Specialised Onboard Power systems
for Service Van, HGV truck, Motorhome, Caravan, Camper van, Ambulance, Catering Trailer,4x4,Utility Vehicles, Canal boats, Marine.
Mobile Installation Service - Shropshire
available in Telford & Shrewsbury, Shropshire areas.
Vehicle onboard power supplies to enable use of 240 volts ac (uk mains voltage), or 110v ac electrical equipment is required on many types of vehicles including
Utility Vehicle Conversions where a panel van , 4x4 or truck has been modified for specialist utility service use
Interior lighting may be 12v or 240v
Vehicle Charging System Voltage
Automotive battery systems recharged by an alternator
operate at either 12 volts DC (charging voltage approx 13v to 14.8v) or 24 volts
DC (charging voltage 28v)
UK domestic appliances operate at 230-240 volts AC mains.
Portable tools for site work ,eg drills, grinders, etc often operate at 110 volts or 240 volts.
Various power supply systems exist to provide 110v or 240v AC onboard power depending on application and requirement.
A suitable power source can be supplied while stationary from :
Mains "hookup" cable
Engine driven generator either seperate portable generator or vehicle engine driven generator which may be mounted to vehicle engine or fitted in driveline and pto driven
DC to AC Inverter to convert existing vehicle electrical power to the required current and voltage
A DC-AC Inverter converts a 12 or 24 volt DC
battery supply input voltage to 110 or 240 volts AC output voltage.
The Inverter output may be Pure Sine Wave (more expensive type) or Modified Sine Wave (cheaper type).
Inverter units may be parallel linked to achieve larger power output or a dynamic inverter system used.
Inverter Input Power Supply
A "leisure" or "domestic" (deep cycle) battery bank is often used as the 12v or 24v power source to supply the inverter system.
The main advantage of an Inverter power supply is quiet operation. Disadvantages include efficency losses and heat output depending on load. Care must be taken to mount in a position which is:
Additional wiring to power sockets etc, for example extension cabling may require testing for wiring regulation compliance.
An inverter may draw large amounts of current (Amps) from the supply battery during use depending upon load.
The current (A) drawn from the supply battery will lower battery voltage. When battery voltage is reduced below a set point the inverter will probably no longer function and cut out resulting in loss of output.
The ability of the inverter to operate relies upon reserve battery capacity at suitable voltage level.
The type, size and number of vehicle batteries used to supply the inverter will determine reserve capacity.
Cabling to Inverter
12 volt DC to AC Inverters can draw large amounts of current from vehicle batteries and depending on type will require heavy duty battery cable to carry the power supply
Various types of battery may be used to provide power supply to an inverter.
Lead Acid Battery
Has advantages of relatively low cost but generally designed for short duration high current output during vehicle starting. Major disadvantages include
Standard Leisure Battery
Designed for slower discharge over a longer period of time. Still has weight disadvantage.
Lithium Iron Phosphate Battery
Lithium Iron Phosphate (LiFePO4) batteries have become increasingly popular as power sources for inverter but may require specialised charging system. Lithium Iron Phoshate batteries have the main advantages of
Major disadvantage is higher initial cost of battery pack.
Leisure Battery Charging from vehicle power source
The vehicle's alternator may be used to recharge both starter battery and leisure battery by use of a split charge relay or battery management system which allows switching between battery banks.
The vehicle can be fitted with more than one alternator, for example no.1 alternator to charge the starter battery and no.2 alternator to charge the leisure battery or both linked to provide greater output capacity.
Split Charge Systems for Seperate Battery Banks
A split charge system separates vehicle starter and leisure battery until the vehicle engine
has started then connects
to link both battery banks.
This prevents the inverter system discharging starter and leisure batteries to a level at which starter motor operation fails rendering the vehicle immobile.
Split charging system using a heavy duty voltage sensitive relay (VSR)
Additional batteries may be linked
to the starter battery by use of heavy duty
voltage sensitive solenoid relay (VSR).
Use of a VSR allows priority charging of starter battery which must reach a preset voltage level before the leisure battery is connected to the charging system only when the engine is running and alternator charging. This reduces the risk of discharging the starter battery to a level at which the vehicle is immobilised.
Secondary battery charging using splitter diodes
This method uses a heavy duty diode fitted in the link wire between starter battery and leisure battery pack. The diode acts as a one way valve to allow current to pass from the starter battery to the leisure battery whilst the starter battery is at a higher voltage potential than the leisure battery allowing rechargeing. The diode blocks current from being drawn from the leisure battery when the starter motor is operated to protect cabling. This system has a disadvantage of power losses due to diode characteristics.
Secondary battery charging using DC to DC battery charger
This preferred method uses a special battery charger to regulate charging voltage and current between battery banks. Use of a DC to Dc battery charger can provide a method of charging auxiliary 12 volt batteries from a vehicle with 24 volt charging system.
Secondary battery used to provide cold start assistance
connecting cables and relays are specified to carry high starter motor current
secondary battery may be linked via switchgear to the starter battery
to improve cold starting.
An effect of reduced starter battery voltage results in an increased current draw as the starter motor operates (see Ohms law ref : Power(Watts)=Current(I) x Voltage(v) ) causing premature failure of starter motor or cabling.
Alternative energy sources for leisure battery charging
Alternative energy sources may be used to recharge leisure batteries such as use of solar panel battery charger (photovoltaic cells) or wind powered generator (sometimes used on marine installation) if sufficient capacity can be achieved.
Leisure battery charging from mains hookup
When the vehicle is parked where a site hookup (via BS4343 connector) is available a battery charger may be used to recharge the leisure battery bank whilst the vehicle is stationary.
110 volt or 240v power can also be achieved by a vehicle powered generator system, or by a stand alone portable generator. Vehicle powered generators may be run from the vehicle engine or via a power take off facility on the transmission driveline.
415 volt Three phase power for heavy duty specialist & industrial applications may be provided by a larger diesel powered generator.
Auxilliary power systems may be integrated so that the inverter system and generator systems work together during periods of peak demand.
Safety & Circuit Protection
240 volts ac power circuits must incorporate the following:
Please note ! Automotive electrical cable intended for use on low voltage systems is not suitable for use on systems operating at mains voltages (Why? Higher voltage potential requires better cable insulation) .
Electrical Installations in caravans and motor homes should comply with section 608-** of the IEE 16th edition Wiring Regulations. " superceded by the 17th edition IEE Wiring regulations which apply after July 2008.
Periodic Inspection preferably not less than once every three years or more frequently if the vehicle is used for more than normal mileage.
For such vehicles , the caravan electrical installation and supply cable should be tested and a report
on their condition obtained as prescribed in BS7671 (formely the Regulations for Electrical Installations) published by the
Institution of Electrical Engineers.
Reducing Power Consumption Consider using energy saving low power consumption devices such as LED Lighting when specifying your vehicle installation. This will mean the power requirement from the vehicle batteries is reduced therefore taking longer to discharge,
and allowing specification of smaller batteries thus saving weight and fuel. LED lights
are available for both interior lighting and exterior
lighting. We will be pleased to help with your vehicle onboard power enquiries by email subject to time constraints.
Reducing Power Consumption
Consider using energy saving low power consumption devices such as LED Lighting when specifying your vehicle installation.
This will mean the power requirement from the vehicle batteries is reduced therefore taking longer to discharge, and allowing specification of smaller batteries thus saving weight and fuel.
LED lights are available for both interior lighting and exterior lighting.
We will be pleased to help with your vehicle onboard power enquiries by email subject to time constraints.