New Battery Charger Wiring, need help

I

imspacemancraig

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So I am about to replace my on-board battery charger and in the instructions, it stated to run a ground cable from the charger to the negative terminal on the bus terminal in the boat.

So, I have an '86 Carver Mariner 3297. Is the negative bus terminal the little strip in the engine compartment just aft of either the port or starboard engine near the bilge floor, but mounted to the stringer? I see other wires connected there, but nothing jumps at me saying whether this is a positive terminal or negative.

Is there a way to easily test this terminal to determine if it is the negative terminal?

All the other wiring I need to do I have figured out, but this through me a bit...
 
I ran mine directly to my single power plant ground, the same large diameter “post” that the negative terminals of the batteries (3) are tied to. Gauge of wire must carry the ENTIRE battery charger current capacity for the length of the run.
 
Well, if you check for voltage with a voltmeter between that terminal and the pos of e of yr batteries, you will know right away if that terminal is neg or pos!

Ad if it is a neg bus, follow the wires, one of them (the heaviest) should lead to the battery neg
 
First I would check the wires from the old charger and see where they go. If they meet the criteria then I'd either clean up the connectors and reuse them or I'd crimp on new ones unless the charger has lugs that clamp down on the wires.
 
There is a big difference between the green bonding wire system on the boat and the ground from 120volt AC. If you can't figure out the wiring from the old charger, I would strongly suggest you get a marine electrician to help you wire up the new charger before you make a serious error.
 
The current charger doesn't have this extra negative cable. The AC wires all line up, so its not the ground for the 120. It says its for the batteries if I use more than one bank. The new one is a Xantrex TrueCharge2 20amp charger. Here is a link to the manual (http://www.xantrex.com/documents/Battery-Chargers/TRUECharge-2/3G%20TC2%20Manual.pdf) Go to page page 17 for the instructions, page 8 for the diagram. By looking at it, I am think it isn't necessary as long as I connect both battery banks to the negative terminal on the charger. The diagram shows the negative terminals from the battery connecting to the negative bus terminal instead.

My current charger has the batteries running the negative straight to the charger, not the negative bus.

Only think I can think of to have that additional wire is to add a ground to the charger itself. I almost don't think I need it at all if I run the battery negatives to the negative on the charge and not go through the negative bus on the boat.
 
Looks like the instructions clearly state on pg 17 that you need to run a ground from the Xantrex chassis to the DC ground buss in your boat [or engine block]. You would use an adequate gauge [for the length and your unit model] green with crimped end connectors, and yes it is most probably the terminal block with all the green wires running to it.
 
Looks like the instructions clearly state on pg 17 that you need to run a ground from the Xantrex chassis to the DC ground buss in your boat [or engine block]. You would use an adequate gauge [for the length and your unit model] green with crimped end connectors.
 
OK, well there is a bus close to the bilge bottom, exposed just below where the battery charger is going to be mounted. Guess I will need to test it to make sure it is a ground. Or I could just run a wire to the engine block, maybe four feet past that...
 
Do not use the straps in the bilge with the extra screws. This is part of the bonding system which should never be used as electrical ground and doing so will create serious galvanic corrosion if there is a fault in the DC grounds. Someone suggested the engine ground which is a better choice.
 
But from the looks of this, those look to be the grounds. Seems like they connect to the shaft, rudders, and other parts. Is that not the correct place to connect the DC negative ground to?
 
Go to the engine ground. Stay away from the bonding straps except for non-electrical metal (IE; struts, rudders, shafts, thru-hulls, trim tabs or swim platform metal). The purpose of the bonding system is to bond all metal to the same reference point giving stray current a better path besides the water. Using any of the bonding system as a DC ground for anything using power defeats the bond by intentionally passing current through it. This will kill your zincs and cause corrosion issues.
 
OK, that makes sense. I have rewired it last weekend and routed to the negative ground on the engine block now.
 
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