2014 Ladies Driving School

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

2014 Ladies Driving School - Tech Seminar

November 16, 2014, 11:25:50 am

Some of the things covered at the Tech Session at the 2014 Ladies Driving School. Other FoFums feel free to add to or correct this listing if I have misstated or otherwise incorrectly relayed what was said:

1. Use the boost switch when cranking the engine. It could possibly extend the life of your starter.

2. Turn off the inverter when it is not being used. Leaving it on could possibly run down the batteries if shore power was lost.

3. Foretravel switched to Optima Yellow Top batteries from Red Tops because during the Iraq war the manufactures sent all of the Red Top batteries to Iraq. Yellow Tops were all that were available for Foretravel to purchase.

4. Unplug from shore power before cranking the engine. If shore power is connected, the large draw from the starter could possibly hurt the inverter/charger.

Larry

Re: 2014 Ladies Driving School - Tech Seminar

Reply #1 – November 16, 2014, 11:31:49 am

1, 2 and 4 is what I do. Good to know I'm doing something right for a change.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #2 – November 16, 2014, 12:09:06 pm

4. Makes sense to me. In another recent thread many suggested that it is OK to stay plugged in while starting. If unplugging reduces risk to any other systems, better safe than sorry. But then there were several who regularly started while still plugged in without adverse issues. Coin toss?

Roger

Re: 2014 Ladies Driving School - Tech Seminar

Reply #3 – November 16, 2014, 12:13:01 pm

I think #4 needs more clarification. maybe Brett could expound on this subject a bit more.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #4 – November 16, 2014, 12:17:11 pm

I don't get # 4 ?

Re: 2014 Ladies Driving School - Tech Seminar

Reply #5 – November 16, 2014, 12:29:29 pm

The intake manifold heater and starter are a HUGE draw. On the chassis battery bank. And, if boost switch is ON (as recommended) it is a huge draw on both banks.

Any time you ask an electronic device to go from float level (assuming plugged in overnight) producing only a couple of amps to its maximum output (depends on inverter, but over 200 amps on many) you are hard timing it. I am sure we have electronics guys here on the forum who can explain that part better than I.

It is the same reason that I do not turn on the back up camera until after starting-- it would go through a serious voltage drop, then spike. May not do any harm, but certainly can not be a positive thing.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #6 – November 16, 2014, 02:22:02 pm

Quote from: wolfe10 – November 16, 2014, 12:29:29 pm

It is the same reason that I do not turn on the back up camera until after starting-- it would go through a serious voltage drop, then spike. May not do any harm, but certainly can not be a positive thing.

I don't know how I got into this routine, but everything is turned off befre I start the coach. I do use the boost switch every time I start then after the engine is running I turn on the backup camera, plug in the GPS TPM and turn on the video recorder. Only external load on he batteries is the starter. Works for me.

Roland

Re: 2014 Ladies Driving School - Tech Seminar

Reply #7 – November 16, 2014, 03:04:10 pm

Quote from: wolfe10 – November 16, 2014, 12:29:29 pm

It is the same reason that I do not turn on the back up camera until after starting

Brett,

How do you turn on the backup camera?

On my dash, I have a monitor on/off switch. To the left of that is a 3-way switch labeled "Select." The top most position displays the tank gauges; the bottom position displays the compass and temperature.

The middle position displays a blank screen. I suspect that this position *might* display the camera, but does not. Adding to the mystery, is that the original owner paid extra for a dual position camera option. I suspect the unmarked switch below the monitor switch may switch between those two views, but on mine, nada.

Guess I need to dig into my camera location above the bed and see what is happening up there. Right now it's snowing and jobs like that have lost their urgency.

Trent

Re: 2014 Ladies Driving School - Tech Seminar

Reply #8 – November 16, 2014, 03:30:14 pm

Trent,

To be accurate, I do not turn on the monitor until after the engine starts. It is more the monitor that I don't want to see go through the voltage spikes.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #9 – November 17, 2014, 10:12:02 am

I used to start up while plugged in, but after hearing James T. explanation, I unplug first. All systems are off except for my VMS pc when I start it up. Now that I have the new batteries and terminals, all seems to work well.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #10 – November 17, 2014, 10:39:01 am

So ,It's bad to start while plugged in to shore power ---how about while the gen set is running

what and how is the difference ?? Don't see it just yet . Is this for certain models , certain years , certain inverters , not that long ago FOT said be plugged in or run the gen set so as to take it easy on your batteries . Can this be a blanket that covers all Fortravel's , have my doubts as there is several different set up's in this area . Brad Metzger

Re: 2014 Ladies Driving School - Tech Seminar

Reply #11 – November 17, 2014, 11:05:45 am

Good question Brad. James says it can cause a spike in the inverter/charger that can shorten the life of the unit.
Since I am not an electrician, it seems to make sense to me not to have the spikes, but maybe some of the electrical folks can chime in?

