Voltage supply issues
are the primary reason why a 12/ 24 VDC compressor
may fail to operate.
It really is simple, there are two voltage issues, both quite separate from each other and each with vastly different consequenses.
Firstly, poor or erratic power supply.
(Power including all from the battery
through to the module terminals.)
All of these 12 / 24 VDC compressors employ a Motor
Driver Module. DC power enters the MDM where it is inverted into an alternating 3 phase current
to power the compressor motor
. TheMDM has several ‘Fail-safe ‘ facilities to protect against under / over voltage, excess current
draw, over heating
If the voltage to the MDM falls away due to a faulty connection, wiring
etc, then the fail-safe may prevent the MDM from starting and running the compressor.
It is simple to check your power supply with a common multimeter. Simply put your meter onto DC volts then hold probes onto the positive and negative terminals at the MDM (See sketch). Monitor
the voltage both BEFORE start up, while attempting a start and if it runs, keep monitoring. If the voltage ‘dies away’ then work
backwards checking all connectors, devices and wiring
. Finally do the same test at the battery during a start attempt.
Secondly, ‘High Voltage Spikes’
(Low voltage spikes don’t exist!)
These high voltage spikes can originate from many external sources, usually extremely high voltage yet with little current. These spikes can travel along any wiring circuit and can damage electronic devices like the fridge Motor Driver Module as their high voltage arcs across insulation
barriers specially on printed circuit boards etc. causing damage Trying to identify or eliminate these rapid spikes is futile. Best to accept that they can occur and protect against them, besides protection is simple and low cost albeit never providing 100% protection.
A simple Transient voltage clamp, AKA ‘Zorp’ or omni-directional DC voltage spike arrestor connected to the compressors DC input terminals (+ & -) is best. (As indicated in in the sketch below in yellow on the Motor Driver.) This will also protect other electronic devices connected to the same DC power supply. These things cost less than $2 and should be on all fridge / electronic equipment
but unfortunately they are not, so best to add one asap and that issue is resolved!
I hope this helps to prevent unnecessary fridge issues. ...
Click on sketch to expand.
Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems