Battery on/off switch

[SweeperForce]

Hello,
I have been read some of the older post, but I would like to have a definate answer. Do I put the on /off switch inline with the positve wire between the battery and the strater solinoid but closer to the battery?

Thanks,
Tom

 

[RickJ6956]

Re: Battery on/off switch

What kind of on/off switch? The switch should be able to handle the current drawn by the starter motor.

Disconnect all of the positive wires from the battery. Connect a short length of heavy cable (4 awg) from the positive battery terminal to one of the switch terminals.

Connect the wires you removed from the battery to the other switch terminal.

Keep the new wire (between battery and switch) as short as possible and make sure all connections are tight.

 

[Silvertip]

Re: Battery on/off switch

Battery switches are available that clamp directly to the positive post of the battery. These are commonly known as "knife" switches. Very high current handling capability.

 

[SweeperForce]

Re: Battery on/off switch

I got the BEP 701 battery switch. Continuous rating 275 amps, intermittent 455 amps, crancking 1250amps.
Thanks for all the info on how to wire it safly.

Tom

 

[capndan]

Re: Battery on/off switch

Silvertip, I did a Google Search on battery switches. Is this one of those things that should be a "marine" product, or will the Autoshop version work?

thanks,

Dan L

 

[Silvertip]

Re: Battery on/off switch

If you have an I/O and the switch is in the engine bay it should be ignition protected. If you have an outboard it doesn't matter. If the switch is mounted in the engine bay keep in mind you cannot run the blowers unless they are wired directly to the battery which sort of defeats the purpose of having a master battery switch. Therefore a switch that is not ignition protected could and likely would make a spark as it was closed and you have a possible "kaboom" scenario. Battery swtiches should be installed on or as close to the positive terminal of the battery as possible.

 

[capndan]

Re: Battery on/off switch

Actually, I have an I/O and an OB...the OB is the one I'm working on, trying to turn it into my fishing boat.

As far as I can tell, the existing electrical system works fine. Ignition, fish finder, Nav. Lights. that's about it. I may add some courtesy lights, but likely not.

All I want to add is a 24V Minn-Kota trolling motor, the 2 deep cycle batteries and an onboard 3 bank charger to charge the 2 deep cycle batteries and the starter.

My understanding is that I can keep the deep cycle batteries up front, with the charger, and connect the 3rd bank to the starter.

Do I even need a master switch?

thanks,

Dan L

 

[Silvertip]

Re: Battery on/off switch

Personal preference. Do you need it? Probably not. Is it a good idea? Sure. Why? Because it prevents battery run down should you forget to turn something off or if some little knob twiddler (kid) gets in the boat and plays with things. If these situations don't concern you then you certainly don't need it.

 

[capndan]

Re: Battery on/off switch

regarding the OB...

I did a search on iBoats for "battery switch", and get 155 choices, most of which seem to be battery selector switches.

I got no hits for "knife switch" at all.

When I googled it I got this: http://www.pplmotorhomes.com/parts/rv-converters/55-9025.htm

Not "marine", but "RV"...Do you have any problem with this, or would you recommend something different.

Also, they suggest mounting to NEG, you prefer POS pole.

I'll ask you about the I/O issues once I figure this out.

Thanks,

Dan L

 

[Mr Crabbs]

Re: Battery on/off switch

Rule #1. ALWAYS follow the manufacturers recommendations on installing any accessory, regardless of what you may read elsewhere. I got in a huge argument with a guy who claimed to be an electrical engineer over this.

Now, when I installed my battery cutoff switch on my travel trailer, I put it in the negative (-) side. Current leaves the battery on that side and returns on the positive (+) side. The closer you can get the switch to the (-) side, the fewer chances you'll have of a short or other 'leaking' voltage.

When in doubt, always referr to rule #1!

 

[RicMic]

Re: Battery on/off switch

I have worked with many many electrical engineers over the decades and MOST of them have no hands on wiring knowledge NONE. How they can let someone graduate with an EE degree and not have a clue on how to strip a wire is beyond me, but try to get one to admit that they don't have a clue!

 

[Silvertip]

Re: Battery on/off switch

Well then -- how about this one! Started a new job with an electronics outfit many years ago and another EE was told to evaluate a batch of fuses. The process he used to evaluate them was to put them in a circuit with a dead short. When asked how the test went he looked at the pile of blown fuses and said "they are all good".