Re: 2014 Ladies Driving School - Tech Seminar

Reply #12 – November 17, 2014, 11:26:25 am

Ok , inverters - chargers - alternators -- generators - all have to ability to charge to a certain pre set amount of voltage . Now if your plugged in they can now charge more -- how so ?? All or most charging devices I know anything about are controlled via diodes . How can you get a spike to pass thru a diode

Now where is this spike coming from . Your using battery and now you have a voltage spike when you hit the starter ?? Brad Metzger

Re: 2014 Ladies Driving School - Tech Seminar

Reply #13 – November 17, 2014, 11:34:22 am

Sounds like the million dollar question. I will have to pass , but maybe someone else can explain in layman's language.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #14 – November 17, 2014, 11:53:22 am

Would it be safe to leave the inverter on while starting? Will the inverter suppress any AC voltage spikes? Am concerned about Samsung 120 Vac refrigerator, which is the only thing on the inverter that might be sensitive.
Thanks, Dick

Re: 2014 Ladies Driving School - Tech Seminar

Reply #15 – November 17, 2014, 01:44:42 pm

I made the original post to this thread. I have removed the word "spike" from the original post.

During the Tech Session at the Ladies Driving School the question of using the boost switch when starting the engine came up. A participant said to assist the batteries when cranking the engine, that he was always plugged in to shore power with the battery charger on. The answer was that the large amp draw from the batteries when cranking the engine could possibly damage the battery charger.

Larry

Re: 2014 Ladies Driving School - Tech Seminar

Reply #16 – November 17, 2014, 01:51:47 pm

Thanks for the help Larry. I knew there was a reason but I could not explain it in technical terms.

Great seeing you and Terri again at the Ladies Driving School.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #17 – November 17, 2014, 06:23:17 pm

Here again , a battery charger can only charge what it is designed for . It can not charge more just because your cranking your engine . Maybe it could heat up if you cranked your engine for a prolonged period of time , but normal cranking , don't see that figuring in anywhere . Brad Metzger

Re: 2014 Ladies Driving School - Tech Seminar

Reply #18 – November 17, 2014, 07:22:26 pm

I don't expect my Prosine inverter/charger to operate differently than anyone else's. It is programmed to limit current or limit voltage according to a "smart" algorithm.

One you are fully charged, it goes into float mode, keeping the battery voltage at 13.5 until something changes.

If the battery is discharged when you plug in, it goes into Bulk mode first, charging at constant current (107A on mine) until the voltage rises to 14.4v, at which time the battery is 75% charged. Then it goes into Absorption mode, where the voltage is held at a constant voltage (14.0 - 14.8 volts depending on temperature), during which time the current decreases as the battery charges. The charger switches from Bulk to Float, a constant 13.5 volts, when the battery is fully charged, and stays there indefinitely. I don't know if the switch from Bulk to Float is because of time or because the current is below a preset threshold.

The important thing to remember, is that the charger is designed to put out it's maximum rated current, and it will not out any more. If it was at float when you closed the boost switch, it might switch to Absorption if the chassis batteries are low, or it might stay at Float. But when you start the starter with the boost switch on, it will see a drop in battery voltage, which might trigger Absorption mode, sending that current wherever needed.

Don't worry, the charger is designed to put out 100A, whether to one or two banks of batteries, or the engine and starter. Amps is Amps.

By the way, this kind of circuit is usually protected by time delays, so a sudden load would need to be present for some amount of time before the charger will switch modes.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #19 – November 17, 2014, 09:29:40 pm

Quote from: LTG – November 17, 2014, 01:44:42 pm

I made the original post to this thread. I have removed the word "spike" from the original post.
During the Tech Session at the Ladies Driving School the question of using the boost switch when starting the engine came up. A participant said to assist the batteries when cranking the engine, that he was always plugged in to shore power with the battery charger on. The answer was that the large amp draw from the batteries when cranking the engine could possibly damage the battery charger.
Larry

