Connecting 230v fridge to solar batteries via 1000w continuous pure sine wave inverter,
Bent Axle Bob said
06:34 PM Mar 16, 2015
Kia Ora Everyone, it's been a while since last on the forum and I need some advice on the heading subject.
My fridge is a TLC 115 litre bar fridge, plate states current 1 amp, input power 100watts, inverter 1000w continuos 2000watt surge pure sine wave inverter. 3 x100w panels feeding via mppt reg to 2x 200watt deep cycle agm batteries. Distance from batteries to inverter = 50cm . Connecting direct to batteries, what size inline fuse should I use, and will the inverter handle the load?
madaboutled said
09:33 PM Mar 16, 2015
Short answer = NO
Long Answer...... At most your panels will produce 25AH and that's really best case senario. If you got really good sun everyday for at least 6 hours (when does that ever happen) then you'll get theriodically 150Amps back into your batteries on one day. Your Bar Fridge will use 100 Watts per Hour x 24 Hours = 2400 Watts divided that by 12Volts = 200AH per day. Assuming best sunlight everyday your batteries are going south to the tune of 50Amps per day.
Note these calculations are very rough and doesn't take into account what the Inverter itself will use to convert 12 volt to 240 volt or anything else you mights be running like lights etc... The inverter would be fine, you'd just need more batteries and panels, and perfect weather everyday!.
Best Advice, chuck the 230v bar fridge & buy an Engel or whatever 12v fridge.
-- Edited by madaboutled on Monday 16th of March 2015 09:37:45 PM
-- Edited by madaboutled on Monday 16th of March 2015 09:40:13 PM
Bent Axle Bob said
10:41 PM Mar 16, 2015
Thanks for that, great answer and easy to understand. It looks like the old Engle 12v gets resurrected for another run around.
-- Edited by PeterD on Tuesday 17th of March 2015 12:06:56 AM
Jaahn said
09:22 AM Mar 17, 2015
Hi Bob,
Not sure about the analysis given so far. In fact I would think it is hard to follow because the confusion of incorrect units, of amps and amphrs and amps per hr.
So I would give this analysis for the benefit of others who are interested in the discussion.The figures have been rounded a bit.
The fridge uses 100 Watts and that translates when converted to about 8amps at 12 volts.
So the 240v inverter needs about 10 amps allowing for losses. The fridge may run for about 75% of the time
So the amp hrs used over 24hrs are about 180 amp hrs per day.
The 300W panels produce about 20amps for about 6hrs (?) so that is 180amp hrs each winter day. More in summer I think, perhaps depending on the setup.
That looks like a rough match for very average solar conditions.
The batteries are about right for overnight storage but two days would be max for safe use without charge. The inverter should be OK to run that.
Cheers Jaahn
-- Edited by Jaahn on Tuesday 17th of March 2015 09:53:26 AM
-- Edited by PeterD on Tuesday 17th of March 2015 12:06:56 AM
Just a note of caution - This test was done in 2003.
Technology would have improved markedly since then I would imagine.
madaboutled said
01:16 PM Mar 17, 2015
Jaahn wrote:
Hi Bob,
Not sure about the analysis given so far. In fact I would think it is hard to follow because the confusion of incorrect units, of amps and amphrs and amps per hr.
So I would give this analysis for the benefit of others who are interested in the discussion.The figures have been rounded a bit.
The fridge uses 100 Watts and that translates when converted to about 8amps at 12 volts.
So the 240v inverter needs about 10 amps allowing for losses. The fridge may run for about 75% of the time
So the amp hrs used over 24hrs are about 180 amp hrs per day.
The 300W panels produce about 20amps for about 6hrs (?) so that is 180amp hrs each winter day. More in summer I think, perhaps depending on the setup.
That looks like a rough match for very average solar conditions.
The batteries are about right for overnight storage but two days would be max for safe use without charge. The inverter should be OK to run that.
Cheers Jaahn
I sometimes get a canning from someone on tech terms like amps and amphrs and amps per hr when using the KISS method to try to explain something with the aim of being easily understood, however from Bob's reply I think I achieved that, and so to Bob.... your welcome. Note to self in future try to use the correct tech terms in the appropriate places.
In my defence of other some points above I did say "Note these calculations are very rough" that point seems to have been lost and yes you are correct in saying "The fridge may run for about 75% of the time" however I believe in running calculations at worst case scenario and not second guessing at what things might run at.
