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Most of my camping trips this year will be State Parks with shore power. I’m wondering if I need a coach battery installed if I’m only using shore power? When home I have my rig connected to shore power and leave my coach battery disconnected for weeks @ a time. Seems OK? Any thoughts?

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Connect it. You might want water or something on the trip.

If you have the old style converter just install a 24 hr timer on the power lead and set it for a couple hr a day if your worried about damaging your house battery

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Posted (edited)

No worries about my house battery. I don’t let the converter charge my battery. It’s on a separate float charger. Just wondering if hooked up to shore without a battery would harm the converter somehow? I don’t think so but could be wrong. And of course I’ll isolate the battery terminals! It is the original converter that works well.

Edited by markwilliam1
More info

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Be aware that the old converters can output AC voltage on the 12 volt DC side. So if you run any electronics (12vdc led lighting, phone charger etc) off say a cig lighter socket or other coach 12vdc source it might eventually be bad for the device. To verify take a multi tester, set it to AC voltage and test a 12VDC outlet or source. 

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Thanks! I never use the cigarette outlet in my coach. Doesn’t the converter convert 110 to 12volts? Why need a coach battery hooked up also if connected to shore? 

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Posted (edited)

If you need to use any high amp drawing appliances like a furnace blower motor you will need the starting amps of your coach battery. Your converter alone may not have sufficient power. 

Edited by fred heath

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Thanks Fred! I didn’t know that. Your a wealth of info Man!

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I checked my converter and it’s rated @ 32 Amps output. Wouldn’t that be sufficient power to run the furnace blower without a battery hooked up also? Excuse my ignorance. 

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Posted (edited)

You could try running your furnace without the coach battery. It will either run or you’ll hear a clicking sound. If clicking, you need the coach battery to make it work. 

Your dealing with two different amp draws. One is “starting amps”, one is “running amps”. A typical furnace needs 9 starting amps(surge)and 4-6 running amps. Remember, with no coach battery everything 12V in your coach is running off the converter. Also, many converters have built in surge protection which will shut them down if they exceed their set limits. 

Power up everything in the coach you would normally be using then try the furnace. If it’s runs, you’re probably ok. 

Edited by fred heath

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Posted (edited)

Your making things way to complicated. Just hook up the battery, do proper battery maintenance and your golden.

You need the battery to run fans, pump water, flush the toilet while traveling.

If you just have to do this, just get a 50 amp switch and place it in the + battery to "disconnect" the battery when hooked up to shore power.

Edited by WME

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Yeah I kind of don't get it. Why don't you just let it work the way it's supposed to. My coach batteries from Walmart have all lasted 5 years charging from my converter and I used to leave it plugged in constantly so I didn't have to remove all the condiments from my fridge and I was always ready to go. I do know that letting batteries just sit will kill them even when disconnected. Your in a moving vehicle. I can't count the times stuff came up and I had dirt on me and I needed the water. No battery no pump. Slurpee in the lap syndrome? It can happen to anyone. In cars your stuck with a mess but part of the wonders of having a motorhome is you can stop and clean up. Break down and a deserted road and a sudden cold snap? Having your motorhome fully functional can save your life.

Linda S

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I appreciate the advice and info. No big trips planned this year. Am hoping to put off buying a new coach battery till next year. I do have a battery switch WME and do as you suggested. 

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The old converter chargers had all kinds of DC power for lights,fridge heaters etc. but very little charging current. Usually it was about 10:1, 30 amps vers. 3 amps charge. Both sides of these things were poorly regulated and filtered. Greg is right they had lots of AC ripple. I agree let the system do as it was intended it has worked like that for decades in campers and RV's. Batteries will self discharge so a charger of some sort needs to be in the mix, the truck isolator usually does a pretty good job and a battery maintainer works fine for long term storage. A battery switch is not a bad idea if left unattended for long periods if for nothing else to reduce any risk of fire.

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On 5/13/2018 at 9:55 AM, markwilliam1 said:

Thanks! I never use the cigarette outlet in my coach. Doesn’t the converter convert 110 to 12volts? Why need a coach battery hooked up also if connected to shore? 

What is the brand and model of your converter? The original 6300 converters already disconnect the battery from the coach 12v circuit and switch the battery to the charger circuit via a large relay when plugged into shore power but the 6300 battery charger is junk. Modern converters leave the battery connected and (most) use a smart charger for battery maintenance. In ether case you really don't need to disconnect the battery for when occasionally connected to shore power. But again, the original 6300 built in charger is junk and If you are on shore power for long periods of time like a week the battery can get over charged. Also with the 6300 the large switching relays can get dirty and cause problems such as voltage drops on the coach and charger circuits etc. You might not ever use the cig lighter socket but what about led lighting. The original 6300 converters use a half wave rectifier to convert the ac to dc. Modern converters use a full wave rectifier and additional filtering to create pure dc voltage. Some led's are ok with some ac voltage, some are not. 

