Sprinter Electrical
I've always looked at power outlets as magic. How do those electrons do their thing? It took a bit of research and consulting to get my head around the details of loads, wire gauges, amp hours, AGM vs flooded batteries, and on and on. I have to give lots of kudos to a neighbor who recently added wiring to his van. He steered me in the right direction and gave me a tour of his system.
As with the rest of our build, simple is the theme. Our power needs are low: we want to charge phones, laptop, run a few LED lights and a low-power fridge. Where to start...well, figuring out how much juice you need for those items comes first so that you can figure out how big a battery is called for. Once you know that, you can:
This crude sketch was the beginning of tangible plans.
I fleshed that out by figuring out that a ~100 Amp-hour battery would meet our needs. That means we could get a battery that fits under the passenger seat. That's a nice spot to keep it out of the way in a space that we didn't plan to use (some folks put a heater here). And it's easy to secure it so it won't fly around in an accident.
Conveniently, there's a connector under the drivers seat (where most of the van's stock fuse box and connectors are) that can be used to charge the house battery from the alternator. And it's easy to run cables between the two seat pedestals through a channel in the floor. My neighbor pointed me to the use of a CTEK D250SA DC Battery Charge controller. This thing is great in that it handles the chores of feeding proper voltage to the house battery while protecting the starter battery. Bonus: it includes a solar charge controller so it's easy to add solar at a later time.
Fuses - important stuff. Each of your circuits needs to have a safety valve in case there's an overdraw on the power. That includes the main feed coming from the alternator.
Here's my second sketch detailing the house battery charging and fuse box set up:
It slowly started making sense. At that point, I could start getting the house battery set up in place. I found a 92 Amp hour AGM deep cycle battery at NAPA autoparts for $200 that fits under the seat and is easy to secure. Unless you're going to use a more expensive lithium ion battery set up, AGM batteries are the way to go. They are maintenance free and don't need to be vented.
Here's how things look under the passenger seat with the charge controller on the left, a disconnect switch in the middle (so we can cut off the house battery circuit from the starter circuit), the new fuse box on the right and the battery on the opposite side. I drilled a couple of holes on each side of the pedestal in order to install 1/2" plywood that's used to mount the controllers, switches, fuses and the battery.
And here's the final outline of the house battery wiring:
A spreadsheet was handy for calculating wire gauge (the longer the circuit the larger the wire needed in order to mitigate power loss) and fuses. It took a bit of time to figure out exactly where I wanted everything. Between sketching things out, measuring distances in the van, and using the spreadsheet, I was able to put order to my chaotic thoughts. I relied on an online calculator for figuring out wire gauge based on electrical load and length of each circuit. By the way, the length of a circuit includes the length of both the hot wire and the ground wire - very important if you want to avoid wires melting in your walls.
In order to minimize the length of some circuits, I added a larger busbar to the factory installed grounding point above the rear driver side door. So some circuits are grounded up front by the house battery and some are grounded in the back.
Here's the expanded rear busbar located above the rear driver side door:
All the hot wires, and about half of the ground wires for each circuit, snake their way up the passenger pillar and then across the ceiling to wherever the light or outlet socket will sit. 8 circuits ended up using over 320 feet of wire!
After switching the system on for the first time, I was expecting blown fuses. Nope. It all worked! Before calling it done, I made sure to test each circuit under load.
Dimmer for controlling the two ceiling LED light circuits:
One of the 5 power outlets:
I decided that lighter sockets are best since you can plug whatever adapter you want into them.
The trickiest place to put wiring was into the rear passenger side door. I added a light there that works for reading in bed and as an outdoor floodlight when the door is open:
There's a cable tube with some existing wiring going to the door. Oh man, taking that off, snaking the wire through it, and reinstalling it properly was not easy. In order to be waterproof, there's a gasket seal on both ends that took me hours to figure out how to remove and reinstall without breaking. Plus I was working outdoors in subfreezing temps. I was not happy that day.