Also on the comment "The 300W panels produce about 20amps for about 6hrs (?) so that is 180amp hrs each winter day. More in summer I think, perhaps depending on the setup. That looks like a rough match for very average solar conditions." My line said "At most your panels will produce 25AH and that's really best case scenario" OK it should have said amps per hour I'm just glad Bob understood what I meant.
At the end of the day we both agree that Bob's system would be inadequate for anything longer than about 2 days. However, my very rough analysis did show that the power being used was going to be greater than the power being replaced and that I think was what the information that Bob was after.
Regards Steve.
Bent Axle Bob said
02:19 PM Mar 17, 2015
Thanks to all for your input. I was unsure about installing the bar fridge and that is why I asked for your help and ideas. I was hoping there would be a little more reserve power storage, and even though I am heading north of Karratha and suspect I would probably harvest a bit more energy daily, it would still be a bit close. So, as I said , the old 12v/230v Engel upright will be installed for one last trip
madaboutled said
02:38 PM Mar 17, 2015
Bent Axle Bob wrote:
the old 12v/230v Engel upright will be installed for one last trip
Good move Bob, enjoy your trip we might even meet on the road somewhere???, heading that way ourselves in a few weeks.
But what's this "one last trip" just keep going til you can't!.
All the best Steve.
Muddy said
05:21 PM Mar 18, 2015
A 1000w inverter will handle a 230W load.....obviously. The inverter will do the job but your set up is way under rated for the load you propose. Is your fridge rated at 1A if so this will draw up to 230W on a 230V system and not 100W so I'm choosing to ignore the 100W input power bit at this stage because it's misleading.
So if the fridge draws 1A maximum on the inverter output side which at 230V = 230W, The current in the 12V supply would be 230W /12V = 20A (rounded up). Then inverter efficiency must be taken into account so divide the amps by 0.85 and you end up with 24A (again rounded up). The inverter supply fuse rating must be slightly above the calculated max current draw OF THE DEVICE and some 15% below the rating of the cabling supplying it. So if your inverter is fully loaded at 1000w then using the same formula 1000W/12v/.85=98A then I'm guessing that to obtain a full load output from the inverter, your 12V supply leads will be rated appropriately fuse could be around 100A. Remember that if you fuse the inverter with one rated for just the fridge, you will blow the fuse each time you plug another device in so fuse your inverter to the right level. Consult with your inverters instructions or talk to the manufacturer or supplier.
The batteries capacities are measured in AH (Ampere hours) not Watts. So you have (when fully charged) 400A to discharge (could be 400A in 1 hour or 40A over 10 hours etc), divide this by 2 (because you should not discharge AGM Batteries below half charge) so this becomes 200A and so 200AH/24A = 8.4Hrs of running the fridge (flat out) before you really should turn it off to charge the batteries. Not good!
If your solar panels are optimized for direction and angle (mobile) you will generate at 25Amps max. If your fridge is running flat chat drawing 24A on a hot day you will not cope as the solar panels output reduces on hotter days by some margin. (They are most efficient on cold sunny days) Problem is, your fridge could be running continuously (all night) but the sun doesn't and so your daily input would be around 300A 6hrs at optimum generating power and assuming the panels are roof top mounted and not mobile and therefore will not be directed perfectly at the sun) and your daily draw is around 24 x 24 = 576A (assuming max current which is always best) But even if the fridge is never opened (cough, er did someone say Bar fridge) the draw over 24 hours will likely discharge your batteries to near flat each day. You will be replacing them very early and we haven't accounted for rainy days yet!!! Basically, it can be done but you have dedicated some expensive and unnecessary kit to JUST keeping your fridge going and not much else. Agree with Maboutled, buy a 12V fridge for sure. Nothing like a coldy on a hot rainy day!
Just a note of caution - This test was done in 2003.
Technology would have improved markedly since then I would imagine.
Yes, technology has improved, mainly in the larger fridges, less so the bar fridge size. It also has in the 12 V fridges. Please prove to me that technology in 12 V fridges has moved at a lesser pace than bar fridges.
Bill B said
10:38 PM Mar 18, 2015
PeterD wrote:
Yes, technology has improved, mainly in the larger fridges, less so the bar fridge size. It also has in the 12 V fridges. Please prove to me that technology in 12 V fridges has moved at a lesser pace than bar fridges.
