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)

Four hours of generator time per day. I’ll pass on that GC.

Big alternators work wonders to regain 50% SOC to 85% SOC.Down here where there is only 1-1/2 hours less sun during winter and a corresponding lack of latitude loss of same, solar is great -- but like many other places, leave panels in a vulnerable position and they'll learn to do the Macarena on down the highway in no time.Been thinking about getting one of those garden tote "Big Red Wagon" and mounting a panel sideways in it. Garden hose spool for 10/2 SOJ wire. And a MPPT controller, which would be permanently mounted at the site of the batteries.But I need my ship to come in. Jump over the jetty and slide up onto the beach...

In full sun at noon last week my 255w panel lying flat on the roof was putting 4.5 amps into a low SOC four- battery bank. (During a brief sunny break) Not much use there. However driving around was putting 25 amps in from alternator charging, which beats the 5 amps from 7-pin with the truck and 5er. I know I can improve on that 25 amps if need be, but we just got this thing and there are other priorities.The big thing was I did not need the generator at all, which is good, because I can't fit the Honda 3000i into the Class C compartments yet. ( I could if I remove the skids from the bottom of the Honda, so that is a possible)I could get by with a lower amp charger, smaller gen, using more gen time as now allowed away from the park, but adding in AH from driving around and any solar that comes in. Different equipment requirements and less expensive at that. The Class C has some advantages over the 5er for that side of things. Some other things were better with the 5er but nothing to do with batteries etc. We are pleased with the switch over at this stage of our RVing life--just thought it was interesting about how you can get away with less equipment set-up for off-grid in our scenario.

BFL13 wrote:In full sun at noon last week my 255w panel lying flat on the roof was putting 4.5 amps into a low SOC four- battery bank. (During a brief sunny break) Not much use there.However driving around was putting 25 amps in from alternator charging, which beats the 5 amps from 7-pin with the truck and 5er. I know I can improve on that 25 amps if need be, but we just got this thing and there are other priorities.The big thing was I did not need the generator at all, which is good, because I can't fit the Honda 3000i into the Class C compartments yet. ( I could if I remove the skids from the bottom of the Honda, so that is a possible)I could get by with a lower amp charger, smaller gen, using more gen time as now allowed away from the park, but adding in AH from driving around and any solar that comes in. Different equipment requirements and less expensive at that. The Class C has some advantages over the 5er for that side of things. Some other things were better with the 5er but nothing to do with batteries etc.We are pleased with the switch over at this stage of our RVing life--just thought it was interesting about how you can get away with less equipment set-up for off-grid in our scenario.BF ..... you're sure preaching to the choir here. It's good to have you finally come over to the non-solar-slave dark side! ;)We're not squatter campers. We camp here and there only a few days at each spot, so we often find that either the sun isn't out at all or it's not out enough. For this style of RV'ing in a motorhome with fat wiring between a big alternator and the coach batteries ... mixed in with some Honda or Onan time when in a campsite ... we have all that's needed to keep up our fast charging AGM coach batteries.We can't count on the sun being there when we need it .... only generators and alternators. To us the humming of a generator or whirring of an alternator is the sound of independence.

When we had a fiver I considered auxiliary batteries in the truck bed to charge while driving, but never followed through.

Equip for Your Scenario | Good Sam Community

BFL13
Explorer II
Dec 18, 2017
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-power/
MEXICOWANDERER
Explorer
Dec 18, 2017
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
Moderator
Dec 18, 2017
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
Explorer
Dec 17, 2017
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
Explorer II
Dec 17, 2017
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
Explorer II
Dec 17, 2017
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
Explorer II
Dec 17, 2017
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
Explorer
Dec 17, 2017
What about these alternator options? Any of these work better for him at idle?

QuickStart High Output Alternators
DiskDoctr
Explorer
Dec 17, 2017
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
Explorer
Dec 17, 2017
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

Forum Discussion

Equip for Your Scenario

About Technical Issues

Related Content

Beginning RVer: Is this Scenario Doable?

Wrong Equipment?

Battery Storage Scenario

Communications Equipment / Radios

Handling home office equipment - hanging files