FAQ's

• When I turn on the inverter it makes a strange sound and then latches off.
• The inverter keeps emitting a continuous tone.
• I turned on the inverter, with no load applied, and it blew its internal fuse.
• The output voltage of the inverter seems very low when I measure it with a multimeter.
• The fuse of the appliance I wish to power blows when I plug it into the inverter.
• The inverter is running very hot.
• After I turn the inverter off the output neon stays on for several seconds.
• I do not seem to be getting the same run time from the inverter/battery as I used to.
• The inverter has difficulty starting my fridge.
• My "Handy Mains" no longer works and when I opened it to check the fuse I found that a capacitor near it had failed.
• When I use the inverter to power a TV/monitor I find lines rolling up (or down) the screen.
• When I use the inverter to power my audio equipment I can hear background noise.
• The inverter does not draw any current at all even though I have checked the fuse.
• The case of my inverter was floating until the live output accidentally touched a battery connection.
• The output of my inverter is intermittent and when I try to power several appliances the output neon keeps flickering.

• UNDER VOLTAGE LOCK-OUT

  The inverter has under-voltage alarm and lock-out circuitry to protect the battery from fundamental discharge.  If  you hear a short tone and the unit turns off when a load is applied there is either a problem with the battery or the wiring between the battery and the inverter is inadequate. 

  The 12V 'Handy-Mains' alarm will start to sound at about 10.5V and the unit will then shut down when the battery voltage falls to 9.5V.  On 24V units the alarm will start at 20.5V and shut down will occur at 19V.  When the inverter starts to emit a sound (gradually increasing in volume) it means that the battery is nearly depleted.  At this stage you should be bulk charging the battery to ensure that it does not become fully discharged.  To avoid  voltage drop you must ensure that you are using a car/lorry type lead acid battery that is capable of delivering high cranking currents.  To check your battery is adequate you should read the plating label located on it.   For instance a good lorry battery would have a 110 AH rating and a cranking current capability of 550A (SAE), a good car battery would have a 55 AH rating and cranking capability of at least 300A (leisure batteries should not be used with our inverters as they are intended to provide low current for prolonged periods of time but have no cranking current capability). The Battery Issues page gives a rough guide to some of the more common battery related questions.

  It has been our experience over the last several years that many of our customers problems have been due to inadequate wiring between the battery and the inverter.  As a rough guideline the following table should give you an indication of the wire gauge you need to use.  If you need to run an appliance away from the battery you should extend the mains output lead (with an RCD) and not the battery input lead. The Wiring Issues page gives guidelines for the installation of the equipment and wiring.

  Input V O L T A G E		WATTAGE
  		200W	600W	1500W
  	12V	6mm2	16 mm2	32 mm2
  	24V	3mm2	10 mm2	24 mm2
  	48V	1.5mm2	6 mm2	16 mm2
  	96V	1 mm2	3 mm2	6 mm2

  The above table is for cable lengths up to 2M.

  The copper cross section area (CSA mm2) is all important.  The higher the copper CSA of the cable the more efficiently the inverter will run.  Do not choose cable by its current rating as very often this is rated at mains voltages where a few volts dropped are immaterial.  You can use multiple cables to make up the cross sectional area that you require.  If you have problems obtaining the cable you can order wiring kits (SM2790/SM2793) direct from ourselves.

  Our inverters will take a high in-rush current, even when unloaded, in order to facilitate switch on. This in-rush current can be as high as 20A but will only last momentarily.

  If you are trying to run the 200W inverter from a bench power supply, ensure that the supply has a current limit capability of 30A or better. At 12V the inverter will draw 1A from the battery for every 10W of load , therefore at 200W the inverter will draw 20A.

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• NEGATIVE 12V TRACK FAILURE
  

  (POSITIVE EARTH CONNECTION IN 200W UNITS)

  If the unit does not draw any current at all you should check for continuity (with an Ohm meter) between the input battery negative connection and the case of the inverter.   If the connection is open circuit the negative 12V track inside the inverter has blown open.  The negative 12V track will rupture in this fashion if it is subjected to very high currents which it is not designed to deal with.  There are several ways in which misconnection can cause this to happen, below is a list of five possible scenarios:

  N.B. In 200W models it is important to bear in mind that the negative input wire, the output earth connection and the case of the inverter are all bonded together.

  1, If the unit was connected to a battery and the case of the inverter touched the positive terminal then the track would blow (this would create a short circuit across the battery inside the inverter because the case of the inverter is connected via the negative 12 volt track to the negative input wire).

