Equip for Your Scenario

[BFL13]

Up to lately with a 5er, camping in provincial parks in the winter off-grid, under the trees with no solar possible, and a two-hour time limit on generators 9-11am and 6-8pm (that one in the dark) using nearly 200AH a day with over a 100 of that furnace-- we could do that, once I had the necessary number of batteries, high amp chargers, and a generator with enough VA to run those chargers.

It may be of interest to members to note that now with a Class C (no toad), doing the same camping routine (which includes a lot of driving around during the day away from the camp site), that this has all changed.

Trying it all out recently, I found that the Class C meant driving around in that instead of in the truck, with the 5er still under the trees in our site.

So, you get alternator charging while driving around, plus any solar you can grab if the sun is out (not often in the winter). You can leave your site and just park out in the open under any sunlight at the campground parking lot and grab some solar time, while still being able to walk the trails or whatever at the campground.

You can spend the day wandering from parking lot to parking lot like PT does in his Class C, same as any homeless person with an old Class C 🙂 like you see around here at the library or grocery stores during the day. This means you are excused the 2-hour time for generator runs plus any solar. You can even pick a spot they won't care if you have a noisy gen. Just go back to your site for the night same as before with the 5er. All good.

So the equipment requirements are less severe than with the 5er doing the same camping time. (As in going up-Island to Rathtrevor for a few days in the winter every month)

[BFL13]

This has some good info. Seems there are two case sizes and two amp sizes for the "3G" that came out in 1992. Shows detail photos of doing the swap and changing the wires. Shows how to tell which 3G it is from the holes in it.

http://www.fourwheeler.com/how-to/electrical/1612-ford-alternator-upgrade-for-more-battery-charging-...

[MEXICOWANDERER]

If your Ford alternator uses a "pivot swing" adjustment arm (has a slot) bracket the chances are excellent that the 130mm 3-G will bolt up. This is quite an alternator. On my test bench I slowed rotor speed down to the point where I could hold the eraser end of a pencil onto the front flange of the pulley and the dang thing insisted on developing 21 amps. The bench tachometer bottomed out at 150 RPM.

Try to get a factory original alternator even if it's used and needs brushes, bearings and a voltage regulator. The coating on the stator windings is a bright pink. Remans, lose too much low speed power because when the stator is re-wound. Like with all remanufactured stators, they BURN the copper out with heat and this destroys the silica coat on the wafer stator laminations.

The 3G uses the 6303 front ball bearing which lasts more than three times as long as the 2G and 70-90 amp big frame Ford alternators.

Be sure the voltage regulator matches usability wise the regulator off the alternator you are replacing. F794 is a common aftermarket part. Even though WAI purchased Transpo, their F794HD regulator uses a MOSFET power transistor and it runs much cooler than the OEM and most aftermarket regs. Out of 2 - 3,000 I built, I had no Transpo reg failures.

[MrWizard]

interesting discussion

by chance does anybody know what a 1997 ford e450chassis 460 engine RV, is most likely to have for an alternator, and will that 130amp 3G big brother fit (if its not already there}

[MEXICOWANDERER]

Start Kubota. It Idles at 1,200 RPM the same as load operating speed (tropical climate). 10-minutes later...

WHAM! 400-amps at 28.8 volts.

X amp hour battery bank 12 amperes
Y amp doubled in size 24 amperes
Z amp tripled in size 36 amperes

Wanna let your engine run for 12 amps? 24? 36? The 36 sounds inviting doesn't it? After all when things are shut down and the load appears it's all about amp hours and nothing else.

That's why I elected to go with a 3300 amp hour bank. 2x 12 (24) volt hundred amp hour batteries piddle at 5 amps. Now times that by 33, and how many piddling amps does that add up to. HOLY SNOT! 165! If I charged the Rolls batteries like I charge the Lifeline, I would be whacking them with 3,300 amps (but their charge acceptance limit would inhibit it).

Feeding expensive fuel to maintain a penny ****-game ain't too swift.

When I consume fuel it is for a good reason.

Think about it.

Yes the penalty is purchase expense and weight. How does this factor into the life style? I would love to have a hundred panels feeding those monsters. But the jungle and summer rains thwart any thoughts of it being practical. A halfassed solar system coupled to a halfassed charger and battery bank would satisfy neither winter or summer loads.