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Yup Greg the original 6300! I’m familiar with the overcharging so I have a battery switch and disconnect the battery when on shore power @ home. You confirmed what I thought that when connected to shore power the battery is now disconnected from the coach’s 12 volt system and relies on the converter only to supply the 12 volts to the coach? So do you really need a battery hooked up when your on shore power? I do use LEDs in the coach and they operate fine on shore power only. One member said I need the battery to run the furnace. Not sure why. No plans to upgrade my converter she works perfectly for my needs. Thanks!

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4 hours ago, markwilliam1 said:

Yup Greg the original 6300! I’m familiar with the overcharging so I have a battery switch and disconnect the battery when on shore power @ home. You confirmed what I thought that when connected to shore power the battery is now disconnected from the coach’s 12 volt system and relies on the converter only to supply the 12 volts to the coach? So do you really need a battery hooked up when your on shore power? I do use LEDs in the coach and they operate fine on shore power only. One member said I need the battery to run the furnace. Not sure why. No plans to upgrade my converter she works perfectly for my needs. Thanks!

Some LED lighting uses a electronic driver to power the LED. AC voltage could damage the electronics. They will work fine until they die. I have custom LED's that use a pulse width modulator to dim the lights. No AC allowed. If I remember correctly I measured 6 volts ac on my 6300 12 v dc coach side circuit.
I do not believe you need the battery to run the heater when on shore power using the old solenoid 6300's but remember that the 6300's disconnect the battery automatically so no need to do that manually. 
As an option for the 6300 the charger can be disconnected from the relay so that it does not connect to the battery or it is possible to rewire the solenoid to add and use a smart charger instead of the 6300's charger. 
I may have missed where your switch is for disconnecting and connecting your battery. This is advice for all. It is advised to use a dedicated battery disconnect switch away from your battery. Lead acid batteries produce explosive gasses that tend to hover around the battery during discharge and charging. The reason for vented battery boxes. One little spark and you become unhappy really fast. I have a friend who had a battery explode in his face. Can not remember if it was from using jumper cables or something else, just that there was a spark and boom. He was lucky, only got a little acid in the eyes but acid was everywhere else. You still though have not said what model your converter is. Newer converters are 100% OK to leave the battery connected. With the older 6300 the 6300 charger is the problem. 

Besides leds, motors such as your water pump, stove vent fan, ceiling vent fans if you have one all run cooler and more efficiently with no ac on the line. Heater control boards are electronic (unless you lite yours with a match) for ignition and gas flow. I have no idea if they have any filtering to keep out the ac. I have replaced a few, ac on the line or just that it failed?

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It’s a B-W model 6332. My battery switch is on the Positive terminal but it is passive just a knob to disconnect the leads easily so I can connect a smart charger. I’m a little confused now. If I have my coach battery hooked up and I plug into shore power doesn’t the converter take the battery out of the circuit completely and is in charging mode only? So why is the battery necessary when on shore power? My LEDs are from Optronics a reputable manufacture and they work fine on just shore power. My Max Air deluxe fan and water pump also no problems on shore power only. Got rid of my stove vent fan. Thanks for your time!

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Yes the older chargers disconnected the battery from the coach in charge mode at the same time it charged the battery with about 3 amps. The relay was inside of the unit and it was energized by the 120 volt line voltage. Once the line was dropped it switched back to the coach battery. The older systems were frankly pretty crude the converter had all kinds of current like 30 amps to run the likes of furnace, water pumps lights,fans and any thing else the battery normally would power. They had a fair amount of AC ripple but for what they were intend it really didn't matter. Enter modern stuff that really would prefer battery power or clean DC so with a bit of AC ripple things like LED's tended to flicker phone batteries took longer to charge just little annoying things. Most of the older stuff would tolerate the AC. no problem. As Greg said check your DC stuff for AC when plugged in with a DVM best spot would be the lighter socket I wouldn't worry too much with readings around a volt of AC or less because the current would be low. There is no real need to disconnect your external charger even when you are plugged in they are protected for excessive reverse current, running both at the same time might confuse the issue though because the smart charger will think the battery is charged.  The battery on line would act as a filter reducing the effect of any AC ripple. To me one of the best upgrades for an old system would be a modern switching converter/charger  they are light year ahead of the old clunky thing with 10# transformers. 

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Excellent information All! Thanks! 

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Here is the manual and schematics.

The 6300's I replaced did not have a fan and used glass barrel fuses

6300_series.pdf

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Thank you! My converter has glass fuses and no fan also.

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On my warrior, when the converter detects 110V ac, the house battery is disconnected as a power source and is then charged from the converter separately.

 

I have removed a terminal from the house battery and with 110v ac present, everything in the cabin worked fine.

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