The Electrical System
I have long envisioned a basic electrical system, comprised of a few solar panels, lead-acid batteries and a modest inverter, supplemented with some propane for cooking and heating.
That has changed recently, with the increasing use of lithium batteries in RV’s. Their ability to accept fast and high charges and their increased Ah storage with a smaller footprint and reduced weight, make these batteries especially attractive for boondogging (i.e. my slang for boondocking).
I started considering to exclude the propane from the system and go with an all-electric layout. That has created some issues around water heating that still have to be resolved, but opened up better ways to charge those lithium batteries.
In contrast with conventional lead-acid batteries, they use a much simpler charging algorithm and are much more suited to be charged through the vehicles alternator. Besides the ability to charge large battery banks within hours, this also lessens the dependency on the sun as a source of power.
How To Use Your Alternator
Several approaches are available to use the alternator’s power to charge the batteries.
- Direct connection between it and the house battery bank.
This has never been an optimum solution and lower alternator voltage output in newer cars makes it even more complicated.
- The current line of cargo vans on the market increasingly support the installation of a second alternator, that separates the charging of the house battery bank completely from the vehicle’s electrical system. A viable system, but pricey at $1500 and higher.
- Battery-to-battery charging.
- My Ford Transit comes with a CCP (customer connection point) with up to 180 ADC (Amp DC) access. This would allow me to use a regular inverter as a source to connect a battery charger to and allows charging while driving.
Where Am I Now
The simplicity of the last charging option makes it the way to go for me, but not knowing the final components of the electrical system, I hesitate to buy an inverter, before a decision is made on the components of the complete system: I don’t want to oversize, but certainly not undersize the inverter.
The full conversion of the van will take its time, yet I will start using it on multi-day trips now, extending the duration of my road trips as the conversion progresses. This means the need to access power for charging a basic phone, camera battery, tablet and/or laptop.
That 1000W-2000W inverter would easily accomplish its task for these modest needs, so I set out to investigate all the different setups and available inverters. I knew, that it would be a pure sine wave inverter and that it had to be capable to support a 40-50 ADC charger, but soon it got complicated with dual inverter/chargers, PFC (power factor corrected) chargers and the limitations of the vehicle’s 12V power supply.
I’ve had some good experiences with Samlex Inverters in the past and contacted their support department for help. 15 Minutes later and a lot wiser, I decided to go ahead with a temporary solution and leave the final electrical design for a later time.
Right now, I will install a Samlex SAM-450-12 Modified sine wave and connect it to the Transit’s CCP as a temporary power source. It can be connected to a 12V lighter socket, but those are limited to 10A and thus a maximum output of the converter of 120W. The CCP will let me use the inverter’s full capacity. All my electronic gadgets can be recharged while driving and a reasonable price of around $35.00 won’t make a big dent in my budget. This allows me to use the van during the conversion, while postponing the installation of a complete electrical system.