dakota Posted September 22, 2013 Share Posted September 22, 2013 Recently ive come across quite a few people who use inverters in their vans to power toasters , microwaves etc etc , surely these things use a lot of battery power whilst running these appliances , now were entering the darker days of autumn/winter when the solar panels arnt charging the batteries so much wil they flatten their batterie quicker ?? Link to comment Share on other sites More sharing options...
Guest peter Posted September 22, 2013 Share Posted September 22, 2013 What do you think?. Link to comment Share on other sites More sharing options...
dakota Posted September 23, 2013 Author Share Posted September 23, 2013 My point being , why not use the gas oven and grill , i dont see the point in buying all these extra solar panels and inverters , when the facilaties are there anyway . Link to comment Share on other sites More sharing options...
Tracker Posted September 23, 2013 Share Posted September 23, 2013 dakota - 2013-09-23 1:25 PM My point being , why not use the gas oven and grill , I don't see the point in buying all these extra solar panels and inverters , when the facilities are there anyway . Fair enough - your choice - but some like to? By the way - I agree - we only use the inverter for the microwave which is so much quicker than a gas oven and a darned sight less hot when the van and weather is already warm enough - everything else is 12 v or gas! Link to comment Share on other sites More sharing options...
mikejkay Posted September 25, 2013 Share Posted September 25, 2013 Question(s).........what is the input power rating of your microwave? and have you checked the current draw from your battery? Is your microwave wired directly to the leisure battery? Do you run the engine while the microwave is on? Do youi use the microwave on full power? The reason for all these questions is that I am in the middle of fitting and extra 12v socket so that I can use a microwave. Even a 700w (output) microwave draws 900w to 1100w which is a huge current draw from a 12v battery. Anybody elses input/experiences would be welcome. I am intending to hard wire directly to the leisure battery (using as short wires as possible), use a continental lighter type socket, separately switched and fused. Link to comment Share on other sites More sharing options...
Tracker Posted September 26, 2013 Share Posted September 26, 2013 mikejkay - 2013-09-25 11:51 PM Question(s).........what is the input power rating of your microwave? and have you checked the current draw from your battery? Is your microwave wired directly to the leisure battery? Do you run the engine while the microwave is on? Do youi use the microwave on full power? The reason for all these questions is that I am in the middle of fitting and extra 12v socket so that I can use a microwave. Even a 700w (output) microwave draws 900w to 1100w which is a huge current draw from a 12v battery. Anybody elses input/experiences would be welcome. I am intending to hard wire directly to the leisure battery (using as short wires as possible), use a continental lighter type socket, separately switched and fused. Answers - 700 watts - no - no - no - yes. The microwave is rated at 700 watts output but up to 1400 watts surge on start up and I was advised that a 1500 watt inverter would be adequate and a 2000 watt inverter ideal. As I already had a 1500 watt inverter I reckoned that if it failed I would get a 2000 watt. But it has not - yet! DO NOT try and run a microwave via a 12 volt socket - you will do serious damage and might even start a fire. If you do not understand how it works PLEASE consider getting someone who does to fit it for you. The 12 volt input side of the inverter is wired directly to the batteries using very heavy duty starter or welding cables, keeping the cable runs as short as possible. Be very aware of the high potential risk of two wires touching and causing a short circuit when wiring up. If it does or you get the polarity wrong the very high current will give you a spectacular flash and bang and will cause damage. The microwave is then plugged into the 230v ac output 3 pin socket of the inverter Link to comment Share on other sites More sharing options...
mikejkay Posted September 26, 2013 Share Posted September 26, 2013 Thanks for the info. I have had many "spectacular flashes and bangs" and have the scars to prove it! I have opted for a 1500w inverter for the same reason as you have. You seem to say that the inverter is not hard wired to the battery, or have I misunderstood? (reading my original post I asked if the microwave is wired directly to the leisure battery, I meant the inverter 8-) ). If it is not hard wired, what sort of plug/socket are you using. Is your system fused? Link to comment Share on other sites More sharing options...
Tracker Posted September 26, 2013 Share Posted September 26, 2013 mikejkay - 2013-09-26 1:52 PM Thanks for the info. I have had many "spectacular flashes and bangs" and have the scars to prove it! I have opted for a 1500w inverter for the same reason as you have. You seem to say that the inverter is not hard wired to the battery, or have I misunderstood? (reading my original post I asked if the microwave is wired directly to the leisure battery, I meant the inverter 8-) ). If it is not hard wired, what sort of plug/socket are you using. Is your system fused? Sorry but I thought this was quite clear and unambiguous - please tell me what it is you do not follow? "The 12 volt input side of the inverter is wired directly to the batteries using very heavy duty starter or welding cables, keeping the cable runs as short as possible. Be very aware of the high potential risk of two wires touching and causing a short circuit when wiring up. If it does or you get the polarity wrong the very high current will give you a spectacular flash and bang and will cause damage. The microwave is then plugged into the 230v ac output 3 pin socket of the inverter" In our case the m/w lead is too short so I fitted a 230 v socket closer to the m/w and ran that back to the 230 v outlet on the inverter. I did not fuse the battery to inverter leads as the inverter supplier said there was no need because the inverter is internally fused. The mains leads already have fuses in the plugs. Link to comment Share on other sites More sharing options...
