If the heater was giving out 450 W the dc input would be 450/12=37.5 amps plus effeciency losses in the inverter[ say 90%efficient,] so around 42A from the batteryr
The inverter VA rating is a bit of a catch as resisistive loads have a PF of 1.0
THe Continious load capacity in WATTS of an inverter capacity given in KVA will be dependent on the Actual PF that KVA rating is given at. THat Watt rating will be around 80<8 5% of the KVA.
PeterQ
-- Edited by oldtrack123 on Monday 23rd of June 2014 12:19:18 AM
SnowT said
12:14 AM Jun 23, 2014
If I was to use something Like that I think I would make up timer/thermostat system that controls when the heater is on and operational..
There are some great modern day thermostats that run off a couple of AA batteries, they have all the functionality that you could need..
- 24hr timer, on/off duty cycle..
- Digital temperature control..
The heater would be set to max temp, and controlled via the Thermostat..
Thank's Phil this topic has directed me to another system that could be quite feasible in a Lithium System..
Juergen
Phil C said
11:41 AM Jun 23, 2014
Aus-Kiwi wrote:
Would it be more efficient if temps were say 15* over night ?? With cosy sheets etc it would still be comfortable .. Like where we are at present it gets down to 10* I assume warmer in the house ?
I do agree Aus-Kiwi, that may be achieved by cycling the heater hour on hour off with a timer. We are very well insulated (our van was built 2013) so I can comfortably say we hold the temperature. Im still a great advocate for the electric blanket.
Safe travels
Phil C said
11:52 AM Jun 23, 2014
Dear all
Lets put a lid on this. Its been a very long time since I taught electronics/electrical theory, seems I may have made a few errors in my comments. The unit I believe uses semiconductor heating which is very efficient. I dont know if I miss measured the DC current on the input.
I am struggling to understand how these things work, and frankly, dont give a toss any more.
Most times at camp we use the electric blankets plugged into the inverter as it prolongs the battery life (only 150W) this can warm us all night with little stress on the battery capacity or performance. If you consider 4 hours of TV before 2200 to 0700 with the electric blankets going its working well.
My sincere apologies if I have offended anybody with some of my comments, one tends to fix "facts" in the head and the rest of the world is wrong
Take care and safe travels
Phil C said
05:32 PM Jun 23, 2014
Hi Guys
It seems my memory of my theory has left me. I apologise for any agro that my comments may have caused. My thinking is based on input current and output current being in phase.
Never mind, I will eat humble pie and retreat to the bush.
Irrespective, this is one great heater.
Safe travels
cooee said
09:54 PM Jun 23, 2014
Hi Phil
No need to retreat !
Thank you so much for your time and effort in trying to get a suitable heater for us nomads. Even if your heater uses more power than you first thought I think a few of us will still consider it for use when we have 240 power available either at home or on the road,
thanks
Dougwe said
05:49 AM Jun 24, 2014
If it works for you Phil, that's all that matters really.
Bryan said
08:45 AM Jun 24, 2014
cooee wrote:
Hi Phil
No need to retreat !
Thank you so much for your time and effort in trying to get a suitable heater for us nomads. Even if your heater uses more power than you first thought I think a few of us will still consider it for use when we have 240 power available either at home or on the road,
thanks
I second that.
Phil C said
10:27 AM Jun 24, 2014
Cheers guys, now that the true spirit of this forum.
Thanks heaps
Mr B2 said
01:21 AM Jun 27, 2014
I dont know, thats why I am asking,
How much drain would an Electric Blanket put on the Batterys, 240 volt double bed Blanket,
I have two 8 D batterys, Would 270 Watts of Solar Panels cope with the drain on the Batterys from the blanket,
I have a 5000 Watt Invertor, With a 10,000 watt surge, I dont have a Generator and dont use C/P's, I only free camp,
Every thing else is 12 volt, including the TV,
Phil C said
10:13 AM Jun 27, 2014
Hi Brian
Im not sure what 8D batteries are. If they are around 100AH each then you should be OK with the electric blankets, my advise is to try it and see.
