1994 Itasca Sunrise Electric Query

[Sara K]

We installed a Sunforce 1500 watt pure sine inverter in our '94 Itasca Sunrise (23ft) using the fourth method listed here: DIY Inverter Install.

So, the inverter is in place and securely connected to the battery bank, and is working fine when an appliance or extension cord is plugged directly into it. However, the goal of this project is to plug our shoreline into the newly installed 30amp outlet and provide power to the coach without the hassle of an extension cord or directly plugging the coffee maker to the inverter, and that is not working.

The rig has a retrofitted 7345ru Parrallax converter, and we are thinking this is the problem- that is, our inability to find a breaker specifically dedicated to turning the coverter off in order to rely on inverter power. [The breaker we originally thought was for the converter just shut off all the appliance circuits.]

...Ha! Okay, as I type this cry for help, my husband just came inside to inform me that he has found and pulled fuses that effectively shut off the converter, and that this did indeed make the appliances work... Unfortunately, the battery is now draining at an alarming/noticeably quick rate.

Could it be that our battery bank is too weak/old (two deep-cycle marine batteries changed "fairly recently" according to the previous owners we purchased from 5 weeks ago.) Does anyone have any experience with this type of installation on a similar model, and/or troubleshooting advice?

Thanks for your time.

[John "T" Nordhoff]

  Okay Sara, here goes, you asked for it lol

 DEFINITIONS

  Just in case you're unaware, I'm "guessing" what you call a CONVERTER (I call them Converter/Chargers if that's what you have??) uses 120 VAC power, converts it to 13 to 14 VDC, and charges the house battery bank when youre plugged into shore power AND ALSO powers the 12 VDC appliances (lights and water pump and furnace etc).

 That Inverter (as I'm sure you're aware) does sort of the opposite, it inverts 12 VDC to 120 VAC so 120 VAC appliances like your Microwave or Coffee Pot  or Hair Dryer or 120 volt lights or appliances etc. can work via your batteries if you're dry camping NOT hooked to shore power. UNTIL THE BATTERIES RUN DRY!!!!

 Sounds like you're onto it. If you're dry camping and not hooked to shore power the house batteries must supply all your energy needs (12 VDC as well as 120 VAC via the Inverter), one of which is the Converter/Charger, which consumes battery energy and yes puts some of it back into charging the house batteries HOWEVER its not a perfect efficient device, there are heat losses, so it cant take energy out of your house batteries and put more energy back into them. If you're dry camping and using stored battery energy, no sense in using some of it to produce heat losses and put less back into the batteries then its drawing out YOURE RIGHT TO TURN IT OFF WHEN DRY CAMPING.

 

 Next, you mention having 2 deep cycle marine batteries??? Lets discuss that. Are they true deep cycle batteries like say Trojan Golf Cart batteries or equivalent?? 6 or 12 volt?? Or are they quasi deep cycle Marine/RV batteries like sold at Wally World?? I like to use Stored Energy Capacity such as Amp Hours when I talking about RV's and dry camping. If your batteries are 12 VDC and you have two in parallel THE AMP HOURS IS ADDITIVE i.e. if you have 2 in parallel and each were say 125 Amp Hours, you now have 250 Amp Hours of stored energy. If they are 6 volt batteries and you place the two in series to obtain the necessary 12 volts, the Amp Hours IS NOT ADDITIVE while the voltage is.

 You mention the batteries are draining at a fast rate!!!! Wellllllll that depends on the amp draw,,,,,,,,,, and your total stored battery energy (say 125 or 250 Amp Hours),,,,,,,,,,and the battery condition. Remember if you had say a 200 watt 120 VAC draw out of that inverter that means MORE then 200 watts are coming OUT OF the battery (Inverter NOT 100% efficient, has heat losses) and at 12 volts that's 16.7 amps so depending on your battery size and type its not surprising they will run down at a rapid rate.

 BOTTOM LINE you may (depends on load) need more stored energy i.e. more batteries, two isn't all that much. ALSO I would recommend the use of true deep cycle golf cart type of batteries (I have 6 volt) versus the quasi deep cycle commonly called RV/Marine batteries.

 In my RV I have 460 Amp Hours of stored battery energy by the use of four 6 volt true deep cycle golf cart batteries in series/parallel. I have one buddy with a bus conversion that has six batteries and another that has 8... FOR EXTENDED RV CAMPING subject to your use and loads, only two batteries isn't all that much.

