Newer AC/DC Refrigerator

[AJMike]

Originally Posted by DavidM

The fridge in the model I am looking at, the Winnie Era 70/170M is a tall (just enough room above it for a microwave) 6-7 cu ft two door compressor fridge with the freezer down. I don't know the model, but I think it draws 5 amps when running. At a 50% duty cycle in moderate 75 degree days, that is 60 Ahs. We will only use another 15 amp hours for other DC loads, but probably more if I add a satellite TV system which will bring it up to almost 100 Ahs daily.

Most of these Sprinter based coaches only have space for two G31 batteries behind the rear wheels. I am not ready for the complexities of Lithium so I am leaning heavily towards replacing the existing batteries with two Fireflys.

The 100 Ah Fireflys will give me 160 Ahs usable if I start from 100%. Our typical camping trip has us moving every 2-3 days- arrive about 3-4:00 and leave at about 9-10:00 the second day. So maybe 40 hours between running the chassis engine. So I can just make it with no solar but if we camp in a sunny spot (and I try not to) the 200 watts of solar could add 60 Ahs daily and let me extend it to 3 days, but that would not be the norm.

So I probably would have to run the genset for an hour or so every other day at camp. I would upgrade the existing 45 amp converter to 80 amps and increase the wire size to the batteries to minimize generator run time.

When we pack up and drive to the next campsite it usually takes 4 hours of driving. I would install a 40A Renogy B2B charger to limit current from the Mercedes alternator but also keep that current up as long as it is needed for charging the batteries. I should be able to just about charge up the batteries fully by the time we reach the next campsite.

Running the generator every other day is a PITA and burns a fair amount of propane, about 0.4 gallons per hour according to Cummins data for half load on their 2,500 watt propane generator. This means filling up the on board 9 gallon propane tank every other week, also a PITA.

So what do you all think?

David

A very complete analysis of what you will have and what you expect to use in terms of power. Just a couple of comments:

> I think it draws 5 amps when running. At a 50% duty cycle in moderate 75 degree days, that is 60 Ahs.

I think that depends on where you are camping, hot how it is inside and outside the RV and what setting you have on your thermostat. I believe we use more than 60AH a day since we go from a full battery pack at night to 12.1 volts in the morning and I tend to turn the fridge thermostat down (ie, warmer) at night because it is generally cooler inside the RV and the fridge does not have to work as hard. One other thing we do to reduce power draw is to put out the awning when the sun is on the side of the RV where the refrigerator is working. That tends to reduce the heat load near the fridge, keeps it cooler and uses less power.

> if we camp in a sunny spot (and I try not to) the 200 watts of solar could add 60 Ahs daily

Again I think that it depends on where you are camping. We have 3 100 watt panels and on a good day we can pull in 100-120AH with the 3 panels and that is in the middle of the Arizona desert. Figure 2/3 of that and you get 60-80AH, perhaps less if the sun is not as strong and, of course, much less in the Winter when the sun is not as high in the sky. In the Winter here in Arizona I consider us lucky to get 60-70AH from the solar panels, and less if it is cloudy.

For us clouds are a big issue in terms of what we get from our panels and I have seen the input power drop to half when clouds cover the sun. Of course the panels in the ERA are rigid and perhaps they are more efficient than the flexible ones on our Fuse so you might get more power than we do.

> So I probably would have to run the genset for an hour or so every other day at camp.

That is what we have done and it has worked for us, but it is noisy and annoying. We tend to do that when we take short hikes so that the sound does not bother my wife, but we also don't run it if we can avoid doing so so as to not bother the other campers.

> I would install a 40A Renogy B2B charger to limit current from the Mercedes alternator

I don't see why you would need or want a B2B if you are not using Lithium batteries. We have 2 AGMs and just allow the alternator to charge them when driving, and since our camping schedule (drive 4 or 5 hours to the next campground) works for us very well I don't see why it would not also take care of your power issue.

Perhaps the Firefly batteries are sensitive to alternator output. I just don't know if that is so.