I just don't have the patience anymore to dink around with a hundred watt hydrocarbon based charging system no matter if I am running the Kubota, the Lombardini, or the Harbor Freight 2-cycle generator.

Weekend warriors can return home and let 24/7 power compensate for a marginal system. I do not have that luxury. Or money to have a generator or engine run for hours and hours.

[pnichols]

Another way of thinking ... that to many probably seems to be off the chart thinking ... is this:

Assume your RV is also sort of a disaster scenario escape module. For that, you need it to be configured to have as many self containment options as possible, or as you can afford. Since you have a large built-in main engine along anyway, a good sized alternator always on tap spun by it adds nicely to those options.

FWIW, we keep our rig stored in the back yard with - as much as possible at all times - all tanks full that should be full, all tanks empty that should be empty, and all batteries full that should be full.

Of course solar (which we do not have) fits in nicely with the above options thinking, too. I've so far procrastinated my way out of adding solar to our rig, as it's large alternator and two generators have muddled my thinking. 😉

By the way, being "always prepared" makes it super easy to get ready for each routine RV trip.

P.S. We are right now in the 35th hour of a massive power outage. The DW slept out in the RV last night with it being kept warm from an electric heater that was powered from a house outlet that was kept active via our emergency 4400 watt whole house generator.

[BFL13]

If the scenario is five days off grid, no solar, no driving around, and one hour of idling a day--- I get about 25 amps now and let's say a new alternator gets me 50 amps--that's 25 more so 125AH.

Two more batteries (I have room for two more) at 225AH would provide 125AH no problem and would be recharged once back home.

However, to make that come out even, the batts have to be down enough to take all 50 amps from the new alternator, where they might be able to take 25 if they are not that low. Am I better off idling for an hour every second day at 50 or every day at 25? Does it matter for the camping activity scenario? Needs some figuring out.

I just did four days as is and was maybe at 55% SOC on departure from about 420AH of bank so that's 189AH net used over 4 days or 49AH net a day. If I ran them down another 49 net on the fifth day, 238/420 = 43% SOC --big deal.

But that was not quite the same scenario so net AH use might be more per day. Anyway, maybe one more 12v instead of two? Adds about 55AH to the existing bank. Might not need any more batts. Also I could cut in the "inverter bank" which has two batts if the main bank got way too low by using jumper cables. Redundancy.

I am inclined to just leave the alternator as is ( don't want it to catch fire though!), and dicker with battery bank configuration. Might be ok as is. Another RVer doing things his way might have a different solution.

But it does illustrate my topic here, that you need a scenario to base your equipment needs upon. Also that you are not stuck with what your RV came with. Renovate! 🙂

[pnichols]

BF,

Wheeewww ... I got dizzy reading this whole thread.

IMHO, just use the K.I.S.S. approach and put a great big aftermarket alternator in your Class C and be done with it. That way you'll not have any serious battery recharging concerns if the sun don't shine and/or if you don't want to have to lug out, gas up, and refuel a portable genny.

I'm getting real lazy during our camping trips. It's more and more tempting just to pay the idling gas price and fire up the super quiet main engine and let it's G-whatever 130 amp Ford alternator dump up to 80 amps (so far .. a new record amperage we hit on our Thanksgiving camping trip) into the coach batteries for a quick one hour top-up. To bring the batteries closer to 100%, I have to break out the little Honda and run it for a few hours.

[DiskDoctr]

What about these alternator options? Any of these work better for him at idle?

QuickStart High Output Alternators

[DiskDoctr]

BFL13 wrote:
I think the existing wiring back to the house batts will limit the amps to the batts, but I don't know by how much, similar to a converter's amps on typical RV wiring to a battery too far away. This could negate some of the advantage of a higher amp alternator, but the wiring paths could be improved.

This MH does not have a built-in gen, so that means portable. Interesting to compare the cost of say a 1000w Honda with a 40amp charger, vs a new alternator that can do 40 amps instead of 24 with the MH sitting there idling, plus better wiring to the house.

How many amps can your battery bank accept? (Assuming you had sufficient wiring upgrades)

Many alternators have smaller pulleys that will spin the alternator at higher rpms while idling. As long as you don't overspeed it while running down the road.

We don't have these overspeed problems on diesels. My alternator is listed up to 6000 rpms, but the only time my Excursion would see 6k rpms was if it sprouted wings and flames were shooting out the back :E LOL!