Make sure you are all charged up to 100% and do a night with the blankets on the inverter. Your batteries may need a suplimentary charge next day as solar panels can only put out limited current. The blankets cycle on and off during the night on lower settings so just have them set to keep the cold away, not to roast you
We have new sunbeam queen size electric blankets (150W according to the spec sheet) 2 110AH batteries 2500W inverter and one 120W solar panel. We ran lights, TV (for 4 hours before bed) and the blankets on the batteries, the batteries needed a big charge from the mains the next day (peaked at 10Amps) BUT we survived the cold night and thats the aim of the game. Therefore it may be wise to invest in a generator.
I love the idea of free camps 100% of the time, however we get a little skittish when we hear of problems with hoons and local dills, how do you protect yourselves? I was thinking of investing in a cattle prod.
Safe travels
Mr B2 said
11:33 AM Jun 27, 2014
Hi Phil, Thank you for that info,
My Batterys are Lead Acid 12 volt deep cycle, 8D RV, Weigh 130 Lbs each, (48 KGS) 245 Amp Hours each, so a total of 490 Amp hours combined together,
One is the coach Battery and one is the start battery, The motor charges both when driving, I have a boost switch that plugs both in when starting the motor,
I also carry another smaller battery just in case, AGM 12 volt, 200 amp hours which I keep fully charged, Its not connected, I have Huge Jumper cables, 400 amp welding cable,
You need big muscles to move these mongrels around, They are very heavy, I do have weight problem with my coach, I need to put another ton in the front of it to lower it down, Spare wheel on a frame at the front might do it, Its the only place it can go,
I took the Genny and the Gas tank out, 150 US gallon Propane tank, Both probably getting close to a ton and a half, So the front of the coach is up in the air, I replaced the gas tank with 3 X 9 Lbers, using one bottle at a time, Inconvenient, But I know how much gas I have left at any time, The steel frame and the 3mm sheet enclosures, Plus moving the batterys forwards helped, but still not enough weight in the front,
I didnt know you could get 12 volt electric blankets, Do they suck as much power as a 240 volt Blanket, ???????? I really dont want or need an invertor, It would have been only for a blanket, 240 volt,
I dont have problems with Hoons, Local Dills, Etc, But thats just me, People seem to be wary of me, and leave me alone, I dont like crowds, So I camp in quiet spots,
Here's one for your nutter to ponder, I just thought of it,
I have a 10 KVA transformer in the Coach for the 240 volt mains power to use the 110 Volt accessories I have still left in the coach, A/C's Etc, I wont be using either of the A/C's, The insulation copes very well with the heat and cold we have here, + 38C to - 4C so far,
Could I run leads from the Battery thru the 240 volt Invertor Pure Sine to the 10 KVA Transformer and run the 110 volt accessories, Microwave, Mixmaster, Vacuum cleaner,
Electric blanket, Only for short periods,
I could use the spare battery for this, and it would not be connected to the Coach in any way, Other than thru the invertor and then the Transformer,
The spare battery would be disconnected to charge it,
Aus-Kiwi said
01:39 PM Jun 27, 2014
Aha get some meat or fat on your bones ahahaha
Phil C said
04:48 PM Jun 27, 2014
Hi Brian
The deal with invereters is to have the thickest cable (I have 2 10mm sq cables each for pos and neg) and the shortest distance between battery and inverter. Your inverter will draw a lot of current from the battery so get some thick cables, be sure to fuse or use a DC circuit breaker in the DC circuit. I probably wouldnt use the invereter for the vacuum cleaner or anything with a larger motor, as at start up the motor can draw a lot of current which could shut the inverter down. That being said, dont be afraid to give things a go, if it fails there will be no damage done.
For 12V electric blanket I would use 6mm sq cable to a fuse (say 25Amp) to the cigarette lighter outlet ONLY for the blanket.
I agree about the aircon etc, we hardly use ours except on very hot nights. We have 2 300mm 12V fans, electric blankets and the convection heater.
Rule of thumb, at 12V you will need a much larger current=larger cables to get the same heat (say 240W) than 240VAC. Its 20Amps Vs 1 amp, go figure. This makes a good case for inverters and/or generators.
