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Bruce and Sharon
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« on: May 26, 2013, 07:51:45 pm »

First, I apologize that this post is longer than I had originally planned, or if I'm being redundant in bringing up a topic that has already been covered in this forum many times.  I'm still new here want to behave myself, but I can't seem to reduce my words and still be clear.
I'm still learning about the features on our new 2350.  We've used it three days in an all hookup RV park and three days of dry camping in a California State Park.  I've learned a lot about battery voltage status by reading many of your posts on this subject going back several years and think I now have a basic understanding of battery charging, etc.  But, just to be sure that I'm not missing something important, I'd like to share my experience with the inverter and generator during our dry camping:  The first morning when it was too early to start the generator, I attempted to use inverter power to run our small 4-cup coffee maker.  Shortly after turning it on, I heard a beeping sound and noticed an error message on the XM1800 inverter panel.  I assumed that the inverter could not handle the coffee maker even though I thought the two house batteries were fully charged.  After that camping trip I've been trying to reassure myself that the batteries are now fully charged (mainly because it will be sitting alone in storage for almost a month starting next Wednesday while we are away on a non-RV trip).
Today I went into the coach, made sure that the water in the batteries was at a good level, put the battery switch into the "use" position, and turned on the Xantrex Pro inverter.  The battery status read full when I pressed the battery button next to the holding tank level buttons.  The XM1800 inverter display had an orange status light glowing and 12.3 volts of "Input Voltage" reading.  I then started and ran the Onan generator for about 30 minutes.  The XM1800 display had a green status light glowing and 13.6 volts of "Input Voltage" reading during this charging time.  When I stopped the generator the XM1800 display had an orange status light glowing again and the "Input Voltage" reading quickly dropped down to 12.5 volts.
My last step was to measure the voltage directly off the batteries with my small test meter.  That showed approximately 12 volts.
Am I correct to assume that my batteries are fully charged and will be safe to leave alone for almost a month?
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« Reply #1 on: May 27, 2013, 07:16:32 pm »

Bruce and Sharon

Here is some information about the charge level of a battery.  You would need a digital volt meter to get an accurate measurement when you measure at the battery terminals.

The State of Charge (SOC) measures the available capacity of a battery and is expressed as a percentage. State of Charge is rated from 0-100%, with 100% representing a fully charged battery and 0% representing a fully discharged battery.

Below is a SOC reference chart for terminal voltage readings for a 12V lead acid battery at 80 degrees Fahrenheit:

Percent      12V Battery
of Charge   Voltage

100      12.70
 95      12.64
 90      12.58
 85      12.52
 80      12.46
 75      12.40
 70      12.36
 65      12.32
 60      12.28
 55      12.24
 50      12.20
 45      12.16
 40      12.12
 35      12.08
 30      12.04
 25      12.00
 20      11.98
 15      11.96
 10      11.94
  5      11.92
  0      11.90


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« Reply #2 on: May 27, 2013, 07:36:40 pm »

Bruce & Sharon,

As you already know i have been wrestling with a similar problem for a year and half. Your questions with this group are always appreciated, we can work on this together. Like you i have read everything and something is just not right. Ths group is so welcoming, they always have an insight or two, even if you ask again. They have been so good to me, the will be to you too.

When my inverter was working it too screamed when i tried to use the Kuerig coffee, the wattage on the Kuerig is too high. look at the wattage that you have on your coffee maker and look at the chart in the Xantac manual to see if you have enough batter power pagwe b4 in my manual. at 600 watts and for 15 minutes take 150 watt-hours.

I am going to try to speak to Kermit tomorrow.

greg & kathy matthews
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« Reply #3 on: May 27, 2013, 09:43:25 pm »

Thanks for the quick replies!
The temperature here on the Monterey Bay was probably about 58 degrees on the morning I took the voltage readings.  Unless the SOC levels for 58 is much different than the 80 degree levels on Barry's chart, the 12.5 volt reading on my XM1800 display means that our batteries are about 82% charged.  Running the generator for about 30 minutes (with no other load on) raised the SOC by about 15%.
I'm assuming that we can go away on our three week non-RV trip on Wednesday and not worry about those batteries.  I don't have the ability to leave a trickle charger on them while in storage, but at least will put them in the "store" position.  Our previous RV had a small solar panel on the roof to take care of this--makes me consider adding one to our 2350.
Bruce
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« Reply #4 on: May 28, 2013, 08:01:54 am »

Our 2007 has the earlier 2000 watt Tripp-Lite inverter.  I wonder if the 200 extra watts allows us to brew coffee...and brew multiple times.  But maybe it's the coffee maker that came with our rig which I just checked to be rated at 850 watts.  This is the coffee maker.
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« Reply #5 on: May 28, 2013, 11:00:01 am »

Wow, that is a coffee maker! 
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« Reply #6 on: May 28, 2013, 12:05:15 pm »

The coffee maker has no carafe.  You press your cup against the gray horizontal bar to release the coffee.  The brewed coffee is retained inside and kept hot which is good when plugged in power or on the road but bad when dry camping because if you forget to turn it off after brewing, obviously you are running down your batteries quickly.  We often brew while driving which works well because the V10 engine's 115 amp alternator keeps up with the demand.

Phoenix USA was installing this coffee maker with Corian door mount as OEM equipment but stopped for a while.  I wonder if they reinstated that feature.  Many PC owners were removing it because they wanted their garbage can in that cabinet.

We love our coffee maker setup and offered to buy one from any PC owner as a backup in case our coffee maker dies.  But nobody has yet offered to sell theirs to me.

