Quote: Originally posted by Darren545 on 05/8/2008
The Conway's like the Pennine's are wired so that a battery is not neccesary if you don't want it. If you are always on EHU then a battery is not required, but as has been mentioned it is a good idea as a back up in case of a powercut.
As for blowing the transformer because there is no battery present; well I've never heard such nonsense. A transformer does exactly what it says i.e it transforms or converts 240V AC mains into 12V DC.
When your unit is plugged into the mains, and the transformer is on, all of your 12V appliances are running off the transformer, not the battery, regardless if you have a battery fitted.
Exactly, but you said it much better than I would have. All I would add is that if you DO have a battery AND plug it into an EHU, the transformer charges up the battery as well (for when it's needed in the future)
One possible reason that the transformer blew when not using a battery:
The transformer does convert 240v to 12v but porobaly only has a rating of 10amps(this is only an assumpumtion) therefore if all your appliances are running at the sametime off your transformer alone it may exceed the maximum rating and blow. When a battery is connected to the transformer it charges the battery but only takes a few amps to do so. The load from your appliances will draw from the battery which is able to handle much higher loads(Car starter moters take a lot of amps)and wont blow the transformer.
------------- Nothing matters half as much as you think it does!
When it's hooked up to the EHU, the charger drives the battery backwards and charges it by supplying just over 12V to the +ve terminal. So the appliances can't draw power from the battery. Plus there will be a 10amp fuse in the circuit so they couldn't take too many amps.
Complicated debate this is becoming isn't it?
I still think it's very simple, when you are on EHU the power comes from the EHU, and the battery charges. When you aren't on EHU, the battery supplies it. That's how car systems work, anyway.
Ive decided to get a battery for backup purposes. Im sorry to have started such a debate, but iy does make interesting eading from you experienced campers out there.
Quote:
I still think it's very simple, when you are on EHU the power comes from the EHU, and the battery charges. When you aren't on EHU, the battery supplies it. That's how car systems work, anyway.
That is correct as I understand it too (providing the relevant switches are in their correct positions )
In my owners manual is a very basic diagram showing the transformer with supply from mains and battery and outputs to 12V and 240V sockets. It clearly shows two separate outputs for the 12V wiring; one via the battery and one omiting the battery.
I have also had a play around with the transformer switch and three way toggle switch in different combinations, and from this it is fairly easy to work out how it's wired without having to crawl around the camper chasing wires
Our unit is a 2002 model so it is a fairly new unit, but older units almost certainly would have been a little different to this. Also keep in mind that some units will have aftermarket electrics fitted (either by an electrician or DIY) so may well be very different.
Ok here's my thoughts on the blown charger (can you tell that this debate is bugging me now )
We know that leaving a charger plugged into a mains socket and switched on is a potential fire hazard e.g. mobile phone chargers, due to the fact that they get very warm.
Meanwhile back at the camper . The charger is housed with and wired into the transformer so when the red switch on the transformer is switched on the charger automatically comes on also. If there is no battery in the circuit then the charger is in fact doing the same as our mobile phone charger i.e charging nothing but getting very warm. This is fine over short periods but I'm guessing that over a prolonged period it can most certainly cause the charger to blow.
To be safe, if there is no battery present I think I would turn off the transformer under the bunk when I was off out for the day.
Keep in mind that this is only my own meandering thoughts and I could be way off the mark but hey, it's a fun debate