libby Posted July 22, 2008 Share Posted July 22, 2008 When returning home after a long time away and connecting to the 240v supply, the inboard power control 'hums' for a while. Please explain the technicalities as to why? LB Link to comment Share on other sites More sharing options...
Geoff Cole Posted July 22, 2008 Share Posted July 22, 2008 Hi Libby, It is most likely that the voltage and therefore current output of your on- board charger is higher than the output to your leasure battery from your vehicle alternator taking into account the losses incurred through relays and wiring, so your charger is probably working hard initialy. Vehicle alternators only supply single stage charging and there for only bring the battery to around 75% of its capacity. Your on board charger if it provides muti-stage charging will bring your battery up full charge. The hum you are hearing will be from the transformer in the unit, this is not unusual, battery chargers always hum when delivering a high charge, and is nothing to worry about, just make sure you have it well ventilated. hope this answers your query. Regards Geoff Link to comment Share on other sites More sharing options...
libby Posted July 22, 2008 Author Share Posted July 22, 2008 That is approximately what I thought. I'm well used to electrics in general but not M/H transformers, although I know their purpose. (Been welding for 64 years) Link to comment Share on other sites More sharing options...
tonyishuk Posted July 22, 2008 Share Posted July 22, 2008 Also the Rapido charging system will charge the Vehicle battery after it thinks it has charged the leisure battery. I have been told that some times having a "old" leisure battery can confuse the electronics. Maybe it defaults and charges both batteries at the same time and load causes it to hum. rgds. PS check the water level in the leisure battery, mine falls at a slow but steady rate when charged on the mains. Link to comment Share on other sites More sharing options...
ROON Posted July 22, 2008 Share Posted July 22, 2008 and that was a SIMPLE question :-( I've no chance :$ Link to comment Share on other sites More sharing options...
cronkle Posted July 23, 2008 Share Posted July 23, 2008 ROON - 2008-07-22 6:05 PM and that was a SIMPLE question :-( I've no chance :$ There is no such thing as a simple question about motorhomes. You should know that by now!! B-) :-> 8-) Link to comment Share on other sites More sharing options...
Clive Posted July 23, 2008 Share Posted July 23, 2008 May be the power supply needs a change of socks. Or perhaps because its working hard Or because its not bthe power supply but a contactor coil making the noise. Could be many things. C. Link to comment Share on other sites More sharing options...
djchapple Posted July 23, 2008 Share Posted July 23, 2008 The power supply in the Devon Monaco (PMS) has a built in fan that makes and audible hum from time to time. Link to comment Share on other sites More sharing options...
Mel B Posted July 23, 2008 Share Posted July 23, 2008 Our Rapido 709F did the same thing, we had it for nearly 4 years without a problem - I wouldn't worry about it. Link to comment Share on other sites More sharing options...
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