Electrical System for RVs, Campervans, Tiny Homes

 

 

Recommended Best Parts

 

Safety

  • Lithium batteries with Bluetooth BMS (Battery Management System) and auto cell balancing preferred

  • EMS (Electrical Management System) to prevent damage from defective 110VAC shore power

  • Breakers and fuses for both AC and DC; quick access emergency cut-off switch

  • Bus bars rather than multiple connections to battery / battery bank

  • No exposed metal: Terminal stud and nut caps; electric tape over exposed metal

  • Caution with component cable/wire inlets too close together - don't let dangling strand touch others

This is a problem with all brands and I don't know why design engineers are so careless about it!?

  • Secure battery and components to withstand bumpy roads

  • If metal braces, etc. used for fastening, etc., wrap with electrical tape

  • Beware of sharp edges on components - keep hot wires away

  • Avoid wire nuts; use heat shrink or strong connectors; many crimped connections are unreliable

  • Grind rough metal edges of components smooth, such as inverter cooling rib ends to prevent wire cut

  • Label all wires and components to prevent miswiring and errors

  • Strip wire ends short to prevent touching adjacent wire on solar charge controllers

  • Grommets at wire through metal holes, photos of wire installs before wall panels and insulation installed

  • Fire extinguisher handy at all times

 

Quality, Reliability and Efficiency

  • Victron brand preferably with bluetooth programming as much as possible

  • Pure sine wave inverter of at least 3,000W continual use rating - Giandel is a great, inexpensive brand

  • Multi-zone solar panel sections with independent solar charge controllers

  • Folding ladder to access roof to clean solar panels; careful not to scratch flexible panels

  • As much as possible DC powered to avoid inverter, but I find it limiting to a few things like lights and fans

  • Solid copper thin stranded wire; 4 AWG is best overall as it's more flexible for tidy install

  • Welder's blanket to protect battery terminals from metallic objects from freezing temp.

 

Convenience and Comfort

  • Quiet, comfortable, reliable heating, cooling and ventilation systems with multiple energy source options

  • Long term off-grid capability without the need for a generator or propane; multiple charging methods

  • Maintenance free, easy to troubleshoot, easy access to repair and upgrade

  • Compact, thin wall mounted hardware out of the way

  • Easy access to abundant 110VAC receptacles and labelling of all plugs

  • Automatic transfer switch, mainly for electric heater

  • 500+ watts of solar panels, yet room on roof for fan, skylight and awning

 

Innovation

  • Share what I have learned and innovated with others; listen to other's constructive feedback (contact)

  • Repurposed EV Lithium Battery Module

  • EV J1772 charging station input (vehicles less than 21' long)

  • Thin, flexible solar panels with different charge controller zones to work even if part shade

 

Lithium Battery Jargon Names (all of the following mean exactly the same thing)

  • Lithium Iron Phosphate

  • LiFePo4

  • LIP

 

Compare 12V to 24V

12V

  • Wider range of components available

  • No voltage converter needed

 

​12V (Name Brand Lithium)

  • Built in BMS available, drop-in convenience, don't have to be an expert

  • Conditional warranty and support

  • 24V (All)

  • Converter steady 13.8V healthier for 12V components

  • Smaller wire gauge saves money and smaller, more flexible wires are easier to work with

  • Double solar charger capacity

 

​24V Tesla or other Used EV Battery Module

  • Promotes re-purposing (eco)

  • Cheaper per kWh / Ah

  • Smaller size and weight per Kw / amp hour

  • Can mount on wall - space saver

  • ​Faster charging and higher discharge amps

 

24V Second Life / Re-purposed Tesla Battery Module Power System

  • Li-Ion 24V 6S 233Ah (466Ah 12V Equiv.)

  • DIY Custom Campervan - RV Sample, Updated March 21, 2019

 

How Eco-Friendly

  • Repurposing a used battery that is very toxic if introduced back into the environment

  • Longest lasting (with proper care)

  • High performance reduces or eliminates need for fuel powered generator or shore power

​

DIY 24V Tesla Battery Power System Essential Parts

  • 24V Tesla Battery Modules

  • Verify 7-pin balancer harness connector

  • Inspect all fuses (tiny metal wires at the end of all batteries)

​

​24V, Li Ion Tesla Model S Battery Essential Specs

  • 6 cells (6S) 233Ah for 5032 Watt-hour capacity.

  • Voltage range: 18.6V soc 0%.  23.1V soc 70%.  24.9V soc 100%

  • Voltage nominal: 3.8V/Cell, 22.8V/Module

  • Charge voltage cut-off: 4.2V/Cell, 25.2V/Module (less than all cheap chargers)

  • Discharging cut-off: 3.3V/Cell, 19.8/Module (less than most inverters allow)

  • Lithium Ion - Nickel cobalt aluminum oxide (NCA / (LiNiCoAlO2)

 

 

Fiberglass Thermal and Fire Protection Blanket

​Wrap the battery to protect from catastrophe and freezing temperatures - ​amazon link

Or you can get a Harbor Freight; use 20% off digital coupon

Looks a lot better - a uniform, shiny tan/amber color

 

Heater Pad with Automatic Thermostat Control -  12V DC (Converter below) - amazon link

Required if battery will ever reach near freezing temperature while charging​

 

Main Battery Wiring for 24V System

4 AWG 15' Red + 15' Black Pure Copper Flexible Cable Wire - amazon link   ​

​(or) 2AWG for a spread-out system or high amps (roof A/C, etc.) - amazon link                                                                                                                           

 

Master Positive Cut-off Switch

amazon link

 

ANL fuse

200A - amazon link

Install 1' from battery

 

Bus Bars

Red & Black 3/8" 4 Stud Power Distribution Block with Cover - amazon link

 

 

Battery Monitor, Partial BMS (no balancing) and Relays

Victron BT battery monitor BMV-712 w/ temp. sensor - amazon link

Comes with a heavy battery shunt that connects to battery positive terminal

 

Full-Time Balancer 6S (6 Cell) - amazon link

​​​​6S (6 Cell) Balancer Cable - eBay link

No external power source version

 

Battery Protect​ (mainly prevents uni-directional over discharge)

Victron 12/24V 220A battery protector - ​amazon link

Not required if voltage will never drop below 19V or you have other low voltage relay

Set display to "2a" = under voltage to 19V (restart 23V)

Also serves as disconnect (pull jumper wire)

To reset and program: Disconnect everything and remote jumper (just pull it out), touch a ground wire to the "program" terminal, hold until "2", then let go, touch and hold ground again until "a" then let go. "2a" should flash. Reconnect pin and cables.

 

12V DC Fuse Box with Warning Lights

BlueFire 12 Way 30A Blade Fuse Box Board, 24 Fuses + LED Warning - ​amazon link                                                                                                                         ​

 

24V to 12V Converter - Regulator

Voltage Converter Regulator DC/DC DC 24V Step-Down to DC 13.8V - amazon link

Provides steady 13.8V for 12V accessories (big advantage vs. 12V battery)

 

24VDC to 120VAC Pure Sine Wave Inverter

​Giandel 3000W, 90% efficient, 1A idle - amazon link

You can't use 120V components when voltage drops below around 20V, but you can use converted 12V components below 20.3V

I tried a similar 2000W inverter and could not handle more than 1,500W

 

Label Maker

Brother P-touch, PTD210 Label Maker Multiple Fonts and Templates - amazon link

Refills (label maker only comes with short amount; recommend buy the refills at same time as label maker - amazon link

 

Tips

Microsoft Viseo is good to create wiring diagrams - amazon link.

​Mount battery where you can always keep it above 0 Celsius during any charge; otherwise you must install a heating pad for the battery module.​

Victron BMV-712 Battery Monitor with Bluetooth and Temp. Sensor

Unofficial Settings for 24V, 6S Li Ion Tesla Model S Battery Module

Battery Settings

Battery capacity:  ​233Ah

Charged voltage:  24.1V (aim for 85% SOC)

Tail current:  4.00%

Charged detection time:  3 minutes

Peukert exponent:  1.02 (or Tesla suggestion)

Charge efficiency factor:  99%

Current threshold:  0.10A

Time-to-go averaged period:  3 minutes

Battery starts synchronized:  off​

 

​Display (your preferences)

 

Misc - Aux input:  Temperature

Relay Settings (close / clear)

Relay mode:  Default

Invert relay:  Off (off = relay open / active)

(Relay) Minimum closed time:  ​1 minute

Relay-off delay:  0 minutes

(Low / floor) SOC relay:  16%  /  18%

Low voltage relay:  20.6V (or 15%) / 20.7V

High voltage relay*:  24.9V  /  24.6V

High temp relay:  105F  /  100F

Low temp relay:    41F   /   43F

 

Alarm Buzzer (on / off)

Low / floor SOC alarm: 18%  /  20%

Low voltage alarm:  20.7V  /  20.8V

High voltage alarm:  24.7V  /  24.6V

High temp alarm:  100F  /  97F

Low temp alarm:     43F  /  45F

Notes

Bookmark and check EcoNeato.org/24v.html for improved settings

The BMV 712 measures a battery bank, not individual cells and does not balance.

