Lofrans Tigress 1500w 12v appropriate cable size?

Nigelb

Nigelb

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I have just replaced my Lofrans Tigres with a new 1500w 12v unit and upgraded my ground tackle from 8mm to 10mm chain with new 20kg Rocna. The existing power cable is 10mm multi strand copper over a length of approx. 10m. Given the more powerful motor, I am now concerned about potential voltage drop. A quick internet search shows i should be aiming for 3/5% So I assume I need to replace with something like...........637/0.3 50mm2 cross section 345amp rating 13.3mm overall diameter 0.000403volts drop per amp per metre?

If so the that is going to cost approx £300, not an inexpensive job, does anyone have any recommendations for cable suppliers Internet or South Coast?

Thanks.
 
Is your length of 10m the total length of positive plus negative return ? If not I think your 50mm² may not be heavy enough .

If the total "there and back" is 20m then you will need at least 70mm², preferably in excess of 100mm²

Welding cable may be an affordable choice.
 
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VicS said:
Is your length of 10m the total length of positive plus negative return ? If not I think your 50mm² may not be heavy enough .

If the total "there and back" is 20m then you will need at least 70mm²
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The Lofrans installation instructions say 50mm² is fine for a run of up to 25m for a 1500W 12v windlass.
 
pvb said:
The Lofrans installation instructions say 50mm² is fine for a run of up to 25m for a 1500W 12v windlass.
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My calcs are aimed at the 3 to 5% volts drop that the OP was talking about
 
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VicS said:
My calcs are based on the 3 to 5% volts drop that the OP was talking about
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Windlass installations aren't usually considered to be so voltage-sensitive. Most windlass manufacturers recommend cable based on a 10% max volt drop.
 
Starting from scratch?

You might consider installing a dedicated battery forward, this reduces heavy duty cable runs and the investment required.

CH
 
Aurai said:
Starting from scratch?

You might consider installing a dedicated battery forward, this reduces heavy duty cable runs and the investment required.
Click to expand...

Not sure about the investment - if it's done properly it's probably more expensive than simply running big cables.
 
You are absolutely correct, the Lofrans installation guide allows for 2 AWG 50mm2 up to 25m. However this would represent a voltage drop of 2.5v or 20%. At their higher spec. of 70mm2 you would still get 10% drop over 25m. So 3/5% would seem a little unrealistic on my part.
 
We are agreed then, Tinned 485amp 70mm2 with 15.5mm diameter £11.23 per metre from Furneaux Riddall, so £224 inc. VAT.

Many thanks for sorting this one out!
 
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Nigelb said:
You are absolutely correct, the Lofrans installation guide allows for 2 AWG 50mm2 up to 25m. However this would represent a voltage drop of 2.5v or 20%. At their higher spec. of 70mm2 you would still get 10% drop over 25m. So 3/5% would seem a little unrealistic on my part.
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I'm don't think you've done your sums correctly! The windlass will take about 130A max. With a 20m cable run (10m there, 10m back) the voltage drop with 50mm² cable will be a shade over 1v - slightly less than 10%.
 
To backtrack a bit, the original 1000 watt Lofrans had 10mm cable. That looks woefully inadequate, yet presumably it worked because the windlass was not fully loaded, and the motor was probably drawing much less than its rated power consumption for most of its run time.

My own 1000 watt Lofrans windlass and the bowthruster share a dedicated 105 AH battery with about 3 metres total run of 50mm cable to the windlass and less than two metres to the thruster, and that battery is wired in parallel with the two main house batteries of 105AH each via about 16 metres total of 50mm cable. The fact that the OP's old windlass worked off 10mm cable makes me wonder if my wiring is actually overkill.
 
A dedicated battery IMHO is not a good way to go. Considering purchase cost of the battery and on going replacement costs. However if you need additional battery capacity it may be practical to fit a front winch battery but have it useable as house battery capacity.
OP has cables already fitted for the old winch. So no need to replace them. If he needs more current less volt drop then paralleling the cables would be a more cost effective approach. So another pair of similar sized cables would halve the volt drop.
He is going to need more power so more current to cope with larger chain and anchor than previously. However I would be tempted to just try the new windlass on the old cables. Excess volt drop will result in slower winching under real laod. Just make sure the cables don't get hot under real load.
NB the current taken by the winch is greater at greatest load and lowest speed. Higher speed means less current. good luck olewill
 
Norman_E said:
My own 1000 watt Lofrans windlass and the bowthruster share a dedicated 105 AH battery with about 3 metres total run of 50mm cable to the windlass and less than two metres to the thruster, and that battery is wired in parallel with the two main house batteries of 105AH each via about 16 metres total of 50mm cable. The fact that the OP's old windlass worked off 10mm cable makes me wonder if my wiring is actually overkill.
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I used 50mm cable as that is what the Lofrans manual recommended. If you have a separate battery feeding the windlass etc then all you need to supply that battery from is cable specced to carry the charging current and/or any proportion of back current from your forward battery when eg the engine is being started etc.

Istm that although the charge current might be very much less than the windlass current you still need substantial cabling to prevent voltage drop which is more significant when charging if you want to get a full charge in. Also the other current situations are a bit hard to calculate so for me, as Olewill above, no forward battery + cables man enough for 100A were the way forward.

William_H said:
He is going to need more power so more current to cope with larger chain and anchor than previously. However I would be tempted to just try the new windlass on the old cables. Excess volt drop will result in slower winching under real laod. Just make sure the cables don't get hot under real load.
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On 10mm cables I would absolutely not be prepared to try it. I don't understand how the OP has got away with that unless the 10mm is the wire diameter not the wire cross-sectional area ? Ie 10mm o/d not 10mm² ?

Boo2
 
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pvb said:
I'm don't think you've done your sums correctly! The windlass will take about 130A max. With a 20m cable run (10m there, 10m back) the voltage drop with 50mm² cable will be a shade over 1v - slightly less than 10%.
Click to expand...

Hmm.. I think I have been plugging the wrong cable spec. into the online calculator, this will save me a couple of quid!
 
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