How long will fridge on battery last in various scenarios





Page 1 of 3 1 2 3 LastLast
Results 1 to 20 of 46
  1. #1
    Join Date
    Mar 2015
    Location
    Pretoria
    Age
    36
    Posts
    857
    Thanked: 396

    Default How long will fridge on battery last in various scenarios

    Okay so the setup is- Paj 2005 3.8v6

    Dometic 40 l fridge freezer 12v/220v

    Second battery in national luna box with national luna solonoid sytem -Deep cycle battery 12 volt 102 amp

    We measured what we could and the fridges seems to draw between 2.5 amp and 3 amps per hour. So in theory the battery when full should sustain the fridge 102/2=51 then 50/2.5=20 hours ?

    Are these calculations correct?

    So what we are thinking, charge battery full, put it on to charge while driving (maintenance or top up) then while driving run fridge of starter battery and only when stopping run fridge off second battery?
    (then solar panel to top up second battery when standing for more than 20 hours (one day), What type and size panel etc and regulator?)

    Or would this not make a difference and the fridge can be plugged in to the second battery when driving and and receiving charge from the first?

    If any assumptions or calculation are extremely wrong , please point out and help us figure it out?
    Our Travel and Photography blog- https://twotracks.co.za

    The Beast - 2005 Toyota Hilux D/C 4L with freeflow

    Daily Drive- Girlfriends Honda Jazz

  2. #2
    Join Date
    Jun 2013
    Location
    Alberton
    Age
    59
    Posts
    6,132
    Thanked: 2638

    Default Re: How long will fridge on battery last in various scenarios

    I have same vehicle and Waeco CF 50 . NL power pack in rear of vehicle. Ran welding cable from main battery through firewall into trunking below the plastic covers (passenger side) I popped mine up just beside the rear seats. Power pack has internal solenoid so that problem is solved.

    I bought a semi flex solar panel and although more expensive than a solid found it easier to pack and deploy. I added a PWM controller to the power pack (this one, cheap as chips, I have three of them)

    https://www.acdc.co.za/products/12-2...olar-regulator

    Works like a charm. Only thing I did do was source some wiring as used by the solar guys for the link ups and used red BH for the fittings.

    Fridge always linked to aux, never main. From the same system we also run a small 16 L fridge which we switch off at night.
    Last edited by Stranger; 2018/10/16 at 04:28 PM.
    Lusted for a Landy but the Pajero was sexier and bigger in the right departments, just like my Missus.

    2004 Gen 3. 3.8i petrol V6 (PAJTU)
    X Factor Bundutop trailer (designed by me)
    1998 Blister Fender Pajero 3500 24V (PAJ) (Sold)
    BMW R1200R

  3. The Following User Says Thank You to Stranger For This Useful Post:


  4. #3
    Join Date
    Mar 2015
    Location
    Pretoria
    Age
    36
    Posts
    857
    Thanked: 396

    Default Re: How long will fridge on battery last in various scenarios

    How many amps does the panel put back? Size of panel?
    Our Travel and Photography blog- https://twotracks.co.za

    The Beast - 2005 Toyota Hilux D/C 4L with freeflow

    Daily Drive- Girlfriends Honda Jazz

  5. #4
    Join Date
    Jul 2009
    Location
    Gauteng
    Age
    52
    Posts
    1,152
    Thanked: 947

    Default Re: How long will fridge on battery last in various scenarios

    https://planetcalc.com/2283/

    The drain of the battery is exponential.
    Calculator above seems fairly accurate to what I have experienced. The reason I have 2 battery packs, DC-Dc charger and solar panels. One battery is always on charge somewhere or both together.
    The last Pilanesberg trip I took the one 105 battery box and lasted me the weekend. Running Waeco 35 at -2.
    It was however very cold at night. Real life cannot be simulated or calculated in my opinion. Too many factors.
    Last edited by AntonN; 2018/10/16 at 04:55 PM.

  6. The Following User Says Thank You to AntonN For This Useful Post:


  7. #5
    Join Date
    Mar 2011
    Location
    Walker Bay
    Age
    76
    Posts
    9,283
    Thanked: 1075

    Default Re: How long will fridge on battery last in various scenarios

    Gifmonster - Twotracks - great web site!
    Enjoying the read!

    “Africa changes you forever, like nowhere on earth. Once you have been there, you will never be the same." - Ernest Hemingway

  8. #6
    Join Date
    Feb 2010
    Location
    Wartburg.
    Age
    38
    Posts
    2,174
    Thanked: 623

    Default Re: How long will fridge on battery last in various scenarios

    Your calculation is flawed, you don't have 102 usable amps.
    More like 50 amps or so.

    Ask Fluffy for advice, he is very good at this sort of thing

    Toyota Land Cruiser 79 DC V8
    Toyota Hilux 2.8 GD6 4x4
    Toyota RAV-4 2.2 D4D

  9. #7
    Join Date
    Jan 2014
    Location
    Western Cape (Heidelberg / Hermanus)
    Age
    56
    Posts
    1,736
    Thanked: 536

    Default Re: How long will fridge on battery last in various scenarios

    I am not to clued up on the calculations. All I know is that testing close to 2 days in my garage translated to a couple of hours in the Richtersveld sun

  10. #8
    Join Date
    Aug 2011
    Location
    Pretoria East
    Age
    42
    Posts
    558
    Thanked: 199

    Default Re: How long will fridge on battery last in various scenarios

    Quote Originally Posted by Chris8d View Post
    Your calculation is flawed, you don't have 102 usable amps.
    More like 50 amps or so.

    Ask Fluffy for advice, he is very good at this sort of thing
    That is why the OP said 102/2 to only allow for 50% usable amps
    2018 Mitsubishi Triton Athlete 2.4 DI-D with SuperSelect II
    2017 Conqueror Companion Platinum Edition

    ** Every father should remember that one day his son will follow his example instead of his advice **

  11. #9
    Join Date
    Feb 2010
    Location
    Wartburg.
    Age
    38
    Posts
    2,174
    Thanked: 623

    Default Re: How long will fridge on battery last in various scenarios

    As is my maths flawed....

    Toyota Land Cruiser 79 DC V8
    Toyota Hilux 2.8 GD6 4x4
    Toyota RAV-4 2.2 D4D

  12. #10
    Join Date
    Mar 2017
    Location
    Pretoria
    Posts
    105
    Thanked: 49

    Default Re: How long will fridge on battery last in various scenarios

    Quote Originally Posted by Chris8d View Post
    As is my maths flawed....
    It is an usual calculation. Discharging: Example: Battery AH X Battery Volt / Applied load . Depth of discharge but lets say you can discharge down to 50% ie 51 AH .The load of your fridge when converted to watts is watt=current × voltage so 2.5 x12 =30 Watts. So 51 AH x 12 V /30 which is 20.4 hours. Please note its not recomended to dicharge a lead acid battery by 50% youll be reducing its life span so 20% discharge you have about 9 hours. This is just an estimation as your fridge motor is on an off so the above is for continuous consumption.

  13. The Following User Says Thank You to Mbu For This Useful Post:


  14. #11
    Join Date
    Apr 2010
    Location
    Port Elizabeth
    Age
    69
    Posts
    1,052
    Thanked: 584

    Default Re: How long will fridge on battery last in various scenarios

    We just have a simple system made up by a professional Solar Panel outfit in PE ..I supplied the bog Standard Wolf Pack with High Roof/Lid ..They mounted a Gel 105ah Deep Cycle Battery in the box with a Brad Harrison inlet Mounted on the side ..outside the box plus a round outlet fitting so I can plug the National Luna 90 Litre Twin Fridge Freezer into once we arrive at say Balule, Tsendze in Kruger Park and or Rooiputs in Kgalagadi. He made up a double 80 watt set of Solar Panels (160 Watt in total) that fold in 2 on a middle set of hinges ..The Folded Panels then fit into a custom Canvas Bag with thin wood internal liners fitted for travel in the Bakkie.
    Method ..We Charge the battery fully at home . We freeze the meat etc to - 20 degrees C at home ..We freeze 5-6 Cold Bricks at home . As we are about to leave PE for say Upington en route to Kgalagadi we pack the Packed Freezer with everything frozen packed in at -18 degrees ..(Keeps everything hard for at least 3 days if you dont open the lid) The stuff we use en route we have on the back seat of the D Cab plugged into the Cigarette lighter port in front. Drive the whole day with Freezer off in the Bak. Get to overnight stay ..Plug into the caravan Park stand supplied electricity to boost cooling back to minus 18 and to top up the Deep Cycle Battery ..Sleep in the trailer while the freezer remains in the Bakkie overnight. In the morning unplug and rehitch the trailer ..Run into Upington 10 Kms away get salads , Fresh Veg etc etc ..Beers and cooldrinks and 25 litre containers of water to ..Drive to Twee Rivieren ..and plug in again that whole afternoon and night ..Charge all camera batteries , LED Lights etc etc ..Next morning drive to campsite 3 Rooiputs ..Set up in Shade and Panels in full sun all day (Just needs to be shifted every 2 hours or so to face direct at the HOT Kalahari sun during the suns daily path across the sky ) at the end of a THICK 7 m cable into the tent of the Skipper Trailer and into the Box via the Brad Harrison Plug and from there into the Freezer next to the Wolf Pack ..At Sunset unplug and bring in the panels (To save power draw and to protect Panels from Lion Shopping during the night. I get up in the Dark to make use of the Golden Hour for photography on my own at the waterhole below the camp before the Twee Rivieren hordes arrive but before that I Put the panels out and Jane just plugs in just after I have left as the sun comes up and she gets up to make her coffee..18 days of Rock hard contents in the freezer..We have just come back from Tsendze Kruger Park and our friends have a new Bushlapa with Panels on roof and he has 2 battery packs and 2 fridges in the back Seat space of his Hilux (He takes the seat out to make space ..What a disaster he had ..Trying to get sun on his panel to charge all those complicated Battery Pack AC/DC/Solenoid what u makcallits ..While I just moved my panels around in the sun while my set up was in the shade all day. My Hilux is a Bog Standard one without all these fitted expensive Double Battery Systems like my friend had ..Our cooling system worked ..his didnt and he had a frustrating time at Tsendze ..He couldnt have an afternoon sleep as his unmovable (With all the attached Poles , Pegs Side walls fitted) Lapa was in full sun but we could ..Keep it simple I say ..Pic of our setup at Rooiputs Name:  Pre Sunrise Camp 3.jpg
Views: 3012
Size:  280.5 KB
    Last edited by Peter Betts; 2018/10/17 at 06:44 AM.

