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Hi folks,

I have 2 leisure batteries in the engine bay, 100ah things that are fine, but I'd like to increase the house bank side. I'd also like to fit a digital volt meter that doesn't suck as badly as the analog one I currently have on my dashboard.

So couple of questions.

My current batteries have post connectors and the usual stuff that goes with them, but a lot of the higher end batteries for 200ah etc are eye and bolt type connectors. Which brings me onto my second query, I bought a BM2 Battery Monitor that comes with a eye and bolt type shunt.

So, seeing how a lot of the higher capacity batteries use eyes, does it make sense to replace the current post connectors with eye types? and if so what should I know before embarking on this project?

Or should I find a shunt that works with post type connectors and replace the one they sent me with that and see how I get on?

IMG_20200205_094912.jpg

IMG_20200205_094957.jpg

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the type of connector should make no difference, just ensure the bolts are tightened properly as a loose connection is a source of heat and can deteriate to the point of failure (fire)

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I would mount the shunt on the bulkhead nearby not directly to the battery, have starter cable straight to battery and rest via shunt, you just need a cable to link.

Yours are just on eyes once you undo that butterfly nut.

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Hi Shunts shouldn't be connected to the battery terminals but in the cable. sorry but your connectors are all wrong you have no vaseline protection on connectors, suggest you remove all the cables and batt terminal wire brush all surfaces smear with vaseline and reconnect then cut off ends of cables smeared with vaseline then recrimped if unable to solder which is best, if possible bolt shunt on bulkhead and redirect cables to this then run one thick cable from shunt to battery smearing ends with vaseline on all surfaces, then when you replace/remove battery you won't damage/disturb cables. HAVE you no battery switch this ideally should be connected by cable from pos term then to switch then to starter and by seperate cable to shunt then on to fuses, it is good practise to have a inline fuze between battery and shunt after  any other take offs with the exception of starter. John

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Thanks for the replies folks.

Sorry I should have possibly been a little more specific, I have no interest in connecting the shunt directly to the battery and it'll certainly be attached to the bulk head. The wiring is current in the condition I bought the boat in and I'm figuring stuff out as I go along.

I'm basically figuring out the best way to do the top half of this picture, bearing in mind that I also want to stick a larger Ah battery into the same spot or the spot on the other side which has pretty much the same wiring.

In the wiring diagram, it seems to show the load on the negative side directly on the shunt and the positive remains as is? But you folks are saying the starter should remain connected to the battery and the rest of the load wires removed and stuck onto the shunt and then the shunt connected to the negative terminal?

Cheers

Tom

Screenshot 2020-02-06 at 10.39.09.png

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Hi Tom Yes if you do it like that fine But in UK the pos usually goes to fuzes and switches not neg ( ie neg earth)not the other way round i guess you have a American wiring dia if the starter and alternator cables go to the pos batt terminal be very very careful to avoid cables touching at dash best to take everything from the one terminal ie in england the pos terminal with negative to earth, if all your wire terminals are as picture i recommend you replace all the crimped ends with new ones that are first dipped in vaseline then crimped , you will be getting high resistance if your other terminals are like ones in picture. John

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Okay here's a full photo of the battery box for one of the batteries. Let me see if I can sum this up in a way we all agree?

Apparantly I need to stick some vaseline onto the connectors and clean them up, that is fair enough, I'm pretty sure I'm capable of that.

With regards to adding the shunt. Obviously it needs to be added to the negative side and attached to the bulkhead. So the consensus was that I leave the starter cable on the battery, remove the smaller cables and attach them to the shunt, and attach the shunt to the wingnut on the battery post connector?

Does that sum stuff up correctly?

Thanks

Tom

IMG_20200207_145431_1.jpg

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It's manually switched by a  big old switch, which does have a both setting as well, so I generally use the other battery as the starter, then flip over to the one photographed above when moored up.

Both batteries are identical as I swapped them out when I got the boat, but thats all I've done with them so far. But I plan to double the Ah of the house bank later in the year.

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Why are you fitting the shunt on the neg side one usually fit the shunt on the live ie pos side? have you a american shunt? or does it say on the instruction to fit on neg side? if you run on the starter batt you won't charge the second batt unless the switch connects both then only domestic and then a all off, is that what you mean?. John

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Well the shunt instructions as you can see in the image a few posts ago show the shunt on the negative side. The battery monitor is made by a UK company, so I'm just doing what they say in the instructions.

There isn't a distinct starter battery, just a rotary switch with 1, 2 and both marked on it, so I, just out of choice more than anything use 1 as the starter, which isn't pictured, 2 as the house battery and don't ever run it on both... other than the first time I used the boat, ran the batteries down then couldn't start it again ;)

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9 hours ago, annv said:

Why are you fitting the shunt on the neg side one usually fit the shunt on the live ie pos side? have you a american shunt? or does it say on the instruction to fit on neg side? if you run on the starter batt you won't charge the second batt unless the switch connects both then only domestic and then a all off, is that what you mean?. John

The shunt for my Victron battery monitor is on the negative (as per the instructions)

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  • 1 month later...

Hi folks,

I finally got around to attempting this and I was wondering if anyone can see any flaws in the plan we discussed earlier in the year.

I wired the battery monitor up, and as you can see it functions.... sorta. Problem is it never shows any load over the battery, even when I switch on the broken fridge, lights, water pump and radio :default_icon_mad:

You can see in the second image, I've currently got the shunt wired up to the negative terminal, like the instructions state, I then removed all the wires except what I assume is the alternator cable? I then added the extra wires to the shunt as explained in the instructions.

Anyway, when you switch on the charger, it shows a charging amp load, but no increase in battery charge, when you switch it off the load drops to zero but never shows a discharge.....

 

Any ideas?

 

(For those freaking out about the shunt, it wont float in midair forever, I just need to figure out the wiring first ;) )

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IMG_20200311_112414.jpg

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So having gone through other forums and videos and stuff they seem to state you can have no other negative connections on the battery. If this is the case, this reverts back to my original question, how does one swap from pole type connections to the shunt bolt type connection?

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Hi Magicaltrout. The only fault I can see is there should not be any other connection to the neg batt post other than the shunt ( i.e the short cable supplied with the monitor) as per the diagram referred to in a previous post.

image.thumb.png.a42f86689040437883b33b14b3a0ee4e.png

In your image you still have a heavy neg cable still connected to the battery. This should be with all the other neg cables on the other end of the shunt.

image.jpeg.5238ac5ed1dc403fcf828fd14bbcaa2f.jpeg

I think, at present, the only current drain that will show will be from whatever the three thin wires are connected to. Possibly additional kit added other than original wiring like extra auto bilge pump, stereo system, spotlight etc.

As to your question regarding the connection to the battery post it appears that you already have copper tube ring connections on all wires although the heavy cable looks to have a larger hole, maybe 12mm. Ideally this should be changed to the same size as the shunt connection which I think is 8mm.

Hope this helps. Don't you just love electrics :default_biggrin:

Colin:default_drinks:

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Hi You cut the clamp battery connector and replace with a spade connector that is crimped and soldiered on as stated you will only measure through the shunt that is connected through the shunt, it will only measure the voltage from the alternator if the starter battery is connected as this is usually wired to starter solenoid, you need to fit a switched solenoid to connect the alternator to domestic batt so that both get charged but when switched of won't then run the engine batt down switching switches can easily be overlooked when mooring up casting off, with the engine battery getting drained or the domestic batt not being charged up looking at your wiring i think a complete overhaul will be the best way forward bring it up to date you ideally want to go on board switch batt switches on start up check oil,  charging ect on gauges are all ok then sail of with everything automatically disconnecting reconnecting during your sail. John

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I agree with John that you may need an upgrade in your electrics. There is nothing worse than having a flat starting battery. My option would be to ditch the big 1.2.both switch and fit separate 'red key' isolator switch for starting and domestic. Trace and extend the alternator out and fit a split diode charge. Preferably the fet type as there is no voltage drop. This would eliminate the risk of leaving the 'big switch' in the both position.

Quite honestly, the sky's the limit with electrics. You can go on and add solar panels and inverters etc. Now this may not be your kind of thing but looking to the future demand on electrics now could save you money later.

Colin :default_beerchug:

P.S. When we bought Lady Linda she had 2dom and a starting battery with a relay that combined the batteries once the engine was running. She now has 3 dom, 1 starting and 1 bow thruster with fet split charge by 70A alternator plus a 260w solar panel for domestics (soon to be upgraded to charge all). This powers everything for 9 months without shore power or running at moorings. Saves diesel too :default_biggrin:

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