> This means filling up the on board 9 gallon propane tank every other week, also a PITA.

Maybe. But if you get a lot of sun you will not need to run the generator so often or so long. I don't know what the propane tank size of the ERA is but we only fill our tank every 6-8 months. Of course you may be camping more than we do.

BTW - The ERA is a really nice RV. We were planning to buy one until my wife noticed that there was no outside storage and we ended up getting the Fuse instead. We both loved the outside and inside and it is well equipped, but without enough storage for us. Good luck in your hunt.

[DavidM]

Thanks for your comments AJMike. A couple of questions/comments:

Voltage is a wild approximation at best of SOC because it is very much affected by current draw at the time you measure the voltage, so I think 12.1 volts could be 50-70% SOC so 60-100 amp hours used from your 200 Ah bank. I wouldn't bother running the generator until the voltage dropped to 12.0 with no load. That will keep them at 50+%.

How do your AGM batteries charge while driving? You have the Ford diesel powered Fuse and I think it is also a "smart" alternator controlled by the engine's ECU. I will certainly try it without a B2B and if it charges fast then no I don't need one. I understand that Fireflys charge just like AGMs.

Yes, climate and latitude determine solar output. Our camping will vary all over the place, from our home base in New England in the summer months, to the Southeast in the winter as snowbirds and we also want to do a western states trip in the fall.

I realize the Era has no outside storage to speak of, so I plan to use a hitch mounted carrying rack to store the bulky stuff: extra 5 gallon LPG tank, camp chairs, BBQ, etc.

David

[AJMike]

Originally Posted by DavidM

Voltage is a wild approximation at best of SOC because it is very much affected by current draw at the time you measure the voltage, so I think 12.1 volts could be 50-70% SOC so 60-100 amp hours used from your 200 Ah bank. I wouldn't bother running the generator until the voltage dropped to 12.0 with no load. That will keep them at 50+%.

For what it is worth we have also seen the voltage down to 11.9 early in the morning but I have never actually turned off the fridge to completely eliminate any current draw and then checked the voltage.

Originally Posted by DavidM

How do your AGM batteries charge while driving? You have the Ford diesel powered Fuse and I think it is also a "smart" alternator controlled by the engine's ECU. I will certainly try it without a B2B and if it charges fast then no I don't need one. I understand that Fireflys charge just like AGMs.

They seem to charge very quickly off of the alternator. Of course I can not get up while driving and check the solar voltage but if we stop after 3 hours the batteries always seem to be fully charged. The term "fully charged" in this case only means that they show as 100% in the solar controller. Until earlier this week I did not have a battery monitoring system installed so I had no other way to check for charge.

Originally Posted by DavidM

Yes, climate and latitude determine solar output. Our camping will vary all over the place, from our home base in New England in the summer months, to the Southeast in the winter as snowbirds and we also want to do a western states trip in the fall.

As I mentioned, for us clouds are the big solar killer. We were getting far more charge than I would have thought possible for 300 watts of solar but even small clouds cut that in half. A cloudy day means the difference between 15-16+ solar amps and perhaps 6 or 7 solar amps and so generally makes the difference between running our generator and not running it.

Originally Posted by DavidM

I realize the Era has no outside storage to speak of, so I plan to use a hitch mounted carrying rack to store the bulky stuff: extra 5 gallon LPG tank, camp chairs, BBQ, etc.

I suggested that to my wife but she liked the ERA because of its short size and ability to fit into pretty much any space so adding more length by attaching a rear rack was something she just did not want to do. And, of course, I was not sure I could find a rack big enough for all of the stuff we carry - leveling blocks, containers for electric extension cords, water hose, dump hose, black tank flush hose, tools, 2 camping chairs and so on. And even with all of the additional storage space in our Fuse my wife still refers to the shower stall as "the storage shed".

