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Old 18-04-2016, 09:23   #1
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I jumped the shunt and other bad things...

Finishing up my solar install. Of course, things not going as planned. Here is a picture of my neg battery wiring:

You can see there is a shunt there. The top of the shunt is going to a busbar located a good 3' of wire away. (See pic of busbar as well).

Bottom of shunt is going to a T handle switch that switches battery neg.Wires labelled BAM2, BAM12 are actually going to the battery. Shunt is there I assume to measure bat state on main elec panel.

So if I attach my solar controller to the shunt, if that switch isn't on, I won't be recharging my battery! Can't risk that.

So I jumped the shunt, and wired directly to the battery, see picture of batteries. Is there a better way to do what I did?

Other questions. Please comment on this.
1. In thinking ahead for hooking up both controllers, I purchased a blueseas battery terminal mount fuse block https://www.bluesea.com/products/502...unt_Fuse_Block

However, it comes as M10 , 3/8" mount, my batteries pos terminal is 5/16, so this fit isn't good. Is there an item besides washers converts this, like a metal sleeve that is 3/8 top and 5/16 bottom? Or should I just use a 5/16 brass washer on top and bottom of battery?

2. I fused each wire at 30A, I am using 10Ga. Controller puts out 20 max.

3. I wanted to use 8ga wire, but even to get terminals onto my solar controller, I had to file down the edges of smallest ring terminals to fit, these I guess are #10 terminals. It would be better to use the fork terminal to fit, but I didn't think this to be as secure. Do they make these for 8 ga wire, I couldn't find anything that small.

4. Not as critical, but bus bar for neg is PACKED. Never used this type of terminal, other side of neg has no connections, are these not used? Not sure why wires not spread out. If I can't use the right side, what is best way to add in to the left.

Sorry some of the pics are turned, they aren't in my viewer, not sure how to make this this case in here.
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Old 19-04-2016, 07:01   #2
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Re: I jumped the shunt and other bad things...

bumping this hoping to get a fresh set of eyes to take a look and give me some answers. thanks.
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Old 19-04-2016, 07:37   #3
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Re: I jumped the shunt and other bad things...

Not sure I understand all the issues but if you connect the solar negative on the battery side of the shunt then the AH meter will not capture the solar charging. Nothing dangerous about this just bad design.

Where larger wire size/ terminals are used for voltage drop I often have to file a little off the lugs to get them to fit. Don't see any problem with that.

The stud diameter issue also should not be a big deal for the lower ampere fuse block. If you were talking a inverter connection I might have concerns.
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Old 19-04-2016, 07:52   #4
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Re: I jumped the shunt and other bad things...

Frankly, thanks for responding. Also got a PM telling me that what Beneteau/Jenuea/Lagoon does by switching neg is not US code, and that shouldn't have this, should really take out switch, and put everything, including battery start wires on top side of shunt. But that is a bigger project than I want to do right now to just get solar power working.

Meter at panel doesn't show A, just V and kind of state. It is lcd monitor that lagoon is shipping on boats now. Not very accurate on that account, but shows battery. MPPT controller has lcd screen showing A, though since that is under a berth, it is a bit hard to see it conveniently.

For the M10 to 5/16, would you put brass washer on top and bottom for better connections?
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Old 19-04-2016, 08:56   #5
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Re: I jumped the shunt and other bad things...

Can you post a diagram of your connections - I think we'll understand your questions better then.
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Old 19-04-2016, 09:02   #6
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Re: I jumped the shunt and other bad things...

A shunt isn't a switch, it's a small calibrated resistance.
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Old 19-04-2016, 09:13   #7
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Re: I jumped the shunt and other bad things...

Quote:
Originally Posted by jbinbi View Post
Frankly, thanks for responding. Also got a PM telling me that what Beneteau/Jenuea/Lagoon does by switching neg is not US code, and that shouldn't have this, should really take out switch, and put everything, including battery start wires on top side of shunt. But that is a bigger project than I want to do right now to just get solar power working.
Then just don't turn off the neg switch so you don't kill solar... Pretty simple really. You still have two positive switches and that is all that is needed to shut down the vessel. There should be no need to shut down the negative battery switch.


Quote:
Originally Posted by jbinbi View Post
Meter at panel doesn't show A, just V and kind of state. It is lcd monitor that lagoon is shipping on boats now. Not very accurate on that account, but shows battery. MPPT controller has lcd screen showing A, though since that is under a berth, it is a bit hard to see it conveniently.
What exactly is a "kind of state"? What exactly is the shunt doing? If there is no ammeter & no Ah counter then it's really not a necessary device for your system. If it's not doing anything it really does not matter where you connect solar neg. Best practice would dictate load side of the shunt...

