AC / DC Generator

[Kenny]

Anyone ever thought about piggy backing say a 50DN alternator to the back of a generator. I've purchased a 10kw generator and am having thoughts about piggy backing a 50DN to the tailshaft coming out the generator head. Would not use to generate AC and DC at the same time. Would just switch on the AC or DC when needed. Any thoughts?

Kenny

[stevet903]

A 50DN is oil cooled, so you would have to find a way to supply the oil.  If you plan to use some type of pulley drive system, you may need to think about the mounting to prevent side loading the crankshaft, which it probably wasn't designed for.  It puts out 270A at 24V, do you need that much power?  If you don't need, I think Bosch  makes some 24V alternators that are air cooled and put out around 180A.  They are physically smaller and lighter, which may make the mounting/drive easier.  Just some thoughts  -  Steve

[Sean]

Lots of material in the archives about making DC generator sets using a DN50 or other large-frame alternator.  It's been done successfully many times.

That said, I would advise against what you propose.  Unless your genset is designed with a PTO expressly for this purpose, you will be overloading the bearings.  Moreover, even at no-load, the DN50 will place enough additional load on the set to possibly present governor or regulator problems with the arrangement.

Besides all that, running two generator heads mechanically at all times when only one of them  has any demand is inefficient compared to simply electrically changing the output of a single head to whatever you need.  If you built a 7kW DC set by coupling a DN50 to an engine you could get perhaps 6.5 kW out of it with a quality inverter.  Likewise you could get nearly 9kW of DC out of your 10kW AC set with a transfomer and rectifier.  A single high-quality inverter/charger could do either of these conversions, and RV-sized models can get you most of what you would need in either direction.

Starting with a DC set will get you faster battery charging, assuming your battery bank is large enough to take that kind of current.  Starting with an AC set will allow most of your transmission equipment to be significantly smaller.  It is a matter of preference and how you use your coach as to which one is more effective.

-Sean
http://OurOdyssey.BlogSpot.com

[TomC]

Delco-Remy makes the new Brushless air cooled 40SI alternator in 240, 275, 300amp @ 12vdc.  MUCH smaller and lighter then the 50DN.  Good Luck, TomC