Wiring Android Head Unit to Coach Batteries

To utilize the Android head unit without starting the engine or depleting the chassis battery (when used with the ignition set to ACC), I rewired the Android head unit to operate off the coach batteries. It's a great way to enjoy streaming media like YouTube, Netflix, Spotify, etc. when parked or relaxing at the campground using the upgraded Android head unit's larger screen. It's also an excellent way to get the navigation started to our destination before starting the engine. A dash switch is installed to toggle the power of the head unit between ignition only and always on. A simple wiring modification and the addition of an automotive relay are all that is required. This is how I did it.

Installing Dash Accessory Fuse Block Powered by Coach Battery

 

I generally draw power from the battery disconnect relay post, but this is inconvenient because it necessitates removing the driver seat every time I need to power something. Installing a fuse block powered by coach batteries under the dash is the simplest approach to future-proof any aftermarket additions.

Finding a suitable placement for the fuse block is not as simple as you might assume; there is barely enough space beneath the dash to put a good-sized fuse block. You could place one over the dash plastic trims, but that would look unprofessional.

ML-ACR and DC-to-DC Charger Transfer Relay with Time Delay Start

 

If you upgraded from Blue Sea ML-ACR to DC-to-DC charger and wants to keep the ACR functional, this is for you. I added a Renogy 40-Amp DC-to-DC charger (this post) and decided to keep the Blue Sea ML-ACR as a backup alternator charger for our coach batteries.  It will come in handy if the starter battery needs a boost from the coach batteries. When connected to shore power, it can also be used to charge the chassis battery. This mod will also work on battery separator system, although wiring for the separator will be different.

The changeover/transfer relay only activates one charger at a time, either the ACR or the DC-DC, turning them on at the same time could cause some issues down the road. I also added a time delay relay for the DC-to-DC charger D+ trigger so that it does not immediately turn on as soon as the engine is started. I added a 3-minute delay (user selectable) to allow the chassis voltage to stabilize before starting the DC-to-DC charger. Here's how I did it.

Replacing/ Upgrading Sprinter Door Speakers, and Dash Tweeters. Installing Sound Deadener on Cab Floor

Our factory door speakers broke, the rubber surround that holds the paper cone has disintegrated into pieces, causing the speakers to sound terrible. I used an eBay speaker adapter to replace it with a larger speaker. The factory speaker is proprietary and cannot be simply replaced with an aftermarket speaker without the use of an adapter or some modifications.

The new speakers have a much better dynamic range and a deeper bass response. I also replaced the tiny dash tweeters and was very pleased with the upgraded speakers. Here's how to change them.

DIY DC-to-DC Chassis Battery Trickle Charger (Trik-L-Start Alternative?)

You've probably heard that the Trik-L-Start DC-DC battery trickle charger has been discontinued, the only commercially available alternative is the Echo 15-Amp Charger by Xantrex. The Echo Charger is quite expensive at around $150 and only compatible with lead acid batteries.

I wanted to add a chassis battery trickle charger from my Solar Charge controller's auxiliary output but couldn't find an inexpensive low current DC-DC trickle charger for my application. The Trik-L-Start trickle charger would have been ideal, but they are no longer sold, necessitating the DIY approach. With the addition of a battery protection module to the circuit, it will mimic the Trik-L-Start trickle charger and can be adjusted to start/stop charging depending on the source voltage.