Quote:
Originally Posted by jbinbi View Post
For the M10 to 5/16, would you put brass washer on top and bottom for better connections?
If there is enough contact area on the lead below the MRBF fuse holder just use a thick flat washer on top of the MRBF holder. Do not put a washer below it.

Alternatively you can use a lead post mount like the one pictured as the bolt is 3/8". I get these from my distributor (wholesale only) but you should be able to find one. If not let me know..
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Old 19-04-2016, 09:15   #8
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Re: I jumped the shunt and other bad things...

Quote:
Originally Posted by cal40john View Post
A shunt isn't a switch, it's a small calibrated resistance.
Lagoon places an ON/OFF battery switch in the negative battery cables....
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Old 19-04-2016, 09:24   #9
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Re: I jumped the shunt and other bad things...

Don't (DO NOT) put anything below the terminal and the top of the clamp. On the top use brass or SS. The main contact area is between the bottom surface of that lug on the fuse block and the top surface of the clamp. Brass, silicon bronze, SS are just not good electrical conductors. Never could understand how a compound that is 95% copper (silicon bronze) could be such a poor conductor.

I am like MS just leave that negative switch in the on position. Not normally found in grounded systems but the real issue is just another part to give trouble down the road.
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Old 19-04-2016, 10:56   #10
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Re: I jumped the shunt and other bad things...

"I am like MS just leave that negative switch in the on position. Not normally found in grounded systems but the real issue is just another part to give trouble down the road."

I want to modify that statement. When you put a switch in the battery negative you better be dam* sure to not connect anything with a ground between the switch and the battery. You might have inadvertently created an alternate return to the battery bank. You can often have what is called sneak circuits. This is just some unknown path that the current will find even if us humans think we clever enough to have it all figured out.

In my previous life I worked for the Navy Seals. They burned up the printed circuit traces on 50K worth or radios because someone told them to install a switched battery negative on one of their small craft. Somebody left the negative switch open and when they started the outboard the starter current found a sneak path through the radio. The copper trace on the circuit board was just not up to handling the starter current.

Put in another ground bus and connect that solar controller with other grounds ahead of the switch.
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Old 19-04-2016, 11:12   #11
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Re: I jumped the shunt and other bad things...

Shunt is not a switch, get someone qulified to sorting out, before smoke take a place.
Your all batteries are parallel, there is lot of energy to dissipate, if you make a single mistake.
If you make any electrical modification ...start with schematics ..check it twice
and than introduce voltage and retest twice. You must be satisfied the modification is successful
....it's electricity, perhaps not dangers voltage but still a lot of amps.
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Old 19-04-2016, 11:22   #12
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Re: I jumped the shunt and other bad things...

Appreciate all the advice. Normally I would just leave the switch on, but I have the boat in some limited charter for hopefully 4 or 5 weeks, and afraid that this switch will get turned off by someone other than myself.

Haven't look at those T handle switches, maybe I can take the handle off with it in the on position. Then I can just attach the solar to the load screw of the shunt, all the grounds from that go to that are in a bus bar that is another 3' of wire away.

Will not put a washer under terminal fuse block, will try to find a brass one for the top. Very hard to find brass washers, west marine doesn't have, nor does local ace hardware!

Again, thanks for all the advice.
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Old 19-04-2016, 14:40   #13
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Re: I jumped the shunt and other bad things...

And do NOT bother using that LOAD terminal on your solar reg.
They are more for running VERY low wattage lights etc.
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Old 19-04-2016, 15:00   #14
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Re: I jumped the shunt and other bad things...

yes. thanks. already know this. not intending on using controller for anything but putting as many amps into batteries as possible.
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Old 19-04-2016, 16:11   #15
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Re: I jumped the shunt and other bad things...

Quote:
Originally Posted by BruceS View Post
And do NOT bother using that LOAD terminal on your solar reg.
They are more for running VERY low wattage lights etc.
I don't know what your solar controller is, but mine came with a load terminal that is solid state switched on whenever the solar panel stops producing current after dark. Then the load terminal is switched off when the panel resumes producing current soon after daybreak. This is ideal for mounting an anchor light to that circuit. If you use an led there are no concerns of flattening battery, and one can be assured the anchor light is turned off and on appropriately whether you are there or not. Which is reassuring if your are swinging on a mooring with newcomers coming near to anchor. Or if your boat is nearest the navigation channel, or you often forget to switch on and off your anchor light manually.
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