 Finally, if you do a lot of extended dry camping like we do, then you might want to consider the addition of Solar Panels that can charge your batteries.

 NOTE for any Billy Bobs or Bubbas who may arrive (you know, the ones who like to play Gotcha)  IT ALL DEPENDS ON YOUR USE AND LOAD so my numbers are only typical and may or may not be correct. If you want to consume anywhere near that 1500 watts of Inverter power, just remember at say1500 watts, that's more then 1500 watts being drawn from your batteries, and at 12 volts, that would be more then 125 amps !!!!!!! and if you only had 125 amp hours of battery energy storage, 125 amps over one hour YOUR BATTERIES ARE WAYYYYYYYYY DOWNNNNNNNNNNNNNNNN  LOL

 If you're dry camping with no shore power you just cant use big high current draw appliances like microwaves or hair dryers or coffee pots (even if your Inverter has plenty of capacity) very long without draining your batteries subject to their capacity and your load. I USE MY ONAN GENSET FOR THOSE THINGS when dry camping.

 For two people with my 460 Amp Hours (4 golf cart batteries) of stored battery energy and 200 watts of rooftop solar panels, if the sun ever shines at all and its not raining day and night for days, we can pretty well be self sustained, i.e. during the day the solar puts as much or more energy into the batteries then we use all day and night... Of course, for a brief AM Coffee Pot use or the wifes hair dryer or occasional Microwave, we use the Onan Genset and our Refrigerator that can run on EITHER 120 VAC orrrrrr LP Gas we run on LP Gas when dry camping so were not having to use up our batteries plus an inefficient Inverter.

 YOU MAY NEED MORE BATTERIES!!!!!!!!!!!!!!!

 John T  Retired Electrical Engineer and RV owner of over 40 years.

[Sara K]

Hi, John! Thanks so much for your response.

Yes, when I typed converter, I meant converter/charger. As mentioned, our old RV was retrofitted with a newer unit than came factory, but the unit is still inefficient compared to the "smart" chargers available today.

The solution we're using (for now) to turn off the converter/charger when we want to run the inverter is to pull the two fuses on the control panel that correspond to the converter/charger. We'll likely just add a single switch to perform that function instead of attempting an automatic relay.

The batteries we have are (2) AutoCraft Marine / RV 12-Volt Deep Cycle Battery, Group Size 24M, 550 CCA. According to Advance Auto's website, each battery has 140 amp reserve. You're right, we don't have a lot of extra stored power at any given time. [We do have a generator; unfortunately, it was hardly ever used and we haven't been able to get it running at its full capacity, but we figure that's a problem for another day, because many of our first planned overnight stops restrict generator use anyhow.]

We definitely want to add a solar set up and a smart charger, not to mention new golf cart batteries with extra amp capability, when our finances allow. Currently, we've just got to work with what we have. Our intent was to be able to watch a movie, use a light or two, and run the 3.2 cubic, AC power mini fridge while we dry docked overnight en route to a destination. It sounds like maybe that's going to be asking too much from our current battery bank...thankfully, we haven't bought the fridge yet.

[John "T" Nordhoff]

 To my way of thinking, its my best "guess" those are what I call Quasi Deep Cycle Batteries made for Marine use where you still need more like a starting battery to crank over a hefty outboard motor but then more like a deep cycle to operate a trolling motor. They sort of do BOTH, maybe call them a semi deep cycle lol That's NOT the same as true Deep Cycle Batteries made more for Golf Cart use like Trojan and several other brands. Id just use them as long as they are good, but if you're serious about longer term dry camping then Id consider the use of true deep cycle golf cart type batteries in the future.

 That being said to watch a movie and run a light and operate a mini fridge, two of those batteries MIGHT (depends on temperature and load and batteries and type of fridge and its efficiency etc) get you by overnight. However, that fridge can be a deal breaker subject to temperature and its size and efficiency as its the BIGGER LOAD load as compared to a small TV or a light or two.  That's why for extended dry camping instead of running our fridge on 120 VAC and having to rely on an imperfect Inverter plus being a substantial battery draw, we run our fridge on LP Gas, as its a dual energy (LP Gas or 120 VAC) device.