  15. The Following 3 Users Say Thank You to Peter Betts For This Useful Post:


  16. #12
    Join Date
    Jul 2009
    Location
    Gauteng
    Age
    52
    Posts
    1,152
    Thanked: 947

    Default Re: How long will fridge on battery last in various scenarios

    Ambient temperature, fridge insulation and how many times you open the door are factors that must be considered as well.

  17. The Following User Says Thank You to AntonN For This Useful Post:


  18. #13
    Join Date
    Nov 2017
    Location
    Edenvale
    Posts
    293
    Thanked: 210

    Default Re: How long will fridge on battery last in various scenarios

    I totally agree on running the accessories off the main battery while driving, then when switched off it runs off the aux battery. I just use a 5 pin change over relay. I normally derate the batteries power - no scientific or mathematical reason. Heat to me is the enemy, it's like taxes - I try and find any way around to reduce it.

    The longer that I can keep the fridge/s off, I am saving power. Park your car in direct sun with the windows and canopy closed then measure how long your fridge really stays on. When the air temp is above 30 degrees, you will see it staying on far longer than planned. All calculations go flying out the window. Especially the fridges where the air inlet is sucking in the hot air from the fridge and surrounding air against the rear door or tailgate.

    Be realistic in how many times that you open the fridge, I planned on 12 times per day - reality it was about 32 times. Drinking beer is hard work, then adding a replacement 6 pack inside makes the fridge work for even longer, more amps.

    I charge all batteries fully, set fridge at maximum cold -18 at home on 220v then while travelling it runs off main battery. When I get to my destination I set the fridge to -2 or around there. I save battery time as the fridge will only switch on when it heats up and reaches the -2 setting. When I travel again I reset it to -18. Solar is ideal - use it as much as you can.

  19. The Following User Says Thank You to HobieDave For This Useful Post:


  20. #14
    Join Date
    Jul 2009
    Location
    Gauteng
    Age
    52
    Posts
    1,152
    Thanked: 947

    Default Re: How long will fridge on battery last in various scenarios

    HobieDave
    That is spot on my regime I follow. I never had battery issues even for extended travel periods. One has to "nurse" the system, monitor drain and plan charging times and cycles.
    The only difference is, I cannot drink 32 beers a day....

  21. The Following 2 Users Say Thank You to AntonN For This Useful Post:


  22. #15
    Join Date
    Jun 2013
    Location
    Alberton
    Age
    59
    Posts
    6,132
    Thanked: 2638

    Default Re: How long will fridge on battery last in various scenarios

    Quote Originally Posted by Gifmonster View Post
    How many amps does the panel put back? Size of panel?
    Mine is 100W, 5.6 amp max
    Lusted for a Landy but the Pajero was sexier and bigger in the right departments, just like my Missus.

