alternator question

[RVbySDI]

Can someone pipe in with their opinion on whether I should install a 35 amp, 60 amp or some other size alternator on my RV9A. I intend to run dual GRT EFIS, Garmin 496, SL40 comm, Garmin GTX330 transponder, ELT, nav/position/strobe and landing lights, and perhaps a circuit or two for miscellaneous gadgets in the cockpit that I am not sure about yet (i.e. XM radio, fan motor for Arctic Cooler, laptop or some other various item that needs power I may not be thinking about at the moment).

I do not wish to have a problem powering everything but also do not want to haul around a heavy alternator that will have more capacity than I need. So what say you? What would work best given this equipment list?

[fmarino1976]

Add the current usage (Not the value of the circuit breakers) of ALL the equipment you will install and of what you might want to install in the future. This current should not be greater than 80% of the current capacity of your alternator. Me personally would rather have a bigger alternator from the start. Remember that the closer to max load, the alternator WILL run hotter, and heat kills electrical parts. My 2 cents here.

Freddy

[gasman]

Originally Posted by RVbySDI

Can someone pipe in with their opinion on whether I should install a 35 amp, 60 amp. I do not want to haul around a heavy alternator that will have more capacity than I need. So what say you? What would work best given this equipment list?

This is it, hands down! http://www.plane-power.com/Bit3.htm This unit is complete. REALLY COMPLETE.... It is small, light, strong 60amp, great overvoltage protection and comes with the belt. AND VANS HAS THE BEST PRICE....... This alt. was 4 pounds lighter than the Toyota alt. that I switched out.
Warren

[erich weaver]

You really need to decide on which electrical goodies you will include on your plane and then do a load analysis, where you add up the amps required by each circuit under various operating conditions. Temporary loads, such as for your starter, transmitting on your radio, etc do not need to be considered in sizing your alternator, as your battery will make up the difference for the short duration in which the extra amps are needed. Get totals for each buss as well as each scenario (day vs night flight for example). Dont forget to include things like the master contactor - typically around 1 amp).

A good load analysis sheet will really help you understand your electrical system and provides a good reference sheet.

I believe example load analysis sheets can be found at Bob Nuckoll's aeroelectric connection web site:
http://www.aeroelectric.com/

erich

[Walt]

alternator, 40 amp. One of the best out there with external regulator. 40 amd capacity should be plenty.

[RVbySDI]

I appreciate all the input. I am not sure what all of these electronic components are going to draw which is why I listed them. I was hoping there would be someone out there who had similar or the same components and knew what the individual and/or total draw was for all of these items. I do not currently have all of these electronic components so I am not familiar yet with how much current they each will draw.

Also, I have talked with Mark Landow (sp) about building an alternator and starter for me. He builds some quality alternators and starters. He thought a 35 amp alternator would be enough but I was not so sure. If I knew definitively that the 35 amp would not provide all the needs I was thinking about asking him to build a beefier alternator. This led me to wonder how much bigger it might need to be and if so how big is big enough. I know I can go ahead and buy a 60 amp alternator (that PlanePower 60 amp that Vans sells looks very good!) but if Mark can build one for me I would like to go that route since he is a friend that lives just a few miles away.

Please continue to post your thoughts as I value you guy's opinions a great deal.

[Mike S]

Take a look here, 3rd one down is a amp load chart.

Take a little time to look at the rest of the site, lots of good wiring info, even if you dont use one of their units.

http://www.verticalpower.com/documents.html

Mike

[RVbySDI]

Originally Posted by Mike S

Take a look here, 3rd one down is a amp load chart.

Take a little time to look at the rest of the site, lots of good wiring info, even if you dont use one of their units.

http://www.verticalpower.com/documents.html

Mike

Thanks Mike! That is exactly what I was wanting to see. A list of components and their amperage draw. I will do the math and see what I come up with on all the components I am looking at using.