 You're on the right track in my opinion if you in the future go to a Smart 3/5 Stage Charger and true Deep Cycle Batteries and add Solar Panels THATS IF YOU WANT THE CAPABILITY FOR EXTENDED DRY CAMPING. Then you can choose between a fridge that only runs on 120 VAC (much cheaper but requires a hefty Inverter and batteries) or a more expensive dual fuel fridge that can run on EITHER 120 VAC or LP Gas. I like having the choice myself of either 120 VAC when plugged up, but LP Gas which is best for extended dry camping as its not sucking a bunch of battery power like a conventional AC fridge and having to use an Inverter.

 YOUR MONEY, YOUR NEEDS, YOUR CHOICE 

 For two people for extended dry camping ours again has 460 Amp Hours of stored battery energy (four 6 volt Deep Cycle Batteries),,,,,,,,a Xantrex Truecharge2 Smart Charger,,,,,,,,200 Watts of Solar Panels,,,,,,,,,,,Onan 4 KW Genset. With that setup and running the fridge on LP Gas (so its not sucking battery power like an AC only fridge)  we can camp indefinitely as far as energy is concerned, but water is the limiting factor so we carry 110 Gallons of Fresh water plus I have added extra Gray and Black Storage Tanks which enables us to stay 7 to 10 days, but by then its time to DUMP and take on fresh water......... 

 Hope this helps, best wishes God Bless

 John T

[Sara K]

Also, and this is just a question I have as I try to understand RV electrical systems. Thanks for bearing with me. You said the converter/charger "ALSO powers the 12 VDC appliances (lights and water pump and furnace etc)."

So, when I pull the fuses on the converter/charger to make use of the inverter instead, the inverter also creates 12VDC power to work the lights? I haven't looked at the water pump or furnace, but I know that the lights work when the converter/charger is disconnected and only the inverter is on...

[John "T" Nordhoff]

  When I said it ALSO powers 12 VDC appliances, perhaps what I could have said (and depending on how its wired) is that it is charging the 12 volt battery and the 12 volt battery is what powers the appliances, that's how my RV is wired and operates. (So in effect, its doing BOTH things when on, charging PLUS powering appliances, a matter of semantics perhaps lol). Many original Converter/Chargers have a built in 12 VDC distribution fuse panel where circuits begin that power lights or maybe the water pump or furnace etc. Those 12 VDC appliances obviously work regardless if you're plugged into shore power because the battery is in the circuit, but when you're plugged in and the Converter/Charger is operating and its voltage is slightly higher then the 12.6 battery volts (its output is more like 13 to near 14) lights will get noticeably brighter so they operate PLUS the battery is still being charged, i.e. its doing BOTH.

 NOTE I have had RV's that utilize a relay in which case if you were to unplug from shore power the lights may go off just a second until you hear a relay activate after which time the 12 volts (strictly off battery) is then powering the lights. On those systems when you're plugged in the battery is still being charged, while the Converter/Charger also has an output circuit that feeds the 12 VDC distribution fuse panel so all that works and a tad brighter as its voltage is higher then the normal 12.6 battery volts.

 Sooooooo like I said, on my RV the batteries are always powering 12 volt loads but when I'm plugged into shore power my Charger is charging the batteries which in turn power the appliances (could say its doing BOTH?), but Ive had RV's with a relay device that act like above where when plugged in the Converter/Charger could be said to be powering appliances and ALSO is charging the batteries. 

 I JUST DONT KNOW WHAT YOU HAVE but now you can see what I meant by saying it still does BOTH things, but subject to how its wired and operates.

 The Inverters INPUT is the battery voltage while its OUTPUT is 120 VAC. When its on its drawing energy out of the batteries,  yet the batteries can still be operating the 12 VDC appliances.

 Got it??

 John T

[Sara K]

Got it! When the INverter is on, it supplies 120VAC power to appliances that use that power, and at the same time the batteries are supplying 12 VDC to the lights/appliances that require that type of power.

If I were to unplug from shore power without utilizing the inverter or generator, the lights and things that use 12 VDC power would still work but those requiring 120 VAC would not; the coverter/charger should continue to supply 12 VDC power to lights/12VDC functions and keep the battery from being discharged.

In essence, if all we wanted was to have basic RV amenities (light, water pump, furnace) we could camp with no power worries save for the converter/charger.

Obviously, we do want 120 VAC amenities even without shore power, and that is why we bought an inverter. When we can upgrade the battery bank and get solar, we'll be able to use those luxuries for longer amounts of time.

Another fun question I've read conflicting answers to all over the internet: can we run the inverter while we're driving? Will the house batteries keep charge if we're inverting their power to run that mini fridge while en route?

