Apparently there's no electrical forum so I'm posting here. I have an OMC Saildrive which is essentially a detuned version of a Johnson 25/35 outboard. The boat currently has no main fuse. Does anyone know how much the starter draws?
Lots for a short duration.how much the starter draws?
Nice! Not even an inch of fuse to fry!Use one of these guys: https://www.defender.com/product3.j...e-block&path=-1|328|2290021|2290030&id=983740 It attaches to the battery post and the cable attaches to the fuse. Easiest and least expensive way of adding a fuse to a battery cable.
Use a clamp on meter. Also, somewhere on the MarineHowTo.com site, RC has an article on this subject. I did a quick search and couldn't locate it. Short on time right now.No point in putting a larger fuse than needed. Anyways, what I'm interested in finding out is the power draw of the starter.
That table tells you how large the wire needs to be for “X” amps of current to have a voltage drop of 3 (or 10) %, with “Y” feet of wire. It really doesn’t tell you what size fuse to use. Normally you want the fuse to protect the wire from a dead short, so use this table: https://www.bluesea.com/support/reference/529/Allowable_Amperage_in_Conductors_-_Wire_Sizing_Chart, I think.There is only about 6' of cabling from the battery to the starter. I'm seeing 80 amps for 4awg wire on most sites
BlueSea recommends 70-100A depending on wire type
The starter isn't likely to be anywhere close to max capacity of the wiring. I've seen what 30A@120v can do. I also have a welder rated at 125A can can penetrate upto 3/8" steel. No point in putting a larger fuse than needed. Anyways, what I'm interested in finding out is the power draw of the starter. I can meter most other components to find this info
@marchem is correct, it is not the voltage drop to fuse for, but the capacity of the wire to handle amperage regardless of length.There is only about 6' of cabling from the battery to the starter. I'm seeing 80 amps for 4awg wire on most sites
BlueSea recommends 70-100A depending on wire type
The starter isn't likely to be anywhere close to max capacity of the wiring. I've seen what 30A@120v can do. I also have a welder rated at 125A can can penetrate upto 3/8" steel. No point in putting a larger fuse than needed. Anyways, what I'm interested in finding out is the power draw of the starter. I can meter most other components to find this info
Actually, there is.No point in putting a larger fuse than needed.
I'd imagine the peak to be 80-120ish?Years ago measured the starter current on my Johnson 9.9hp outboard.
38 amps constant cranking, I did not attempt to measure the peak.
I think it will depend on how close to the peak the draw is. If the fuse is getting maxed out on a regular basis, its life might be shortened. So if the peak is 140 amps and the fuse can sustain a 140 surge, it wouldn't blow, but its life might well be shorter than if the fuse could sustain a 200 amp surge. Like the old fashioned incandescent light bulbs, the more they cycled on and off, the shorter the life span.Will lots of peaks "damage" the fuse over time or are they rated appropriately?