View Single Post
Old 04-10-2012, 12:57 AM   #13 (permalink)
Ryland
Master EcoModder
 
Ryland's Avatar
 
Join Date: Jan 2008
Location: Western Wisconsin
Posts: 3,903

honda cb125 - '74 Honda CB 125 S1
90 day: 79.71 mpg (US)

green wedge - '81 Commuter Vehicles Inc. Commuti-Car

Blue VX - '93 Honda Civic VX
Thanks: 867
Thanked 434 Times in 354 Posts
Quote:
Originally Posted by steffen707 View Post
Do you mean that the defrost, wipers, fan and headlights would draw too much power from the dc/dc converter and so to not worry about the capacity, you'll just have the motorcycle battery to buffer the higher amp draw?
Motors tend to draw higher amps when they start up, so while the wiper motor might only draw say 50 watts or around 4 amps while it's running (a guess) it might draw 4 times that for a fraction of a second when the motor first kicks on, so if you have your head lights and wipers on, then turn the deforst fan on, that deforst fan is going to have a high surge when it first turns on as well and there might be the freak timing where everything gets flipped on at the same time and a little 8 pound, 6amp hour motorcycle battery can handle a big surge, after all it's designed to handle a 200 amp load of the motorcycle starter for a few seconds, or you can keep your stock starting battery and use that as the buffer, and if you need to replace your starting battery soon think about getting a smaller/cheaper starting battery that is of course still sized large enough for your starter, it would making wiring all of this up a lot easier, then your higher voltage pack would be using the dc to dc converter to keep the starting battery up at 13.7v, just like the alternator did.
  Reply With Quote