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Class B Motorhomes

Class B Motorhome power systems are built with the following considerations:

  • Small roof space allows for only a few small solar panels.
  • The potential for high current alternator charging.
  • Tight spaces for batteries and inverters.

The step-by-step guide below takes you through the myriad of options and design considerations for developing a custom power system.

Educational Videos for Class Bs

Battery Bank

1.  Select a battery bank:  The battery bank is the heart of the system. We recommend LifeBlue lithium batteries because of their built-in Bluetooth monitoring, high quality, and ability to expand over time. Usually, in a Class B, there is only room for 2-3 batteries.

We sell LifeBlue batteries as a base kit, which includes one battery, a Victron BMV-712 battery monitor, cable, lugs, and heat shrink, plus expansion kits, which include one battery and parallel cables. For two batteries, select one base kit and one expansion kit. If you want three batteries, get one base kit and two expansion kits.

LifeBlue batteries come in three size configurations, choose what will fit best for your application.

100Ah: H 9.4″ x W 12.5″ x D 6.5″ 28lbs

200Ah: H 10.8″ x W 20″ x D 6.9″ 57lbs

300Ah: H 9.5″ x W 20.25″ x D 11″ 83lbs

 

If your plan is to run an air conditioner, you will get about 1 hour of runtime on a 15,000BTU A/C running at full per every 200Ah of lithium battery capacity. You will also need at least a 3000VA Inverter, an Easy Start Kit, and three LifeBlue batteries, which means relocating the battery bank to a bay or inside.

Do not let your lithium batteries get below -10° F. Lithium batteries will not charge below 32° F.

Estimated Installation Labor

200Ah LifeBlue Lithium System with BMV-712
10 hours / $1,450

 

  • LiFeBlue Lithium Battery Bank with BMV-712 Monitor

    This is a complete LiFeBlue lithium RV battery base kit with a Victron BMV-712 Bluetooth battery monitor. The monitor is included to provide cumulative battery bank data, compatible with Victron VRM monitoring. LiFeBlue offers the most comprehensive Bluetooth monitoring showing status, temperature, voltage,...

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  • LiFeBlue Lithium Battery Expansion Kit

    This kit is designed to be an add-on to an existing LiFeBlue battery system. LiFeBlue offers the most comprehensive Bluetooth monitoring showing status, temperature, voltage, current, cycle life, battery health, faults and state of charge. These batteries can only be parallel connected due...

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Other battery bank options:

  • Victron Lithium Battery System with Monitor (Single Battery)

    ****Online Purchase for Local Pickup Only**** This kit is designed to work with one or two Victron lithium batteries. It does not use a Lynx Distributor to combine batteries. When adding alternator charging or DC distribution, be sure to use kits specifically recommended...

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  • Victron Lithium Lynx Battery System with Monitor (Multiple Battery)

    ****Online Purchase for Local Pickup Only**** This kit is designed to work with 1-4 Victron lithium batteries in 12V, or 2-8 Victron lithium batteries in 24V. It uses a Lynx Distributor to combine and fuse batteries. When adding alternator charging or DC distribution,...

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  • Victron Lithium Expansion Kit

    ****Online Purchase for Local Pickup Only**** Add a Victron Lithium battery to an existing Victron lithium system. Do not mix battery ratings in the same system. Parallel Expansion kits are for 12V battery systems. 24V battery systems can be built from an equal...

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  • LiFeBlue LiFePO4 12V Drop-In Battery

    LiFeBlue lithium batteries have integrated controls to automatically protect against overcharging, overly discharging, and frozen charging. This integration makes installation much easier for DIY projects. LifeBlue offers the most comprehensive Bluetooth monitoring showing status, temperature, voltage, current, cycle life, battery health, Faults and...

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Alternative Charging

2.  Alternator Charging: When upgrading to lithium batteries you will need to upgrade your battery combiner for alternator charging. Without this modification, the higher resting voltage of a lithium battery will trick the existing battery combiner relay into thinking the alternator is running and the lithium battery bank will be paralleled to the starter battery, even when the ignition is turned off. The result is lithium batteries draining into the starter battery until they crash to a dangerously low voltage or the lithium batteries’ internal BMS engages, preventing further discharge.

If you have a battery bank consisting of two LifeBlue batteries, and/or a smart alternator, you will need to use the Sterling Battery to Battery Charger. This keeps the charging current at a safe level and can be programmable for any battery chemistry. The Sterling Battery to Battery Charger can bring a battery up to 100% state of charge.

If you have a lithium battery system that can handle a charging current of 150A or more (three or more LifeBlue lithium batteries), and you do not have a smart alternator (here’s the Smart Alternator Test) you use the Victron Cyrix-Li-Ct battery combiner, variant “Lithium / 230A”. The Victron Cyrix-Li-Ct can quickly charge a lithium battery up to about 80% state of charge.

Neither device is needed if AGM batteries are used.

Estimated Installation Labor

DC/DC Charger
4 hours / $580

  • DC/DC Charging: Motorhome, Van, Skoolie

    Enable DC/DC charging from your alternator to a secondary Lithium, AGM or Flooded battery bank. This kit is ideal for van conversions and skoolies with older alternators or lithium batteries with input current limits under 100A. Ideal for: Vans, skoolies, motorhomes *Please note...

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  • Victron Cyrix Battery Combiner

    Victron Cyrix battery combiners connect your house battery bank to your starter battery and alternator to allow alternator charging. Additionally, when a charge is applied to a house battery bank the Cyrix will close and allow current to flow to the starter battery....

