Maintaining RV batteries

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plumkrazee70

plumkrazee70

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We have a new to us '94 Fleetwood Southwind with a GM 454.

The RV part has two 6-volt deep cycle batteries wired in series and a regular 12v battery for the engine.

We bought it last year and we kept it plugged in, using the RV plug you would use when you go to a campsite, however when we took it to have a few minor repairs done, it had to be jump started.

The mechanic said we fried all three batteries. He said we couldn't keep it plugged in without adding water to the 6v batteries. I didn't think you had to add water to batteries anymore. I didn't talk to the mechanic, my wife did. And she was gets flustered, easily.

I don't know much about RV batteries, but can I just buy a trickle charger/maintainer for the 6v batteries and a separate trickle charger for the engine battery?

If I have to add water, I can do that.

I am new to RV's, so I want to do it the right way.

Thanks!

Mike
 
Any lead/acid battery needs distilled water from time to time. RV batteries even more so. Do you have a battery isolator and if so does it work properly? The RV batteries get discharged and the alternator will work overtime to recharge them. If the isolator isn't working it will overcharge the engine start battery. I had tool trucks for 28 years with the same issue.
 
I don't really know a battery isolator is. lol.

We took it out on a few trips last year and had no trouble starting it and using it. We camped for a whole week with it plugged in and had no trouble either. I am just wondering what the best way to maintain the batteries charge while during the winter months.

So do you think I could use a battery maintainer and keep an eye on the water level every month?
 
plumkrazee70 said:
I don't really know a battery isolator is. lol.

We took it out on a few trips last year and had no trouble starting it and using it. We camped for a whole week with it plugged in and had no trouble either. I am just wondering what the best way to maintain the batteries charge while during the winter months.

So do you think I could use a battery maintainer and keep an eye on the water level every month?
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Depending on how low your batteries are you can fill them and use the maintainer during the winter. If your batteries have been boiled out they may need replaced. Only a refill, charge, and test will tell. Look up "battery isolator" on the net and see what they look like. Your battey cables will all be attached. Usually they are under the hood.
 
toolmanmike said:
Depending on how low your batteries are you can fill them and use the maintainer during the winter. If your batteries have been boiled out they may need replaced. Only a refill, charge, and test will tell. Look up "battery isolator" on the net and see what they look like. Your battey cables will all be attached. Usually they are under the hood.
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Oh ok. We went and had all three batteries replaced, so they are all new. I just wanted to prevent it from happening again.

What does the battery isolator do?
 
plumkrazee70 said:
Oh ok. We went and had all three batteries replaced, so they are all new. I just wanted to prevent it from happening again.

What does the battery isolator do?
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It separates the two systems so one system doesn't get overcharged if it doesn't need it.
 
plumkrazee70 said:
Oh, I see. So the alternator charges both sets of batteries?
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When needed. The engine start batteries don't need much charge. They start the engine and their job is done. The coach batteries (camper) Get discharged regularly. The alternator overcharges those batteries easily.
 
toolmanmike said:
When needed. The engine start batteries don't need much charge. They start the engine and their job is done. The coach batteries (camper) Get discharged regularly. The alternator overcharges those batteries easily.
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That's why they get the liquid boiled out.
 
Thanks! I'll check for the isolator this week. I'm also gonna call interstate and get an idea of what battery tender they recommend for the RV deep cycle batteries. (They are their brand)
 
If one of the 6 volt batteries went bad, it will take out the others. But if all are new then no worries there. A charger on a timer would be my choice for the coach batteries,
5 amp charger for an hour a day should maintain them nicely.i see no sense trickle charging 24/7 when not in use.

it should already have an isolator, but its likely faulty.
If all 3 were dead.or it was installed incorrectly.

if shopping for a new one, dont cheap out, it needs to at the very least match the alternator’s output.
 
Tooljunkie said:
If one of the 6 volt batteries went bad, it will take out the others. But if all are new then no worries there. A charger on a timer would be my choice for the coach batteries,
5 amp charger for an hour a day should maintain them nicely.i see no sense trickle charging 24/7 when not in use.

it should already have an isolator, but its likely faulty.
If all 3 were dead.or it was installed incorrectly.

if shopping for a new one, dont cheap out, it needs to at the very least match the alternator’s output.
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I had 2 trucks that didn't have a isolator but a constant duty relay. It worked just OK.
 
toolmanmike said:
I had 2 trucks that didn't have a isolator but a constant duty relay. It worked just OK.
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They work. Less prone to failure.
And wont burn up when they go bad. Saw one that had a total meltdown. Lucky whole truck didnt go up.
Manual battery switches,although old school are the most dependable. But easy to forget.
 