Larry,
I feel that taking the word "spike" out of the original post, is a step in the wrong direction. It's actually the very short duration "spikes" that represent the greatest threat to inverters, battery chargers and to appliances primarily designed for residential use (vs. mobile RV service). It is also my understanding that it is energy "spikes" that are the principle cause of Pro Sine failures.
In electrical engineering, spikes are fast, short duration electrical transients in voltage (voltage spikes), current (current spikes), or transferred energy (energy spikes) in an electrical circuit. We are talking spikes that are many times shorter in duration than a 60 cycle sine wave in duration.
Fast, short duration electrical transients (over voltage, as well as under voltage) in a Residential power circuit are typically caused by

Lightning strikes

Power outages

Tripped circuit breakers

Short Circuits

Power transitions in large equipment on the same power line

Malfunctions caused by instability on the power company grid

Electromagnetic pulses (EMP) with electromagnetic energy distributed typically up to the 100 kHz and 1 MHz frequency range.

Inductive spikes caused by large motors during startup or shutdown

[/list] Plugged into shorepower, of course the same electrical transients will be seen in motorhome circuits, but guess what! A motorhome experiences FAR more transients than a normal residence would ever see and a motorhome will see the transients far more predictably, more frequently, and more severely (Depending upon your specific equipment and how good you are to your coach, maybe as high a factor as 100::1).
For instance:

During competing power supply source regulation excursions (Alternator vs battery charger vs. batteries, shore power vs. generator, vs. inverter, etc.)

Intentional or inadvertent application or interruption of power while large appliances are still under load

Poor quality or improperly wired power sources (shorepower in ever varying forms – RV parks, service facilities, residential, onboard power supply problems, etc.)

The effect of a voltage spike (E) is to produce a corresponding increase in current (I = current spike). Since I = E/R and R = E/I. If the load (R = resistance) stays fixed and voltage goes way up for an instant, the current is going to go way up for an instant too and before the voltage (or current) regulation circuits can bring the spike back under control, lasting damage may occur in sensitive electronics. Some voltage spikes may be created by current sources. Voltage may be caused to increase as necessary so that a constant current will flow. Current from a discharging inductor, such as during the shutdown of an AC Motor, is an example of that.
For sensitive electronics, excessive current will flow if the voltage spike exceeds a material's breakdown voltage (where material = diode, transistor, integrated circuit, CPU, solid state device in general), or if the excess current causes avalanche (overcurrent - an auto generative increase in current) breakdown. In semiconductor junctions, excessive electric current may destroy or severely weaken that device. Depending upon the sophistication of the sensitive electronic component and the engineering design parameters built in to protect it, an avalanche diode, transient voltage suppression diode, transil, varistor, overvoltage crowbar, or a range of other overvoltage protective devices can divert (shunt) this transient current thereby minimizing the size of the voltage transient (spike).
But, that's why one doesn't start a large diesel engine, while sensitive loads are connected to two or more power sources. The DC current inrush and large ongoing current to the starter causes the battery charger to "go to battle stations" in trying to recover the low battery voltage, the resulting shorepower load spikes high trying to supply the inverter/battery charger's power needs, the engine alternator is trying to figure out what is going on and trying to kick in as well as it also sees a low battery voltage at the start batteries and there is general instability until the massive starting current disruptions are brought under control by the various voltage and current regulation devices. How many home refrigerators or computers or stereo systems or TV's are designed (by the original residential appliances engineers) to handle that sort of upset and confusion?
Actually, RV inverters and battery chargers are FAR better designed to handle these "spikes" than residential appliances, because the transients, "spikes" are anticipated to occur, and often time delays are implemented, but not always. But, from analysis of failure mechanisms, we also know that chargers/inverters still remain among the most susceptible, especially when they are undergoing transition from one operating mode to another, such as when starter inrush loads and the resulting voltage/current and energy disruption spikes occur. The same is true for other RV appliances and their control boards IF they are specifically designed for RV use (RV refrigerators and RV water heating systems and furnaces, etc.). Those, at least, have the benefit of original design forethought regarding perturbations to the power supply systems and the need to suppress and/or otherwise mitigate the expected spikes.
While generally referred to as a voltage spike, the phenomenon in question is usually an energy spike, in that it is measured not in volts but in joules; a transient response defined by a mathematical product of voltage, current, and time. Thus, while not perfect, dedicated surge suppressors offer considerable protection if one intends to use appliances not specifically designed for mobile RV expected spikes.
As an aside, an uninterrupted voltage increase that lasts more than a few seconds is usually called a "voltage surge" rather than a spike. These are usually caused by malfunctions in the power source system (shorepower, generator, inverter) or short term, high loading of the power source, such as during the depression of battery voltage during the several seconds of starter motor "cranking" before the engine starts.
So the bottom line is:
If you want to improve the length of life and reliability of your Foretravel and its appliances, find ways to treat the electrical system gently and sensibly with regard to potentially harmful power changes:

Use a good Electrical Maintenance System protection device like the Progressive Industries EMS-HW50C (hardwired, so that you are not tempted to cheat) on both, or individually, on the shorepower and generator power feeds.

