimf909]

The Victron MPPT has load output terminals that allow most/all loads to be connected to the MPPT. This provides battery protection with a low voltage disconnect and some battery monitoring capabilities. I recommend wiring the fuse box to that load output, esp. given that the lead-acid battery doesn't have a BMS.

https://www.victronenergy.com/upload/documents/Dat...8V-EN-.pdf
Load output

The intelligent Load output function prevents damage caused by running batteries 'flat'. You can configure the voltage at which BlueSolar disconnects a load - thereby preventing excessive drain on your batteries. And here's the clever bit: BlueSolar will attempt a 100% recharge every day. If it can't - during periods of poor weather - it raises the disconnect voltage, daily, until it achieves success. We call this feature BatteryLife because it maintains the health, and extends the life of your battery.

Agreed on the DC-DC charger in that you'll need it with a LiFePO4 battery in the future unless solar panels charge the batteries everyday which isn't likely if camped under trees or there are multiple cloudy days.
_________________
- Jim

[vanagonjr]

[DanHoug]

[Phishman068]

Wow, some folks really chimed in without looking at the diagram here.
The original poster does NOT have a lithium battery and has not asked about adding or changing to a ilthium battery- yet every response comes from folks who did their own install once on their lithium battery, about how great the components they selected were.

So, take that with a grain of salt, as each of these responses mentions an DC-DC charger, which while you CAN use it with your current battery, there really isn't a need and that isn't a glaring flaw in your wiring diagram.

Yes, using a DC to DC charger can allow you to "upgrade" to lithium later, but it's about an expense and redesign that isn't necessarily necessary right now. Additionally, I have lithium batteries in all four of my busses without DC-DC chargers and have settled on a system that works extremely well for me and several others that have created similar systems (We don't integrate to the alternator at all!).

1: ya, you've got a bad wire somewhere. There's also multiple ways to wire the radio's trigger/turn on function. I no longer wire these into the aux battery and highly suggest against it, as this type of scenario can melt your entire fuse box and dash wiring, just so you can use your car's stereo with the vehicle off?
Well, your car's stereo is profoundly bad at doing that job. It consumes as much as 10-20 AMPS, so your battery which has between 66-110ah according to the internet, lets take that average and settle at 80ah..... that being a lead acid battery can only be safely and repeatedly drawn down to 50%, so running your stereo for 1-2 hours will completely drain that battery.
But if you get a little USB chargeable bluetooth speaker for $50ish, you're now taking the music to where you want to be, and not worrying about the power consumption at all. You can recharge that little guy over and over again, and it's truly a better setup than a stereo powered off the Aux battery.
Less likely to burn down your car too. (Our Buddy is on his third dash wiring harness!).
Personally- I'd un-wire that, solving several problems at the same time.

2: 14 gauge is not sufficient for that wire run, remember your stereo head unit is potentially consuming 10 amps (POTENTIALLY 20!), so while 14ga might not burn your car down, it's pretty insufficient when you consider all the things running through that 14 ga wire. Here's a great chart for general reference of wire thickness-distance. For most of our applications we can go with that 10% non critical drop section, and we'd probably be at 12 ga, if that wire ran JUST the stereo. 14 ga is I believe the thickness of the wire coming from the fuse panel to the FACTORY (less wattage) stereo and 12v radio, lights, cigarette lighter, clock circuit, and it's pretty barely sufficient, 14ga is not enough to carry the current safely all the way from the back seat to those functions, id be running at least 12ga. We run 10ga from the fuse block to the stereo/dash wires, and that's just from the fuse block- not feeing the power.
Also make SURE that wire is fused, especially making sure it's fused "weak" so that fuse will blow before the wire melts! If you've got a potential for 20 amps on that circuit, I'd be running a 10 amp fuse till you see if it starts blowing, then assess accordingly. Fusing things weak just creates and inconvenience and diagnostic opportunity when they blow- you carry spares, it's easy.