Any sellers out there?  I really wished we had a "Barter" section.  I have other PC parts I could sell or trade.
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« Reply #7 on: May 28, 2013, 01:46:34 pm »

Yeah, me too (the barter section). We have a vinyl windshield cover for a 2010 Sprinter (we had it on our 2350 which we owned for one year) and it wouldn't fit on our 2551. Been in the garage for a few years. If anyone's interested PM me.

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« Reply #8 on: May 28, 2013, 09:02:05 pm »

This is an update on our earlier posting re battery status:
Visited the coach in storage lot after two days.  The XM1800 inverter panel now shows "Input Voltage" of only 12.3, so we're back to where we were before running the generator to recharge the batteries.  No time to deal with this until we return from our non-RV trip near the end of June.
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« Reply #9 on: May 30, 2013, 04:41:46 pm »

There is always voltage loss when you are just sitting in storage.
Converters and Generators never charge your batteries up to 100%, so you don't have the available watt hours that you think you have.
Heating with electricity is inefficient.

So here is what I do,
I use a perc. coffee maker on my gas stove, told Phoenix to keep the electric pot.
I use solar arrays which will charge your batteries completely.

Reads Handi Bob's blog, a little wordy, but you will learn a lot.
http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/
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« Reply #10 on: May 30, 2013, 04:55:17 pm »

I use a perc. coffee maker on my gas stove, told Phoenix to keep the electric pot.
But then how will Irene brew coffee while I am driving?  That is the beauty of the electric coffee maker mounted in the base cabinet.  The bonus is that the V10 engine alternator is keeping up with the demand of the 110v/850 watt coffeemaker....no drain on the batteries at all.

I had to give you a little jab there, but I get your point.  Smile
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« Reply #11 on: August 29, 2013, 04:36:22 pm »

Months ago Ron D. posted helpful info on charging low coach batteries, but I can't find it.  I vaguely recall that one way was to use a 40 amp battery charger (?).  If so, don't you have to run the Gen to powerthe charger?

Also, it has been suggested that you could run (idle) the cab engine for charging.  How much time might that require and how does the time compare to Ron's battery charger; and to pluging-in at an RV park?

Although there will a 150 watt solar panel on my ordered 2350, I know how an entertainment sytem (+ an inverter) can  (cheer)drain power at night, in a canyon, and with heavily overcast skies.
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« Reply #12 on: August 29, 2013, 10:27:47 pm »

The 40 amp charger requires either the generator or shore power to opperate.

The main cab engine does charge the coach batteries, but I believe it does only after it has completely charged the chassis battery.  Idling will charge, but this assumed the chassis battery is satisfied, and all chassis accessories and chassis lights are off, or the chassis will likely continue to demand the charge.  Time-to-full-charge is very dependant on chassis and coach battery condition.

We are wrapping up our 4 week road trip now.  I have learned that without our tow vehicle, we drive the PC daily which the driving-charge keeps up with the our charging needs.  I never had to pull out the 40 amp charger.

This year we disiplined ourselves to use the coffee maker only when driving or when the generator is running which has kept our coach battery reserves in the safe-zone.  That coffee makers works off the batteries alone, but the consequences are tough. requiring the 40amp charger with the generator to bring them back to "green".

Driving our PC daily seems to keep everything in check.  When parked for days at a time, that is when charging becomes something to be thinking about.  The 40 amp charger is then a good tool for catching up.
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« Reply #13 on: August 30, 2013, 10:02:27 pm »

Thanks, Ron....after being parkedfor days, how long do you typically have to run the charger?

Also, do you connect the charger to 6 volt batteries wired in series like you would if you were connecting it to a 12 volt battery; i.e.,  negative and positive cables are connected to corresponding terminals and you do that for each battery?
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« Reply #14 on: August 31, 2013, 12:32:35 pm »

Here is my understanding of how the batteries are charged when using a traditional three stage battery charger.  The three stages or steps are BULK, ABSORPTION and FLOAT.

The PC is equipped with two12V batteries (group 27) wired in parallel from the factory.  This configuration provides a 12VDC source with an Ampere Hour rating equal to the sum of the Ampere Hour rating of each battery.  The battery charger will see this configuration as a single battery not two separate batteries.

The Xantrex converter found in newer PC's is designed to function as a three stage battery charger.

STEP 1 - Bulk Charge

This is the stage that the batteries are able to accept the greatest amount of charge.  The charger will supply a constant output current with a slowly rising voltage (usually between 14.2VDC and 15VDC) to the batteries for the duration of this stage.  At the end of the BULK Charge the batteries will be between 80%  and 90% charged.

STEP 2 - Absorption Charge

This stage is used to bring the batteries to full charge.  The charger will supply a constant output voltage with a slowing falling current.  The batteries would ideally be charged to 100% by the end of this stage but practical limitations result in batteries that are charged to a level of over 95%.

STEP 3 - Float Charge

This stage is used to maintain charged batteries.  The output voltage is held constant (usually between 13.2VDC and 13.6VDC) with a very low current.  The Float charge can be applied to batteries for very long periods of time without causing any harm.

NOTE:  A battery can be damaged by heat if charged to fast.  Most reference material I have read  recommend the battery charger be rated at 1/5 to 1/8 the Ampere hour rating of the battery.  For example an acceptable battery charger for a 200 Ampere Hour battery would be rated between 40 Amp and 25 Amps (200 Ampere Hours/5 = 40 Amp or 200 Ampere Hours /8 = 25 Amp).  A smaller charger 15 Amp or 10 Amp would also be good but would take longer to charge.

The exact size of a battery charger for a specific application should be fully researched before any purchase.  It should also be noted that as batteries age the Ampere Hour storage will decline.


Barry
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