Flipping the switch! Much happier at that point :-)
As with the rest of our build, simple is the theme. Our power needs are low: we want to charge phones, laptop, run a few LED lights and a low-power fridge. Where to start...well, figuring out how much juice you need for those items comes first so that you can figure out how big a battery is called for. Once you know that, you can:
- figure out how big a house battery you need and how much room you need for it;
- how to connect the house battery to the alternator in order to charge it;
- whether you want or need solar to keep it charged;
- how many circuits you need to wire and what size fuses they need;
- how to get the wiring from the battery to the fuse box and to all the spots you need juice;
- what size wiring you need for all those circuits.
This crude sketch was the beginning of tangible plans.
I fleshed that out by figuring out that a ~100 Amp-hour battery would meet our needs. That means we could get a battery that fits under the passenger seat. That's a nice spot to keep it out of the way in a space that we didn't plan to use (some folks put a heater here). And it's easy to secure it so it won't fly around in an accident.
Conveniently, there's a connector under the drivers seat (where most of the van's stock fuse box and connectors are) that can be used to charge the house battery from the alternator. And it's easy to run cables between the two seat pedestals through a channel in the floor. My neighbor pointed me to the use of a CTEK D250SA DC Battery Charge controller. This thing is great in that it handles the chores of feeding proper voltage to the house battery while protecting the starter battery. Bonus: it includes a solar charge controller so it's easy to add solar at a later time.
Fuses - important stuff. Each of your circuits needs to have a safety valve in case there's an overdraw on the power. That includes the main feed coming from the alternator.
Here's my second sketch detailing the house battery charging and fuse box set up:
It slowly started making sense. At that point, I could start getting the house battery set up in place. I found a 92 Amp hour AGM deep cycle battery at NAPA autoparts for $200 that fits under the seat and is easy to secure. Unless you're going to use a more expensive lithium ion battery set up, AGM batteries are the way to go. They are maintenance free and don't need to be vented.
Here's how things look under the passenger seat with the charge controller on the left, a disconnect switch in the middle (so we can cut off the house battery circuit from the starter circuit), the new fuse box on the right and the battery on the opposite side. I drilled a couple of holes on each side of the pedestal in order to install 1/2" plywood that's used to mount the controllers, switches, fuses and the battery.
And here's the final outline of the house battery wiring:
A spreadsheet was handy for calculating wire gauge (the longer the circuit the larger the wire needed in order to mitigate power loss) and fuses. It took a bit of time to figure out exactly where I wanted everything. Between sketching things out, measuring distances in the van, and using the spreadsheet, I was able to put order to my chaotic thoughts. I relied on an online calculator for figuring out wire gauge based on electrical load and length of each circuit. By the way, the length of a circuit includes the length of both the hot wire and the ground wire - very important if you want to avoid wires melting in your walls.
In order to minimize the length of some circuits, I added a larger busbar to the factory installed grounding point above the rear driver side door. So some circuits are grounded up front by the house battery and some are grounded in the back.
Here's the expanded rear busbar located above the rear driver side door:
All the hot wires, and about half of the ground wires for each circuit, snake their way up the passenger pillar and then across the ceiling to wherever the light or outlet socket will sit. 8 circuits ended up using over 320 feet of wire!
After switching the system on for the first time, I was expecting blown fuses. Nope. It all worked! Before calling it done, I made sure to test each circuit under load.
Dimmer for controlling the two ceiling LED light circuits:
One of the 5 power outlets:
I decided that lighter sockets are best since you can plug whatever adapter you want into them.
The trickiest place to put wiring was into the rear passenger side door. I added a light there that works for reading in bed and as an outdoor floodlight when the door is open:
There's a cable tube with some existing wiring going to the door. Oh man, taking that off, snaking the wire through it, and reinstalling it properly was not easy. In order to be waterproof, there's a gasket seal on both ends that took me hours to figure out how to remove and reinstall without breaking. Plus I was working outdoors in subfreezing temps. I was not happy that day.
Flipping the switch! Much happier at that point :-)