Did I say that it had.
I was merely pointing out that the article was written 13 years ago.
Jaahn said
09:00 AM Mar 19, 2015
Muddy wrote:
A 1000w inverter will handle a 230W load.....obviously. The inverter will do the job but your set up is way under rated for the load you propose. Is your fridge rated at 1A if so this will draw up to 230W on a 230V system and not 100W so I'm choosing to ignore the 100W input power bit at this stage because it's misleading.
So if the fridge draws 1A maximum on the inverter output side which at 230V = 230W, The current in the 12V supply would be 230W /12V = 20A (rounded up). Then inverter efficiency must be taken into account so divide the amps by 0.85 and you end up with 24A (again rounded up). The inverter supply fuse rating must be slightly above the calculated max current draw OF THE DEVICE and some 15% below the rating of the cabling supplying it. So if your inverter is fully loaded at 1000w then using the same formula 1000W/12v/.85=98A then I'm guessing that to obtain a full load output from the inverter, your 12V supply leads will be rated appropriately fuse could be around 100A. Remember that if you fuse the inverter with one rated for just the fridge, you will blow the fuse each time you plug another device in so fuse your inverter to the right level. Consult with your inverters instructions or talk to the manufacturer or supplier.
The batteries capacities are measured in AH (Ampere hours) not Watts. So you have (when fully charged) 400A to discharge (could be 400A in 1 hour or 40A over 10 hours etc), divide this by 2 (because you should not discharge AGM Batteries below half charge) so this becomes 200A and so 200AH/24A = 8.4Hrs of running the fridge (flat out) before you really should turn it off to charge the batteries. Not good!
If your solar panels are optimized for direction and angle (mobile) you will generate at 25Amps max. If your fridge is running flat chat drawing 24A on a hot day you will not cope as the solar panels output reduces on hotter days by some margin. (They are most efficient on cold sunny days) Problem is, your fridge could be running continuously (all night) but the sun doesn't and so your daily input would be around 300A 6hrs at optimum generating power and assuming the panels are roof top mounted and not mobile and therefore will not be directed perfectly at the sun) and your daily draw is around 24 x 24 = 576A (assuming max current which is always best) But even if the fridge is never opened (cough, er did someone say Bar fridge) the draw over 24 hours will likely discharge your batteries to near flat each day. You will be replacing them very early and we haven't accounted for rainy days yet!!! Basically, it can be done but you have dedicated some expensive and unnecessary kit to JUST keeping your fridge going and not much else. Agree with Maboutled, buy a 12V fridge for sure. Nothing like a coldy on a hot rainy day!
Hi Muddy and all,
I write this to promote a good discussion not to argue. This seems a topic which people are interested in, so some correct answers would be helpful. Your analysis is good, but.....
Muddy has made an assumption that the 1A at 240V is a better assumption for power use that the 100W. I do not believe this is correct. That current is the max start current. From my experience 100 Watts is about correct for a small fridge. So basing the power usage on this is OK IMHO and having been inverted from 12v to 240 will draw about 10amps+ at the low voltage end, depending on the quality of the wiring and the state of charge of the batteries.
The inverter must be well oversized to start a fridge or it will trip out on overload or low voltage. Up to 4x or 5x the rated power is needed to "kick them away". Depends on the inverter AND the wiring too. If the wiring is a bit poor the inverter will not handle the surge needed because the voltage drops too low. Note this surge when sizing the wires and the fuse. As Muddy said above the full capacity of the inverter should be allowed for i.e. actually 1000W cont- 2000W surge.
Most bar fridges would benefit from a layer of foam insulation glued on the sides and top. Door too.They have minimal insulation.
Cheers Jaahn
-- Edited by Jaahn on Thursday 19th of March 2015 09:06:42 AM
-- Edited by Jaahn on Thursday 19th of March 2015 09:08:52 AM
DeBe said
10:50 AM Mar 19, 2015
Newer bar fridges have the condencer built in to the sides of the fridge. If you stick insulation on the sides of these it wont work very well.
Muddy said
04:46 PM Mar 19, 2015
Hi all and Jaaahn.
If you have experience of bar fridges and related wattages I bow to your greater knowledge. I just wanted to say that I didn't say that the 1A was a "better" figure to use, just that I was confused...it happens... and wanted to allow for worst case scenario. I agree that start up currents are higher with AC machines and can be more than your quoted figure of 4 -5 times.
