Chargers and lug issues

Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
As part of upgrading the battery wiring in my Catalina 310 I increased the battery charger wire size to #2. I first connected it to a 30A Promariner Pronautic charger and discovered that a #2 heavy duty lug would not fit on the charger positive stud-it ran into the power transistors on the circuit board just above the stud. So I had to grind about 1/4" off the top of the lug to make it fit.

Yesterday I upgraded the charger to a Sterling 50A model (bigger batteries, bigger charger to keep them happy). This time the negative lug wouldn't fit-there was a diode mounted vertically that blocked the lug (on the 30A charger the diode was flush mounted on the circuit board and out of the way). So that one got ground off also.

I didn't have any #2 starter lugs, so I don't know if they would have fit fine, but I was quite surprised that neither charger was able to accomodate the heavy duty lugs without modification. Here's a picture of the 50A Sterling charger showing the fit after grinding. I should add that these are not FTZ lugs, they are NSPA, but I can't imagine that the length of the lug past the hole would be that different between them.

I also discovered that there's no possible way for the plastic cable holder to fit over a #2 cable with heavy duty lug, so I just left that off.
IMG_1109.JPG
 
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Dec 19, 2006
5,809
Hunter 36 Punta Gorda
Try using smaller lugs on charger and bigger lug on other side to battery and make wire strains smaller for charger side.
Nick
 

Ward H

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Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
@marchem
Since you already have run the #2, I think you did what you needed to do, without trying to go with a smaller size wire. I looked at other size lugs comparing FTZ and NSPZ and I don't think the FTZ would have been different.
Since you cannot use the charger clamp for the wire, have you clamped the wire below the charger for strain relief?
That's what I would do.
 
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Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
@marchem
Since you already have run the #2, I think you did what you needed to do, without trying to go with a smaller size wire. I looked at other size lugs comparing FTZ and NSPZ and I don't think the FTZ would have been different.
Since you cannot use the charger clamp for the wire, have you clamped the wire below the charger for strain relief?
That's what I would do.
I did clamp the wires below the charger. In hindsight #2 may be overkill. I know it's specified for <3% loss, but that's at 50A when the batteries are drawing max current and probably don't care all that much about some voltage drop. Once the current drops to 10A even #8 is ok (but not a good idea). Now I have to figure out how to balance the SOC in the batteries, or if it's really necessary, given our usage-which sounds similar to yours.
 
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Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
I plan to follow Maine’s response to my question in the new battery thread on how to balance the batteries.


I was lucky to have a good location for the charger that only needed a 4’ run of 6 AWG for my 30A charger.

One more work day and I should be done and ready to buy the batteries.
 
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Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
I plan to follow Maine’s response to my question in the new battery thread on how to balance the batteries.


I was lucky to have a good location for the charger that only needed a 4’ run of 6 AWG for my 30A charger.

One more work day and I should be done and ready to buy the batteries.
That sounds like a good idea.
 
Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
http://www.genuinedealz.com/cable-lug-tinned-copper-ring-2-awg-gauge-stud-size-1-4-inch
I don’t remember the stud diameter but this may fit. Are you jumping the three outputs to one?
On my run I used 4awg and they had small terminals to fit.
Those are "flared starter lugs". Probably would have fit ok, but I didn't have any of them, just the heavy wall lugs. If I had read Maine Sail's article on battery cables more closely I might have realized that the smaller lugs are a better choice in some cases, like this. Oh well, live and learn, hopefully somebody will read this and buy the correct ones for their project.

I did jumper all three outputs, but with #10. Since it's such a short run the voltage drop is <0.5% @ 50A, so no big deal. Both Sterling and Promatiner now say you don't have to do that, but it's easy to do (well, sort of easy) and can't hurt.
 

Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
I did jumper all three outputs, but with #10. Since it's such a short run the voltage drop is <0.5% @ 50A, so no big deal. Both Sterling and Promatiner now say you don't have to do that, but it's easy to do (well, sort of easy) and can't hurt.
@marchem
I read the instructions that came with my 30A Sterling charger this morning prior to starting it up for the first time.
I was surprised to find in the instructions that they did suggest to tie the outputs together. Like you I jumpered the outputs on mine with 10 AWG.
I have some of the flared starter lugs on the way to see if they fit better on the starter and alternator than the heavy heavy duty lugs. I'll compare the differences and let you know.
 
Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
@marchem
I read the instructions that came with my 30A Sterling charger this morning prior to starting it up for the first time.
I was surprised to find in the instructions that they did suggest to tie the outputs together. Like you I jumpered the outputs on mine with 10 AWG.
I have some of the flared starter lugs on the way to see if they fit better on the starter and alternator than the heavy heavy duty lugs. I'll compare the differences and let you know.
The Sterling written instructions say to jumper, but I got an addendum with mine from the distributor that said you don’t have to. The Promariner instructions say no need.

I used the big ones on the alternator and starter, but it wasn’t easy.