House Batteries 18V24D

[Kayak73]

Sometimes you get lucky...Over a week ago I ordered two Trojan T-105 batteries for the new View. After not getting the call to pick them up long after they were due in I called the guy and he said "we did not order them". Great! Great because I have been seriously checking our amp hour draws in the little beast and T-105s would not make it for a real boondock, possibly with a lot of generator usage. Factors involve long term CPAP user who must use the humidifier, wanting to actually wash hands, flush toilet and maybe listen to music or even watch a bit of TV.



Lots of thing to add up but it appears with frugal and limited use of features we need about 170 amp/hrs per night. That is fair comfort range and 120 amp/hours is bare minimum. Thanks for the refrigerator WGO! Reality bites but we must move on.



Next the brain is looking at all the options, T-1275s with mods to the battery box and 85lbs additional weight over OEM - not perfect. Then a few discussions about lithium. That is the only way to go and not impact the OCCC. We travel spartan but still are on the cusp because we travel with a BIG dog, love him, he keeps danger away, big baby really but if he barks (because of a threat only) you and I will hear it far away. I hate the cost of lithium but as others have pointed out that is cheaper than dumping this rig after 5 months of ownership. Besides that, even with all the early issues, we really like this little rig.



Where are we going to stuff one single 12 volt 300 amp/hr lithium? Under the kitchen sink of course. Major mod is coming. Cutout a space for the battery to sit through the cabinet bottom and onto the floor below, drill a hole through the floor, run battery cables to original under step box, install two four port copper panels for connections in the step box, plug it up and get happy - hopefully. Yes, it would go in the nearest storage bay but inside it is climate controlled and these new batteries are not dangerous, no fumes, no gassing possible. Now if WGO is reading this stuff, this is a real option to offer when you put in a compressor refrigerator. Oh, almost forgot, there is NO weight penalty with the lithium - just dollars, lots of those. Still evaluating different brand name lithium but they seem to be around the $3k point regardless of brand for this amp/hr. I will also put in a 2000 watt PSW inverter under the sink for a few things like making a cup of coffee and leave the stock 1000 watt PSW in place for the CPAP. Probably install an outlet on top of the big counter from the new inverter as well as an outlet on the baseboard under sink. Sometime this summer we have got to get on the road for our fall adventures.


Hopefully an additional solar panel on the roof will help keep the big honker charged up but the View rooftop is a limited space. We'll see over the months as work progresses. Still have to get the replacement solar panel for the dead one and the A/C fixed. Hope that will do it for new rig stuff.

[LarryW]

“Hopefully an additional solar panel on the roof will help keep the big honker charged up but...”

A realistic energy survey times 1.5 should tell you, kayak, necessary battery amp hours which leads you to needed solar panel watts, correct? Please remember T125s are the same size as T105 but have 15 more amp hours. Might help.

[Kayak73]

Larry, that's my pretty well defined survey above based on the refrigerator and CPAP draws. I'll typically be in the CPAP about 6-7 hours but the fridge is running > 50% duty at 5.6 amps. Yes, I checked parasitic and the TV etc. In dry camp we won't use the sat normally but the antenna if we watch any TV. I added in everything we normally use, minutes of water pump, etc. The Truma is unmeasured and I know it does draw some in recirc mode for the internal pump but that I have not measured. Honestly I don't think 300 watts of solar will do it, 420 would be much better but there is always a diesel genny in the rig. Since the lithium accepts the charge much faster it should be workable. We really want to get back to BLM and boondock mode, one big reason we dumped the pusher for the View. I like the idea of solar and in a big rig you can add enough panels to make it really deliver but again, on a rainy, cloudy day the amps are much less. That's why we have the diesel. Many places do allow 2 hours AM and early evening of genny run.

[Kayak73]

Realistically if you get 4 hours of good sun it might be possible to put back perhaps 60 amp/hrs into the battery with 300 watts of solar but that's a good day's sun. That tells me I'll probably need a better charger so the generator run will put a faster charge back into the lithium battery. Now 420 watts is a lot better because the fridge is still running a heavy duty cycle all day, taking 5.6 amps > 50% of the time. I really don't have a recording meter now but my guess, based on watching and listening to run times is about 75amp/hrs a day at least for the refrigerator, a lot. Half of that will be at night at least so daytime has to be recharge. If my estimates are correct 3x100 watts panels will not even replace the energy used by the refrigerator daily given solar variables. Now if you run the refrigerator at a setting which gives 20*F in the freezer that duty cycle drops significantly. In cold weather you can chance dropping the control level at night since the door stays closed, then bump it back up in the daytime to help save energy. I am running the thing so it holds 1-2*F in the freezer right now in monitor mode. My last test of the OEM batteries with 75 amp/hrs each in parallel got me to below 12vdc reading in three hours or less after good sun on the panels (when two were working, 7-9amps output), with the battery at pretty near 100% SOC at the beginning of the day when I unplugged from shore. That did not include a recovery period for the batteries to tell me how much I really had beat them down because I just plugged the shore cord back in at that point. Absolutely nothing else running in coach except parasitic draws, nothing. Of course that reflects the quality of those OEM batteries and how insufficient they are for the application.