So at 100W the current draw will be 100/12/0.85 = 9.8A (not 20) giving essentially twice the amount of run time than I quoted initially. Daily draw 240A - Daily input (when sunny) 300A so provided you enjoy non cloudy days you will be OK. I would still favour not using it as you could run a 1battery set up with a 12V compressor fridge with one panel for 4 days without sun. Save weight (fuel costs) and set up cost (unless you already have. The temptation will be to run your batteries flat after you have had 2 cloudy days which will cost you for two new batteries ($800)? after not too many trips. AGM's HATE running below 50%
Thanks for the pointer Jaahn, good luck Bent Axle Bob
oldtrack123 said
07:01 PM Mar 19, 2015
Muddy wrote:
A 1000w inverter will handle a 230W load.....obviously. The inverter will do the job but your set up is way under rated for the load you propose
[1]is your fridge rated at 1A if so this will draw up to 230W on a 230V system and not 100W so I'm choosing to ignore the 100W input power bit at this stage because it's misleading.
[2]if the fridge draws 1A maximum on the inverter output side which at 230V = 230W, The current in the 12V supply would be 230W /12V = 20A (rounded up). \
Then inverter efficiency must be taken into account so divide the amps by 0.85 and you end up with 24A (again rounded up). The inverter supply fuse rating must be slightly above the calculated max current draw OF THE DEVICE and some 15% below the rating of the cabling supplying it. So if your inverter is fully loaded at 1000w then using the same formula 1000W/12v/.85=98A then I'm guessing that to obtain a full load output from the inverter, your 12V supply leads will be rated appropriately fuse could be around 100A. Remember that if you fuse the inverter with one rated for just the fridge, you will blow the fuse each time you plug another device in so fuse your inverter to the right level. Consult with your inverters instructions or talk to the manufacturer or supplier.
The batteries capacities are measured in AH (Ampere hours) not Watts. So you have (when fully charged) 400A to discharge (could be 400A in 1 hour or 40A over 10 hours etc), divide this by 2 (because you should not discharge AGM Batteries below half charge) so this becomes 200A and so 200AH/24A = 8.4Hrs of running the fridge (flat out) before you really should turn it off to charge the batteries. Not good!
If your solar panels are optimized for direction and angle (mobile) you will generate at 25Amps max. If your fridge is running flat chat drawing 24A on a hot day you will not cope as the solar panels output reduces on hotter days by some margin. (They are most efficient on cold sunny days) Problem is, your fridge could be running continuously (all night) but the sun doesn't and so your daily input would be around 300A 6hrs at optimum generating power and assuming the panels are roof top mounted and not mobile and therefore will not be directed perfectly at the sun) and your daily draw is around 24 x 24 = 576A (assuming max current which is always best) But even if the fridge is never opened (cough, er did someone say Bar fridge) the draw over 24 hours will likely discharge your batteries to near flat each day. You will be replacing them very early and we haven't accounted for rainy days yet!!! Basically, it can be done but you have dedicated some expensive and unnecessary kit to JUST keeping your fridge going and not much else. Agree with Maboutled, buy a 12V fridge for sure. Nothing like a coldy on a hot rainy day!
Hi Muddy
You need to rework your figures ,the fridge is rated @100W
[1]THe current of 1Amp @ 240v represents 240VA@ a PF 0.xx[ Not Watts]
[2]consumption should be based on WATTs plus inverter losses
PeterQ
-- Edited by oldtrack123 on Thursday 19th of March 2015 07:54:23 PM
Jaahn said
08:39 PM Mar 19, 2015
DeBe wrote:
Newer bar fridges have the condencer built in to the sides of the fridge. If you stick insulation on the sides of these it wont work very well.
Hi DeBe
Correct! If the fridge has the condenser built into the side walls then definitely do not put insulation there. In fact the side should be ventilated.
That was an interesting post about your fitting a bar fridge with another compressor etc. I like real figures and readings.
I wasn't recommending or not recommending a bar fridge, just trying to provide some realist and correct units to base a decision on. Incorrect units of electricity tend to confuse more than anything else on here.
Jaahn
oldtrack123 said
09:06 PM Mar 19, 2015
Jaahn wrote: Hi Muddy and all,
I write this to promote a good discussion not to argue. This seems a topic which people are interested in, so some correct answers would be helpful. Your analysis is good, but.....
