180 Amp Altenator or 220 Amp Altenator?

[SSteilow]

I am planning to buy a Ram Big Horn 6.7L 3500 w/ the Aisin transmission 4X4 Crew Cab to tow a Fifth Wheel.
The Fifth Wheel weight between #13,000-#18,000.
Was wondering if i should add in the optional 220 amp Alternator instead of the 180 Amp Alternator.
Would that give more charging to the Fifth Wheel, while towing?
Just want to make sure i have a good truck that is configured correctly for towing my 5er.
Thank you for your replies.
Scott

 

[MattandLana]

Look I don't have personal experience with Dodges and 5ers but I expect there's two answers to this.

The long answer is that you can calculate the load your 5er will pull when charging/running, the load from all add-ons to the truck, etc. You can then find out what the truck's 'base' load is so you know how much spare amperage there is in the 180A unit. Compare the two and you'll know whether the 220A is needed.

The short answer is that over time you will always want more power: phones, ipads, laptops, torches, light bars, decorative LEDS, fridges, accessories, accessories, accessories. It will never be cheaper to upgrade your alternator than right now. I forget how much the extra is but it's a trivial additional cost on top of the truck as a whole. Go for it.

To answer your specific question, yes it will give you a bunch more charge for your 5er. I don't know how you guys set things up over there, but an extra 40 amps is a lot of juice.

A grossly oversimplified example: The more amperage your truck can provide to the 5er, the faster it will charge, especially if it's running on lithium batteries. Say the truck and all its accessories barring the 5er needs 140A, so that the 180A unit has a 'spare' 20A for the 5er. If you'd drained say 10A for 12 hours overnight in the 5er, that's 120 A/h you've used and need to get back into the 5er's batteries. At 20A, pretending 100% efficiency for simplicity, that's 6 hours to recharge the 120 A/h. (Actually it will be more than 6 hours, especially if the 5er has lead acid batteries, because there are limits to how fast lead-acids can absorb charge especially as they start getting full.) Now switch to the 220A unit. All else being equal you now have 60A to play with. For 120 A/h that's just 2 hours' charging. Now this is much oversimplified, because nothing is 100% efficient so there is power loss at every step of the process. Also each different type of battery has a different charging profile. Lead acids can only accept high rates of charge when nearly empty. Lithium batteries are (a) more linear, ie. the rate of charge doesn't fall off as fast as they approach full; and (b) can accept much higher absolute charge rates than lead acid anyway, so for both reasons a power surplus will benefit you more with lithiums. But either way, whatever your batteries, more amperage on tap will usually mean a faster charge.

BTW on some options you can (or at least used to be able to) specify a whole additional 220A alternator. Snow plow prep I think. Juice galore!

Good luck with the purchase!

 

[SSteilow]

Look I don't have personal experience with Dodges and 5ers but I expect there's two answers to this.

The long answer is that you can calculate the load your 5er will pull when charging/running, the load from all add-ons to the truck, etc. You can then find out what the truck's 'base' load is so you know how much spare amperage there is in the 180A unit. Compare the two and you'll know whether the 220A is needed.

The short answer is that over time you will always want more power: phones, ipads, laptops, torches, light bars, decorative LEDS, fridges, accessories, accessories, accessories. It will never be cheaper to upgrade your alternator than right now. I forget how much the extra is but it's a trivial additional cost on top of the truck as a whole. Go for it.

To answer your specific question, yes it will give you a bunch more charge for your 5er. I don't know how you guys set things up over there, but an extra 40 amps is a lot of juice.

A grossly oversimplified example: The more amperage your truck can provide to the 5er, the faster it will charge, especially if it's running on lithium batteries. Say the truck and all its accessories barring the 5er needs 140A, so that the 180A unit has a 'spare' 20A for the 5er. If you'd drained say 10A for 12 hours overnight in the 5er, that's 120 A/h you've used and need to get back into the 5er's batteries. At 20A, pretending 100% efficiency for simplicity, that's 6 hours to recharge the 120 A/h. (Actually it will be more than 6 hours, especially if the 5er has lead acid batteries, because there are limits to how fast lead-acids can absorb charge especially as they start getting full.) Now switch to the 220A unit. All else being equal you now have 60A to play with. For 120 A/h that's just 2 hours' charging. Now this is much oversimplified, because nothing is 100% efficient so there is power loss at every step of the process. Also each different type of battery has a different charging profile. Lead acids can only accept high rates of charge when nearly empty. Lithium batteries are (a) more linear, ie. the rate of charge doesn't fall off as fast as they approach full; and (b) can accept much higher absolute charge rates than lead acid anyway, so for both reasons a power surplus will benefit you more with lithiums. But either way, whatever your batteries, more amperage on tap will usually mean a faster charge.

BTW on some options you can (or at least used to be able to) specify a whole additional 220A alternator. Snow plow prep I think. Juice galore!

Good luck with the purchase!

Thank you MattandLana for your reply.
I will be moving back to the main land in a few years to South Dakota. Do not have any RV's on Honolulu.
Will probably contact Dave Smith Motors in Kellogg ID before the move, to see what i can work out coming through the area.
That's what i was figuring more Amps for charging the 5er while on the road, and if you have to dry camp on a over night stop.
Appreciate the information.
Scott

 

[Shadrach]

On the 2014 Ram website you can select dual 220 amp alternators. David

 

[moparnut72]

The snow plow option includes a 220 amp alternator.
kk

 

[B.G. Smith]

Unfortunately, just because you have extra charging capacity will not equate to charging the RV battery quicker. The bigger alternators or two alternators are ususlly intended for ambulance or wrecker type service where they have a high amp draw all the time. The RV or the truck batteries could not handle a shot of 180 amps for long anyway. about 20 or 30 amps will bring the batteries in the truck back to full charge pretty quick and even if you are driving with head lighrts on and the AC blower on high you are probably not using more than 45 or 50 amps so the alternator is putting out 80 amps. The alternator output is regulated according to the battery voltages is sees via the computer. Doubt that you would ever need 220 amps output with just an RV. bg

 

[RikDavis]

The usual charge rate pf an RV battery from a tow vehicle is below 10 amps because of the resistance of the long cable going back there and the small differential in voltage between the 2 points, Actually I rarely see over 5 amps. Increasing the current capacity of the Alternator won't make any difference. Increasing the voltage would but the regulator won't allow that as it is getting it's information from the truck batteries.

 

[PC12Driver]

The gauge of the hot wire in the harness going to the trailer is pretty small. It's sized for about 15 amps.

 

[SSteilow]

The usual charge rate pf an RV battery from a tow vehicle is below 10 amps because of the resistance of the long cable going back there and the small differential in voltage between the 2 points, Actually I rarely see over 5 amps. Increasing the current capacity of the Alternator won't make any difference. Increasing the voltage would but the regulator won't allow that as it is getting it's information from the truck batteries.

Thanks RikDavis,
I was thinking about the long cable, that it would lose the amps going back to the trailer.
Makes a lot of sense now. Will just go with the 180 amp alternator.
Scott

 

[SSteilow]

Unfortunately, just because you have extra charging capacity will not equate to charging the RV battery quicker. The bigger alternators or two alternators are ususlly intended for ambulance or wrecker type service where they have a high amp draw all the time. The RV or the truck batteries could not handle a shot of 180 amps for long anyway. about 20 or 30 amps will bring the batteries in the truck back to full charge pretty quick and even if you are dricing with head lighrts on and the AC blower on high you are probably not using more than 45 or 50 amps so the alternator is putting out 80 amps. The alternator output is regulated according to the battery voltages is sees via the computer. Doubt that you would ever need 220 amps output with just an RV. bg

Thanks B.G Smith,
Appricate the information. Makes sense now. Will go with the 180 amp alternator.

Scott

 

[MattandLana]

Well it depends on your setup. In Oz some of us set up a separate very heavy cable running through a large Anderson plug and driving a 12v to 12v charger. Than can provide higher charge rates. But you guys will know better how RVs are set up in the States.

 

[Bill Stockard]

Well it depends on your setup. In Oz some of us set up a separate very heavy cable running through a large Anderson plug and driving a 12v to 12v charger. Than can provide higher charge rates. But you guys will know better how RVs are set up in the States.

I installed 8-gauge wiring for the charge line (with an inline circuit breaker) and ground to my truck's driver side battery for charging my slide in truck camper battery and to run the fridge on 12-volts driving in certain crosswind situations. My truck camper has a built-in automatic battery separator that isolates the truck's starting batteries from the camper battery when the truck’s engine isn’t running. The factory charge line is too small to effectively charge the camper battery and/or prevent discharging the camper battery when the fridge is running on 12-volts.

Bill

 

[SSteilow]

I installed 8-gauge wiring for the charge line (with an inline circuit breaker) and ground to my truck's driver side battery for charging my slide in truck camper battery and to run the fridge on 12-volts driving in certain crosswind situations. My truck camper has a built-in automatic battery separator that isolates the truck's starting batteries from the camper battery when the truck’s engine isn’t running. The factory charge line is too small to effectively charge the camper battery and/or prevent discharging the camper battery when the fridge is running on 12-volts.

Bill

Interesting Bill. Where did you install your inline Ckt Breaker. In your Truck, using one of your Aux Switches?
Silly Question, Dodge has Dual Batteries in all years of the their 3500's trucks, or is that a option to add Dual Batteries?
Will research more on adding a 8-gauge wire charge line, and see about adding Auto battery separator in the Trailer, if one is not installed.
Thanks for the information,
Scott

 

[Bill Stockard]

Interesting Bill. Where did you install your inline Ckt Breaker. In your Truck, using one of your Aux Switches?
Silly Question, Dodge has Dual Batteries in all years of the their 3500's trucks, or is that a option to add Dual Batteries?
Will research more on adding a 8-gauge wire charge line, and see about adding Auto battery separator in the Trailer, if one is not installed.
Thanks for the information,
Scott

Dodge/Ram trucks with the Cummins diesel engine option have been equipped with dual batteries standard since the ’94 model year. I installed the circuit breaker on the fender cover under the hood near the driver side battery. The 8-gauges wires, both positive and negative, are connected directly to the driver side battery posts.

Bill

 

[Joseph Donnelly]

180 amp is a pretty big alternator already. I remember 134 amp and smaller alternators in older Ram diesels. If I had ordered, I might have paid the small extra price for one 220, but I was not upset when the Ram I found with other equipment I wanted had the 180.

 

[SSteilow]

Dodge/Ram trucks with the Cummins diesel engine option have been equipped with dual batteries standard since the ’94 model year. I installed the circuit breaker on the fender cover under the hood near the driver side battery. The 8-gauges wires, both positive and negative, are connected directly to the driver side battery posts.

Bill

Thanks Bill.
Appreciate the information.
Will be adding a bed side plug, to hook the trailer cord into.
Scott

 

[SSteilow]

180 amp is a pretty big alternator already. I remember 134 amp and smaller alternators in older Ram diesels. If I had ordered, I might have paid the small extra price for one 220, but I was not upset when the Ram I found with other equipment I wanted had the 180.

Thank you Joe.
Will use the 180 amp Alternator that comes with the Ram.
Scott

 

[RVTRKN]

I ordered my C&C with the 220amp alternator, not that I would need it though. I ordered my Boat with a V6 instead of a V8, because I planned on using it for long distance runs thinking I would get better GPH (Gallons Per Hour for the non boating crowd) but soon learned when I needed the extra power it would cost a heck of a lot more to increase it to a V8, then what the difference would have cost if I had bought the V8 in the first place. BTW, the GPH was not much better!

My recommendation would be to get the 220 amp alternator, you never know whats in the future.

 

[mpaulson]

I ordered mine with the dual alternators simply because it wasn't that much more cost and I planned on running things like my 3/4 hp air compressor, fuel pump (sometimes at the same time), off road lights etc. Now running duals may be costing me 1/4 mpg or something, who knows. Fact is like Joe said, we've all been running 180's for years along with towing our RV's etc. with no problems.
I guess I fit the crowd like RVTRKN was implying, the guy who will think "go big or go home" mentality which doesn't always make practical sense.

 

[Newsa]

IMHO only need the 220 amp if you use 110 v outlets or 110 voltage converter.

Mine came off the lot with it. Probably don't need it. But it kept my trailer batts charged and ran all the running lights beautifully for 2500 miles on my summer camping trip.