Newby trying to figure out battery and furnace issue

[JOBE1]

I recently bought a 2008 Rockwood ultralite. My battery appears to be dead (no spark) it is a 845 marine cranking amps 12v marine battery with threaded studs. The lights in the camper will only flicker on and I am not able to get the furnace to come on.
This is my first camper so I'm not sure what to address first.
I've read numerous articles about purchasing a new battery, but not sure what is best for the camper. I will use it in cold temperatures. It is plugged in at the campground, but the battery I currently have won't hold a charge. Do I need an external battery charger if I'm going to use the camper all the time? I also keep reading that we need to add distilled water to the battery? Is this with all RV batteries?
Is there something I need to check with the furnace?

Thanks in advance to whoever may be able to help!

[SeaDog]

Welcome to the forum its a great place to get your questions answered. Remove the battery and have it tested sounds like it is dead. If its plugged in and still the furnace or lights won't com on you may have a problem with the converter run a 12V test of your converter. If you don't understand the systems get some of your neighbors to give you a hand. Good luck let the forum know what you find.

[JOBE1]

Thanks for your quick response SeaDog! Do you have any recommendations for battery replacement? If there is a converter problem will it cause any issues if we attach a new battery?

[67L48]

Welcome to the show.

First of all, 12V batteries and battery systems are pretty confusing. At least, I think so. It's strange because they're so apparently fundamental, with Edison championing the direct current system a very long time ago. Little has changed. Yet, it's not super easy.

First of all, don't use sparks and other means to determine battery health. Go get a cheap multimeter for $35 and test the battery. 12V batteries aren't linear. A full battery isn't at 12.0 VDC, it's 12.6 VDC and higher. A dead battery isn't at 0.0 VDC, it's at around 10.5 VDC. A 50% dead battery is in the 11.6 VDC range. Sort of strange.

Walmart and most parts stores have devices that will test your battery. They measure volts, apply a small charge, monitor storage/discharge, and give a print-out health report card. This is free and easy.

Also, here is a great place to start with learning about 12V systems: 12V primer. You don't need to know everything on that site, but it's a great place to learn.

To your specific application, you need to understand a bit about battery ratings. Batteries can specialize in one of two areas: they can offer a lot of storage and power capacity or they can offer a lot momentary power for starting things.

The 845 cranking amps is for the latter. That's what helps the battery turn over power-hungry engines to get them going. But, engine systems have really nice alternators and other power generator devices. So, the batteries in our cars and boats don't really need a ton of capacity ... the batteries aren't actually powering our stereos, dash lights, and such -- the engine is doing that with the alternators/etc. We just need a battery that can provide enough power to crank the engine.

You have no need for this in an RV (not including motorhomes that still need a battery like your car/truck does to start/run the engine).

What you need is capacity and storage. Cranking amps (CCA) ratings are meaningless. What you're looking for is the Amp-Hour rating. And, you also want a battery that is designed for that type of use. They are called "Deep Cycle" batteries and are literally build differently than the lead-acid batteries in your car. Same operating principles, but thicker lead plates and such.

Amp-Hour ratings can get super confusing, too. It turns out that a battery's capacity is dependent on how quickly you discharge it. But, let's ignore that for now. For now, let's take the following battery label (I don't necessarily recommend this brand/type, but it's a good label to illustrate the points):


These so-called marine batteries are sort of hybrid and can be a bit of a controversial topic. They're not as good as true deep cycle batteries made by Trojan and other premium manfucaturers. But, you can actually buy these marine batteries in most locations (Walmart, auto parts stores, etc) ... I've never seen a premium battery on any store I frequent.

What we see are the typical cranking amps ratings. Again, these are garbage. Ignore them. We're not starting engines. We're powering lights, furnaces, etc. And, if you look around, you find an Amp Hours (or A-H, or Ahr, or something else that signifies the Amp-Hour rating). This is what we want.

Now, this is a Walmart battery and Walmart cheats the numbers by using a non-standard discharge rate to inflate the A-Hr rating. But, again, let's ignore that for now. This battery has a rating of 114 amp-hours and we'll accept that as fact for this post.

Your furnace is probably consuming around 4 amps when it runs. Remember, it's just powering a fan motor ... no power-hungry heating coils or anything like that. So, on a chilly night, maybe your furnace cycles on for a total of 7 hours. Thus, you will have consumed 28 Amp-Hours during the night by using that furnace. Lights, CO/LP detector, water pump, and other items also use power.

So, you need a battery, you need a deep cycle battery, and you need to get one with a healthy Amp-Hour rating (I try to buy 120+ Amp-Hours).

Remember, that discharging a battery below 50% of capacity can/will permanently damage it and limit its future capacity. So, if you think a weekend camping trip will burn through 68 total amps, then you need a battery with at least 136 Amp-Hours (2*68).