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Solar Charging

3.  Select solar charging system: Add a solar charging system that will fit on your roof.  As a rough rule of thumb, every 100W of solar will produce about 25Ah (or 300Wh) of charge per day.  If you have a solar pre-wire, check out section 3a of the Airstream page

 

For a complete explanation of everything you would want to know about how to design a solar charging system, check out our Solar Charger Design Guide

The Victron SmartSolar MPPT charge controllers are compatible with any battery type, can work on 12V or 24V battery systems, and communicate status via Bluetooth.

One of the most popular configurations for a Class B is two 110W solar panels on the 20A charge controller. This gives you room to add one more 90W panel if you want to expand.

If you want to use a portable panel, we recommend oversizing the central charge controller so it can handle both the roof array and the portable panel.

The Victron SmartSolar MPPT charge controllers are compatible with any battery type and communicate status via Bluetooth.

Estimated Installation Labor

2x 110W on a 20A Controller
12 hours / $1,740

  • Complete Solar Charger (20A)

    These kits offer everything one may need in order to put up to 290W onto an existing battery bank.  With the advanced MPPT charge controller and Bluetooth communication, these kits form an ideal foundation for a small power system mounted to a rigid...

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  • Complete Solar Charger (30A)

    These kits offer everything one may need in order to put up to 440W onto an existing battery bank.  With the advanced MPPT charge controller and Bluetooth communication, these kits form an ideal foundation for a medium power system mounted to a rigid...

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Solar Charging Kits and Components:

  • NOIR 110W Solar Panel

    Custom designed by Grape Solar for mobile applications, this 110W panel is ideal for Airstreams trailers, vans, truck campers, and any application where roof space is limited. The Grape Solar NOIR 110W panel comes in several kit variants.  Select the correct kit to...

    • Wattage: 110W
    • Type: Monocrystalline
    • Operating Voltage (Vmp): 21.3V
    • Open Circuit Voltage (Voc): 25.7V
    • Operating Current (Imp): 5.18A
    • Short Circuit Current (Isc): 5.60A
    • Size: 68" x 15.4" x 1.38" 17.9lbs
    • Frame: Black Anodized Aluminum
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  • Zamp 90W Long Solar Panel

    Designed for narrow spaces using 6" cells, this panel is ideal for small systems. Made in Bend, Oregon, United States. AM Solar Part Number:  SOLAR-ZS90L, 11-102-ZS090L, 11-102-ZS090LS Zamp uses tempered, low iron, 3.2 mm, AR coated(which stands for anti-reflective) solar glass. The benefits include:...

    • Wattage: 90W
    • Type: Monocrystalline
    • Operating Voltage (Vmp): 18.0V
    • Open Circuit Voltage (Voc): 23.6V
    • Operating Current (Imp): 5.0A
    • Short Circuit Current (Isc): 5.2A
    • Size: 58.3" x 13.6" x 1.38" 14.3lbs
    • Frame: Silver Anodized Aluminum
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  • Zamp Obsidian 90W L Solar Panel

    This panel has it all, a low-profile, a narrow footprint, and high output. It is ideal for van conversions, Airstreams, or anyone wanting the latest in mobile solar panel technology. Custom-engineered by Zamp Solar and made in Bend, Oregon. Narrow Footprint: Perfect for...

    • Wattage: 90W
    • Type: Monocrystalline
    • Operating Voltage (Vmp): 18.0V
    • Open Circuit Voltage (Voc): 23.8V
    • Operating Current (Imp): 5.0A
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  • TEROSON MS 5510 Sealant (legacy)

    Ideal for Airstream roofs, Teroson protects the VHB tape from the elements and is UV rated. Use it to seal around mount feet, cable management hardware, and combiner boxes attached to roofs. Do not use Teroson on TPO roofs. TEROSON® MS 5510™ WHITE...

AC Input/Output

4.  Select an Inverter/Charger System:  The Victron Multiplus inverter/chargers combine an inverter and a charger in one unit.  They also offer PowerAssist, which means that they can combine shore power with battery power when necessary. Our kits come with everything you need to upgrade your trailer or 5th wheel.

For a Class B Motorhome, you will want kit variants that include the phrase “RV Upgrade Kit”.

The 3000VA inverter/charger is only slightly more expensive than the 2000VA and shaped differently. The 3000VA inverter/charger gives you the option of running an air conditioner or running multiple appliances at the same time, like a coffee pot and a microwave. Installation time is the same for both inverters.

In order to fully support the 3000VA inverter, you will need a battery bank that can handle 300A of current outflow, or three LifeBlue batteries. A 3000VA will work on a smaller battery bank, but will only work like a 2000VA inverter if only two batteries are used.

If you plan on running an air conditioner, you will need the 3000VA inverter system with an Easy Start kit. If you plan on running two air conditioners, consider a 24V system with a Victron Quattro 5000.

Estimated Installation Labor

Multiplus Inverter (RV Upgrade Kit)
17 hours / $2,465

  • MultiPlus 12/2000/80-50 - 120V Inverter/Charger

    The MultiPlus is a powerful true sine wave inverter, a sophisticated battery charger that features adaptive charge technology and a high-speed AC transfer switch in a single enclosure. Rated at 2000VA. Note: Some Keurig coffee makers are known to be incompatible with inverters....