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chris_gee 09-17-2009 02:46 AM

Link 20 rewiring
Ok. I have 2 gp 27 in parallel bank 1 and a starting battery bank b, with a link 20 and pathmaker battery combiner.
The old Lifeline AGM batteries had probably never been floated due to cruising and lack of power source with PO.
While attempting to charge and equalise them myself I noticed on the charger one bank showed neg current going in the other positive while on the charger. Odd I thought.
Anyway while I got some improvement I took them to the Battery Clinic and had them reconditioned, with an excellent result at low cost.
Meanwhile I thought I should rewire the Link as all eight wires were white not colour coded.
Now trying to interpret p33 of the link manual, it says all load grounds go on this side of the shunt ie left and bank 1.
My winch is on bank 2 so does the neg of that go on the left or the right where there is a small "load" on the diagram but nothing on the equivalent negative terminal of bank 2.
It also has No other wires connect direct to battery. I took this as being only negatives but may be wrong. I have only an off on battery switch, which I take as being for the motor and an off on switch on the panel but three thick positive cables on bank one and two on bank two. HMM does that sound right?
Anyway now the problem having read what I could I reconnected everything using coloured cable and following the manual as best I could follow it with admitted inexperience. Comes to the last touching the neg cable to bank 1 negative I get quite marked sparking. Testing the neg cable from battery two of bank one to the neg cable of battery one of bank 1 I get 13.2 volts.
Okay it seems to me if bank 2 is at 12.7 and bank 1 at 13.2 or so even if the negative for the winch should be on the right side of the shunt thing there shouldn't be a current between the winch and bank 1, and two even if one bank is at 13.2 and the other at 12.7 that shouldnt give 13.2 volts between the negatives of bank 1.
I noticed the same sparking before I touched anything. Also that some of the wiring on the right bank 2 side did not seem right.
It seems to me that there must be short or a miswiring in one of the wires supposed to be negative?
The PO did it himself.
I hesitate to ask but I don't mind admitting a lack of expertise but it seems to me there must be a rational explanation. I could get the local electricians who wired up the winch but since that took 7 hours, including changing a tricolour lightbulb and they made two mistakes to my knowledge I am a wee bit hesitant as well as stubborn.
Any insights appreciated.

Omatako 09-17-2009 05:09 AM


I installed my Link 20 about a year ago so my recollection is a little sketchy but I have the manual on my boat and if what I tell you now doesn't help and you need more assistance I will bring the manual home and walk through it with you. For now . . .

The Link20 has a double shunt. That's the thing that the negative cables from your bank connect to. Nothing else should connect to these shunts and nothing else should connect to the negative poles on the batteries. Only one cable from each bank.

Each shunt monitors a different battery bank. So onto one end of the shunt goes the negative cable from your battery, onto the other end of the shunt is the cable that goes to the circuits that the bank will supply.

For example, on my boat, I have the negative on bank one going to the shunt then from the other end of the shunt to a ground bus and everything that is served by the house bank is earthed to this bus. On the other shunt the cable goes to the ground on my engine and this forms the earth circuit for the starter bank.

The positive cables from each bank go to the circuits that each bank serves.

So again, on my boat, the house bank positive goes to the main distribution panel (via a 1-ALL-2 switch) and from there it is split to all domestic appliances. The negatives from the appliances go back to the ground bus referred to above.

The positive cable from the starter bank goes directly to the starter motor connection. From here all the engine circuits are fed (alt, instruments, etc.)

OK, here is where it gets hazy and if I need to continue I will need my manual. If there are others that can continue and describe the small wires then so be it. If not I will check back on the thread in a day or three once I have been to my boat.

I can say that off each side of the shunt there is a "twisted pair" that is the data connection to the monitoring panel. If you don't have twisted-together wires then there is a problem.

The other thing that is perhaps important to note is that it is not dangerous or dodgy to connect earth wires directly to the negative battery pole. The only thing that makes this undesirable is that if any appliance is earthed directly to the battery, it will not be included in the monitor's measurement. In other words, it will draw current but the monitor will not know it and the resultant readings will be inaccurate.

Hope this helps a little so far. I'll check back in a few days and see how you're getting on.

chris_gee 09-17-2009 09:35 AM

Thanks. I have the manual and the small wires seem ok.
My concern was the sparking when connecting the neg lead from the battery one shunt to the negative on the battery, and that there was a 13.2 voltage from that lead tested against the negative on the second battery of that bank. That seems to suggest that one of the smaller ground negative connections is in fact live and I need to try and isolate which one and why. At the moment everything is switched off so that reduces the chance of a short circuit.

Omatako 09-18-2009 01:22 AM


I think that getting 13.8 volts between the dosconnected neg cable and the shunt is probably correct. Remember that one of the functions that the Link measures is voltage and the connection between the neg and the shunt completes that circuit.

That also may be the reason you're getting a spark when you connect. If the Link is connected right it will be connected irrespective of the main switches and stuff being turned off.

The one thing you haven't mentioned yet is what is happening on the display. What lights are on when everything is connected and are you getting any sensible readings when you push the buttons? Also, has the thing been properly calibrated? Meaning is the Link expecting to see the extent of the battery bank that you're showing it? There is a setup routine outlined in the manual that is a little iffy but it works if you follow it step by step.

I'm about to leave for my boat. I'll bring the manual back and we can have a more meaningful look at it.

Enjoy your weekend.

mitiempo 09-18-2009 02:15 AM

All Xantrex manuals are on the web and easy to find. Just googled Xantrex Link 20 and it's the top of the list. Here's the link to the pdf.

chris_gee 09-18-2009 03:12 AM

Ok I have narrowed it down to a 13 odd v between the negative shunt for the bank 1 and the neg terminal for battery 1 the link that sparks when I try to connect it so I haven't. And the same for that first to the second battery of bank 1.
I havent been game to complete hooking up the negatives of bank one. Maybe it is some residual through the link 20 with a voltage but low current. There isnt really anything showing up on the link maybe because it needs bank one circuit completed. I have programmed it before so that isnt a problem. The yellow light of the pathmaker battery combiner which I didn't touch is on but I haven't read up on that yet well I have in the past but not lately.
I did find one fault causing the voltage between the two neg terminals of bank one so the main problem now seems to be that that negative terminal on the shunt shows a voltage. I rolled my eyes in despair and sought prof help but was told the week after next (maybe on past experience). Fish to be caught.
I have a couple of things to try like only connecting one battery and disconnecting the link by removing the fuses but really the fundamentals of electricity were a long time ago and then theoretical, I dont know if diodes were even invented then. I don't mind payng professionals but paying an apprentice tradesman's rates to get it wrong even if they were available sticks in the craw a bit.

mitiempo 09-18-2009 03:38 AM

2 Attachment(s)
What do you mean by "I haven't been game to complete hooking up the negatives of bank one"? Only one negative wire goes to each battery bank. See below.

mitiempo 09-18-2009 03:47 AM

1 Attachment(s)
Bank one has only one negative terminal - regardless of how many batteries in the bank.

chris_gee 09-18-2009 03:53 PM

Yes I know I meant both black cables though only one goes to the shunt.

SteveInMD 09-18-2009 04:03 PM

I'm not exactly sure what you are asking at this point, but...If you are getting sparking when trying to make a connection there is a load on the system. Make sure everything is off including the shore power and inverter.

All grounds from the various should go to a heavy gauge bus bar. Then just one cable to the shunt.

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