Hope this helps. Good luck.

[Cypressloser]

Originally Posted by JOBE1

I recently bought a 2008 Rockwood ultralite. My battery appears to be dead (no spark) it is a 845 marine cranking amps 12v marine battery with threaded studs. The lights in the camper will only flicker on and I am not able to get the furnace to come on.
This is my first camper so I'm not sure what to address first.
I've read numerous articles about purchasing a new battery, but not sure what is best for the camper. I will use it in cold temperatures. It is plugged in at the campground, but the battery I currently have won't hold a charge. Do I need an external battery charger if I'm going to use the camper all the time? I also keep reading that we need to add distilled water to the battery? Is this with all RV batteries?
Is there something I need to check with the furnace?

Thanks in advance to whoever may be able to help!

As SeaDog already said, test the battery (or have it tested) including a load test. If it is below 50% SOC (State Of Charge) and you don't know how old it is then replace it. A good option is to look for a golf cart battery, either 2 6 Volt or 1 12 Volt, the cold cranking Amps are less important than the Amp hour rating printed on the label. And yes, you need to check and maintain the fluid level inside the battery regularly and top it off with distilled water. A good and well maintained battery can last 6 - 8 years easily, if not maintained properly it can go bad within days
If your trailer is connected to 120 Volt AC power then the power goes into the converter box and gets transformed into 12 Volt DC power which is then used to charge the battery and run the lights, water pump, furnace and maybe a few other systems. FYI, a single 12 Volt battery is barely enough to last a day with the furnace running when not hooked up to shore power.

[SeaDog]

Originally Posted by JOBE1

Thanks for your quick response SeaDog! Do you have any recommendations for battery replacement? If there is a converter problem will it cause any issues if we attach a new battery?

You will hear all types of responses with regard to batteries and my take is it depends on how you use your RV. If you boondocks then large capacity batteries if you campground then a good quality RV/Marine or RV battery like the interstate will do.

If your converter is gone (only supplying 110V and no 12V) then yes the battery will drain and not charge even if you are plugged in. Fix one thing at a time replace the battery if that fixes the lights and furnace good (you can always charge with an external charger) now check the converter. good luck

[camaraderie]

You said you will be plugged in. If you don't dry camp then a cheap dual purpose battery from walmart like the one shown above is your best bet. You WILL have to remove the caps and refill with distilled water from time to time..check once a month or so. There are also kits (flow rite) to make "watering" easy. If you plan to dry camp a lot...then there are other choices in batteries...but no need to worry if you're gonna be plugged in 95% of the time.

All the battery voltage charts above are for a battery that has NOT been plugged in or used for 24 hours. Let autozone or walmart test capacity for you rather than try to figure it out for yourself. BUT you still need to get familiar with a basic voltmeter. Two things I would suggest:
1. With the unit plugged in measure voltage at the battey terminals. You should see over 13 Volts. Less...means your converter is NOT working ...more means it is.
2. Assuming you find the converter is working....Unplug the unit and remove the black negative cable from the battery. Test voltage again...if it is below 11.5V or so...head to Walmart for a new one. Get the LARGEST size that will fit the space you have available. That means....Group 31, Group 27 or Group 24 in that order. Don't worry about cranking amps ...get a deep cycle or dual purpose labled model if you don't dry camp.

[Grumpy7159]

Originally Posted by JOBE1

I recently bought a 2008 Rockwood ultralite. My battery appears to be dead (no spark) it is a 845 marine cranking amps 12v marine battery with threaded studs. The lights in the camper will only flicker on and I am not able to get the furnace to come on.
This is my first camper so I'm not sure what to address first.
I've read numerous articles about purchasing a new battery, but not sure what is best for the camper. I will use it in cold temperatures. It is plugged in at the campground, but the battery I currently have won't hold a charge. Do I need an external battery charger if I'm going to use the camper all the time? I also keep reading that we need to add distilled water to the battery? Is this with all RV batteries?
Is there something I need to check with the furnace?

Thanks in advance to whoever may be able to help!

I had the same symptoms in my 2017 Silverback and found a loose connection on a terminal strip in the trailer. Battery did not charge when on shore power because of the poor connection. I had my batteries load tested at Auto Zone for nothing. They do not load test unless they are charged however. 67L48's comments are spot on otherwise.

[jboczek]

Deep Cycle batteries are made to be discharged and recharged. They're typically used in fishing boats on trolling motors. They're designed to take the "deep cycles" without hurting them. If you're dry camping without plugging in, this is what you may need as the battery will be discharged and recharged frequently.
Look for a battery with good reserve capacity, as stated on the labels. That will tell you how much power you can get out of the battery for how long. Check your converter to make sure it is powering your 12 volt lights and appliances when the camper is plugged into 120 volts. If it's not working, fix it or get it fixed. You'll be much happier with it working and won't need an external charger to recharge the battery every day.
I've personally used a "cheap" group 24 battery in my TTs for over 20 years without a problem. My converters have always worked and I've never had a problem with 12 volt appliances and lights working.
Distilled water? Not necessarily. If the water is good enough to drink, it should be good enough for the battery. I've never used distilled water for batteries.
Just my thoughts.