Hmm, I see that quick splice and the fuse removed- is it possible, at all, that your system is back feeding? Those quick splices can get you into a lot of trouble if you snag the wrong wire and it divides somewhere, it's possibly you're feeding into more then one wire, even with that fuse removed, something to consider.

https://www.bluesea.com/support/articles/Circuit_P...DC_Circuit

3: see #2

4: There's a few ways of setting things up when we're talking large cables between batteries, it's very possible that if you drained your house battery to 0% and fired up the car, it would consume beyond 80 amps, and in that instance- hopefully your fuse just blows. But, where's the fuse? Is it on which end of the cable? Because 8 gauge is rated for about 40 amps max- your system is at risk of melting the wire before blowing the fuse- BAD.
So, you need to cap that fuse at a 30amp fuse with the way your system is set up now. Remember- the fuse is there to protect the wire.
I see you keep mentioning audio wire, while wire SHOULD be created equally relative to it's measured size, we know it's not, and when you get into some of those real low quality super flexible "audio wire" setups, they're not necessarily true to size, so if that's a concern- de-rate the wire by one, pretend it's actually 10 ga, now you see how insufficient that really is.
I don't know for sure that you need to be sizing the system for 80 amps, it just depends on how vigilant you are from keeping your battery towards zero- size your fuses and wires accordingly.

5: I'm not familiar with the Stinger but am very familiar wit the Blue seas ARC, I'm a big fan.... but I see a major flaw in them and it's why I stopped incorporating them into systems. Because they're voltage sensing- NOT current sensing, and you have a solar panel, they'll combine and you'll drain your starting battery! I've seen this happen wayyyyy to many times.
Unless you put in a forced isolation switch (which solves this, just isolate when camping), if your 100 watt solar panel is say putting out 10 watts, while parked in your garage- it'll see that as a charging voltage and combine batteries. If it sits in your garage for a while, systems running, you'll find you won't be able to start it, because if you're putting in 10 watts and taking out 200 watts- it still potentially stays combined (it's voltage alone, so some solar applications will trigger this even at very low battery voltages, allowing it to reallllllly drain things). Yes, you'll be able to potentially eliminate the trigger/signal wire by moving to the Blue seas system, but that trigger wire and current system is what's preventing exactly the problem I just pointed out.
Most DC to DC chargers require a trigger wire, so don't go physically removing it- in case you wish to go Lithium in the future.

After designing and redesigning, troubleshooting, etc plenty of yachts and vessels of all sizes, as well as building out systems in a lot of vanagons, here's the system I've fallen in love with:

100ah "mini" lithium battery fitting between the water tank and the vertical wall (Meaning ZERO loss of internal space, recovering that super useful space under your back seat by only extending/moving a few wires about three feet to the left)

NO means of connecting the lithium battery to the starter/alternator.
Some folks will hate me on this one, but the starting battery is for starting the car and running the car systems, the aux battery should do the house systems. I prefer them to be fully isolated because as mentioned in the blue seas issue above- you can be camped in the woods for a few days and go to start your car, and find that isn't going to work out for you! A very well designed system can also function to jump start your car, but if you start playing with lithium- that's just a bad idea. Also the wire sizes necessary to safely do this are in the 1ga or 2/0 range, so..... expensive, big, etc.
In the boat world- we use extremely high amperage switches that allow us to start, isolate, or combine batteries manually, all fed by giant wires. Theres not many advantages to doing this in a vehicle that isn't in the middle of the pacific.

So, how do we charge that Aux battery?
a 30-50 amp dedicated, built in charger, and 100+ watts of solar via an MPPT charger.
I install Iota engineering chargers under the driver seat (where some people put a battery), wiring them back to the aux via some 6ga wires, unfused on both ends but very cautiously protected from chafing. On a wire run this short, fusing at both ends doesn't necessarily solve anything, and the charger itself has a fuse in it, so we're good in that direction. I run the 110v power over and splice it in to the house power- so when I'm plugged in via the side of the car I can go from 10% (Remember lithium batteries can go down to 10%, so I'm working with 90 usable AH vs your 40ah- with no loss of space under the back seat! DOUBLE your power capacity!) to 100% in around 2 hours, but I can also peak it off whenever I need to. Often I'll plug in for an hour before taking a last minute trip somewhere while I pack my final things, and I'm good to go.
And Solar. A 100watt panel ($80) mounted to my roof rack puts out around 50 usable AH per day into the battery, under "normal conditions". In the spring and fall, that's a little less, in the summer, might be a little more. An MPPT Victron charge controller bumps that up a little higher (probably 10ah more) per day then a non-mppt charge controller. And with my 15amp charge controller, I can run two panels If I want to, so I've got a super thin 100 watt folding setup with a 20 foot cord (sometimes I carry 40foot) that stashes up in the top bunk, complete with MC4 connect based Y connectors, so if I'm going to be parked somewhere for more than a day or two, or I want to hide in the shade- I can position that panel in the sun and generally get about 80ah of input per day.

