Alternator options

Hi from Kuwait

Coming out of the wood work finally. Been a lurker for many years now, been reading and studying my way thru the RV world. I am well read on the subject. Thanks to the wonderful contributors of the many caring RVers on this site I am an expert on RVing with hardly any experience. Hopefully, when DW and I takes the plunge this year we will be in a better position to contribute to the cause here.

For right now I am on my last deployment then I will be dual retired and enjoying the RV life style. This bring me to purchasing our new truck for our too be purchased 5th wheel. As many have said ?that you never run out of learning and experiencing new things RVing?.

Well, I have a question concerning alternators. I am ordering the truck soon and now is my opportunity to order it exactly or as close to perfect as I can. The alternator is a stock 150 amp on a diesel engine. I will be towing a large 5th wheel and probably traveling no more than 350 to 500 miles on any particular day. I am retired don?t care how far we get. Any ways will that 150 amp stocked alternator be enough to charge and maintain the house batteries in the 5th wheel? Most likely at this point the batteries will be 1 or 2-12 volt stocked batteries.

The options are a dual alternator set-up with 150 and 200 amp or an upgrade from 150 to 200 amp alternator. More than likely we will do some boon docking in the future. I am good with an added expense now to save a few bucks later. I am looking at a 200-300 dollar upgrade for a 200 amp and the dual set-up. Cost wise not much difference for upgrade. Any and all comments are welcomed and appreciated.  Save time and inquiries I am looking at 2018 3500 GMC Denali diesel, dual wheel 2X4, crew cab, 8 foot bed to include 5th wheel package. YUP, my retirement present. Can?t wait.

Uh, depends on how far you drive every day.  with Trailers the limiting factor is not so much the alternator as it is the roughly 50' of too small to carry high  current wire between the alternator and the bastteries.  To fast charge you need at least Starter casble, not 12 ga

I have dual alternators in the diesel truck that I use to pull my 5er. I've never been able to find a way to make any use of all that available current. The limiting factor is the size of the wires/ The wires from the alternator to the 7 pin connector and the wire in the 5er's cord are either 18 awg or 16 awg. That limits you to either 16 or 22 amps for charging your batteries. Ripping out and replacing the wires with something much bigger, would have all kinds of problems, and just doesn't seem to be worth the effort.

The two 12 volt batteries that you are considering, are probably marine / deep cycle batteries. They are a hybrid, half way between a normal starting battery and a true deep cycle battery. You would be much better off with two 6 volt, golf cart batteries. I do a lot of boondocking, and use four 6 volt batteries. I wish I had room for six.

Having all the time in the world to get there, when you're retired, is a myth. I used to believe it before I retired. Now, I in just as much of a hurry as I ever was. This week, I'll be leaving on a 1500 mile trip from northern Illinois to southern Florida. I'll do it in three days. Four days would be easier, but why would I want to waste an extra day of driving, when I could be out enjoying myself?

Finally, your post would be much easier to read, if you had proken it up into three paragraphs.

Joel

Since you?re planning on doing some boondocking anyway, you might consider outfitting your fiver with solar.  Properly set up, it can be an effective way to charge your batteries.  Lots to learn there, too...

And most days a solar charger is working when you are boondocking... or going down a highway.

( Thank you for your service, godspeed home...I spent 10 months in Kuwait...what a S hole.  8) )

No matter how big the alternator, I believe the design of the seven pin connection circuit limits it to a few amps.

It basically provides power to battery while under tow to make up for the trailer's phantom loads.

When you think you have the trailer you want selected, rent a similar unit for a week or so on the road. To will learn a lot about RVing in a very short time. 

Books and board advices pale in comparison to a week or ten days of the real thing.

Good luck.

TonyDtorch said:

And most days a solar charger is working when you are boondocking... or going down a highway.

( Thank you for your service, godspeed home...I spent 10 months in Kuwait...what a S hole.  8) )

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We are going to spend 6 months traveling around the south west for the winter and making our way back home to Maryland Mid May. Then the DW and I will decide then if we are going to this full time. If we decide full time then we will invest in solar and doing more boon docking. We have spent the last 5 years inspecting 5th wheels at RV shows and dealerships, so we pretty much know what we want in a 5th Wheel. In the past 5 years we have seen many changes in the RV industry and we are glad to have waited for the right time to purchase. I know many more improvements will be made long after we make our purchase, that goes with anything you buy. 

I believe everyone is on the same page about the wiring and so with that I will take that advice and leave the alternator option at the manufacturer. I believe we will be better off scraping the 12 volts for 4-6 volt batteries and see how they do while traveling and we will be that much ahead if we go solar.

Oh Kuwait what a wonderful place.   I was here 15 years ago on my way to Iraq, when it was really a S hole, now not so bad, considering it is what it's suppose to be. I will be home sometime in August and it will be on RV time.

Great Horned Owl said:

I have dual alternators in the diesel truck that I use to pull my 5er. I've never been able to find a way to make any use of all that available current. The limiting factor is the size of the wires/ The wires from the alternator to the 7 pin connector and the wire in the 5er's cord are either 18 awg or 16 awg. That limits you to either 16 or 22 amps for charging your batteries. Ripping out and replacing the wires with something much bigger, would have all kinds of problems, and just doesn't seem to be worth the effort.

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If the second alternator does nothing but charge the trailer batteries, make it remote sensing.  Run a remote sensing wire back to the trailer batteries (or at least to the trailer connector) and connect it in place of the alternator's internal voltage sensing point.  The wire doesn't have to be any particular size since it's sensing voltage, without any significant current flow through it.

This will make the alternator's voltage increase and cancel out the wire loss between the alternator and where you connected the remote sensing wire.

You'll get much better charging delivering a constant 14 volts to the trailer batteries, or even to the trailer connector, compared  to the stock setup.

In stead of a 2nd alternator and all the work to install it. How about a Honda EU-1000I and a Progressive Dynamics 9245?

Or a EU-2000i or Yahama EF1200 and any 9200 up to 9280?  (the 9280 needs (at max load) a full 1000 watts perhaps a touch more. the HONDA Eu-1000i can not do that. I think it is 900 watts continous.

John From Detroit said:

In stead of a 2nd alternator and all the work to install it. How about a Honda EU-1000I and a Progressive Dynamics 9245?

Or a EU-2000i or Yamaha EF1200 and any 9200 up to 9280?  (the 9280 needs (at max load) a full 1000 watts perhaps a touch more. the HONDA Eu-1000i can not do that. I think it is 900 watts continuous.

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Thanks John for the reply, to fill you in the truck will be ordered and the alternators would be an add on option. We plan on getting a generator and solar if we decide on boon docking, which we probably will later on. Need to get some real hands on RV experience first and actually see what our power consumption tends to be on average. When the generator day does comes it will probably be in the lines of a 4 to 6K Yamaha inverter gen. I have always been go big or go home.  ;D

The main reason for the alternator option was to make sure the house batteries were maintained while traveling between RV sites, especially if we boon dock at a Walmart or somewhere that we didn't have shore power.

Two will put out more amps at lower rpm, main advantage. 

The 150A is plenty for traveling, at least during daylight hours (no headlight power draw).  Unless you upgrade the wiring to the trailer, you probably can't move more than 10-20A down the wire anyway.  A fairly standard trailer 12v line is fused for either 20A or 30A.  Further, two typical trailer batteries won't accept a lot more than that unless they are really discharged , and even then it would draw more only for a short period.  The optimum charge rate for 200 amp-hours of battery capacity is around 20A anyway. For example, two Group 24 12v's are about 170 AH, and a pair of GC2 6v batteries are about 225 AH. You can only use about 50% of the theoretical capacity, so you won't be putting back more than 85-110AH in most cases. That's about 4-5 hours of driving @ 20A peak.