As for the "knife swtich" -- don't know what you were searching for CAPNDAN but here is just one the gazillion on the market.

http://www.gemplers.com/search.aspx...HP&s_kwcid=TC-2261-291018464021-S-36913828021

 

[capndan]

Re: Battery on/off switch

Thanks, Silvertip,

what I meant to say was I didn't find any on iBoats, and was wondering if they had to be "marine"...I think you answered my question, though.

D

as for the EE, hey, he did do what he was asked, right?

 

[Silvertip]

Re: Battery on/off switch

No he didn't. Fuses have an amperage rating. He should have plotted some curves and used a circuit that he could "sneak up" on the rating of the fuse to see how close to its rated value current got before the fuse blew. Blowing a bunch of fuses proves nothing other than they blew. He had no clue at what current rating they blew.

 

[capndan]

Re: Battery on/off switch

heh heh...I see your point.

Now, my I/O...the battery is in a compartment, next to the engine compartment, that I assumes fills up with the same fumes as the engine compartment, and ventilates along with it.

Where would you put the battery switch, in this application, and would you still use a knife blade, or something else?

thanks,

Dan

 

[RicMic]

Re: Battery on/off switch

Personally, I would consider using an ignition safe circuit breaker with a manual test button, like the Bussman hi amp. It replaces having a fuse at the battery and to disconnect the battery, all you have to do is hit the "test" button, that opens the circuit like a switch, but without any sparks, thus "ignition safe" for use in engine compartments. They are resettable, by just flipping the lever. I noticed that some electronics are drawing current, even when they are "off" and using a circuit breaker that also operates as a battery switch, kills multiple birds with one stone. I have tried several cheaper automotive and imported "waterproof" circuit breakers and I won't waste my time or money on them again and end up replacing them in a year or so, when they are all rusted.

 

[capndan]

Re: Battery on/off switch

Personally, I would consider using an ignition safe circuit breaker with a manual test button, like the Bussman hi amp. It replaces having a fuse at the battery and to disconnect the battery, all you have to do is hit the "test" button, that opens the circuit like a switch, but without any sparks, thus "ignition safe" for use in engine compartments. They are resettable, by just flipping the lever. I noticed that some electronics are drawing current, even when they are "off" and using a circuit breaker that also operates as a battery switch, kills multiple birds with one stone. I have tried several cheaper automotive and imported "waterproof" circuit breakers and I won't waste my time or money on them again and end up replacing them in a year or so, when they are all rusted.

The fuse it replaces is a 15A fuse, is it not? Would that be the appropriate size for circuit breaker? I googled "Bussman Hi Amp" and didn't see anything that small.'

 

[Silvertip]

Re: Battery on/off switch

Just to clarify -- if this switch is being used to disconnect everything on the boat, including the engine electrics, then 40 amps will not cut the mustard as the starter current draw alone would toast it. I would not use any non-ignition protected switch inside the engine bay as you would not be able to run the blowers with the switch turned off. Perko makes a battery ON-OFF switch that can be installed outside the engine bay and is a little more attractive than a simple knive switch would be. Plug the connections are protected whereas a knife switch is practically live no matter where you touch it.

 

[capndan]

Re: Battery on/off switch

I'm confused. I'm looking at the "generic boat wiring " diagram and it shows a 15amp breaker coming out of the starter battery.

why wouldn't the current from the starter toast that? what am I not getting, here?

can that perko switch be on the dash panel, or is that too far away from the battery?

 

[Silvertip]

Re: Battery on/off switch

Because starter current doesn't flow that way. There are two wiring systems on a boat. If you look at the battery you will see the big cables from the battery go to the ENGINE. You probably also have two smaller wires (about 8 gauge) that go up front to the fuse panel. It is that circuit that is protected by the smaller fuse or breaker at the battery. There is no protection on the large cables because it would have to be a couple hundred amps during starting. There is a breaker at the engine to protect the engine electrics (minus the starter). The gauges are powered through the engine harness going to the control box. Everything else "generally" gets powered through the boat harness.

No - it is impractical to install a Perko On-Off or a Dual Battery Switch at the helm because you would need to run the very large (and expensive) battery cables up there and back to the engine. I really think you are over-thinking (or possibly under-thinking this).