All my wires are run as duplex pairs, 12 or 14ga Anchor brand wiring. That means that all the grounds also come back and terminate at the fuse panel (get a fuse panel with ground lugs!) so that I can run all the grounds that run on the house system through a Shunt, in this case a victron shunt, so I can track via bluetooth the exact percentage of my battery, as well as all my input and output uses. It can tell me at a glance that I'm at 78%, with 1.5 amps coming in. Meaning, if I had 4 amps going out as loads, and 5.5 amps coming in via solar, it would measure that net positive and indicate that I'm "Winning". Easy.
I can stand in my garage and check the exact battery state of all four of my busses from my phone-very very nice. Gathering this data from my phone without getting out of bed adds a lot of peace of mind towards how the system's working while camping, and its an incredibly useful tool for knowing what your actual loads are- for instance the difference between start up load and running current on my furnace, fridge, etc.

With this system in place, I'm able to turn on my fridge in April, and shut it off in October- always having cold beer with me, without ever plugging in. Yes, I have once gone an entire year with a bus sitting in the driveway, fridge running, never plugged in to the charger- so the system is adequately balanced (to run my ARB Fridge alone) with just the 100ah battery and 100 watt solar panel. So why would I need to add complexity, reduce reliability, and add cost to integrate it into the alternator? If I'm ever low on power I either deploy the mobile panel and double my input, or plug in and be full in an hour or so.
And while alternator driven systems will be full when you get to your destination...... usually mine is too, as my outputs are less than my inputs, having designed a system that is designed from the ground up for my region, uses, etc.
If I'm running the furnace and fridge together in the early spring/late fall, combined with low solar angles that time of year, and running my cell booster (that sucks some power) and charging lots of devices- that's the only time I feel like it would be nice to have a second battery (increasing my ability to tolerate cloudy days) or I deploy my second panel.
For the most part, I don't worry about power at all any more. Last summer I traveled for 3 weeks without plugging in once, running lots of power heavy stuff- so for me, charging off the alternator is not a benefit- im against it.

Everyone's mileage may vary, but this system has worked really well for the past few years on quite a few busses in our club and is absolutely the system I'll put into the next one.
Sorry for typing so much.
_________________
http://www.thesamba.com/vw/forum/viewtopic.php?t=559766&highlight=winter+rust
http://www.thesamba.com/vw/forum/viewtopic.php?t=482402&highlight=sunroof+syncro
http://www.thesamba.com/vw/forum/viewtopic.php?t=569774
http://www.thesamba.com/vw/forum/viewtopic.php?p=6864936#6864936

"Along with the ability to go fast, one looses the desire to hurry."

[Phishman068]

Also note- I have the solar output from the charge controller set up in such a way that I can fairly easily bypass it from the house battery to temporarily jump it to the starting battery.
So, in that scenario where the car won't start and we somehow killed the starting battery, while I can't directly jump start it from the house battery (without jumper cables, and with no desire to do that- as lithium shouldn't be used this way!)...... I can in just a few minutes have 200 watts of solar directed at the starting battery. Realistically, about 10-12 amps, about the same current my household/garage battery charger would put out if I was at home and wanted to recharge that starting battery.
Since most starting batteries are really only around 40-50ah, even a "pretty dead" battery at say 12.2 volts will be back up and ready to start the car in two hours.

I've got two hours, heck- the fridge is full of cool beverages.
_________________
http://www.thesamba.com/vw/forum/viewtopic.php?t=559766&highlight=winter+rust
http://www.thesamba.com/vw/forum/viewtopic.php?t=482402&highlight=sunroof+syncro
http://www.thesamba.com/vw/forum/viewtopic.php?t=569774
http://www.thesamba.com/vw/forum/viewtopic.php?p=6864936#6864936

"Along with the ability to go fast, one looses the desire to hurry."