Muddy has made an assumption that the 1A at 240V is a better assumption for power use that the 100W. I do not believe this is correct.
[1] 1A current is the max start current.
[2]my experience 100 Watts is about correct for a small fridge. So basing the power usage on this is OK IMHO and having been inverted from 12v to 240 will draw about 10amps+ at the low voltage end, depending on the quality of the wiring and the state of charge of the batteries.
[3]The inverter must be well oversized to start a fridge or it will trip out on overload or low voltage. Up to 4x or 5x the rated power is needed to "kick them away". Depends on the inverter AND the wiring too. If the wiring is a bit poor the inverter will not handle the surge needed because the voltage drops too low. Note this surge when sizing the wires and the fuse. As Muddy said above the full capacity of the inverter should be allowed for i.e. actually 1000W cont- 2000W surge.
Most bar fridges would benefit from a layer of foam insulation glued on the sides and top. Door too.They have minimal insulation.
Cheers Jaahn
-- Edited by Jaahn on Thursday 19th of March 2015 09:06:42 AM
-- Edited by Jaahn on Thursday 19th of March 2015 09:08:52 AM
Hi Jaahn
[1] 1amp is not the start current
Start currents are very rarely ever listed in specs
Unless a soft start is used ,are between 5&10times the actual run current
The 1A is the actual run current on 240V but is not equal to 240W
It actualy means 240VA
There is a big difference between Watts &VAs[power factor]
Watts can / are used to calculate both power consumption & work capabilty/done
VAs must be used for ALL calculations involving AC cables ,Inverter size ,240V generator size ,etc
Yes, understanding application & correct terminology is very important .
[2]The draw on the Battery should be based on the WATTS input
[3] yes the inverter must be oversised to take
[a ]The 5 to 10times start current surge
The ACTUAL continuous running current @V =VAs
PeterQ
-- Edited by oldtrack123 on Thursday 19th of March 2015 09:14:10 PM
Bent Axle Bob said
05:59 PM Mar 20, 2015
Thanks everyone for info and suggestions. The old engel ,external heat exchanger, has been given a bit of a once over . The sides have received an extra 10mm of foam covered with laminex ply, the heat exhanger has gained 2 x12cm 12v fans and the top covered with varnished and urethaned 7mm ply. Has been wired to a 60 amp circuit breaker and bus bar. Been switched on for three hours, radio on , 2x 12v flouro s and a 12 inch fan. Fridge was hot and empty. Mppt regulator was showing float and after 3 hours it has not altered. So at this point in time, I'm happy. Will leave on overnight minus radio and lights and take a peek in the morning
Kia Ora Everyone, it's been a while since last on the forum and I need some advice on the heading subject.
My fridge is a TLC 115 litre bar fridge, plate states current 1 amp, input power 100watts, inverter 1000w continuos 2000watt surge pure sine wave inverter. 3 x100w panels feeding via mppt reg to 2x 200watt deep cycle agm batteries. Distance from batteries to inverter = 50cm . Connecting direct to batteries, what size inline fuse should I use, and will the inverter handle the load?
Short answer = NO
Long Answer...... At most your panels will produce 25AH and that's really best case senario. If you got really good sun everyday for at least 6 hours (when does that ever happen) then you'll get theriodically 150Amps back into your batteries on one day. Your Bar Fridge will use 100 Watts per Hour x 24 Hours = 2400 Watts divided that by 12Volts = 200AH per day. Assuming best sunlight everyday your batteries are going south to the tune of 50Amps per day.
Note these calculations are very rough and doesn't take into account what the Inverter itself will use to convert 12 volt to 240 volt or anything else you mights be running like lights etc... The inverter would be fine, you'd just need more batteries and panels, and perfect weather everyday!.
Best Advice, chuck the 230v bar fridge & buy an Engel or whatever 12v fridge.
-- Edited by madaboutled on Monday 16th of March 2015 09:37:45 PM
-- Edited by madaboutled on Monday 16th of March 2015 09:40:13 PM
An interesting read for you - A fridge test, battery power consumption comparison between a household 240 volt 140 litre bar fridge, and a 12 volt 140 litre Waeco fridge, for camping.
