Camper Van and RV Electrical Systems

Camper Van Electrical System components

Before we start on a RV electrical system we should decide what Battery type or battery chemistry we will be using. Lithium batteries provide major benefits, but they do have specifically different needs. They mustn't be overcharged and then mustn't be allowed to run flat and require a BMS. The Van or RV will already have a starting battery and you can add a separate Battery or Batteries for the house or service loads.

The following blog posts will go some way to helping you understand the difference. Rather than promoting one over the other, we are providing information to help you make your choice.

Blog post         Lithium v Conventional batteries PKYS

                        Victron Energy Lithium ion v AGM

From these articles it becomes apparent that to compare RV Batteries we must compare the amp hours AH of the Lithium battery to twice that for AGM batteries. If we have a 180 AH lithium we need to compare it to 2 180 AH AGM’s. The reason for this is that AGM batteries need recharging when they are down around 50% depletion. See the usable energy diagram below. So you will need to charge the AGM batteries much sooner that with Lithium or have twice as many AH.

If we use equal AH’s as the control, the AGM batteries will be a lot heavier and take up a lot more space as there will be two of them.

Also when you consider the life cycles of Lithium v AGM you will have to replace the AGM’s. Life cycles are the number of time a battery is discharged from full and then back to full again. For Lithium this is in the range of 2000 – 4000 while AGM’s are 400-1500.

Take the above two points we can see the initial cost of Lithium Van Battery is high, but you will have to buy 2 AGMS and then have to replace them later while the lithium may well outlive you. When you look into it more the initial shock wears off and you can look at the benefits.

Lithium Battery PROS

• Light Weight
• Smaller Space required
• No need to be vented
• Voltage output of Lithium will be 12.5 volts or above.
• Can be discharged deeper without affecting battery life

Lithium Battery CONS

• Expensive
• More sensitive to high/low voltage or current and high/low temperatures*
• Cannot be charged below 0C (32F)*
• Needs a Battery Management system BMS

If you choose to go with Lithium you will need a BMS Battery Management System. So what does that do?

In a nutshell, the BMS will cutoff the battery if the voltage/current/temperature is out of range for safe charge/discharge.  Lithium batteries are more complicated than regular batteries.  They mustn't be overcharged and then mustn't be allowed to run flat.  The individual cells in the battery need to be balanced.  All this is the job of the Battery Management System (BMS).  The BMS will send a signal to disconnect the load from the battery if any cell gets to its minimum voltage and it will also send a signal to turn off the charge if any cell reaches its max voltage

Victron’s Battery Management System is external to the Battery and can be set for many configurations. Some modern LiFePO4 batteries come with a built-in Battery Management System (BMS), but these cannot be adjusted.

Blog posts/Technical Reviews        

Conventional Batteries

Lithium Batteries

Shopping link  Batteries conventional and Lithium

Tourig are a Sprinter Van conversion company in Colorado, with heaps of experience. We have been working with them for many years and have this nugget from them about space utilization.

Using the BEP 770 EZ installer 400A switch which allows the wiring to be done from the front, enables Tourig to fit the components in a tight space. With their shared interconnection height, EZ-Mount battery switches "cluster" directly with the Pro Installer Bus bar Range, resulting in fast compact installations.

This installation shown in the following photo by Tourig on a Mercedes Sprinter van shows how they fitted most of the controls in a small accessible space.

• The BEP 770 EZ pro installer battery switch and links to Class T fuse. (Top of picture)
• Victron MPPT 75/15 Solar Controller (bottom left)
• Victron BMV712 Battery monitor shunt (bottom right)
• Blue Seas 5032 fuse block (middle)
• Victron Lithium battery just seen right

You can see how the link bars make for simple installations.

Since you’re going to be a long time off grid it’s useful to know the health of your batteries. To manage this you’ll need a monitor and a simple way of viewing the data.

The Victron BMV range of battery monitors are probably one of the most popular items in the Victron range. The picture shows the BMV 700 Battery monitor with Dongle to provide Bluetooth. Both Conventional and Lithium batteries can be monitored by the BMV battery monitor.

Using the VictronConnect app your smartphone can display all the important Battery data via the BMV with the ability to change settings. Settings such as Battery capacity, full charge voltage, alarms for low voltage etc. The smartphone display is easy to use and the easy to read. Both Conventional Battery types and Lithium Batteries can be monitored with the BMV700 series.

Reviews

Victron BMV 700 review in truck camper adventure written by one of our customers.

Since this article was published both the Victron Battery Monitor and the MPPT solar controllers now have Bluetooth integrated. In fact now almost all the Victron energy range of products are smart.

Technical reviews        BMV monitors

Shopping link              Victron battery monitors BMV712, 700 and 702

Battery protect

 

Inverter Chargers

Solar Charge Controllers

Finally