  2, If the unit was connected to a positively earthed system, i.e. the chassis of the system is bonded to the positive of the battery rather than the negative, then this would cause the track to blow (if the inverter is connected to the battery and the case is bonded to the chassis a short circuit across the battery will occur via the positive connection of the case, through the negative 12 volt track, to the negative input lead).

  3, If the unit was connected to a battery and then the earthed metal work of the appliance plugged into the inverter touched the positive terminal of the battery high current would flow, which in turn would blow the negative 12 volt track in the inverter ( the current would flow from this connection through the output earth connection of the inverter to the negative input connection via the negative 12 volt track).

  4, If the units case, or the earthed metal work of any appliance plugged into the inverter, was bonded to a negatively earthed system and the input wires were reverse connected high current would flow. This current would flow via the positive terminal of the battery, through the negative input lead (due to reverse connection) and then through the negative 12 volt track to the case of the inverter which is bonded to the negative terminal, thus causing a short circuit.

  5, The negative 12 volt track would blow open circuit if the unit was grossly overloaded whilst the input fuse was shorted out or upgraded to a higher value than that specified.

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• INVERTER FAILURE

  If you power the inverter from the battery with no load applied and the system fuse or the internal fuse (of the inverter) blows then the unit has failed and needs to be returned to us for investigation.   Before returning any goods to us you should contact us on our technical help line number (44) 0118 930 2213 as many minor problems can be resolved over the phone.

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• OUTPUT VOLTAGE MEASUREMENT
  
  The output of our inverters is a stepped square wave (quasi sine) rather than a sine wave.  Most conventional hand held multimeters take an average voltage reading and therefore if you attempt to measure the output of one of our inverters with an averaging meter you will get a low reading.  This reading can be in the vicinity of 170-210VAC.
  
  In order to obtain a true reading  you must use a true RMS or Moving Iron meter.   The RMS output of the inverter will vary depending on the input battery voltage level but it will remain within the UK Mains specification. 
  
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• APPLIANCE FUSE FAILURE
  
  If the internal fuse of the appliance you wish to power fails occasionally when connected to the inverter it may be due to the high in-rush current available from a stepped square wave output (rather than a normal mains sine wave).
  
  Some appliances that utilise transformers, especially toroidal or cheap laminated type transformers, may momentarily saturate when stepped square wave power is applied.   Very often these type of appliances have very low fuse ratings with no surge protection and may therefore fail after repeated power cycling.
  
  DO NOT ATTEMPT THE FOLLOWING IF YOU ARE AT ALL UNSURE, however if you are technically capable, you could try inserting a 22 ohm 7W wire wound resistor in series with the live between the inverter output and the appliance.  This resistor will act as a current slug and should limit the current in-rush.
  
  If you are unhappy about carrying out the above operation you can return the unit to us and we will perform the modification for you.

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• THE INVERTER IS RUNNING VERY HOT
  
  If your inverter is running very hot (above 50 degrees Celsius) there is a good chance that the load or combination of loads you are using is exceeding the maximum live to neutral capacitance that the inverter can handle.
  
  This live to neutral capacitance limit is technical in nature and if you do not understand the following discussion you should send back your inverter and the appliances you wish to power so that we can take steps to eliminate excessive dissipation in the inverter.
  
  Most modern appliances have live to neutral capacitors which perform power factor correction/filtering roles.  Below is a table of the maximum L-N capacitance our inverter ranges can handle.

  Maximum Live to Neutral Capacitance
  Table

  UNIT WATTAGE	MAXIMUM CAPACITANCE
  200W	0.47µF
  700W	2.0µF
  700W High Surge	3.0µF
  1500W	3.0µF

  These capacitors are placed across the live and neutral tracks of the appliances power supply and very often before the power switch.  This means that even with the power switch in the off position the inverter can still be dissipating energy into the capacitors.  Due to the fast rising edges of the stepped square wave output of the inverter large current transients are drawn as the capacitors are charged at 50Hz.  These current transients cause excessive dissipation in the output transistors of the inverter which in turn causes a heat rise in the unit.
  
  An individual appliance is unlikely to exceed 0.47µF but several appliances connected to the one inverter could very well exceed this limit. Fluorescent light fittings usually have a very high level of capacitance. 
  
  If you find you are exceeding the limit you should take steps to remove the capacitor/s from the appliances and you will then find that the inverter runs much more efficiently.

  If you are unable to remove the appliance capacitors or if you are in any doubt about the above, you should contact our technical help desk on (44) 0118 930 2213.
  