You could wire up something with more capacity, but for most RVers that would be of little value. As Old Flick points out, dual alternator will produce a bit more amps at low (idle) rpms. That's useful for ambulances and other vehicles with large power needs while parked, but not so much for RVs that are mostly towed at highway speeds. If you expect to use the truck alternator to charge the batteries while at the campsite, that's a different matter.

A downside of two alternators is a slight decrease in mpg - it takes power to drive the belt and spin the 2nd alternator. If you want to get a bit more capacity, I'd choose the single alternator @ 200A.

Thanks Gary,
        I believe I will stick with the stock 150 amp alternator with the good reasons you indicated. Thanks for the advice given, made my decision much easier and saved me a couple of bucks in the process. 

          One more hurdle today, signing for the truck order today, just one more thing to clear up on the invoice and it will be a go. Once, I take possession I will change signature line.

Probably cheaper and more flexible to buy a good generator.

Many fifthwheels come with way inadequate batteries.  Add more if you're going to boondock.

Most likely you will want to get better batteries for the trailer, both better quality and larger capacity.  A typical trailer comes with one or two Group 24 size 12v "Marine/RV deep cycles", each with an 85 AH capacity.  Better ones will have a pair of 6v GC2 "golf cart" batteries with a 210-230 AH combined capacity. The GC2's are have more capacity and last2x or more longer than the Marine/RV types.  For future reference, you might read my RVForum Library article on RV Battery Choices: http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf

However, may as well use what comes with it for awhile.

Gary RV_Wizard said:

Most likely you will want to get better batteries for the trailer, both better quality and larger capacity.  A typical trailer comes with one or two Group 24 size 12v "Marine/RV deep cycles", each with an 85 AH capacity.  Better ones will have a pair of 6v GC2 "golf cart" batteries with a 210-230 AH combined capacity. The GC2's are have more capacity and last2x or more longer than the Marine/RV types.  For future reference, you might read my RVForum Library article on RV Battery Choices: http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf

However, may as well use what comes with it for awhile.

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Once I have the 5er I will have all summer to get my the upgrades and do-dads on her. One of the upgrades will be a batteries box with 6volts battery system. I like to be ready as far as batteries go for the advent of going solar for boon docking. The one thing I do not like doing is doing it over. Do it right the first time and maintain it there after. I be back I have a stinking Army meeting to go to...to be continued.

Gary RV_Wizard said:

Most likely you will want to get better batteries for the trailer, both better quality and larger capacity.  A typical trailer comes with one or two Group 24 size 12v "Marine/RV deep cycles", each with an 85 AH capacity.  Better ones will have a pair of 6v GC2 "golf cart" batteries with a 210-230 AH combined capacity. The GC2's are have more capacity and last2x or more longer than the Marine/RV types.  For future reference, you might read my RVForum Library article on RV Battery Choices: http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf

However, may as well use what comes with it for awhile.

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Supporting what Gary said.. Those Grouip 24's are about 75 Amp Hours each or 150 total and of that only about 40-50 usable before rapid aging sets in on them (Marine batteries like to be fairly full, like 80 percent)

A pair of GC-2, in series, is 220 give or take about 10 and half thgat (110) usable that is over twice the power. and about the same price.

However... I agree with Gary you should not replasce a good set of batteries till the need ari9ses. I mean why throw away a good battery?

OH.. A toy I have,, A 100 dollar jump start battery pack... Very useful toy
It starts my car when the battery is low
It ran my main slide in and out when the control system fai9led (I built a new control system)
When wife was alive I used to build campfires for her.  The campground where I did this went with those new concrete monstrosity fire rings (Well they are safe the outer culvert pipe never gets hot)
Getting enough air in there for a proper fire was very easy.. Piece of exhaust pipe bent to a pattern I( specified.  12 volt mini-fan in one end, other in fire pit. portable car (The jump pack) feeding the fan.  Worked great.