[DiskDoctr]

pnichols wrote:
Hmmm ... that reminds me of a "labeling quirk" on the generator control panel on the wall in our Itasca motorhome: To start the Onan, there is a little two-way momentary rocker switch that is labeled "Start" on the left side and "Stop" on the right side.

The Stop position of course stops the Onan if it's already running. However, it the Onan is not running, the Stop position primes it and I can hear a muffled clack-clack of it's priming pump. I always prime it for a few seconds before pushing the left "Start" side of this rocker switch to start the generator.

We had owned our rig for some time before I discovered this double function for the rocker switch's Stop position (I should have read the manual sooner). I wonder how many other RV control panels have an Onan Start/Stop rocker switch that is labeled this way and operates this way ... unbeknowns to their owners??

THAT is interesting!! :C

[BFL13]

I think the existing wiring back to the house batts will limit the amps to the batts, but I don't know by how much, similar to a converter's amps on typical RV wiring to a battery too far away. This could negate some of the advantage of a higher amp alternator, but the wiring paths could be improved.

This MH does not have a built-in gen, so that means portable. Interesting to compare the cost of say a 1000w Honda with a 40amp charger, vs a new alternator that can do 40 amps instead of 24 with the MH sitting there idling, plus better wiring to the house.

I also have the option of just taking along more batteries for a scenario of under a week away from home. Then I don't have to do anything. Any longer time off-grid with us means summer out in the open, so now the solar can do just about all of it, so again I don't have to anything.

So--back on topic---I have to sort out just what scenarios I need to equip for. This rig's layout allows for several different set-ups, so at least that is not a limitation like a TT's tongue limit or whatever.

BTW, the split battery banks with one doing inverter only and the other doing furnace, lights, etc worked great. No worries about running the bank down so the inverter would hit the 11v alarm.

I ran the "main bank" down as expected with lots of furnace, and the inverter bank stayed up where it could run the inverter no problem.

I was able to "control" that bank by choosing to boil water in a pot on the stove instead of using an electric kettle so much. Meant no threat of not being able to use the toaster or microwave as needed. Not much control over the main bank since the amount of furnace is not really optional unless you want to freeze to death 🙂

[brulaz]

BFL13 wrote:

...
I have not tested to see if I get more amps by stepping on the gas. Would I?
...

Dunno if this is relevant for yours, but RAM publishes a plot of my alternator's Amp output at 14V versus alternator rpm. Output starts low, rapidly rises, then almost plateaus with increasing rpms. The alternator's rated 220A is only reached at the highest rpms at the end of the plateau. (And amps decrease with alternator temperature.)

RAM also publishes a pulley multiplier for each engine so you can calculate the Amp output for that alternator at each engine's rpm from the graph. Turns out that my engine's idle rpm (~1000 rpm) is at the beginning of the graph's plateau, giving ~190A, and 220A is reached at the higher end of the plateau at ~2300 rpm. Not a huge difference.

My guess is that most alternator/engine/pulley combos would be designed this way, so that the engine would not have to be run at too high an rpm to get the rated Amp output.

But from Mex's comments this may not be the case ...

[MEXICOWANDERER]

I should have written...

In gear...idling.

Whatever your 2G is capable of, the 3G will kick it's butt.

There is a big brother to the 95 amp small frame 3-G

It can slide right on in, if the adjustment bracket with the long slot hole can be levered wider to accommodate an extra inch and a half increase in diameter, the swap is a snap. The 130 ampmodel is almost unbelievable at idle compared to a 2G - try ninety to a hundred amps!

The voltage regulator fit, is different between the 2 alternators the 2G ad the 3G. If your rig has a full digital instrument dash the alternator demands a white colored regulator.

The big 130 amp 3-G has a violet color stator that is visible through the holes in the case.

[BFL13]

Mex wrote:

"•The higher amperage model of the small frame Ford 3G is 95 factory rated amps
•The 2G IAR, is 75 amps, when not on fire
• At idle the 3G develops 33 amperes, the 2-G when not on fire ZERO amps"

Please clarify the idling amps.

From the photo it looks like I have the 2-G, but when idling I get about 24 amps to the house battery (as seen on the Trimetric). I have not tested to see if I get more amps by stepping on the gas. Would I?

My 1991 has about 62,000 miles on it. (It has mostly been on the Island here.) So far so good on the alternator, but that can change fast, I know.