Battery Choices

[bottle]

Got space for four leisure batteries (330L x 172W x 242H)

 

 

The HydroLink would solve the height issue and straddling the engine (Cruiser stern!), though I couldn't find anywhere in the UK that sells it.

 

Not Hydrolink but this company (see links below) does many different ways of topping up, including automatic

 

Have no connection, other than talking to them at Crick many years ago.

 

http://www.pbbatteries.com/

 

and this is their 'Watering systems page

 

http://www.pbbatteries.com/battery-watering-systems/

[Ex- Member]

All very nice gadgets, but I'll not bother enquiring as to the price as I doubt any will be cheap.

 

I have awkward access but rigged up this gadget for a couple of quid. There's info on it here.

 

http://www.canalworld.net/forums/index.php?showtopic=66561&hl=%2Bchecking+%2Bbatteries+%2Bwith+%2Btight+%2Bclearance

[swmenzies]

All very nice gadgets, but I'll not bother enquiring as to the price as I doubt any will be cheap.

 

I have awkward access but rigged up this gadget for a couple of quid. There's info on it here.

 

http://www.canalworld.net/forums/index.php?showtopic=66561&hl=%2Bchecking+%2Bbatteries+%2Bwith+%2Btight+%2Bclearance

 

I'm very impressed, that's a pretty ingenious set-up

[swmenzies]

I'm going to bite the bullet and get the Trojan T105s, this is going to take a little re-jigging of my cabling. I have read that all the terminal cables should be equal in length (parallel), does this apply to the interconnecting (series) cables? Can the two series cables be of the same length but different to the parallel connections?

[bottle]

Yes

[Ex- Member]

I'm going to bite the bullet and get the Trojan T105s, this is going to take a little re-jigging of my cabling. I have read that all the terminal cables should be equal in length (parallel), does this apply to the interconnecting (series) cables? Can the two series cables be of the same length but different to the parallel connections?

 

Yes! not necessarily the same length as the cables to posts. You only need short stub leads to connect/link the 6v batteries together, we have 6 x 6v 3 pairs. So in essence 3 x 12v units.

 

 

All the Pos and Neg cables leading to the Neg Shunt and Pos Battery switch should all be the same length. Nothing else what so ever should be connected to the battery bank terminals except for a battery temp sensor wire in some cases.

 

The 2 posts below accept Alt charging leads, plus supply to inverter and 12v system, some are connected to the other end of the posts under the floor.

[swmenzies]

Did you crimp your own cables? or did you buy them pre made?

[nicknorman]

Yes, ideally the series linking cables should be the same length, and the paralleling cables should be the same length (but not necessarily the same as the series cables). In reality with thick (eg 70mm) cables with properly crimped connections, it doesn't matter that much. Do get a proper crimping tool (eg hydraulic ones from ebay - cheap!) and put some heatshrink over the border between the insulation and the crimp sleeve, to keep corrosion at bay.

[swmenzies]

I measured the thickness of the cable to be 18mm inc. sheath, would that be 70mm² cable?

[bottle]

Area (mm²) = 2r*π. r = radius. 2r = diameter.

 

So assuming insulation is 1mm thick your cable is 16mm diameter

 

2r = 16mm

 

π = 3.142

 

So 16*3.142 =50.272 or 50mm²

[nicknorman]

I measured the thickness of the cable to be 18mm inc. sheath, would that be 70mm² cable?

Obviously it depends on the thickness of the insulation, but presuming you mean the diameter then yes, sounds like 70mm².

[bottle]

How have I got it wrong then?

 

Is my formulae wrong?

 

I was working from a very old memory.

[nicknorman]

Area (mm²) = 2r*π. r = radius. 2r = diameter.

 

So assuming insulation is 1mm thick your cable is 16mm diameter

 

2r = 16mm

 

π = 3.142

 

So 16*3.142 =50.272 or 50mm²

Check your formula!

How have I got it wrong then?

 

Is my formulae wrong?

 

I was working from a very old memory.

Pi R squared. You calculated pi diameter, not the same thing! There must be an R squared for it to be dimensionally consistent.

 

Pi D is circumference.

Edited June 5, 2014 by nicknorman

[nicknorman]

Just checked, Barden's flex 95mm^2 cable is 17.9mm OD so it may even be 95, depending on the insulation.

[bottle]

Sorry, SW Menzies

 

 

Still going wrong somewhere....

 

π = 3.142

 

measured diameter 18 mm, so assuming 1mm insulation, actual measurement of core = 16mm

 

therefore radius is 8mm

 

transpose into formula, π(r2)

 

3.142 * (8*8) = 3.142 * 64 = 201.088

Edited June 5, 2014 by bottle

[nicknorman]

The insulation is a lot more than 1mm thick. 95 mm^2 =5.5mm radius, so the insulation is about 3mm thick, which sounds reasonable.

[bottle]

Thanks Nick

[swmenzies]

So lets assume it's either 50mm² or 70mm², what effect could this have if I used one thickness to join the leisure batteries in series & parallel and one thickness for the starter battery?

[bottle]

None as the two systems will not be connected, other than by the neutrals.

 

Each bank (domestic, start) should have its own neutral back to the common point on the hull

[nicknorman]

So lets assume it's either 50mm² or 70mm², what effect could this have if I used one thickness to join the leisure batteries in series & parallel and one thickness for the starter battery?

I would say it's either 70 or 95. But anyway, it doesn't matter if you use a different thickness for the starter battery. 50mm would be quite adequate for that.

[swmenzies]

None as the two systems will not be connected, other than by the neutrals.

 

Each bank (domestic, start) should have its own neutral back to the common point on the hull

 

Yes, very good point!

 

Thanks

Edited June 5, 2014 by swmenzies

[nicknorman]

Or, to be picky, the negatives. "Neutral" is normally reserved for AC power.

[bottle]

No, not being picky but absolutely correct, as I should have been.

[swmenzies]

My batteries have arrived and so have the cables, I've got some work to do this week end!

[swmenzies]

I got the batteries installed without shocking myself or blowing any equipment.

 

One thing I had not considered when buying the batteries was the terminal height, on one of the positive and negative connections I had three lug connections which was too tall for the nut to grip the thread. Thankfully I had a number of post to thread connections but they needed opening out to fit around the larger/wider post bottoms (see image 1.), this however is defiantly not ideal as the post height (below the screw thread) is not full height. This leads me to my question, can anyone recommend a solution to my problem?

 

Looking on the internet I found a couple ideas but not a real solution. Image two, multiple connections for large lugs and smaller connections for voltmeters/ammeters the problem with that is the post connection. Image three is technically viable (so I believe), I can put one or two lugs on the terminal, pin down the extension with the lugs and the nut then put the remainder of the wires onto the additional threaded connection, the real problem is that I cannot find a UK/European supplier.

 

I guess the correct solution would be to install high current bus bars, I am a little resistant to this idea as this would mean making big changes to the wiring and the battery box.

 

 

 

Many thanks,

 

Scott

Edited June 20, 2014 by swmenzies