Manually shut off all large loads before connecting to any (opened) shorepower breaker. Supply shorepower by closing the shorepower breaker (NOT by plugging into a live power outlet). Plugging into a live outlet can cause some of the most damaging of spikes because all three (30 A) or all four (50 A) contacts do not engage simultaneously.

Manually shut off all large loads before opening a shorepower breaker. Remove shorepower by opening the shorepower breaker (NOT by unplugging from a live power outlet). Same reason.

Always follow the same two load shedding processes before starting or stopping the generator set.

Never start the diesel engine when the generator set is operating. Stop the Generator, start the diesel, restart the generator. Otherwise, as the alternator overshoots on startup, the battery charger may rapidly deenergize and reenergize several times as it overshoots and charging control shifts back and forth. (YMMV, as not all battery chargers are designed the same).

Never start the diesel engine when the coach is connected to a closed shorepower breaker.

Unless you are conducting Preventative or Corrective Maintenance (or evaluation), start the diesel engine with the boost switch closed (Start and House battery banks paralleled). Fix the problem, if the design starting battery bank does not start the coach properly/effectively.

Neal

Re: 2014 Ladies Driving School - Tech Seminar

Reply #20 – November 17, 2014, 09:53:39 pm

Neal, please clarify. Are you saying to not start with the boost switch thrown, what I might call "on", that is to say it lit up red? I recall reading or being told on the ISM to only start with it activated as the ISM requires more rpm to start than some other diesels (150 rpm as I recall)

Bet I got this wrong, not good to remember wrong things!

Mike

Re: 2014 Ladies Driving School - Tech Seminar

Reply #21 – November 17, 2014, 10:39:34 pm

Quote from: Michael & Jackie – November 17, 2014, 09:53:39 pm

....................Neal, please clarify. Are you saying to not start with the boost switch thrown, what I might call "on", that is to say it lit up red?.....................................

Mike,

I'm saying, as James Triana says, always parallel the battery banks when starting the coach and that means "Boost on", Boost switch light "red", except when you are testing/confirming start battery bank performance.

With the Boost switch on and the battery banks parallel (and you can probably add more):

the start battery is not depleted as much during engine start

the alternator has to work less (less heating and bearing load) to restore the start battery bank back to nominal (battery sense is on the start battery bank (+) terminal), so until its voltage is back to nominal, the house battery bank is at the mercy of the start battery bank.

the alternator belt lasts longer

less lost energy in terms of engine efficiency

the isolator imbalance is less after start (two small currents and heating vs. one large current and heating on the start side diode and zero current and no heating on the house side diode)

the engine spins faster

the oil galleys fill faster and more unloaded engine rotations occur before engine running loads occur

the engine starter heats up less and fewer loaded revolutions

the boost switch and relay operation is confirmed frequently, before it may become necessary in an urgent situation.

Neal

Re: 2014 Ladies Driving School - Tech Seminar

Reply #22 – November 18, 2014, 12:04:56 am

Ok, was doing that right. But I think I picked up a good list from you post with the list, e.g. Not start with gen operating....I am sure I must have if stopped to eat, left gen running and then started up diesel

Thanks

Re: 2014 Ladies Driving School - Tech Seminar

Reply #23 – November 18, 2014, 12:49:33 am

I wouldn't worry about starting the engine with the boost switch on while the charger is receiving ac power from either the shore cable or generator. 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. The charger is designed to to that without difficulty, it probably occurs after a suitable delay, and ramps up rather than being a step function. It is no different to the charger than plugging into ac when the batteries are discharged, as the charger quickly ramps up from zero to around 100 Amps.

Re: 2014 Ladies Driving School - Tech Seminar

Reply #24 – November 18, 2014, 07:18:25 am

Interesting discussion. More batteries in the system would seem to be a better buffer at startup.

I warned customers about not plugging in the shore power correctly with only some of the contacts hitting.

Beaver fixed this issue by having a manual switch from gen to shore power or off in a bedroom side cabinet and the breakers there also. 1989?

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

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