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ContinuousWave: Small Boat Electrical
Need Battery Junction Box/Terminal Block
|Author||Topic: Need Battery Junction Box/Terminal Block|
posted 11-23-2009 11:13 PM ET (US)
I'm not sure what to call it but what I need is a junction box/terminal block in order to split a battery cable to serve twin motors. The battery set up on my Outrage 22' consists of 2 batteries mounted in the console that run through a Guest battery switch (B1/B2/both/or off). From the switch the cable is run through the rigging tunnel and to the sump on the starboard aft corner. There in the sump the 1 cable is split into 4 cables to provide power to twin 120hp motors. The split occurs in the sump by simply clamping the cables with stainless bolts thrugh lugs on the cables. Since the sump is is often awash due to the twins this is far from ideal but the boat came to me rigged this way and I've tried to ignore it but the cables have finally bit the dust.
What I would like to do is run the main cable the same way from the console but extend it from the sump to a junction box/terminal block placed on the side of the hull under the gunwale and from there split it to each engine. This is simple and straight forward except that I can't find a terminal block/junction box big enough to accomadate #2 cable or that has a cover. Maybe I'm not calling this part by it's rightful name but my search is comming up empty. Does anyone know the name of this part or where one maybe located?
posted 11-24-2009 09:50 AM ET (US)
Blue Seas makes a very wide range of wiring accessories for small boat rigging of electrical distribution. Check their catalogue.
Your proposal to wire the two outboard motors in parallel to a common battery is not a good design in my opinion. You might consider alternative arrangements. Check the installation instructions from the outboard engine manufacturer for advice on how to install the primary battery distribution with twin engines.
posted 11-24-2009 10:48 AM ET (US)
I'm curious why wiring them in parallel would not be a good idea. Could you please explain.
You can build your own terminal strip using 3/4 inch phenolic block and 2 studs.If it is up under the gunnel and not in view, I wouldn't worry about a cover.
posted 11-24-2009 12:52 PM ET (US)
Regarding installing twin engines and wiring them in common to a single battery, I have two concerns:
--to maximize the redundancy of twin engines, their electrical power systems should be kept isolated and separate. A failure in one engine or one battery system should not be able to affect the other engine or battery. A better arrangement is to have isolated electrical systems, with the ability to merge or combine them in a useful manner in case of emergency.
--connecting sources of electrical power in parallel, that is, the two alternator outputs of the two engines, is not a good practice. Whether or not the alternators will tolerate being connected in parallel may depend on their design. This is why I recommended consulting the manufacturer's installation instructions for twin engines.
posted 11-24-2009 03:26 PM ET (US)
Thanks, Jim......makes more sense.
|L H G||
posted 11-24-2009 04:32 PM ET (US)
I would say it's time to finally re-wire the battery situation. Since you have two batteries in the boat, one should now be dedicated to each engine.
I have three twin engine Outrages, and in each I have one battery for each engine, all placed in the stern where BW recommended them to be. I use combination starting/deep cycle batteries, for plenty of draw down capacity (without damaging the battery), if needed. I don't bother with battery switches, since I consider them needless rigging clutter and expense in these open boats. I realize that is counter to most rigging recommendations, but I think they are not needed. In twin engine boats, the negative terminals of the two batteries have a permanent ground cable run between them anyway, so all that is needed is a short positive (red) jumper cable should one batt be dead. Simple and effective, and practically never even needed.
The real rigging problem with twin oil injected engines on a cut transom 22 Outrage, is no place for the [batteries] and tanks in the stern. It has to be one or the other, and neither solution is ideal. Twin engines on Outrages, 1971-1993, 18-22' boats, need either 4-strokes or 2-strokes that carry the oil on the engine. My preferred battery location on these Outrages is the stern, eliminating all the heavy gauge cabling in the boat's tunnel, as shown here: (the Merc's carry their own oil tanks)
But if you want to stay with the [batteries] in the console and external oil tanks in the stern corners, I would use large terminal/stud blocks to connect the engine cables to the heavy cables from the boat's tunnel, located near the top of the inside gunwales at the stern. I would elimate the clutter of the [battery] switch in the console, install the short common neg ground between the [batteries], and make up, for emergency, use a positive short jumper cable.
|L H G||
posted 11-24-2009 09:10 PM ET (US)
The battery cable terminal connectors you want are in the West marine cataolg, and are called "Power Post Single Terminal Connectors" They come in either 5/16" or 3/8" stud size, and have an insulating cover. $15/each.
I have seen these factory installed by Boston Whaler, on Montauks with battery in the console.
posted 11-30-2009 10:21 PM ET (US)
Thanks for the quick replies and sorry for my absence. I was was taken ill on last Wed. and didn't feel right until Sat. evening. I guess it was the flu but it slammed me and I spent my favorite holiday in bed. The only thing I got was one turkey sandwich on Sunday, not that I could have eaten anything earlier.
Jim I understand what you are saying about the parrallel circuit. But, it has worked with no ill affects for the 8 plus years I've owned the boat and I assume before that as well. The redundency/isolation of your method does make sense though. I do have the full 3 inch binder engine manual but haven't felt good enough to wade through it yet to check their recommended procedure.
Larry my engines had the VROs removed before I purchased the boat so I mix my own, no tanks to worry about. When and if I repower I will look for engines with self-contained oil tanks as you have recommended in other posts.
I'm leary of running 4 sets of cables down the rigging tunnel because of all the rigging already there. If I am to run two sets of cables then it seems to be either all four under the gunwale on the starboard side or one set under each gunwale. Hanging four together would seem logistly difficult, hanging two more doable. I did see the Blue Seas terminals and the post tops but what I was looking for was a full cover with cutouts on the sides to pass cables into. I could make the ones recommended work and I guess well but guess I was looking for for a part that hasn't been dreamed up yet.
Does anyone see a problem running the cable in the same area as the fuel fill hose? Any more suggestions?
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