-- Edited by PeterD on Tuesday 17th of March 2015 12:06:56 AM
Hi Bob,
Not sure about the analysis given so far. In fact I would think it is hard to follow because the confusion of incorrect units, of amps and amphrs and amps per hr.
So I would give this analysis for the benefit of others who are interested in the discussion.The figures have been rounded a bit.
The fridge uses 100 Watts and that translates when converted to about 8amps at 12 volts.
So the 240v inverter needs about 10 amps allowing for losses. The fridge may run for about 75% of the time
So the amp hrs used over 24hrs are about 180 amp hrs per day.
The 300W panels produce about 20amps for about 6hrs (?) so that is 180amp hrs each winter day. More in summer I think, perhaps depending on the setup.
That looks like a rough match for very average solar conditions.
The batteries are about right for overnight storage but two days would be max for safe use without charge. The inverter should be OK to run that.
Cheers Jaahn
-- Edited by Jaahn on Tuesday 17th of March 2015 09:53:26 AM
Just a note of caution - This test was done in 2003.
Technology would have improved markedly since then I would imagine.
I sometimes get a canning from someone on tech terms like amps and amphrs and amps per hr when using the KISS method to try to explain something with the aim of being easily understood, however from Bob's reply I think I achieved that, and so to Bob.... your welcome. Note to self in future try to use the correct tech terms in the appropriate places.
In my defence of other some points above I did say "Note these calculations are very rough" that point seems to have been lost and yes you are correct in saying "The fridge may run for about 75% of the time" however I believe in running calculations at worst case scenario and not second guessing at what things might run at.
Also on the comment "The 300W panels produce about 20amps for about 6hrs (?) so that is 180amp hrs each winter day. More in summer I think, perhaps depending on the setup. That looks like a rough match for very average solar conditions." My line said "At most your panels will produce 25AH and that's really best case scenario" OK it should have said amps per hour I'm just glad Bob understood what I meant.
At the end of the day we both agree that Bob's system would be inadequate for anything longer than about 2 days. However, my very rough analysis did show that the power being used was going to be greater than the power being replaced and that I think was what the information that Bob was after.
Regards Steve.
Good move Bob, enjoy your trip we might even meet on the road somewhere???, heading that way ourselves in a few weeks.
But what's this "one last trip" just keep going til you can't!.
All the best Steve.
So if the fridge draws 1A maximum on the inverter output side which at 230V = 230W, The current in the 12V supply would be 230W /12V = 20A (rounded up). Then inverter efficiency must be taken into account so divide the amps by 0.85 and you end up with 24A (again rounded up). The inverter supply fuse rating must be slightly above the calculated max current draw OF THE DEVICE and some 15% below the rating of the cabling supplying it. So if your inverter is fully loaded at 1000w then using the same formula 1000W/12v/.85=98A then I'm guessing that to obtain a full load output from the inverter, your 12V supply leads will be rated appropriately fuse could be around 100A. Remember that if you fuse the inverter with one rated for just the fridge, you will blow the fuse each time you plug another device in so fuse your inverter to the right level. Consult with your inverters instructions or talk to the manufacturer or supplier.
The batteries capacities are measured in AH (Ampere hours) not Watts. So you have (when fully charged) 400A to discharge (could be 400A in 1 hour or 40A over 10 hours etc), divide this by 2 (because you should not discharge AGM Batteries below half charge) so this becomes 200A and so 200AH/24A = 8.4Hrs of running the fridge (flat out) before you really should turn it off to charge the batteries. Not good!
If your solar panels are optimized for direction and angle (mobile) you will generate at 25Amps max. If your fridge is running flat chat drawing 24A on a hot day you will not cope as the solar panels output reduces on hotter days by some margin. (They are most efficient on cold sunny days) Problem is, your fridge could be running continuously (all night) but the sun doesn't and so your daily input would be around 300A 6hrs at optimum generating power and assuming the panels are roof top mounted and not mobile and therefore will not be directed perfectly at the sun) and your daily draw is around 24 x 24 = 576A (assuming max current which is always best) But even if the fridge is never opened (cough, er did someone say Bar fridge) the draw over 24 hours will likely discharge your batteries to near flat each day. You will be replacing them very early and we haven't accounted for rainy days yet!!! Basically, it can be done but you have dedicated some expensive and unnecessary kit to JUST keeping your fridge going and not much else. Agree with Maboutled, buy a 12V fridge for sure. Nothing like a coldy on a hot rainy day!