Still, I really liked the idea of being able to drive a more normal sized vehicle like the ERA, fit into parking spaces at the grocery store, fit into pretty much any camping space and not have to put out slides when we stop. I really like our Fuse but there are times I just don't really want to have to set up completely - level, put up the stabilizers and open the slide - just to stop for a short night's sleep.

The other side of the coin is that I am happy to have the Ford and its diesel rather than the MB sprinter chassis. The cost of an oil change for the MB is really high here and I did worry about finding a shop to service them while on the road. The Ford is much easier to take care of and I don't have a biodiesel issue like the MB diesels do, so there is that.

[DavidM]

I understand the concerns about the problems with the Mercedes diesel. There are a few horror stories on Sprinter-Source about failures that required long distance towing to a suitable repair facility.

Apparently you can avoid most of the problems by not letting the low DEF indicator go on. When it does and you fill it, it sometimes doesn't turn off, necessitating a trip to a truck Mercedes or Freightliner dealer and a few thousand dollars to fix it. But with the financial incentive of a 60,000 mile warranty I think Mercedes has worked hard to eliminate these.

We will probably buy a 2018 so it will have at least a few years of free fixes if needed.

I did look hard at the Fuse for just that reason- a Ford diesel. But I concluded that service facilities for that engine might also be few and far between. It is only used on the Transit chassis and I doubt that your average auto and light truck dealer would know how to do anything with it.

The Fuse is a bit shorter and has a shorter wheelbase, both of which led me to the Era.

David

[AJMike]

Originally Posted by DavidM

Apparently you can avoid most of the problems by not letting the low DEF indicator go on. When it does and you fill it, it sometimes doesn't turn off, necessitating a trip to a truck Mercedes or Freightliner dealer and a few thousand dollars to fix it. But with the financial incentive of a 60,000 mile warranty I think Mercedes has worked hard to eliminate these.

Other than finding a repair shop my biggest concern with the MB diesel was its inability to regularly use biodiesel. My understanding is that they recommend never using anything more than B5 and I remember seeing an article about MB denying an owner warranty work on a failed diesel because they regularly used diesel fuel with a higher percent of bio than B5.

[Walter]

We have a 2017 view D. Had problems with fridge, changed batteries to 6 volt. Helped some. Then upgraded solenoid. Under passenger seat in ours. Haven’t had a problem since. Been on road for 2 months without hookups. We do run generator some but not after 8 pm. Can even keep ice cream in freezer now

[CoreyinWP]

Originally Posted by Walter

We have a 2017 view D. Had problems with fridge, changed batteries to 6 volt. Helped some. Then upgraded solenoid. Under passenger seat in ours. Haven’t had a problem since. Been on road for 2 months without hookups. We do run generator some but not after 8 pm. Can even keep ice cream in freezer now

What model fringe do you have now?

[AJMike]

Originally Posted by Walter

We have a 2017 view D. Had problems with fridge, changed batteries to 6 volt. Helped some. Then upgraded solenoid. Under passenger seat in ours. Haven’t had a problem since. Been on road for 2 months without hookups. We do run generator some but not after 8 pm. Can even keep ice cream in freezer now

What solenoid? What does it do?

[Walter]

Originally Posted by CoreyinWP

What model fringe do you have now?

. Fridge is Norcold DE0061. What exactly the solenoid does I’m not sure but believe it has to do with charging the batteries. Have a great RV guy in Auburn California, he tested solenoid found it wasn’t producing properly. Recommend upgrading it. Cost $26 installed myself quite easily.

[Elkman]

There are battery isolation manager devices designed primarily so the house batteries do not drain the engine battery. For lithium batteries I had the Li-BIM 225 that Battleborn sells installed.

With the factory lead acid batteries the fridge would drain the two batteries to 50% SOC after less than 2 days of operation and with no opening of the fridge doors. With the lithium-phosphate that time is doubled and the new batteries charge in a third the time with the generator as the factory lead acid ones.

The Boeing Dreamliner uses many lithium batteries to operate it in flight and so the engineer work has been done to make them safe. Ever read of a problem with an RV using these batteries?