Electrics in caravans and RVs can be a minefield if you dont get it right, I would talk to a qualified sparky or use this forum before picking up a spanner or screwdriver. There are some special techniques in electrical servicing that can be dangerous if done incorrectly. Sorry to tell you that one.
Aus-Kiwi I agree about the fat on the bones, I have enough for a few.
Safe travels
BTW, your batteries sound like they are up to the task.
Your question on the transformer being run by the inverter, technically in practice I would imagine a very large startup current in the transformer primary as it is highly inductive, so probably not a good idea to do that. With stuff like aircons, transformers etc they are highly inductive and draw a heap of current for a few milli seconds at startup.
-- Edited by Phil C on Friday 27th of June 2014 04:49:37 PM
-- Edited by Phil C on Friday 27th of June 2014 04:56:41 PM
Mr B2 said
06:19 PM Jun 27, 2014
The electrics were all done by Professionals, and approved,
The lead from the outside plug, remote 240 to the Transformer is one single lead, If I remove that totally, Could I put the leads from the invertor directly onto the transformer,
So it will be down to just the Microwave and the Built in Food Processor, (Mixmaster,) Thats all I want to use, Fridge and Heaters, Pumps, Dunny, Shower and Bath, Fans, are Gas and 12 volt,
This is from the Spare battery that is not connected to anything, My invertor is Five Thousand Watts, Pure Sine,
The vacuum cleaner is just a waste of space, Like the Icemaker and Garbage compactor, They all work connected to the 240 extension lead outside, Inc the A/C units, But I wont be using them at all.
I want to go full 12 volt, and no 240 at all, If I buy a Gennie, It will be only 12 Volt to charge the batterys,,
Mr B2 said
06:21 PM Jun 27, 2014
I like being thin, Its too hard to get the fat off me, so I dont put it on to start with, Hahahaha I just lot a stone,
oldtrack123 said
10:41 PM Jun 27, 2014
Mr B2 wrote:
{1] I took the Genny and the Gas tank out, 150 US gallon Propane tank, Both probably getting close to a ton and a half, So the front of the coach is up in the air, I replaced the gas tank with 3 X 9 Lbers, using one bottle at a time, Inconvenient, But I know how much gas I have left at any time, The steel frame and the 3mm sheet enclosures, Plus moving the batterys forwards helped, but still not enough weight in the front,
[2]I didnt know you could get 12 volt electric blankets, Do they suck as much power as a 240 volt Blanket, ???????? I really dont want or need an invertor, It would have been only for a blanket, 240 volt,
I dont have problems with Hoons, Local Dills, Etc, But thats just me, People seem to be wary of me, and leave me alone, I dont like crowds, So I camp in quiet spots,
Here's one for your nutter to ponder, I just thought of it,
[3]I have a 10 KVA transformer in the Coach for the 240 volt mains power to use the 110 Volt accessories I have still left in the coach, A/C's Etc, I wont be using either of the A/C's, The insulation copes very well with the heat and cold we have here, + 38C to - 4C so far,
Could I run leads from the Battery thru the 240 volt Invertor Pure Sine to the 10 KVA Transformer and run the 110 volt accessories, Microwave, Mixmaster, Vacuum cleaner, Electric blanket, Only for short periods, I could use the spare battery for this, and it would not be connected to the Coach in any way, Other than thru the invertor and then the Transformer,
The spare battery would be disconnected to charge it,
Hi
[1]Well, I hope all that work was done by a licensed GAS fitter who testdd ALL the appliances , regulators pipe work etc & issued you with a compliance certificate
[2]THe power of the blankets should be shown on th label or in the specs curent draw of the blankets
That can range from as low as 95W <200W
So it is the WATTS rating that deitermines how much power they use.
100W at 12V uses the same amount of power as 100W @ 240V, this has been explained in previous posts to this thread
[3]So you have a nonapproved set up with THAT transformer It does not comply to the Aust Electrical Standards
You have enough safety risks now with out adding anymore, by running that transformer off an inverter!!!