Yes, technology has improved, mainly in the larger fridges, less so the bar fridge size. It also has in the 12 V fridges. Please prove to me that technology in 12 V fridges has moved at a lesser pace than bar fridges.
Yes, technology has improved, mainly in the larger fridges, less so the bar fridge size. It also has in the 12 V fridges. Please prove to me that technology in 12 V fridges has moved at a lesser pace than bar fridges.
Did I say that it had.
I was merely pointing out that the article was written 13 years ago.
Hi Muddy and all,
I write this to promote a good discussion not to argue. This seems a topic which people are interested in, so some correct answers would be helpful. Your analysis is good, but.....
Muddy has made an assumption that the 1A at 240V is a better assumption for power use that the 100W. I do not believe this is correct. That current is the max start current. From my experience 100 Watts is about correct for a small fridge. So basing the power usage on this is OK IMHO and having been inverted from 12v to 240 will draw about 10amps+ at the low voltage end, depending on the quality of the wiring and the state of charge of the batteries.
The inverter must be well oversized to start a fridge or it will trip out on overload or low voltage. Up to 4x or 5x the rated power is needed to "kick them away". Depends on the inverter AND the wiring too. If the wiring is a bit poor the inverter will not handle the surge needed because the voltage drops too low. Note this surge when sizing the wires and the fuse. As Muddy said above the full capacity of the inverter should be allowed for i.e. actually 1000W cont- 2000W surge.
Most bar fridges would benefit from a layer of foam insulation glued on the sides and top. Door too.They have minimal insulation.
Cheers Jaahn
-- Edited by Jaahn on Thursday 19th of March 2015 09:06:42 AM
-- Edited by Jaahn on Thursday 19th of March 2015 09:08:52 AM
Newer bar fridges have the condencer built in to the sides of the fridge. If you stick insulation on the sides of these it wont work very well.
If you have experience of bar fridges and related wattages I bow to your greater knowledge. I just wanted to say that I didn't say that the 1A was a "better" figure to use, just that I was confused...it happens... and wanted to allow for worst case scenario. I agree that start up currents are higher with AC machines and can be more than your quoted figure of 4 -5 times.
So at 100W the current draw will be 100/12/0.85 = 9.8A (not 20) giving essentially twice the amount of run time than I quoted initially. Daily draw 240A - Daily input (when sunny) 300A so provided you enjoy non cloudy days you will be OK. I would still favour not using it as you could run a 1battery set up with a 12V compressor fridge with one panel for 4 days without sun. Save weight (fuel costs) and set up cost (unless you already have. The temptation will be to run your batteries flat after you have had 2 cloudy days which will cost you for two new batteries ($800)? after not too many trips. AGM's HATE running below 50%
Thanks for the pointer Jaahn, good luck Bent Axle Bob
Hi Muddy
You need to rework your figures ,the fridge is rated @100W
[1]THe current of 1Amp @ 240v represents 240VA@ a PF 0.xx[ Not Watts]
[2]consumption should be based on WATTs plus inverter losses
PeterQ
-- Edited by oldtrack123 on Thursday 19th of March 2015 07:54:23 PM
Hi DeBe
Correct! If the fridge has the condenser built into the side walls then definitely do not put insulation there. In fact the side should be ventilated.
That was an interesting post about your fitting a bar fridge with another compressor etc.
I like real figures and readings.
I wasn't recommending or not recommending a bar fridge, just trying to provide some realist and correct units to base a decision on. Incorrect units of electricity tend to confuse more than anything else on here.
Jaahn
Hi Jaahn
[1] 1amp is not the start current
Start currents are very rarely ever listed in specs
Unless a soft start is used ,are between 5&10times the actual run current
The 1A is the actual run current on 240V but is not equal to 240W
It actualy means 240VA
There is a big difference between Watts &VAs[power factor]
Watts can / are used to calculate both power consumption & work capabilty/done
VAs must be used for ALL calculations involving AC cables ,Inverter size ,240V generator size ,etc
Yes, understanding application & correct terminology is very important .
[2]The draw on the Battery should be based on the WATTS input
[3] yes the inverter must be oversised to take
[a ]The 5 to 10times start current surge
The ACTUAL continuous running current @V =VAs
PeterQ
-- Edited by oldtrack123 on Thursday 19th of March 2015 09:14:10 PM