This is why setting ranges should be conservative in case one cell goes out of balance.

To sync 100% SOC: 1) balance cells, 2) charge to 24.9V, 3) sync., 4) discharge to 24.1V.

Charging Methods

​Solar Charging (Highly Recommend)

Victron 50A (up to 1200W Solar, 24V) MPPT Bluetooth - amazon link

Get this larger one if not sure or plan to add solar later

​Victron 30A (up to  720W Solar, 24V) MPPT Bluetooth - amazon link

Victron 20A (up to  480W Solar, 24V) MPPT Bluetooth - amazon link

​Victron 15A (up to  360W Solar, 24V) MPPT Bluetooth - amazon link

Victron 10A (up to  240W Solar, 24V) MPPT Bluetooth - amazon link​

SPACER

 

Battery Protect (prevents over discharge)

Victron BatteryProtect 12/24V-65A - amazon link

Also serves as solar disconnect (pull jumper wire)

 

Experimental Tesla Module Parameters for Victron MPPT Bluetooth Charge Controller

Battery

Battery voltage:  24V

Max charge current: (enter your charger amps)

Charger enabled: (select)

Absorption voltage: 24.40 / max 6h

Float voltage: 24.20

Equalization voltage: 24.40 (not to be used)

​Automatic equalization: Disabled

Temperature compensation: -32.40mV/C

Low temperature cut-off: 4.0 C

​Load output

Operation mode: user def. algorithm 1

User def. algorithm 1: (off<20.50V, on>24.60V)

Load switch high voltage level: 24.60V

Load switch low voltage level: 20.00V​

Notes

Do not leave at below 15% SOC or above 85% SOC (State of Charge) or damage will occur.

It's OK to charge to 100%, but you should quickly use the energy to 85%.

Divide panel wattage by battery voltage to get amps. Add Voc if in series to get the max voltage; Voc of one panel if there are few in parallel

​​

​Alternator to Battery / DC-DC Charging (Highly Recommend)​

 

​Victron Buck Boost 50A (23A @ 24V) DC to DC charger for smart alternators - $653 PKYS free Priority Mail

Place near starter battery to keep the 12V charging cables as short as possible​

Printer-type USB cable to PC for programming (charger has to be connected to a battery) - amazon link

Choose "Automatic Search and Connect" to connect

Picture

Picture

Picture

Internal parts (not recommended to open)

Picture

Unoffical Settings - Caution: Experimental Mode

Battery Quick Connect / Disconnect Wire Harness Plug Kit - amazon link

Allows quick removal / relocation of components (chargers, etc.)

 

Shore Power / Charging (Frequent low solar campsites with power)

iCharger X6 charger / balancer - amazon link

Use with 120VAC / 240VAC to 24VDC Power Supply - amazon link

Fully programmable; balances once on command, not all the time

May take several hours to learn (read the manual - click for PDF download link)

Can balance via shore power to PSU below or plugged into inverter

 

​  (and)

​120VAC / 240VAC to 24VDC PSU (Power Supply) - amazon link

Use with iCharger X6 - amazon link

Can also be used with EV charge station - detail link

 

Only use a charger that allows customized charging parameter of 23.8 to 24.4V. Beware of chargers that say they charge at 24V because they may actually charge at 26+V which will eventually cause a fire!

Instead of charger/converter, you can still install a 15 and/or 30A inlet that goes to a breaker box and then to an automatic transfer switch to power 120V appliances (air cond., heater, stove, microwave). This will not charge the battery and then you don't have to worry about over voltage to the battery. By powering all or most of the 120VAC components with shore power, the battery can charge good with minor solar.​

 

EV (Electric Vehicle) Power Station Charging (Individual preference and availability)

Eco Friendly: Reduce generator and alternator charging and propane dependency.  Details here​

Fueled Generator Power and/or Charging

​(Frequent low solar campsites without power and/or high energy consumption such as roof air conditioner)

First try methods above. If you still need more power, click here to see how to get off the generator.

If you still have to have a generator, Honda and Yamaha make the best, most quiet ones.

Webpage Created Dec. 15, 2018, Tesla Module First Installed & Tested Feb. 1, 2019 in Morro Bay SP, CA

 

​WARNING AND DISCLAIMER

​Many settings, parameters and configurations are unofficial and in experimental stages.

Installation errors, charging >25.2V, >113F or unbalanced cells may result in damage, smoke, fire and/or injury.

If you often use high amps, you must water cool the battery module and/or add another module.

No guarantees are implied herein; install at your own discretion and risk. Two fire extinguishers recommended.

​​