I spent the big bucks ($350.00) for an RV AGM battery for our trailer...it lasted barely a year...now won't take a charge.
 
You want a battery tender, NOT the RV on board charger as it is likely NOT regulated properly. A battery tender runs somewhat lower voltage than your charging system what they call "float" voltage. That voltage is supposed to minimize battery activity and water loss

I would NOT run a solid state battery isolator. Instead use a high current what is called a "continuous duty" solenoid. This solenoid is activated by the vehicle ignition switch and connects the two systems when the key is on
 
67Dart273 said:
You want a battery tender, NOT the RV on board charger as it is likely NOT regulated properly. A battery tender runs somewhat lower voltage than your charging system what they call "float" voltage. That voltage is supposed to minimize battery activity and water loss

I would NOT run a solid state battery isolator. Instead use a high current what is called a "continuous duty" solenoid. This solenoid is activated by the vehicle ignition switch and connects the two systems when the key is on
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I've always used tenders, but the guy I bought the RV from said to plug it in to charge the batteries. Lesson learned.
 
The power converters/battery chargers that come in RVs are usually a poor choice for maintaining RV batteries, as they are mainly for providing a 12 volt power source during camping when you're plugged in to 120VAC. They will keep your batteries charged when not camping but they are not well regulated. I have a 2002 slide in truck camper with two 6 volt batteries in series. I replaced the original Magnetek/Parallax converter/charger that came in the camper with a Progressive Dynamics converter/charger that includes a three-stage smart charger to keep the batteries maintained. I have used OEM converter/chargers to maintain RV batteries in the past but have come to the realization they aren't optimal for that purpose, and for $200 I can have a better system.

Do an online search for Magnetek and Progressive Dynamics and you'll have plenty of information to read. There are vendors other than PD that make smart charger/power converters, but I chose PD and am happy with it. Much quieter than OEM and works well.

As for your engine battery getting cooked along with the RV batteries, it does sound like you have a battery isolator issue.
 
Any modern vehicle has a small battery drain that happens at all times. After a month or two the battery may go dead. Weak or dead batteries die an early death from sulfation on the plates.

To store batteries for long periods of time a battery should be disconnected [isolated]. There are disconnects that mount to a battery post that work well. Just a handy on/off switch.
 
67Dart273 said:
You want a battery tender, NOT the RV on board charger as it is likely NOT regulated properly. A battery tender runs somewhat lower voltage than your charging system what they call "float" voltage. That voltage is supposed to minimize battery activity and water loss

I would NOT run a solid state battery isolator. Instead use a high current what is called a "continuous duty" solenoid. This solenoid is activated by the vehicle ignition switch and connects the two systems when the key is on
Click to expand...
The bad thing about the constant duty relay is that it charges the engine start battery whether it needs it or not. FYI, I had the best luck with Golf car batteries for the coach.
 
Batteries like to be stored in cold areas WHEN they are fully charged. A small [6 or 10 amp] battery charger with an ammeter should be enough. The charge rate may start at full charging with a weak battery, and after several[?] hours the ammeter will drop down to near zero. A sign it is fully charged. Disconnect the charger. Wait a day and measure the batteries' voltage. Should be 12.6 or so. Remeasure the voltage every month and if you notice a drop in voltage from the 12.6, recharge the battery. It may go for 6 months without the need for recharging. This only applies IF the batteries are isolated!!!!
 
toolmanmike said:
The bad thing about the constant duty relay is that it charges the engine start battery whether it needs it or not. FYI, I had the best luck with Golf car batteries for the coach.
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This is not true. All a solenoid does is to parallel the batteries. This in itself is not absolutely optimum, but it is the best you can do. A solid state (diode) isolator is actually worse, as there is voltage drop through the diodes.