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• HALF SIDE AC FAILURE
  
  If you notice that the output neon of the inverter stays on for several seconds after the unit has been turned off you should look closely at the neon.  The neon on units above 200W will stay on for a couple of seconds if the output is unloaded as residual voltages die down.  However if this occurs on a 200W unit then it needs to be return for repair as it has suffered a half side AC failure.  This type of failure can occur if the output has been short circuited or the unit has been subjected to high levels of live - neutral capacitance (see the dialogue above).

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• BATTERY HOLD-UP
  
  Care should be taken not to heavily deplete batteries as this will seriously reduce their life expectancy.  As a rule of thumb you should never deplete a battery of more than half it's A/h rating.  When planning a battery application you should determine the power you require from the battery and the duration that you need it for.  For instance if you require 10 amps (at 12V) for 5 hours  you would need a total of 50Ah (10x5), to ensure long battery life expectancy you would therefore need to double this amount and provide a 100Ah 12V battery or batteries in parallel.  Different types of lead acid batteries have different charging characteristics.  If you keep discharging your battery before fully recharging it you will cause the plates to sulphate which will gradually diminish the batteries life.  For more information see our page on battery selection.


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• STARTING A FRIDGE
  
  Fridge compressors can take several times their rated power when starting up and this inrush surge is exacerbated when a compressor is powered by a stepped square wave output inverter.  If you are contemplating using one of our inverters you should select a unit that has a surge rating that is ten times as powerful as the fridges rating plate.  For instance you would need to provide an inverter capable of a 600W surge to power a 60W fridge.


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• INPUT CAPACITOR FAILURE
  
  There are three possible scenarios in which the input capacitor of 200W Handy Mains models can fail and they are as follows:
  
  1, Positive earth connection can cause the input capacitor to blow in some circumstances.  See Negative 12V Track Failure.
  
  2, If the input voltage exceeds the maximum permissible level stated on the unit, i.e. 15VDC for a 12V battery input unit.
  
  3, The input capacitor will fail if the cable between the battery and the inverter is too long or insubstantial.  May we suggest that to make the unit run more efficiently, the cable between the battery and the inverter is as short as possible even if this means lengthening the cable between the inverter and the appliance being used.  Any resistance in the input cabling will cause a large ripple voltage across the input capacitor which will eventually cause overheating and failure. The Wiring Issues page is a guide to help proper selection and installation.


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• 50 HZ NOISE BREAKTHROUGH
  
  If you find you have rolling lines on your TV or audible low frequency on your audio system you are experiencing 50Hz noise breakthrough.  Unfortunately every piece of equipment has different characteristics so therefore there is no universal "cure all" for this problem.  The noise comes in two forms, either conducted or radiated.  If the noise is radiated a screened (shielded) mains cable should be used between the inverter and the appliance, this should help to eliminate the noise.  If the noise is conducted then a ballast resistor fitted in the live line, between the inverter and the appliance, should help.  The value of this resistor will need to be arrived at empirically, try starting with a 22 ohm 7 watt wire wound resistor and work up to 56 ohm until you overcome the problem.
  
  If none of the above solutions work for you phone our technical help line on 0118 930 2299 and we will be happy to assist.


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• RESIDUAL CURRENT LEAKAGE
  
  If your inverter is supplied as isolated, it means that the metal case is not connected to either terminal of the battery source.  The case of the inverter must be grounded to local metalwork either by use of the flying earth lead or by connection to the case metalwork (a stud is usually provided).  The problem with not grounding either battery terminal is that the battery system can rise to quite high voltages with respect to the systems chassis. This leakage current is a direct result of small filter capacitors found in most modern appliances.  Although the voltage can be quite high the current available is very small, still an undesirable tingle may be felt.  To limit the level of this voltage it is clamped to within safe limits inside the inverter.  If, due to an external fault, a dangerous amount of current flows a safety device will operate to latch the battery to system ground to contain the dangerous situation.  This shock protection method is a one time only protection.  In the event of this happening the unit will need to be returned to us for repair/reset.  Of course, the external fault must be cleared before re-fitting the repaired inverter.


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• "POWER PUSH" CURRENT LIMITING
  
  The 700W and 1500W inverter models have output "Power Push" current limiting which may cause some confusion in certain applications.  This current limiting operates in two distinct modes.
  
  1, In very heavy overload situations the output of the unit will shut down entirely. After a second or two the unit will attempt to lift the output load and the output should then stay on. For instance if several high power filament light bulbs are placed across the output of an inverter at once the unit will lock out as the load will be very low impedance (and thus very high) until the filaments warm up, the unit will then lift the output thus heating the filaments slowly (less than a second).
  
  2, If the load is too much for the inverter it will continuously keep trying to lift the output quickly and then shut down, the output neon will flicker repeatedly when in this mode (at a rate of several times per second).  If you experience this problem you need to select a larger inverter.


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