PeterQ
Phil C said
01:23 PM Jun 29, 2014
oldtrack123 wrote:
Mr B2 wrote:
{1] I took the Genny and the Gas tank out, 150 US gallon Propane tank, Both probably getting close to a ton and a half, So the front of the coach is up in the air, I replaced the gas tank with 3 X 9 Lbers, using one bottle at a time, Inconvenient, But I know how much gas I have left at any time, The steel frame and the 3mm sheet enclosures, Plus moving the batterys forwards helped, but still not enough weight in the front,
[2]I didnt know you could get 12 volt electric blankets, Do they suck as much power as a 240 volt Blanket, ???????? I really dont want or need an invertor, It would have been only for a blanket, 240 volt,
I dont have problems with Hoons, Local Dills, Etc, But thats just me, People seem to be wary of me, and leave me alone, I dont like crowds, So I camp in quiet spots,
Here's one for your nutter to ponder, I just thought of it,
[3]I have a 10 KVA transformer in the Coach for the 240 volt mains power to use the 110 Volt accessories I have still left in the coach, A/C's Etc, I wont be using either of the A/C's, The insulation copes very well with the heat and cold we have here, + 38C to - 4C so far,
Could I run leads from the Battery thru the 240 volt Invertor Pure Sine to the 10 KVA Transformer and run the 110 volt accessories, Microwave, Mixmaster, Vacuum cleaner, Electric blanket, Only for short periods, I could use the spare battery for this, and it would not be connected to the Coach in any way, Other than thru the invertor and then the Transformer,
The spare battery would be disconnected to charge it,
Hi
[1]Well, I hope all that work was done by a licensed GAS fitter who testdd ALL the appliances , regulators pipe work etc & issued you with a compliance certificate
[2]THe power of the blankets should be shown on th label or in the specs curent draw of the blankets
That can range from as low as 95W <200W
So it is the WATTS rating that deitermines how much power they use.
100W at 12V uses the same amount of power as 100W @ 240V, this has been explained in previous posts to this thread
[3]So you have a nonapproved set up with THAT transformer It does not comply to the Aust Electrical Standards
You have enough safety risks now with out adding anymore, by running that transformer off an inverter!!!
PeterQ
Mr B2
You raise some important safety issues here as does PeterQ. OK lets cut to the chase.
If you allow a safety margin when you hook up the inverter to the transformer eg a normal DC fuse in the battery line, and be very aware of crackles and dirty acrid smells I say give it a go, just make sure NOTHING is connected to the 110V side, then connect each appliance in turn then try multiple appliances.
I would be very interested in the results, just dont blow the crap out of yourself and your equipment.
PhilC
turbopete said
06:13 PM Jun 29, 2014
Use a gasheater buttttt make sure u have ventilation
HI
450W is 450Watts, does not matter if AC or DC
If the heater was giving out 450 W the dc input would be 450/12=37.5 amps plus effeciency losses in the inverter[ say 90%efficient,] so around 42A from the batteryr
The inverter VA rating is a bit of a catch as resisistive loads have a PF of 1.0
THe Continious load capacity in WATTS of an inverter capacity given in KVA will be dependent on the Actual PF that KVA rating is given at. THat Watt rating will be around 80<8 5% of the KVA.
PeterQ
-- Edited by oldtrack123 on Monday 23rd of June 2014 12:19:18 AM
There are some great modern day thermostats that run off a couple of AA batteries, they have all the functionality that you could need..
- 24hr timer, on/off duty cycle..
- Digital temperature control..
The heater would be set to max temp, and controlled via the Thermostat..
Thank's Phil this topic has directed me to another system that could be quite feasible in a Lithium System..
Juergen
I do agree Aus-Kiwi, that may be achieved by cycling the heater hour on hour off with a timer. We are very well insulated (our van was built 2013) so I can comfortably say we hold the temperature. Im still a great advocate for the electric blanket.
Safe travels
Lets put a lid on this. Its been a very long time since I taught electronics/electrical theory, seems I may have made a few errors in my comments. The unit I believe uses semiconductor heating which is very efficient. I dont know if I miss measured the DC current on the input.