[Mooneypaul]

Another thing to consider is the parasitic draw from the propane switch. There is a mod that reduces by about 90% the draw that is used to keep the electric valve open. You can read about it on the View/Navion Motorhomes Facebook group or the Minnie Winnie Yahoo group.

The valve uses about 20 amp hours per day. I installed the one engineered by Leonard Casella there are two available.

[LarryW]

Excellent analysis of your situation, kayak. I can get 60 amps back in my batteries with my 300 solar watts most days.

[Kayak73]

Originally Posted by Mooneypaul

Another thing to consider is the parasitic draw from the propane switch. There is a mod that reduces by about 90% the draw that is used to keep the electric valve open. You can read about it on the View/Navion Motorhomes Facebook group or the Minnie Winnie Yahoo group.

The valve uses about 20 amp hours per day. I installed the one engineered by Leonard Casella there are two available.

Thanks! I downloaded several videos showing the process. Have not worried with it yet because in the new Views you don't need the LP turned on very often. Compressor refrigerator, runs on 12VDC. So...you leave the LP switch turned off more than 90% of the time. Just turn it on when you want hot water and the Truma is instant hot water which makes the LP switch draw pretty low on a daily basis, give it maybe 2 amps for the entire day or maybe 1 amp/hr or less on the units with compressor fridge. When it becomes a contributor is on cold nights in dry camp when you must leave the Truma in ECO mode to prevent possibility of freeze up, then it is a hit as you have noted so it is a nagging thing I should get around to.

[LarryW]

“The valve uses about 20 amp hours per day.“

That’s terribly inefficient...a propane value. Who designed that?

[Mike Owens]

Make sure you get a charger with a temp probe. That way you can monitor the charging while taking it to the max. Maybe an inverter / charger two birds with one stone.

[LarryW]

I agree with Mike.

[Old Crows]

Bill, interesting situation. Suggest backing up a couple steps here. You have made an energy consuption estimate & use study. Good. Noting your comment about repairing a defective solar panel, it might be a good idea to do that first and sort out your 'actual' solar gain averages before jumping into a lot of work and expense. Once the solar bank is working properly, you can get a better handle on modifications needed, if any.

Right now it looks like your consumption is exceeding your storage and replentishment capabilities because you have a solar panel casuality. Batteries are like tanks of water. They store energy. Li batteries have a high power density. You know this. But, like all tanks, how long the last depends on how "wide" you have the valve open. Compressor fridge, "instant" hot water, and 'conveniences' are energy parasites sucking energy out of a very small tank.

Batteries do not need to be 100% charged on a daily basis. (Yes, a contrarian Crow opinion!) They can comfortably operate between ~40-50% to ~90% state of charge for a long time with occasional bumps to 100% & a maintainance cycle. While it is important to have the ability to fully and adequately charge the battery bank, not necessary to do it all the time. You just have to live within the capabilities of the system. Like using your fresh water or your toilet paper.

We don't top up your gas tank every time you finish driving your car do we?????

A cool thing about RVs is that they are technologically complicated and have grown up to have redundant capabilities. If you have a genny, solar and the Sprinter, you have three ways of generating electical power for use and charging. Four if you count shore power. It is a matter of figuring out how to use them effectively and manage the use of the energy.

