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Old 11-15-2016, 10:39 AM   #15
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Originally Posted by Just For Fun View Post
All good info.

But looking at this logically (That's been the quandary of my existence), if I've been on the road and my "coach's charging system" is working properly, my batteries should be fully charged. Right?? ...
Yes and maybe no. Without knowing the specifics of the coach you are looking at it depends on how it is set up.

My coach as what is commonly referred to as a BIRD that is a bi-directional charging controller. When on shore power it diverts some charge to the chassis batteries to keep them topped off. When driving down he road it diverts some alternator charge to the house batteries to help keep them charged.

In theory, if the coach you are looking at has anything similar you would be correct in your assumption.

All that being said, I've seen my coach go into high current, bulk charge for a short period of time even when my battery monitor kit (ME-BMK) says 99% state of charge (SOC). However, I also see that it recovers rather quickly by reducing the current down to much smaller levels in as little as 10 minutes.

The bottom line is that you will still need to learn a new coach's tendencies. Theory is great but practical is king. Unless you find something wrong with the charger system, it will be what it will be.

Again, if you have an EMS that will shed high draw circuits you can sit back and let it do its work understanding that it will let those devices come on line when power is available. OTOH, if you learn how much current devices draw (AC typically 13-15 amps, microwave 10-12 amps...) you can actively manage your power usage both while the charger is stabilizing and then later under normal use.

FWIW, while on 30 amp served you will want as much on LP as you can. You can't run both ACs on 30 amps if you are running anything else and in some cases you can't run them together successfully. As an example, most EMS systems will prioritize AC #2 as next to last and AC #1 as the last high draw device to shed when power is not sufficient. So...say your charge is fully stabilized and you are drawing zero amps (not likely but for the sake of argument....) you have AC1 running and drawing 14-15 amps. When AC2 fires up it will initially draw 17ish amps which will turn around and shut it right back down. The compressor then waits the appropriate time and AC2 tries again and the same thing happens. Repeats ad nauseum until AC 1 shuts down on its own. None of that considers anything else running.

This doesn't even consider when the spouse fires up the hair dryer or a vacuum without checking with you...
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Old 11-15-2016, 10:42 AM   #16
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Originally Posted by Just For Fun View Post
All good info.
But looking at this logically (That's been the quandary of my existence), if I've been on the road and my "coach's charging system" is working properly, my batteries should be fully charged. Right??

Assuming that I didn't run them down dry camping the day before without using the generator AND that I drove a sufficient distance prior to plugging into 30 AMP service. My batteries should be at fully - or almost full - charge. Thereby eliminating the need to "...wait one hour before turning on any appliance." Right???
What you are saying makes sense to me. That part may have been put in the manual to cover discharged batteries. Some people just don't understand how batteries and how electronic components work. Could also be that your RV does not charge the batteries when driving down the road and if it does that may have been a add on option and the manual does not reflect that.

If I know my batteries are charged I would turn my AC on shortly after I hear the transfer switch.
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Old 11-15-2016, 10:56 AM   #17
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I think, as someone else mentioned, that this is a 'conservative' approach from the manufacturer in order to make you aware of certain situations that can arise when certain conditions exists - such as overloading a 30a shore power BREAKER, or your internal breaker(s).

In most situations, this is not a concern since the coach is built to handle normal usage of electrical requirements, such as air conditioning, water heating, battery charging, etc. by the generator or with full 50a shore power connection, even with multiple uses at the same time.

When you adjust 'down' to 30a shore power, though, you may need to be aware of what electrical supply requirements are happening in the background that could impact 'over usage' of the available power. With 50a service, you actually have a Maximum of 100a of power, but with 30a you ONLY have 30a - that's less than a third of 'normal'.

If you arrive at a campsite and plug into 30a shore power, your battery Charger may be requiring a lot of amps to recharge your batteries, your water heater electric option may be in demand, and someone may want to use the microwave while the air conditioner is on. This would probably amount to MORE than 30a, and would trip a Breaker. If the 30a breaker is not located at the power pole, you may find yourself hunting the whole campground to find it.

The owners manual is really telling you to be aware that the Charger will probably be requiring a large amperage draw when you first plug into shore power and you may not have enough available power to run large appliances, like air conditioners, especially in conjuction with other items.

One option is to just turn OFF your Charger in this situation, and only turn it on when you are several hours from leaving the site, or overnight when few other items are demanding power...
If you have a 'Shore Max' setting on your Inverter/Charger, you can set it lower to 5a or 10a so that the charger only uses that much maximum power during the charging process.

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Old 11-15-2016, 01:22 PM   #18
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Jut remember the Rigs alternator primary responsibility is to charge/maintain chassis batteries and secondarily house batteries.......

Plus cahrge line to house batteries can limit current for charging

SO house batteries can be low and NEED some charging when first hooking up to AC Source

I don't think an 'hour' is necessary before using AC appliances.
Just need to see what kind of demand and use other AC appliances accordingly
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Old 11-15-2016, 06:44 PM   #19
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Per the Owner's Manual:

"Inverter/Converter Charging the Batteries:
When the motorhome is plugged into shore power
and the ignition is off, the unit senses the voltage on
the house batteries. When this voltage goes above
13.3 for approximately 12 seconds, as happens
when the inverter is not heavily loaded, it will close
the isolator relay to provide charging current to the
chassis battery. If the voltage should fall below 12.8
for more than four seconds, the relay will drop out to
prevent the house loads from discharging the chassis
battery. This might happen when a heavy demand
is placed on the inverter/converter. When the house
battery voltage again goes above 13.3, the relay will
close in four seconds and retry charging the chassis
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Old 11-15-2016, 06:47 PM   #20
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"The function of the alternator is an electrical
system voltage maintainer, not a battery charger.
When the engine is operating, the alternator
maintains electrical system voltage relative to a load,
such as headlights and windshield wipers. When
a heavy load is placed on the alternator, such as
trying to charge dead house batteries, the operating
temperature of the alternator will increase. Excess
operating temperature of the alternator for extended
periods of operation can lead to premature failure of
the alternator.

The alternator is not designed to charge
the house batteries from a complete
discharge to a full state of charge. The
alternator will maintain the battery
charge during travel, supplying the DC
current necessary to operate running
lights or other DC loads."
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Old 11-15-2016, 08:00 PM   #21
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If not 50 AMPS, then 30 AMPS. But wait 1 hour!!

All good comments and information. As for my experience. Before a road trip I always make sure my chassis battery and my (4) - 6volt batteries are fully charged or at least very close. One of my favourite parks only has 30 amp service unfortunately. And since I use that park during the cold winter months here in Canada I run (2) 15 amp heaters while I am there. When I park onsite and level my coach, the 1st thing I do is plug into the available 30 amp power. Within minutes I am starting one heater. Minutes later I start the 2nd heater. Never had a problem. Ever! Of coarse keeping an eye on the built in amperage monitor always helps.

I agree that manufacturers are printing some Worst Case Scenarios in the manuals.

As always the choice is ours. But there is plenty of comments to support their reasons listed in the previous posts.

Just thought I would share my experience.
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