[fxr]

[shagginwagon83]

[boxer74]

Also no need to run dedicated grounds back to shunt for it to work properly. Just use chassis ground and place shunt in ground path from battery negative post to chassis. All set and you saved the cost of all that duplex marine wire.
_________________
74 Super
84 Westy

[Phishman068]

[fxr]

Seriously, the chassis is one huge zero-ohm ground plane. OK, not actually zero, but a lot less even than large gauge copper wire. Micro-ohms...
_________________
Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300

[dobryan]

Sorry OP to get a little off topic.

The Victron manual does not mention individual grounds back to the shunt though:

1. Connect the negative battery terminal to the M10 bolt on the "BATTERY MINUS" side of the shunt. Tighten the shunt bolt with
a maximum torque of 21Nm (300A model: 10Nm).
Note that there should be no other connections on this side of the shunt or on the negative battery terminal. Any loads or
chargers connected here will be excluded from the battery state of charge calculation.
2. Connect the negative of the electrical system to the M10 bolt on the "SYSTEM MINUS" side of the shunt. Tighten the shunt
bolt with a maximum torque of 21Nm (300A model: 10Nm). Make sure that the negative of all DC loads, inverters, battery
chargers, solar chargers and other charge sources are connected “after” the shunt.
Note that up until 2020, the SYSTEM MINUS connection was labelled LOAD MINUS.
3. Connect the ferrule pin of the red cable with the fuse to the shunt by pushing the pin into to the “Vbatt +” terminal.
4. Connect the M10 eye terminal of the red cable with the fuse to the positive terminal of the battery.
_________________
Dave O
'87 Westy w/ 2010 Subaru EJ25 (Vanaru) and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[boxer74]

[jimf909]

[vanagonjr]

Here’s a good write up and why a DC-DC charger is beneficial for a deep-cycle marine battery. https://www.emarineinc.com/Marine-Batteries-Maintenance-101

A Victron 12-12/18a DC-DC charger is about $150. Money well spent in my mind.
Last trip, I ditched the solar panel and just ran the DC-DC w/ 60ah aux (lithium) battery to run my fridge and light/phone and friend’s Pro DSLR charging.

Despite not driving very far many days and my low amp DC-DC unit, I was always fine.
I’ll probably get a larger battery in the future and skip my planned permanent Solar panel, but if you can has a permanent one already in-place, I’d leave it be, at least for now.

(I’ll take my panel first when I stay put for 3 days or more, buts that’s only 2x a year for me.)
_________________
John - 86 Wolfsburg Westfalia "Weekender"
Flint reversed 1.8T W/Passat 5-Speed
LiMBO (late model bus club) www.limbobus.org
LiMBO is on Facebook too! https://www.facebook.com/groups/
FAQ thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=525798

[tuanis]

Hey all, thanks for all the helpful advice thus far. There’s a ton of good info in the replies and I really appreciate it. A few notes:

The run from the aux battery to where it splices under the dash is maybe 10 or 12 feet. It runs the radio, and powers the cigarette lighter (which I’m planning on replacing with a USB outlet), interior lights and the clock. I’m not positive how to figure out the amperage the stereo is drawing in order to do the math on the required wire size.

A note on the radio - when we are camping over multiple days we usually do just run a bluetooth speaker. That said, we spend a lot of time in ferry lines in Seattle and I prefer to keep the option of running the van stereo without worrying about killing the starter battery.

I’m undecided about the DC to DC charger upgrade. On the one hand I like the idea of future proofing the system, but I don’t have plans to upgrade to a LiFePO battery anytime soon. If I were to upgrade it seems like something like this might be a good option? I forgot to mention the MPPT does have the optional Bluetooth module so I do have the Victron App.

Connecting the load output side of the MPPT controller sounds like a great idea, I will add that in to my next iteration.

Plan is to draw up another diagram for review before I start changing anything. I also neglected to mention that I have a propex heater waiting to be installed and I will include that on my next diagram.
_________________
1989 Westfalia - 2.5L Subie
1988 VW Westfalia - Stolen

[vanagonjr]

[jimf909]