Running a frig and using cooling devices

[Tony's Dream]

I wanted to buy a van and convert it, but the money just isn't there.  So we bought an solid side A frame popup camper.  When we are hooked up to shore power, everything is great.  When we go off grid, it seems like we have power problems.  The camper does not have an inverter (changing 12V to 110), certain things run on 110 only and other things run on 12V only.  We went to a remote site and during the day we ran our generator and everything worked great.  At night we shut down the generator.  The frig can run on 110/12V/propane, so we switched it over to 12V power.  We only had it running and the radio and in about 6 hours the battery was dead.  The camper came with a deep cell marine and I know that was not going to work, so we are buying 2 100 amp hour batteries and see if this works better.  Then we can recharge them during the day with the generator and eventually solar panels.

The question I have is options.  If I would have simply turned off the frig, would it have kept everything cold enough until we switched the power back on in the morning?  What if I supplement the frig with cooling devices like the freezer packs or regular ice.....would that help?

 

[Lowdesertpatrol]

Run it on propane. Lol.

NEVER run those on 12v. It wont barely cool anyway and sucks tons of current to do next to nothing.

Dont bother with 2 100ah batteries. Get one lifepo4. You will need a converter that charges faster as your stock one is weak. Getting lead batteries requires 100% charge everyday and that takes 6-12hrs no matter how much current you can give them. A lifepo4 can take a huge charge very fast and doesnt have to be charged 100% which is very hard to do camping. Its 1hr vs 6, 8, 10hrs.

Its expensive but in the end is cheaper when you get enough solar and run through all the gas a regular battery demands. Can build your own for about $500

 

[Almost There]

I really wouldn't advise turning off the fridge overnight.

I had to do so when I had power problems and the chest fridge (12v Whynter) that I use went from 40 F to well over 50 on a night when the ambient temperature was not much more than 50 F. At that temp you are taking a big chance on milk spoiling as well as any meat degrading to the point of danger.

I would also suggest that if you're going to recharge those 2 - 100 amp batteries with a generator (hopefully an inverter/quiet one) that you also invest in a battery charger that is matched to the batteries you buy. It will still take a minimum of 5+ hours to fully charge the batteries but you'll do a better job with a good charger than with any 'smart charger' or the converter that might? be built in to the camper.

Edit: Missed that you can run the fridge on propane - it should run great on propane. The 12V was only meant for when you're running down the road where you should have the propane shut off, not for use when you don't have 120V.

 

[Tony's Dream]

There is a charger in the camper, when we are connected to shore power or when it's connected to my truck, the batteries are recharged. If we add the new batteries, are you saying the charger may not do a good job of recharging it?

Lowd.....does it use a lot of propane when I use that method? I haven't found any data on how much it consumes while running the fridge.

 

[Lowdesertpatrol]

Yeah but stock chargers are lame in most RV's. They might do 10A and you will want at least 40a with 2 lead batteries and ypu can do 100ah with a single lithium.

Propane use should be about .25 - .75lb a day. It all depends on how hot it is and how much you use it. Theres about 17lbs in a single tank. 20-30 days on a tank.

 

[Tony's Dream]

I have found the LifePro4 100ah batteries. It is more money but cheaper than the 2 100 ah batteries I was looking at. Looking at the chargers, there are only about 1000 different kinds. I am trying to look at the specs and find how fast it charges.....but not really finding anything. What am I really looking for?

 

[Lowdesertpatrol]

RV converter chargers; Powermax, IOTA, progressive dynamics, WCPO.

What size generator you got? 1kw running is good for about 35A

2 lead acid 6v's run about $200 a set 215-235ah.

 

[Tony's Dream]

We have a champion that generates about 4500 watts. Problem is that it's too noisy. We bought it to back up the house if we loose power. Trying to find a silencer for it, but they don't make one for this brand and size. We are looking at buying a WEN 56200i Super Quiet 2000-Watt Portable Inverter Generator.