mikejkay Posted September 26, 2013 Share Posted September 26, 2013 Thanks, that clears that up. I didn't read your post properly. My problem is that my leisure battery is located in a box beneath the floor of the underbed stowage. I was looking for a way of connecting the inverter without having to lift the bed and grovel in order to switch on the inverter. I can easily run the 240v AC output to a bulkhead socket that would be accessible from outside the locker. I'm a little uneasy about leaving the inverter connected to the battery and hidden away in a locker even though there should be no current draw while the inverter is switched off. I will probably install a "proper" battery isolating switch that can be accessed from outside the locker. I expect to use a cannibilised set of jump leads for the low voltage wiring. My wiring will be negative directly to inverter, positive directly to inverter via a single pole isolating switch. The Inverter will be left switched on and located in a cage in order to allow air to circulate. The 240v AC output will be wired to a switched socket mounted on the bulkhead. The microwaves that I have been looking at have 700w output and 1000w to 1200w power input. Max current draw should therefore be 100a. Where did you get you information re startup surge? Link to comment Share on other sites More sharing options...
Tracker Posted September 26, 2013 Share Posted September 26, 2013 mikejkay - 2013-09-26 4:24 PM Where did you get you information re startup surge? Both on this forum and from the inverter suppliers. Jump leads may not be man enough for the purpose unless they are very good quality copper ones. Jump leads only have to work for a few seconds at a time with full starter load and even then many of them and especially the terminals and clamps can get very warm. With home made leads the weak point is the terminals. Starter leads with proper crimped terminals from a motor factor or Halfords may be better. The longer the lead the greater it's electrical resistance and thus the potential for voltage drop and this can be somewhat alleviated by using heavier cable and very secure terminals. You are asking a lot from one leisure battery and fitting a second would be advisable. In which case you will need to link them with the same heavy duty cable and preferably draw the inverter power from the positive of one battery and the negative of the other so they both contribute equally to supplying the power. An inverter draws about an amp when connected and switched on but not in use which is not a good idea as it will flatten the battery(ies). Inverters need an airflow around them as they can get very warm so inside a locker, even caged, may not be the best place? Can you fit ventilation grilles to help with airlow? Once it's all wired up and running feel all the joints and cables for acceptable heat after the m/w has been working for a few minutes and while it is still running. Link to comment Share on other sites More sharing options...
mikejkay Posted September 26, 2013 Share Posted September 26, 2013 Maybe it's back to the drawing board !!!!! Link to comment Share on other sites More sharing options...
Tracker Posted September 26, 2013 Share Posted September 26, 2013 mikejkay - 2013-09-26 5:39 PM Maybe it's back to the drawing board !!!!! Absolutely - great care is needed as there is a lot of power and a lot of heat potentially on the loose here and I don't have enough knowledge to advise fully. Perhaps a chat to an auto electrician experienced in the control of this sort of power and heat would be beneficial? Link to comment Share on other sites More sharing options...
mikejkay Posted September 27, 2013 Share Posted September 27, 2013 Just dug out a couple of sets of starter cables from the dark hole beneath the house that is supposed to be a garage. One set had 37 no. 0.22mm dia. aluminium wires which would be rated at 26 amps. I didn't bother to calculate the voltage drop. I remembered why they had been chucked in the garage, they were useless! The other set had 7 no. 1.3mm dia copper wires and would be rated at 154 amps. Looked good until I calculated that the voltage drop over a 1.5m circuit would be about 5 or 6 volts. Looks like I will need a minimum of 16mm sq. cable and 25mm sq would be better. Link to comment Share on other sites More sharing options...
Tracker Posted September 27, 2013 Share Posted September 27, 2013 mikejkay - 2013-09-27 5:22 PM Just dug out a couple of sets of starter cables from the dark hole beneath the house that is supposed to be a garage. One set had 37 no. 0.22mm dia. aluminium wires which would be rated at 26 amps. I didn't bother to calculate the voltage drop. I remembered why they had been chucked in the garage, they were useless! The other set had 7 no. 1.3mm dia copper wires and would be rated at 154 amps. Looked good until I calculated that the voltage drop over a 1.5m circuit would be about 5 or 6 volts. Looks like I will need a minimum of 16mm sq. cable and 25mm sq would be better. Agree about aluminium - not worth the hassle - but are you sure about the voltage drop on the copper leads because if so that means they would be useless as jump leads which are all generally longer than 1.5 metres? Link to comment Share on other sites More sharing options...
mikejkay Posted September 27, 2013 Share Posted September 27, 2013 I've given up on the idea of using cut down jump leads. Looks like I'll have to get some made up cables. I used an american website, http://www.powerstream.com/Wire_Size.htm, to calculate the voltage drop. I'll find another site to check as a 5 to 6v drop seems a lot. I am assuming that the calculated drop should be applied to the charging voltage of about 14.5v if the engine is running. I know that the inverter will switch off if the input voltage drops too much. Advertisers on ebay indicate that 16 mm sq cable is good for 107 amps but conveniently don't mention voltage drop. I wouldn't want to go with 16 mm sq only to find that it wasn't up to it. Link to comment Share on other sites More sharing options...
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