[Wilco]

It could be the built in converter (battery charger) of your RV is bad. The fact that you are plugged in at the campground means the converter should provide 12v to your lights and furnace while charging your battery.
If you have a battery charger, connect it to the battery and see if it charges up. If it does then the converter is bad and needs replaced.

[Barb RPod CA]

I had to hunt for a schematic showing how electrical worked in travel trailers. It is odd that is not included in manuals, as well as flow charts for propane and water. Specifics in buying are always helpful, keeping in mind the way things are used and for what type of RV. Am happy to continue learning from those of you with experience and knowledge, and especially happy when you use baby steps, explaining tech-talk for us still learning. Thanks.

[clr]

You should always use distilled water in a battery. This is so that you are not placing minerals into the battery that will over time foul the battery plates. Distilled water has no dissolved minerals that is why you should always use distilled water in your battery.

[Scrapper]

JOBE1, Hello and welcome to the forum. Any group 24 or group 27 marine battery will work for your trailer. Deep cycle batteries are better if your not going to be plugged in to a pedistal.

The best person on the forums when it comes to electrical is wmtire. He has a list of documents and web sites that he recommends for people with electrical problems.

wmtire is a site team member and he may be responding to your post shortly.
You should be able to send him a PM.
Good luck with your problems.

Rich

[djemgoss]

Make sure that the breaker is on position on the shower power box. If its not, turn it to the on position! Your lights and the converter should turn on if they are functioning correctly! If the converter doesn't start (fan running) you may have a problem with it. Also check the battery cut-off switch, located near the battery, is in the on position. Charge your battery and see if it will take and hold a charge.

[vasnipe]

Here are a couple of links Herc and others have posted in the past to help explain 12v DC power . They sure helped me.

12v Side of Life Part 1
The 12volt Side of Life (Part 1)

12v Side of Life Part 2
The 12volt Side of Life Part 2

Hope this helps some.

Chris in Virginia

[67L48]

Originally Posted by vasnipe

Here are a couple of links Herc and others have posted in the past to help explain 12v DC power . They sure helped me.
[...]

Agreed. That's why I referenced and hyperlinked the 12V Side of Life in my earlier post!

Originally Posted by jboczek

[...] Distilled water? Not necessarily. If the water is good enough to drink, it should be good enough for the battery. I've never used distilled water for batteries.
Just my thoughts.

Definitely not. We're not talking about opinions on this one. This is hard science. Without getting too heavy into electrochemistry, the battery cycle needs distilled water for maximum efficiency.

It's not like your battery will blow up with tap water, but you're poisoning it. Like anything else, poisoning your battery will reduce its efficiency (capacity, in this case) and cause premature death. Walmart and other grocery stores sell gallons of distilled water for about $1/gallon. I can't think of a good reason to not use distilled water in your battery ... or radiator, for that matter.

Good luck.

[vasnipe]

Ooops.
My bad!

[herbike]

If your battery is completely depleted (dead) there is a great possibility that the converter will not power the lights, furnace or any other 12vdc users. We had that problem with our older Kit trailer. We went to an RV dealer and his tech told me I needed a converter. They didn't have one on hand and we were on our way to camp with my son and his wife.

My WIFE & the FEMALE parts person suggested maybe it's that the batteries are dead. Of course I didn't really agree with them until I checked the batteries for age, they were 6 or 7 years old, (we didn't use it much then). So, off to Costco we went, put in two new batteries and problems solved.

About three years later the replacement converter would run the trailer without being hooked to a battery. That trailer and it's converter were 21 years old.

You can depend, my wife hasn't let me forget that her and the parts lady were RIGHT!

[JOBE1]

Thank you all for your help! Who knew there was such a big learning curve when buying a travel trailer?! So the battery did have a dead cell. We ended up getting another battery from Walmart since that's all that was close to us. Although, we also checked the converter as suggested and its only showing about 5.6. I'm assuming that it is possibly going out also? I would rather replace than wait for it to go out completely also. Is a converter ok to switch out ourselves or is that something we should pay to have done?

[herbike]

The converter is fairly simple to change out, if you can get to it. I changed ours out with no problems other than where it was located made it difficult.

Here's a site that has reasonably good prices and if you call them they will help you figure out which one you really need.

Contact Us

I have no affiliation with them other than I bought mine there a year ago last July. They were very helpful.

Good Luck. Report back on how this project turns out!