 

[Lowdesertpatrol]

Yeah so a 45-55a with that small one. That would fill a lithium from 20% to 90% in about 1.5hrs.

With fridge on propane and a single lithium you would probably only run generator every 3-4 days. Again versus 6hrs min at near idle for half the time every single day for a lead acid. Add a panel or 2 and you maybe run generator once a week if at all.

 

[Gypsy Freedom]

[quote="Tony']
There is a charger in the camper, when we are connected to shore power or when it's connected to my truck, the batteries are recharged. If we add the new batteries, are you saying the charger may not do a good job of recharging it?

Lowd.....does it use a lot of propane when I use that method? I haven't found any data on how much it consumes while running the fridge.
[/quote]

the "charger" in your camper is not even doing a GOOD job of charging the battery you have. if you are going to charge your batteries from a generator you will really benefit from having a power factor corrected charger that is capable of a constant current bulk charge phase followed by a constant voltage absorption phase and then go into a constant voltage float phase.

the good charger will allow much quicker recharge times regardless of battery chemistry.

the power factor corrected charger will allow you to run almost 2 times the size battery charger on the same generator and with the same fuel consumption. someone mentioned above that a 1000 watt generator was good for about 35 amps of charger. with a good quality powerfactor corrected charger you can run a 60 amp constant current charger while burning the same amount of fuel it would take to run a 35 amp NON-powerfactor corrected charger. i run a pronautica promariner 60 amp charger from my honda 1000i inverter generator.

with your existing fridge, if it is working ok. run it on propane when away from "shore power" like when you are camped out with no place to plug in or not driving. you can switch to 12 volt while driving and if someplace where you can plug in then switch to the 120 volt. if this fridge does not work good enough. adsorption type fridges are notorious for not working well. especially if they have been used imporperly in the past or you use them improperly like not being level. then i would look at replacing with a compressor type unit, either 12v dc or 120v ac (would need inverter)

while lithium batteries are the cats meow, and if you can afford a high quality drop in like the battle born or the trojan trilium units you will probably be pretty happy. if you have not already or plan on researching alot and possibly making some mistakes and ruining a few lithium batteries (expensive learning curve) then i would not suggest do it your self till you have more knowledge/experience

the lithium batteries will charge quicker, are much lighter and do not degrade if left at a partial state of charge (failing to fully recharge after discharge) but it does come with sticker shock $$$

the firefly carbon foam AGM batteries are a mid ground. not as big a sticker shock but also do not degrade from partial state of charge abuse

but the reality is that if you can run your fridge on the propane, you may be happy with what your existing battery can do for you. especially if you get to where you can charge it fully. either from solar (highly recomended) or from a good battery charger on the generator

as an example, i recently installed 100 watts of solar on a roadtrek with propane fridge. even though they did a lot of driving they could never get their rv battery (house bank) fully charged and it would often run low in the night from lights/laptop/fan and such. now with the 100 watts of flex solar mounted on the roof and a quality mppt charge controller and still using the existing battery she is having much more power through the night and getting the battery fully charged on most sunny days.

another example i am working on for a customer as we speak is an older westfalia vanagon. we have replaced the propane fridge with a 12v dc "truck fridge" and added 225 watts flex mobile solar with cheap PWM controller for testing. this set up is keeping up with electrical demands to run the fridge and even freeze a water bottle in the little freezer compartment. this is with the old rv battery it came with. and the battery keeps the fridge just fine over night and the solar has the battery fully charged by the time the sun starts slipping behind the trees. and this is in oregon in NOV, pretty low sun angle. we will be upgrading the solar charge controller to a quality (victron) mppt unit and the battery to a pair of golf cart lead acid batteries. that will make for a very robust system

as for your unit not having an inverter, my suggestion is to see how hard it would be to convert the 120v ac only devices to 12v dc so you dont have to buy and deal with the idle consumption of an inverter. but if an inverter is needed. there are lots of options out there. just make sure to calculate your needs so you get the right one. some of the better inverters can be had as combination inverter/chargers. aims power and victron are 2 that i know of that have power factor corrected chargers built into some of their pure sine inverters. i prefer the victron, but the aims power are probably less than half the price.

