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Topic: 2014 Ladies Driving School - Tech Seminar (Read 1261 times) previous topic - next topic

Re: 2014 Ladies Driving School - Tech Seminar

Reply #25 –
Quote from: Caflashbob –

Power breakers off on the pedestal  would seem to be a help?

Absolutely.  Always have the outlet breaker off BEFORE you plug in or unplug.  If not, the tips of your shore power cord will arc in that instant between when the gap between outlet and prongs of your cord are too far apart to conduct electricity and where they are snug and conduct properly metal to metal.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 2014 Ladies Driving School - Tech Seminar

Reply #26 –
My coach always starts without the boost switch.  However, after reading all the above I'll start using the boost.  So my question is, how long after the engine starts should you leave the boost switch on? 
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Mark & Mary Benko
Former coach: 2005 U295 3823
Jeep Cherokee, Honda Fit

Re: 2014 Ladies Driving School - Tech Seminar

Reply #27 –
I always unplug before starting the engine.  I have never turned my boost switch on to start the engine.  Only used when crank batteries would not turn it over fast enough.  Only couple times has this been needed.  Engine always starts with only couple of turn over anyway. Is the boost on really a good thing????  Appears from this topic I need to start turning on the boost switch??  DAN
Dan & Shirley Stansel
2002 U295 4020 AGDS Build#6054
Towing Buick Enclave & M &  G Braking
Emerald Bay, Lake Palestine, Texas
MC# 16650

Re: 2014 Ladies Driving School - Tech Seminar

Reply #28 –
Quote from: Mark Benko –
My coach always starts without the boost switch.  However, after reading all the above I'll start using the boost.  So my question is, how long after the engine starts should you leave the boost switch on? 
Mark,
As soon as the engine starts, oil pressure is up and you have placed the engine on high idle, open the boost switch. Why?
    • The "closed" boost switch is still fresh in your mind, you won't forget and leave it closed going down the road
       
    • Once the engine is running smoothly, the alternator is feeding the isolator and both battery banks are taking their "as needed" share of the alternator output.  No more need for the battery paralleling connection through the boost switch at this time.
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: 2014 Ladies Driving School - Tech Seminar

Reply #29 –
Quote from: Tom Lang –
...........................The only spike is really not a spike at all, just the charger switching over to low current to high current charging as it sees the needs change while cranking the engine...................................
Tom,
Apples and Oranges
Most people want to think in terms of visible voltage changes:
I'm talking about (and the thread addresses) voltage changes that occur in nano (10E-9) or pico (10E-12) seconds and are many times greater in magnitude than that of the normal circuit voltages (voltage spikes, current spikes, energy spikes, as induced by lightning, etc. etc. etc.
You are talking about voltage transitions as in when a battery charger assumes or sheds load (voltage surge or transition that occurs over several to many seconds which is hundreds of thousands to millions of times longer in duration than the voltage spikes that I'm trying to make people aware of).
As mentioned before, voltage spikes are one of the top "killers" of inverters/battery chargers (with excess heat buildup -- poor ventilation -- being the greatest killer).
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: 2014 Ladies Driving School - Tech Seminar

Reply #30 –
Thanks Neal.  I always appreciate an answer with an explanation.  The "why" makes it easier to remember.
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Mark & Mary Benko
Former coach: 2005 U295 3823
Jeep Cherokee, Honda Fit

Re: 2014 Ladies Driving School - Tech Seminar

Reply #31 –
On my coach a previous owner, James Stallings, installed a system to divert power different ways.  His main concern was to isolate the chassis batteries from the alternator when charging the starting batteries to prevent overheating the alternator.  This is why one should turn off the boost solenoid after starting the engine to lessen the draw on the alternator.  This system shows not only voltage in both banks but alternator amps as well depending on which bank is being charged.

While the draw on the batteries is large it only lasts for a few seconds and is quickly replaced. The house batteries can be very run down from boon-docking and will put quite a strain on the alternator.

Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: 2014 Ladies Driving School - Tech Seminar

Reply #32 –
Quote from: Keith and Joyce –
This is why one should turn off the boost solenoid after starting the engine to lessen the draw on the alternator.

Keith
If coach is wired per OEM the house batteries receive a charge from the alternator through the isolator board regardless of the boost switch position. At least it does on my coach.

Roland
1993 U280 4341
2010 Jeep Liberty
The Pied Pipers

Re: 2014 Ladies Driving School - Tech Seminar

Reply #33 –
Quote from: Roland Begin –
If coach is wired per OEM the house batteries receive a charge from the alternator through the isolator board regardless of the boost switch position. At least it does on my coach.
Roland
Roland, Correct. 
I think there are several misunderstandings here.
And James/Keith's setup may well be 100% unique (and therefore may lead to confusion).
 
A very high percentage of FT's (I'd guess 95% or more) remain configured as OEM and the boost switch position will have different effects once the alternator is supplying power to the center Isolator terminal.

FOR OEM configurations:

Alternator output power, to the center terminal of the isolator, is going to go to both battery banks, split in opposite proportion to the two battery bank voltage values.  The alternator's "sensed" (start battery (+) terminal) voltage tells the alternator's voltage regulator what voltage to put out to restore the start battery to it's target voltage. 

If one has been boondocking and has not  used the generator long enough to bulk charge the house battery bank in the morning, the house battery bank may be quite low in voltage.  With the boost switch open, the alternator will only see the start battery bank.  After an easy start, the alternator will see a nearly "full" start battery bank.  Therefore, the alternator will only put out a low voltage/current and the house battery bank (being "at the mercy of the start battery bank") will receive very little charge.  Thus at the end of a day's driving, the house battery bank may be only partially recharged.  When we are traveling cross country, I often notice this to be the case (the Javelina display doesn't get back up to my desired 14.0 Vdc Gel Cell target voltage).  The way I take care of that (while driving) is to close the boost switch to provide another charge path.  The start battery bank transfers energy to the house battery bank, starting bank battery voltage drops, the alternator "sense" line sees that and increases alternator output, and all voltages come up as desired.

Conversely, if the morning after boondocking, one has used the generator long enough to fully recharge the house battery bank. Then, in starting the coach, the starting battery bank is drawn way down (or the start bank resistance is high or is otherwise weak for any reason), with the Boost Switch open, the alternator senses a very low start battery bank and the alternator will put out lots of voltage and current.  In this case, way too much current is going to go to the house battery bank (remember -- it's already fully charged) and it will be "cooked" into a permanently damaged condition.  Again, this can be seen on the Javelina display.  The house battery bank will start to creep up over the target 14.0 Vdc Gel Cell target voltage because the alternator is charging too hard.  The solution (while driving) is to again close the Boost switch, which allows the house battery bank to flow current to the starting battery bank, increasing the sense voltage, decreasing the alternator output and both banks come into spec.

So what some owner's have done, probably 5% or less, is install various (other) ways of being able to manually control the sensing points for an alternator and the charges being applied to either or both of the battery banks (as James has done with Keith's coach). That's all well and good if one understands what one is doing (and the future owner's also understand) and if you remember to keep track of it all.  But it is also very easy to misunderstand what has been done (future owners particularly), or miss something and irreparably damage expensive batteries and alternators.

Of course there are also more costly "smart chargers" that will automatically regulate the alternator's output (voltage and current) and do a better job of controlling all aspects of the battery banks and the alternator's health.  If one is going to spend upgrade money on improving the control of alternator output, that is the way to derive the most beneficial "bang for the buck" and the longest possible alternator and battery bank health and life.  I know Don plans to do that.

Anyway, know what you know, ask when you don't and be careful about guessing, because lasting damage may occur in a couple day's drive.

Neal

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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten