dual alternators

54suds wrote:
Two alternators can also serve as a jerry-rigged replacement for larger alternators by combining two in series to reach the same level of power output, which is particularly helpful in improvised repair situations.

??

Your post is confusing.

They aren't hooked in series.

jimh425 wrote:
As far as two versus one goes, redundancy is usually a good thing and probably why Super Duty diesels have two batteries.

Two batteries is the norm on Duramax equipped trucks too. It's not there for redundancy, it's because diesel trucks need the extra power to start.

My f550 could have had two but didn't so I got sick of replacing the stock ones and put a 250 amp one in it's place. There is a heavy duty rewire kit that I got at NAPA. It's been on over two years now and no problems and no half charged batteries. Couple of hrs to install.

Dual Alternators for High-Power Drain Applications
Alternators are particularly helpful for high-drain vehicle power applications where the vehicle needs to have sustained power output without the engine running, without sacrificing the vehicle's ability to turn over. Vehicle engineers can approach this from two separate design approaches. The first is to connect both alternators to a large battery bank shared among the starter, spark plugs and other vehicle systems. A shared system offers the advantage of inexpensive simplicity; however, extended use without running the motor runs a real risk of draining the batteries to the point where the engine will not turn over. The second design philosophy approach sets up two separate power systems, one for critical systems and another for secondary optional devices. A dual independent power system approach prevents the vehicle from getting stuck due to draining too much power from the batteries but adds significant expense. The dual power system design works well with vehicles like RVs or police surveillance vehicles. Two alternators can also serve as a jerry-rigged replacement for larger alternators by combining two in series to reach the same level of power output, which is particularly helpful in improvised repair situations.

My Ford has dual alternators, 1-200 and 1 150 amp.
At start up in the Winter, I am drawing well over 200 amps.The supplemental heater is 1200 watts(120 amps), glow plugs, two seat heaters, air compressor, head lights, plus the other 25 lights or more if trailer and camper are hooked up, and the draw that all the 12 volt and 120 volt outlets have, stereo and other things I forgot.

Four of the trucks are Ford.. all have dual alt's. Faster recovery for sure. One gives out, code is sent, but the second keeps working= not stranded.

Electric cabin heater is standard on new Super Duty Diesel's in cold climates. It is simply a supplemental heater to help with cabin warm-up in cold climate since Diesel engines have such a long warm-up time when the vehicle is operated at light load.

In terms of two batteries, that is to provide enough current to crank the Diesel engine in cold climates while at the same time maintaining current for your glow plug system.

I give. What is an electric cabin heater and why does someone need one?

As far as two versus one goes, redundancy is usually a good thing and probably why Super Duty diesels have two batteries.

I order electric cabin heater for my F350 and was forced to take dual alternators.
I still think it is overkill.
Mercedes sedans have such heaters and they go by with single, 200 amp alternator.
One point might be that 2 of 120 amp alternators cost way cheaper than single 200 amp one.

I just pulled the windows sticker.

It is listed as a separate option, not part of a "package" (such as a snow plow prep package or the like)

Dual 125 amp alternators, $270 option

I don't know what the RPO code for it is.