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Old 12-28-2014, 10:59 AM   #1
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Automotive battery charger question

When using an automotive battery charger along with a generator to charge my TT battery, do I need to disconnect the battery from the trailer before clamping the posts with the charger clamps?

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Old 12-28-2014, 02:40 PM   #2
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I assume that you intend charging with the trailer converter. I don't think it would be advisable charging with both chargers in use at the same time. If you are talking about only using the automotive charger, it doesn't need to be disconnected to use your automotive charger.

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Old 12-28-2014, 04:32 PM   #3
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Originally Posted by Rockypointers View Post
When using an automotive battery charger along with a generator to charge my TT battery, do I need to disconnect the battery from the trailer before clamping the posts with the charger clamps?
Personally, I would use the generator connected to the TT's shore power to charge the batteries. The TT battery charge controller is probably capable of 45Amps (check your documentation) and it is designed for use on deep cycle batteries (marine/RV & true deep cycle batteries), whereas the automotive battery charger is designed to be used on automotive batteries (not deep cycle) which has different charging characteristics. So the amount of time that they spend in each of the charge cycles will be different.

The issue for connecting both chargers at one time is that you will PROBABLY not get the most out of either unit. The TT's charge controller will look at the battery and see a higher battery voltage (from auto charger) and the automotive charger will see a higher battery voltage from the TT's battery charge controller, which neither is the TRUE battery voltage needed by the controllers. Sooooo they will meet somewhere in the middle, and more than likely both will under perform.

Just my thoughts,

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Old 12-28-2014, 06:21 PM   #4
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My battery bank is a 255ah capacity using three each Interstate 85AH 12VDC batteries. When these batteries drop down to around 12,0VDC when using them while camping off the batteries I will connect my trailer up to my 2KW Honda Generator using the trailer shore power cable and a RV30AMP to 15AMP adapter long cable from WALMART. This operates my on-board converter/charger unit PD9260C which charges my battery bank. Sine this is a smart mode charger I can re-charge my 255AH battery bank back up to their 90% charge state in around three hours of generator run time. This will allow me to do all of this all over again for the next day/night run off my batteries.

I can do around 12-14 cycles of 50% to 90% charge states on these batteries before I have to do a full 100% battery charge which normally tales about 12 hours of generator run time. This is usually when we go home as most camp gounds won't allow us to run our generator that long of time.

When the generator is running is also when we make up some good fresh ground bean coffee that dumps up into a thermos to use all day long... Our electric coffee grinder/maker only takes five minutes of generator run time to make 10-cups of coffee.

This is how we do it...

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Old 12-28-2014, 09:39 PM   #5
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I would look at your converter and make sure you understand the capability of it. IF it is a multiple stage charger then it may be all you need. If it is a stock single stage charger, then it really won't do much towards replenishing your battery in a short period of time and in that case the automotive battery will be more useful. Ideally if the TT isn't already set up with a multiple stage advanced converter/charger, it's worth upgrading if you believe you'll be doing much dry camping.

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