I come from a parts background, and was privy to TWO serious marine failures and and couple more truck failures of diode isolators and refuse to use or recommend them. Here is what happens:

A diode isolator is two big diodes fed from the alternator to each battery. The diodes have some voltage drop and do generate heat. The voltage drop CAN ALSO affect battery charge level because of the voltage drop. Same issue as "us Mopars" have in the typical harness voltage drop problem. The diode to the main battery is usually under more stress. If/ when that main diode opens, here is what happens:

The VR is sensing the main circuit. When the diode to the main opens, the VR is getting low sense voltage because the main is no longer being charged. Now, the VR ramps up the voltage because "it thinks" it needs to......because the main is in fact low. But the main is NO LONGER connected to the alternator output!!!! The now very high alternator output is being fed to the accessory battery---which is boiling away like crazy.
 
PlumCrazzy70, what power/converter is currently in ur motorhome?

I agree with MCMlvii..... !!

I swapped out my Magnetek 6345 with a PD9245C - 45 Amp RV Converter/Charger - Progressive Dynamics as this has 4 stages of battery charging/maintaining.

There’s no need or reason to have an auxiliary battery tender if ur power converter is doing it’s job.

The standard Magnetek Charger/converters were FAMOUS for boiling batteries.....
 
plumkrazee70 said:
We have a new to us '94 Fleetwood Southwind with a GM 454.

The RV part has two 6-volt deep cycle batteries wired in series and a regular 12v battery for the engine.

We bought it last year and we kept it plugged in, using the RV plug you would use when you go to a campsite, however when we took it to have a few minor repairs done, it had to be jump started.

The mechanic said we fried all three batteries. He said we couldn't keep it plugged in without adding water to the 6v batteries. I didn't think you had to add water to batteries anymore. I didn't talk to the mechanic, my wife did. And she was gets flustered, easily.

I don't know much about RV batteries, but can I just buy a trickle charger/maintainer for the 6v batteries and a separate trickle charger for the engine battery?

If I have to add water, I can do that.

I am new to RV's, so I want to do it the right way.

Thanks!

Mike
Click to expand...

It has already been mentioned, but the Intellipower power supply/charging system was the best electrical upgrade I ever did to our RV.
Progressive Dynamics Inteli-Power 9200 Series 60 Amp Converter/Charger with Charge Wizard-PD9260CV - The Home Depot

Look into the details on one and you will notice the storage maintenance feature of them.
They have a square wave "electronics quality" clean output and a fantastic battery tending function with what's called a desulfation function.
This function gives the batteries a short burst every 24 hours or so which extends the life of stored batteries.
I always left it plugged in when not in use, because this is what it was made to do.

FYI, 2 six volt golf cart deep cycles will last about 4 times longer than a 12v deep cycle.
I was running 4 six volts for the coach and run everything including the stereo for 3 day weekends without ever being plugged in.
 
TrailBeast said:
It has already been mentioned, but the Intellipower power supply/charging system was the best electrical upgrade I ever did to our RV.
Progressive Dynamics Inteli-Power 9200 Series 60 Amp Converter/Charger with Charge Wizard-PD9260CV - The Home Depot

Look into the details on one and you will notice the storage maintenance feature of them.
They have a square wave "electronics quality" clean output and a fantastic battery tending function with what's called a desulfation function.
This function gives the batteries a short burst every 24 hours or so which extends the life of stored batteries.
I always left it plugged in when not in use, because this is what it was made to do.

FYI, 2 six volt golf cart deep cycles will last about 4 times longer than a 12v deep cycle.
I was running 4 six volts for the coach and run everything including the stereo for 3 day weekends without ever being plugged in.
Click to expand...
That looks like a good one. After 28 years on the tool route, 4 trucks with 3 using the constant duty relay, I wired only the engine start batteries to the relay and controlled it with a toggle switch. I ran the diesel in the summer for a/c and heat in the winter. The interior lights stayed on most of the time so I needed a lot of current to run it all. The dual 12 volt engine start batteries got charged on the way home. No more boiling them dry.
 
We just sold our 2000 RV.. we had it for a number of years and it had the same setup. The batteries were reported new (from the previous owner who I trust) when we got the RV. Never had a problem with them.. as I read the paperwork all this stuff like Chargers and isolators we're all built into the system.
The stories my wife tells about getting taken from mechanic shops before I met her are incredible....
 
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