Stupid Question...

[NealLauderman]

I just got done re-wiring the boat. I tested all the accessories and they worked great. I then went to crank engine and I blew the battery fuse which was 100 amps...

I don't think there is an issue with it being connected wrong... I'm kinda thinking 100 amps is to small when cranking a 200hp engine.

Below is a quick drawing of what I am looking at. The battery switch was set to battery 1.

What are your opinions and what size are others using? I'd hate to run it without a fuse or breaker protecting it.

Here is a diagram to give a visual:




Here is the blow fuse:

 

[sam am I]

Uh oh...........Not this topic!!!

Wrong or right, best practice or not, someones lame/warranted opinions/justifications/logic, real experiences or lack thereof of fusing a/the starter battery......I will just say just this,

YES......100 Amps is too small for that size of motor/stater. I've measured and merc spec's about 175 Amps on that size of motor.

Waiting for the Worms.........

 

[Rriverdude]

I will assume your diagran is incorrect and not indicative of the actual. You have the Bat 1 on the switch going to battery 2, and same with Bat 2 on switch to Battery 1.

 

[NealLauderman]

Sam, thanks for the response. If I could get around fusing the motor I would but not sure it's safe or how I would do it. River, thx for the response. You are correct. 1 goes to 1 and 2 to 2. Battery 1 is back by engine and batt 2 is under center console. Also the negative for engine is hooked to battery 1 rather than the negative bus bar.

 

[sam am I]

Sam, thanks for the response. If I could get around fusing the motor I would but not sure it's safe or how I would do it.

np, but let me "ask" then if I may?........ Did this setup(your boat) come from the manufacturer with a/the fuse/s already on the battery/batteries that are intended/being used to start the boat with?

 

[Silvertip]

Either your diagram does not match the wiring you have or if it does, it is funny anything works.
1) It makes no difference if you have battery #1 Positive wired to BAT 2 on the switch and vice versa.
2) You do not need 100 amp fuses in the battery positive leads to the engine. You need fusses in the ACCESSORY feed(s) that connect to the COM terminal on the switch (those that feed a positive bus bar or accessory).
3) You are missing a negative connection to the batteries from the engine. (See #7)
4) The negative terminals from the battery connect to the engine block, not a bus-bar.
5) The COM terminal on the switch connects to the engine starter solenoid.
6) Each of the negative bus bars connect directly to the negative terminals on the battery.
7) The Positive feed to any POSITIVE bus bars or accessories also connect to the COM terminal on the switch.

NOTE: COM (common) on the switch is not GROUND. It is poorly named but in reality is either the POS feed from BAT 1, BAT 2 or BOTH depending on what position you have the switch set to.

 

[NealLauderman]

Alright... I probably could have saved a lot of time just posting the below diagram. The diagram below is exactly how I just wired the boat except I put a 30 amp in-line fuse between the positive bus bar and the Fuse Panel...

Sam, I got the boat used and someone did a lot of crappy electrical work. Lot of dead end wires and cut wires which is why I started this project. The boat had two batteries run in parallel. I decided I wanted to put in the switch so I would hopefully never find myself with 2 dead batteries on the water.

Silver, hopefully the diagram clears up a few of the things you mentioned. Would you recommend just removing the two fuse blocks and not worry about the wires running from the battery to the switch?

 

[sam am I]

No sweat Neal, was just curious how those types(and how used) of fuses might have got there on those batteries, FWIW, I think/pretty sure the PO installed them as it's not too common to fuse from the battery to the starter, ty for following up.

As i said in #2, wrong, right, good, bad, best practice or not, opinions(lot of those here, weed that out) or experienced(sorta rare, but its here, just gotta look hard, few here and there, see link, google it, etc.....lil light reading for later) , they'll see around 175 amps on avg. cranking for that size motor.

http://forums.iboats.com/forum/boat-...-needed-or-not

BTW, I knew what ya meant in your drawings, not all of us are autocad expects eh?

 

[bruceb58]

Dump the 100A fuses between the battery and the switch.

 

[NealLauderman]

Dumped the 100A fuses and everything seems to be working great! Thanks for the help fellas!