I am struggling to understand how these things work, and frankly, dont give a toss any more.
Most times at camp we use the electric blankets plugged into the inverter as it prolongs the battery life (only 150W) this can warm us all night with little stress on the battery capacity or performance. If you consider 4 hours of TV before 2200 to 0700 with the electric blankets going its working well.
My sincere apologies if I have offended anybody with some of my comments, one tends to fix "facts" in the head and the rest of the world is wrong
Take care and safe travels
It seems my memory of my theory has left me. I apologise for any agro that my comments may have caused. My thinking is based on input current and output current being in phase.
Never mind, I will eat humble pie and retreat to the bush.
Irrespective, this is one great heater.
Safe travels
Hi Phil
No need to retreat !
Thank you so much for your time and effort in trying to get a suitable heater for us nomads. Even if your heater uses more power than you first thought I think a few of us will still consider it for use when we have 240 power available either at home or on the road,
thanks
I second that.
Thanks heaps
I dont know, thats why I am asking,
How much drain would an Electric Blanket put on the Batterys, 240 volt double bed Blanket,
I have two 8 D batterys, Would 270 Watts of Solar Panels cope with the drain on the Batterys from the blanket,
I have a 5000 Watt Invertor, With a 10,000 watt surge, I dont have a Generator and dont use C/P's, I only free camp,
Every thing else is 12 volt, including the TV,
Im not sure what 8D batteries are. If they are around 100AH each then you should be OK with the electric blankets, my advise is to try it and see.
Make sure you are all charged up to 100% and do a night with the blankets on the inverter. Your batteries may need a suplimentary charge next day as solar panels can only put out limited current. The blankets cycle on and off during the night on lower settings so just have them set to keep the cold away, not to roast you
We have new sunbeam queen size electric blankets (150W according to the spec sheet) 2 110AH batteries 2500W inverter and one 120W solar panel. We ran lights, TV (for 4 hours before bed) and the blankets on the batteries, the batteries needed a big charge from the mains the next day (peaked at 10Amps) BUT we survived the cold night and thats the aim of the game. Therefore it may be wise to invest in a generator.
I love the idea of free camps 100% of the time, however we get a little skittish when we hear of problems with hoons and local dills, how do you protect yourselves? I was thinking of investing in a cattle prod.
Safe travels
Hi Phil, Thank you for that info,
My Batterys are Lead Acid 12 volt deep cycle, 8D RV, Weigh 130 Lbs each, (48 KGS) 245 Amp Hours each, so a total of 490 Amp hours combined together,
One is the coach Battery and one is the start battery, The motor charges both when driving, I have a boost switch that plugs both in when starting the motor,
I also carry another smaller battery just in case, AGM 12 volt, 200 amp hours which I keep fully charged, Its not connected, I have Huge Jumper cables, 400 amp welding cable,
You need big muscles to move these mongrels around, They are very heavy, I do have weight problem with my coach, I need to put another ton in the front of it to lower it down, Spare wheel on a frame at the front might do it, Its the only place it can go,
I took the Genny and the Gas tank out, 150 US gallon Propane tank, Both probably getting close to a ton and a half, So the front of the coach is up in the air, I replaced the gas tank with 3 X 9 Lbers, using one bottle at a time, Inconvenient, But I know how much gas I have left at any time, The steel frame and the 3mm sheet enclosures, Plus moving the batterys forwards helped, but still not enough weight in the front,
I didnt know you could get 12 volt electric blankets, Do they suck as much power as a 240 volt Blanket, ???????? I really dont want or need an invertor, It would have been only for a blanket, 240 volt,
I dont have problems with Hoons, Local Dills, Etc, But thats just me, People seem to be wary of me, and leave me alone, I dont like crowds, So I camp in quiet spots,
Here's one for your nutter to ponder, I just thought of it,
I have a 10 KVA transformer in the Coach for the 240 volt mains power to use the 110 Volt accessories I have still left in the coach, A/C's Etc, I wont be using either of the A/C's, The insulation copes very well with the heat and cold we have here, + 38C to - 4C so far,
Could I run leads from the Battery thru the 240 volt Invertor Pure Sine to the 10 KVA Transformer and run the 110 volt accessories, Microwave, Mixmaster, Vacuum cleaner,
Electric blanket, Only for short periods,
I could use the spare battery for this, and it would not be connected to the Coach in any way, Other than thru the invertor and then the Transformer,
The spare battery would be disconnected to charge it,
Hi Brian
The deal with invereters is to have the thickest cable (I have 2 10mm sq cables each for pos and neg) and the shortest distance between battery and inverter. Your inverter will draw a lot of current from the battery so get some thick cables, be sure to fuse or use a DC circuit breaker in the DC circuit. I probably wouldnt use the invereter for the vacuum cleaner or anything with a larger motor, as at start up the motor can draw a lot of current which could shut the inverter down. That being said, dont be afraid to give things a go, if it fails there will be no damage done.