if you have questions or dont understand some of this, feel free to contact me via pm and i can work one on one with you

good luck and welcome to the club

 

[Lowdesertpatrol]

Your honda may be able to run that especially at sea level but many generators will struggle. I just went through all this. The generators are simply overrated. My 1400 running watt struggles especially at 8k+ ft elevation to run a 55A. PFC is available on all brands in the higher amp ranges and gives about 7-8% efficiency.

Better to be a bit conservative with sizing.

 

[ZoNiE]

the 12V setting on a 3-way is for running when rolling down the road. The tow vehicle's alternator powers it if the trailer is wired with a charge wire. Use it on Propane when not running the genny.

 

[brahmon]

does that time include charging with a load on them?

 

[Gypsy Freedom]

that is one of those questions that can only be answered by "that depends"

if the load on the battery is high enough to off set the charge coming in then all charging may never be completed

in the first stage of charging "bulk" the battery is accepting all the current/amps the charging sources can provide.

assuming a 100% efficiency of charging (which is not even remotely accurate) lets say you used 1 kilowatt hour of energy over night then if your charge source is putting out 200 watts it would take say 5 hours to recharge in that perfect fantasy world of 100% efficiency but after the battery gets recharged to around 70-80% the battery will no longer accept the full current available from the charging source. this is what we call the absorption charge phase. so in this hypothetical scenario it wuld take 4 hours to get to the absorb phase but you can see that if you have 200 watts charge available but you are continuing to use 100 watts then you are going to roughly require 2 times the hours to get up to that 70-80%.

once you reach the absorb phase, it takes a considerable amount of time to reach "full charge" regardless of the available charge source because the battery is not accepting all of it any way. there are many different and conflicting ideas of how long this actually takes and in not part of this discussion but everyone agrees it take a while and there is no way to speed it up.

during this time of absorb phase charging there is extra charge current available from the charge source. this power can then be used to power other loads with out affecting the time required to fully charge the battery. of course if you draw more of a load than is available as extra then there will not be enough charge current to maintain the absorb phase and it will drop back into bulk phase and the battery may even be discharging or losing ground on getting fully charged if you pull a large enough load

 

[brahmon]

so it's safe to say that if i can get 14.4 i can run all appliances full blast?

 

[Gypsy Freedom]

ya, if you are holding the 14.4 (assuming that is your bulk/absorb set point) and running the appliances you are good to go.

i try to design solar packages to provide kinda "double power" as i like to call it. i want to be able to recharge my batteries from the overnight draw down while still running all my loads during the day. that way i can use what i want through the day and still have a full battery come sundown

 

[brahmon]

mahalos for the good intel!

 

[Tony's Dream]

Wow, your knowledge is impressive. In my world we would call you a SMA (subject matter expert). I will be retiring in about 3 years and I am trying to test different products and appliances. I want to find the right combination of equipment that will serve me best. I will not be a nomad, but I do anticipate traveling for 4-5 weeks at a time. Then returning home, refit and save some cash, then go again.

 

[Gypsy Freedom]

nice, sounds like a great plan to get out and enjoy the world around you.

i am happy to help you figure out you system and where you might want to take it. i consult with people on projects like this all the time. i dont charge to just talk about it so feel free to reach of if you have more questions. hit me up Via PM and we can chat one on one if you like

 

[Tony's Dream]

I appreciate it. I have some electrical and construction knowledge but the 12V and solar is somewhat beyond me, just because I have never had to deal with it. It's winter in Nebraska so everything is on hold until spring. I will be in touch with you when I pull it out and take a look at things.