[Kayak73]

Old Crows, all great advice and appreciated! I know exactly the maximum output of the solar panels when both are working in optimum conditions. Each panel will provide at maximum optimal conditions near 5.6amps. So I'm talking about around 60 amp/hrs per good sun day with both good OEM panels. Other comments well heeded and agreed on. No issue at all when SP is available, only in dry camp - one main, albeit flawed, reason for moving back to the little View from our DP. After all the rigs and years doing this you would think I considered the flaw of the compressor fridge vs energy storage and truthfully I did - in passing - and went straight to purchase because we really loved the floor plan in a small rig. Many things to say in hindsight but as they say...that's easy. The difficult thing is to adjust reality. I'm really drawn to the used Tesla battery market because the fridge and my CPAP both operate native on 24VDC - nice. That, however, makes the install a lot more complex and time consuming than moving to a drop in replacement lithium battery off the shelf. I seriously can't think of any other way to provide adequate energy storage based on the DE0061R energy use and my CPAP. Fortunately CPAP use is less than 1/3 of the day but I must use the humidifier. Now if there were no weight restrictions I would go with larger Trojans, easy. Unfortunately every thing we put in the View has to be well considered and weighed based on OCCC. The diesel generator is there and a great power source but limited in many situations/parks to four hours daily as you know. We have about 7 weeks before heading off on a long venture which hopefully will include a lot of dry camp time.

[Mike Owens]

Can you swap the fridge out to a absorption unit and be done?

[LarryW]

That's interesting, Mike. Why not?

[Old Crows]

As Mike Owens & LarryW have said. Maybe the 'solution' is retrofitting an ammonia cycle fridge/freezer and dumping the compressor job. That may solve several issues.

It may be less complicated and less expensive to swap out the fridge. You may be able to get by on what you have in terms of batteries, chargers, panels, & inverter.

Obviously, very low current draw over time. The offset would be you need LP. But once cooled, it shouldn't take very much to keep it down to temp. It will run off AC (genny or shore power) and they can run off the Sprinter alternator underway. Auto shifting power source would be a plus. You might be able to rig the fridge to be powered off the inverter/battery bank if you have the solar array working up to snuff.

The other issue would be to put in two vents in the side of the RV for venting the fridge. Not a big deal but must be done carefully with an eye to making sure the installation instructions are followed to assure good convective air flow.

There may be another option. Set up a separate power supply for your CPAP that is independent of the RV's system. As long as you can recharge your CPAP battery bank (solar?) you would be in business. AND, you have redundancy by plugging in to the RV system if you would ever need to. Sort of like a reserve parachute....

(For the life of me, I'm just not understanding WHY... WBGO would be installing compressor fridges in Class C RVs. And THEN, they don't bother putting in 110V AC power for it. Ammonia cycle fridges/freezers have been around for over 100 years and they work pretty darn well on the whole. And, with a three way ammonia cycle you have lots of options. With a 110V/12V you got one, or none.

(Yes... two physicists held patents on improved designs from 100 years ago. Little known guys: A. Einstein & Leo Szilard. Now all that is owned by a little Swedish company, Electrolux. )

[LarryW]

Old Crows, I read the numerous posts about how bad absorption fridges are but I just never have had an issue. A residential fridge would complicate my boondocking adventures in our smaller TT. I do use a battery operated fan inside the fresh food compartment however.

[Kayak73]

OK, every RV we owned since 2000 has had a Dometic absorption refrigerator, never had a single problem, never really thought about the refrigerator - just used it. Boondocks were easy, stay out as long as you want, the refrigerator used very little LP. Replacing the compressor unit would indeed require two access panels outside, the bottom larger one with vent and a vent on top - probably not too hard to pay someone to do properly. Run LP line and it would work. My guess is that would be about the same money as installing a drop in LifeBlue 300amp/hr at $2798 right now, free shipping. I could not agree more on the insanity of the setup from the factory. BTW, I would not be terribly surprised if someone looked and found my refrigerator is plugged into 120ac and 12vdc...just saying. If the generator is running 4 hours that offloads four hours of fridge runtime so in effect the house battery is being charged better during the generator run. Lot of speculation but it comes down to keeping the weight down for OCCC and supplying reserve energy to function. Adding another AGM for the CPAP is just more weight again. LiFeP04 prices have dropped a lot since 2013 and will drop a bit more before stabilizing probably. For a drop in battery the LifeBlue might be fine with the BMS they use, monitor from the tablet or phone. The big deal is keep the recharge below 93% SOC so it does not really hurt to use the float charge. I need to learn a bit more about their BMS to know.

[LarryW]

Good comments, kayak.

[SarahW]

Originally Posted by Kayak73

BTW, I would not be terribly surprised if someone looked and found my refrigerator is plugged into 120ac and 12vdc...just saying.

OK, so there is a 120AC behind there?

[SeeTheUSA]

Originally Posted by SarahW

OK, so there is a 120AC behind there?

Hmmmmm ..... is now ..... maybe .....