For 12V electric blanket I would use 6mm sq cable to a fuse (say 25Amp) to the cigarette lighter outlet ONLY for the blanket.
I agree about the aircon etc, we hardly use ours except on very hot nights. We have 2 300mm 12V fans, electric blankets and the convection heater.
Rule of thumb, at 12V you will need a much larger current=larger cables to get the same heat (say 240W) than 240VAC. Its 20Amps Vs 1 amp, go figure. This makes a good case for inverters and/or generators.
Electrics in caravans and RVs can be a minefield if you dont get it right, I would talk to a qualified sparky or use this forum before picking up a spanner or screwdriver. There are some special techniques in electrical servicing that can be dangerous if done incorrectly. Sorry to tell you that one.
Aus-Kiwi I agree about the fat on the bones, I have enough for a few.
Safe travels
BTW, your batteries sound like they are up to the task.
Your question on the transformer being run by the inverter, technically in practice I would imagine a very large startup current in the transformer primary as it is highly inductive, so probably not a good idea to do that. With stuff like aircons, transformers etc they are highly inductive and draw a heap of current for a few milli seconds at startup.
-- Edited by Phil C on Friday 27th of June 2014 04:49:37 PM
-- Edited by Phil C on Friday 27th of June 2014 04:56:41 PM
The electrics were all done by Professionals, and approved,
The lead from the outside plug, remote 240 to the Transformer is one single lead, If I remove that totally, Could I put the leads from the invertor directly onto the transformer,
So it will be down to just the Microwave and the Built in Food Processor, (Mixmaster,) Thats all I want to use, Fridge and Heaters, Pumps, Dunny, Shower and Bath, Fans, are Gas and 12 volt,
This is from the Spare battery that is not connected to anything, My invertor is Five Thousand Watts, Pure Sine,
The vacuum cleaner is just a waste of space, Like the Icemaker and Garbage compactor, They all work connected to the 240 extension lead outside, Inc the A/C units, But I wont be using them at all.
I want to go full 12 volt, and no 240 at all, If I buy a Gennie, It will be only 12 Volt to charge the batterys,,
I like being thin, Its too hard to get the fat off me, so I dont put it on to start with, Hahahaha I just lot a stone,
Hi
[1]Well, I hope all that work was done by a licensed GAS fitter who testdd ALL the appliances , regulators pipe work etc & issued you with a compliance certificate
[2]THe power of the blankets should be shown on th label or in the specs curent draw of the blankets
That can range from as low as 95W <200W
So it is the WATTS rating that deitermines how much power they use.
100W at 12V uses the same amount of power as 100W @ 240V, this has been explained in previous posts to this thread
[3]So you have a nonapproved set up with THAT transformer It does not comply to the Aust Electrical Standards
You have enough safety risks now with out adding anymore, by running that transformer off an inverter!!!
PeterQ
Mr B2
You raise some important safety issues here as does PeterQ. OK lets cut to the chase.
If you allow a safety margin when you hook up the inverter to the transformer eg a normal DC fuse in the battery line, and be very aware of crackles and dirty acrid smells I say give it a go, just make sure NOTHING is connected to the 110V side, then connect each appliance in turn then try multiple appliances.
I would be very interested in the results, just dont blow the crap out of yourself and your equipment.
PhilC