    2004 Gen 3. 3.8i petrol V6 (PAJTU)
    X Factor Bundutop trailer (designed by me)
    1998 Blister Fender Pajero 3500 24V (PAJ) (Sold)
    BMW R1200R

  23. The Following User Says Thank You to Stranger For This Useful Post:


  24. #16
    Join Date
    Jun 2009
    Location
    George
    Age
    57
    Posts
    383
    Thanked: 152

    Default Re: How long will fridge on battery last in various scenarios

    Ek het 2 102 AH batterye op my wa en hardloop permanent ‘n Snomaster 62 liter vrieskas op -16grade.

    Terwyl ek sleep “laai” die stelsel maar op hierdie trippie het ek dit nie eens gebruik nie. Het ook 150 watt son paneel en was nou week in Kgalagadi by Rooiputs. My stelsel is teen 8:30 in die oggend vol gelaai. Dag temp was so 35 grade.

    Ek gebruik ook af en toe ‘n 1 500 watt inverter sonder probleme op die stelsel.
    2012: Triton 3,2 DC 4 x 4 (Simson, soos gedoop in die Namib woestyn);

    2006: Colt Rodeo 2.8 DC 4 x 4 (Moses die eerste, soos gedoop in die Limpopo)

    We come into this world with nothing and we leave this world with nothing..........................

  25. The Following User Says Thank You to HendrikG For This Useful Post:


  26. #17
    Join Date
    Mar 2011
    Location
    Walker Bay
    Age
    76
    Posts
    9,283
    Thanked: 1075

    Default Re: How long will fridge on battery last in various scenarios

    Have always set the fridge at -5C but having just come back from Kgalagadi have adopted -2C.
    This avoids the compressor running flat out non-stop in a hot car when temps are 35C+
    The fridge usually achieves a temp about 1 degree below the setting.

    I agree with really freezing everything at -18C before you leave home.

    “Africa changes you forever, like nowhere on earth. Once you have been there, you will never be the same." - Ernest Hemingway

  27. The Following User Says Thank You to Paul Dold For This Useful Post:


  28. #18
    Join Date
    Aug 2013
    Location
    Forest Hills, KZN
    Age
    41
    Posts
    3,223
    Thanked: 873

    Default Re: How long will fridge on battery last in various scenarios

    I don't know the calculations but...

    I installed the new NL box with a 105AH Semi-Deep cycle charged through a WRND charger.

    Went camping, took the NL box out the car and put it in the tent to charge a Dometic CF50 fridge (pre-cooled). That was on the Friday evening about 6pm. By Sunday 3pm the fridge was still being powered by the battery alone and the battery was still going. We also charged some camping lights and cellphones using the socket on the NL box.

    I'm happy with that performance bearing in mind the weekend average day temp was i'd say 24 and night at 12.
    2004 LR Discovery 2 Td5 GS - Hybrid Turbo, Intercooler, 33's, 2" Lift, V8 TC, Ashcroft CW&P 3.75 + ATB lockers. [GoldiloX]
    2003 LR Discovery 2 Td5 ES - Lots of Mods(check thread) - [Husky]
    2010 LR Discovery 4 V8 HSE - Lifted with IIDtool, Powered by Petrol and Running on Cooper AT3 LT (new spec) 265/65/18s [Imvubu] - SOLD

  29. The Following User Says Thank You to douglash For This Useful Post:


  30. #19
    Join Date
    Mar 2011
    Location
    Walker Bay
    Age
    76
    Posts
    9,283
    Thanked: 1075

    Default Re: How long will fridge on battery last in various scenarios

    On solar power one doesn't usually achieve the rating - conditions vary.

    Obviously the more panels the better. While some forum members seem to manage with relatively low amounts of solar for me a good rule of thumb is 160W.

    When temps really heat up like Kgalagadi or Richtersveld the ambient temp has a huge impact on fridge and battery. Batteries don't seem to be as efficient at high temperatures.

    “Africa changes you forever, like nowhere on earth. Once you have been there, you will never be the same." - Ernest Hemingway

  31. The Following User Says Thank You to Paul Dold For This Useful Post:


  32. #20
    Join Date
    Aug 2016
    Location
    Centurion
    Age
    68
    Posts
    169
    Thanked: 117

    Default Re: How long will fridge on battery last in various scenarios

    Plan for the worst scenario you think you will encounter, add 50 % and then out there be aware of what is happening and have some sympathy. Do not open the fridge 32 times

    Read the article in SA4x4 August

  33. The Following 2 Users Say Thank You to Pieter de Waal For This Useful Post:


Page 1 of 3 1 2 3 LastLast

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •