I can't envision a likely situation where having the extra power available for a short period of time would make much of a difference, but the incremental cost for the larger electric motor
is pretty minimal, so why not.
I didn't realize you were going to have 1000 watts of solar
, so the battery
bank size makes more sense now, but still seems like overkill, especially on a weight-critical multihull
. You didn't mention where you plan to sail or your usage of the boat (long periods at anchor
vs moving most days), but it seems to me that sizing the battery
bank based on consumption
input potential) makes more sense. I sized my battery bank to have a useful capacity equal to 2 days of usage. Even on overcast days I get at least some solar gain, so I actually have enough capacity to last 3 cloudy days before I have to fire up the generator
. Since 3 cloudy days in a row only happens about once a month where/when I cruise
this seemed like the sweet spot in the cost curve. The incremental cost of having to occasionally run a generator
to top off the batteries is minimal.
A couple of other questions:
1) What kind of solar panels
are you planning to mount on the Amas? Framed, or flexible/glue down? I've got flexible glue down panels
on my camper van and it seems like they would make the most sense for mounting on Amas, but the energy density is lower. fitting the 3 (or 4) panels
you talk about on each Ama seems like a challenge.
2) Why are the battery packs going in the Amas instead of in the center hull
? Your biggest amperage draw is the motor
in the main hull, so I would think that that's where you would want the batteries, in order to minimize wire size and voltage drop, not to mention keeping the weight out of the Amas. With the batteries in the main hull the the wires running to each ama would only have to be sized to accomodate the 4 KW output of each generator, not the 18KW of the engine
3) I'm amazed that you can do a system like this for 20-30K. I would have guessed more like 60K. I guess prices have really come down since the last time I looked, when even DIY lithium battery packs were in the $0.50 to $1/Wh range.
4) Apologies if it sounds like I'm trying to challenge you; I'm really just trying to understand your design decisions since I might try to design a similar system in the future myself.