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Discussion Starter · #1 ·
Considering a 2017 F450 Platinum. Playing with the Build & Price and saw an option for the Dual Heavy Duty Alternators. (I believe the guide added dual alternators when I added the upfitter switches.) We do have a residential refrigerator (and inverter) in our trailer, so having any charge go to the trailer batteries while traveling would be great. Anyone know if dual Heavy Duty Alternators would provide any advantages in providing some additional amperage to the trailer while towing? Somehow I've developed the idea that only so much amperage will go to the trailer no matter how much excess amperage the alternators can provide. Not sure the heavy duty alternators are needed. Thanks! David
 

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I could be off on this. --- In a RV forum I frequent I followed a discussion regarding trailer battery charge times. The question basically was if dry camping and running the RV batteries way down, how many hours of driving will it take to charge them fully the next day? The discussion covered lots of issues such as alternator amperage output. But as I recall, most of the posters that seemed to have a lot of experience basically agreed on one thing. It was that no matter how many amps you are able to produce by one or more alternators, if your truck and trailer charging wire sizes are not significantly enlarged, you will see no benefit in battery charge times. --- So I guess my point is, does Ford increase the trailer charging wire sizing when you order a extra heavy duty or dual alternators? Also the charging wire on your travel trailer harness would need to be enlarged.
 

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Discussion Starter · #3 ·
Thanks! You said it better than I did, but that's what I'm trying to find out. In our current case, we're traveling with a residential frig using 7-9 amps - unless it's decides it needs to power up to cool. We see 25-33 amps at the inverter when this occurs. I'm pretty confident we don't get 7-9 amps from our truck when traveling now. (We do get power - it's just not enough to maintain the voltage at the trailer batteries over the trip.) Just was thinking with the dual heavy duty alternators, there might a chance we could see 7 - maybe 8 amps. Would help on those long trips where - at the end of the day - you're dry camping and you're limited in the hrs you can use your generator. Don't even think about it when traveling to a campground where we have electric hookup. Real answer to up our number of batteries on the trailer. Currently have 4 6v golf cart batteries. Need 6. And no, DW will never go back to an RV frig. David
 

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The circuit to power your battery is backed up by a 25 amp fuse in the truck. From what I have been able to read this circuit is set up as a trickle charge so 2-3 amps may be all that makes it to the battery. Our 5th wheel has a residential fridge as well. It only pulls 4.3 amps when the compressor is active. If just the fan is running it is around 1.1 amps. Our 5th wheel has a 2500 WATT inverter which will equate to about 20 amps of total availability. 25-33 amps for just the fridge seems way to high! 33 amps is 4000 WATTS on 120V! Something else has to be on when you are drawing 25-33 amps. Check the sticker inside the fridge. The amp reading is on it and that is the highest it will ever pull. It should only pull about 85% of the tag number…a little more if voltage falls below 115. I just looked at the one in my house which is a 31 cubic feet LG and it only pulls 5.2 amps under full load. Fridges have got very efficient over the last few years.
 

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Discussion Starter · #5 · (Edited)
Sorry I wasn't clearer! When I'm talking amps I was assuming everyone knew I was talking 12v and only when traveling. My fault. When I saw 33 amps at the inverter, the inverter also showed 12.7 volts at the trailer batteries (we were stopped for luch at a rest area and I just looked at the inverter to see what the reading were. (We saw 25 amps on the inverter at 11.6v when we first turned on the inverter yesterday morning after 4 days of dry camping. We'd left the inverter off overnight due to low voltage. Didn't help that our generator failed the evening before - but it's 8 yrs old - it happens.) Only the frig runs from our inverter. We have a Progressive EMS, but I can't say for certain what the frig is pulling on 120v.

Thanks for the info on the tag. It states 1.1 amps @ 115v. I think that equates to 10-11 amps at 11.6v if I've done the math correctly. We're running a Xantra Prosine Sine Wave 1800, and it only shows battery voltage and amps. Based on the owners manual, I don't believe we're even close to pulling enough power to run our inverter efficiently. So that hurts us some, too. I can't explain the 25 - 33 amp readings we're seeing on the inverter, but it's what I 'm seeing. They could have been momentary readings that I just happen to catch.

All-in-all, it doesn't sound like the dual heavy duty alternators would help our situation. But I'd probably get them, anyway, should we order one.

Thanks, again! I always learn something when you guys respond. David
 

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If you are going to order the truck I'd add them on. In the future you never know what you may want to add and need power for on these trucks. Plus anything you do RV wise could be fed from the truck. You would just need to be smart about how to wire it up. Another option to add now would be the supplemental heat.
 

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Dual alternators aren't a requirement but it gives you the power to add on later such as some do with the snow plow or an inverter or booster cable setup. You can always run a dedicated 12v from a battery isolator to the trailer that would give you extra amps.

As state above, add the supplement heat and if you have pets or kids, add the rear seat heater, both of these can not be added after the truck is built.
 

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On the Ford build and price, if you order the Rapid Heat, you can't order dual alts nor upfitter switches? Maybe I was doing something wrong.
Joe
 

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you are doing something wrong or they are already included in a package you had previously selected. I priced out a truck yesterday on the site and had no problem selecting the duals, supplemental heat and rear seat heating.
 
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