[John "T" Nordhoff]

  Your Question:

  Another fun question I've read conflicting answers to all over the internet: can we run the inverter while we're driving? Will the house batteries keep charge if we're inverting their power to run that mini fridge while en route?

 ANSWER .......... MAYBE

 First of all, most Motorhomes have a solid state or mechanical isolation relay whereby the engine battery (which Alternator charges) eventually (subject to possible time delays) gets connected to the RV House battery once the RV is up n running. That way while driving the engines Alternator is charging BOTH engine and house battery. However, once the engine is shut off, the relay eventually opens and the batteries are no longer connected because you don't want RV use to discharge the engine battery so the engine cant be started.

 Sooooooooooo the Inverter is simply just another load on the house battery just like 12 VDC lights or water pump or vent fan etc., and you can use those while driving.. Sooooooooooooo yes you could use the Inverter while driving HOWEVER NOTE there exists a possibility, depending on the current the Inverter draws which depends on the 120 VAC loads it supplies, the Inverter may be too much of a current draw which could over tax the engines alternator provided its connected to house battery via a closed isolation relay discussed above BUT THATS IMPOSSIBLE TO SAY NOT KNOWING THE ALTERNATOR RATING AND THE INVERTER CURRENT DRAW. If the alternator cant keep up with the Inverters current draw you could eventually discharge the house batteries and/or the engine battery and/or fry the alternator subject to its own protection.  

 If you were to tell me the Inverter requires X Amps to power the fridge which draws X amps at 120 VAC at a X% duty cycle etc., and we knew if the alternator was say a small 55 amp or a larger 80 to 90 amps, we could come closer to a better guess. If the fridge is small and very efficient and you have a good high amp alternator like an 80 or 90 or even 100 amp, then Id say you can likely get by using it while driving. IT DEPENDS ON SIZE OF ALTERNATOR AND HOW MANY AMPS THE FRIDGE REQUIRES.

 I say therefore, the ONLY correct answer is MAYBE because without knowing the Inverter current (which depends on the fridge current) and alternator rating, those gents who say definitely yes or definitely no sure cant guarantee their answer...........

 That's my story n Ima stickin to it

 John T   Retired Electrical Engineer and RV user/dealer of 40 years 

[John "T" Nordhoff]

One last PS:

  Iffffffffffffffffff your fridge is one of those small efficient units and Id "guess" your alternator is maybe at least 60 to perhaps even 80 amps and theres no other huge loads other then your RV engine's ignition system, maybe a light or two, maybe an AC electric clutch engaged and a fan, and your Inverter is sufficient rated to allow the fridge to start and then operate I WOULDNT BE AFRAID TO AT LEAST TRY AND OPERATE IT WHILE DRIVING. After all its just a battery load (albeit bigger) like all other loads you may operate time to time while driving, so if the Alternator isn't over taxed and your fridge draws relatively low amps it may well work BUT AGAIN NO WARRANTY NOT KNOWING THE FRIDGE CURRENT DRAW AND DUTY CYCLE ETC..........

 John T

[Jimco_W001]

Sara,I run my AC fridge off the inverter all the time.It works great when traveling and is four cubic feet in size.This fridge pulls about 30 DC amps from the batteries when running off the inverter and 3 amps when its running off shore power.My alternator is rated at 50 amps and the inverter is 1000 watts with a 3000 watt max.

[John "T" Nordhoff]

  GREAT INFORMATION Jimco man......... See, knowing the actual amps the Inverter requires to run the fridge and knowing the alternators rating IS THE ONLY WAY TO CONFIDENTLY ANSWER HER QUESTION. Hopefully she can get that info about her fridge and there's a darn good chance (subject to her fridge) she can get by the same as you do while driving  Yayyyyyyyyyyyyyyyyyyy

  It also shows her (and our other readers) how she couldn't get by dry camping for an extended period running a 120 VAC AC Fridge off an Inverter with only her two batteries grrrrrrrr lol

 Happy Memorial Day Thanks Vets

 John T 

[Jimco_W001]

Sara,good batteries and a way to charge them is very important.How old and what type are your batteries?

[Sara K]

Howdy, Jimco; thanks for your reply!

The (2) batteries are AutoCraft Marine / RV 12-Volt Deep Cycle Battery, Group Size 24M, 550 CCA. I am unsure of an exact age, as we just purchased this RV approx. 7 weeks ago, and the previous owner simply said they'd been replaced 'fairly recently.' We have had the RV hooked up to shore power for the bulk of time we've owned it.