tqh

Hi, I wonder how "heavy" the heavy duty alternator in the towing prep package is? I only have two DC outlets, no AC. How many amps can I draw from them safely? Thanks

GRMick

Checking the part catalog, for 2007-2009, the towing package alternator shows 130 amps, with the standard alternator 2007-2009 being 100 amps. In 2010-2014, it appears Lexus went with a 150 amp alternator for all RX350 models, although the 2014 models show a different part number alternator even though it is still 150 amps.

In any event, the alternator is not the limiting factor, the fuses on those circuits and the design of the outlets are. Take a look at your manual under "other interior features" for the maximum amp draw for each of the outlets. I think the max draw is also printed on the outlet covers.

Hope this helps.

tqh

Thanks Mick, The outlet says max 120W, while the manual says the fuse is 15A (x12V ~ 180W). I think these numbers are printed the same regardless of whether the "towing prep package" is installed or not...
So if the fuse is the limiting factor, the heavy duty alternator is for show only?

GRMick

From the load on the outlets, the tow prep package doesn't do anything. I think the higher output 2007-2009 alternator was included to provide extra charging capability for when trailer lights are used. A larger radiator and larger transmission fluid cooler are also included.

SteveCraig

Small utility trailers will typically have lights only. Larger utilities& small hardtop campers will have lights, electric brakes including an on-board battery in case of trailer break-away. Battery also keeps the small fridge running while towing. Gotta keep the beer cold !

tqh

I see. Thanks all :-)