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Post by Clinton Cool on Nov 14, 2016 22:32:38 GMT
I have a wind turbine with a Marlec controller. The controller sits on the bulkhead at the back of the boat, alongside other controllers/ meters. All very nice. Other than that there's a significant length of wire to get it there, then back to the battery, there's a large voltage drop because of this.
It crossed my mind to uprate the wiring, reduce this voltage drop. If I kept the existing set up not only would I need to buy loads of thick expensive wire; I'd also need to re drill the holes in the bulkhead, make them bigger.
It would make sense to move the controller to under the cruiser deck, close to the battery. This would reduce the wire run by two thirds and no hole drilling would be needed. My thinking is to epoxy 2, 2x1 battens to the hull adjacent to the leisure battery. I'd then wire the controller then screw it to the battens but within one of those clip down, waterproof plastic boxes. I'd cut the bottom out of the box to allow the controller to cool. This would protect the controller from the inevitable drips in what is a very damp environment.
Might this work, or is under deck a completely unsuitable environment for a controller?
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Post by tonyqj on Nov 14, 2016 22:34:59 GMT
Do the instructions state to install in a well ventilated dry environment? If so then no, it's not suitable.
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Post by Clinton Cool on Nov 14, 2016 22:48:04 GMT
The manual states: "Select a covered dry wall location in a ventilated area close to the batteries"
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Post by tonyqj on Nov 14, 2016 23:09:08 GMT
The manual states: "Select a covered dry wall location in a ventilated area close to the batteries" Where it is right now would appear to cover 4 out of 5 of those. I suggest you bite the bullet and buy some thicker cables. If the bulkhead through which they pass is steel then please also fit some suitable glands or grommets. |
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Post by smileypete on Nov 15, 2016 10:00:16 GMT
Would be good to work out what cable is needed for the current setup to work best.
How far from the batts is the controller and what is the max current the controller can put out in practice?
Would also help to know what charge voltage the controller can go up to, the Trojan batts can probably be a bit flexible on this at the upper end.
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Post by Deleted on Nov 15, 2016 11:55:29 GMT
I moved my solar panel controller from the cabin to under the semitrad deck ( also protected by a tonneau) after I startted getting some odd readings. The instructions said to mount close to the batteries because the thermometer for the temperature compensation for charging was inside the controller. So when the engine was or had recently been running the batteries were warmer than the controller, later on it was the other way round. Since moving it things have been much more predictable. I would add that my controller is designed for harsh environments.
The ideal would be a remote temperature sensor to get the best of both worlds. Something I will look for next time. Condensation damaged another piece of kit mounted there by dripping onto it, so now I've got a cover and make sure the bilge is dry to prevent it raining under there
Top Cat
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Post by phil70 on Nov 15, 2016 14:46:49 GMT
My take on this is never to put anything electrical under the deck boards too dodgy IMHO.
Phil
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Post by Clinton Cool on Nov 16, 2016 17:47:12 GMT
I emailed Marlec they've advised that the controller would fail in a damp environment. Bigger wires it is then!
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Post by tonyqj on Nov 16, 2016 17:58:25 GMT
I emailed Marlec they've advised that the controller would fail in a damp environment. Bigger wires it is then! What controller (max output) and how long will the cables be? Then we can tell you how fat I am they need to be. |
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Post by Clinton Cool on Nov 16, 2016 18:04:42 GMT
I'm not sure what the output of the controller is, it's not specified anywhere. However it's designed for the Rutland wind turbine which is rated at 300W. Wire length: I'd say 4-5 metres from the turbine to the controller, then 2-3 metres from the controller to the battery. I'm not very good at wire thickness. I bought 30A rated wire from an automotive supplier on Ebay. It's pretty thin. I posted something else in 'help wanted' about voltage drop v amp drop, to try to work out if it's worth the bother of doing this.
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Post by smileypete on Nov 17, 2016 11:19:10 GMT
OK let's look at the cable between controller and batts first, then the cable between turbine and controller. If the turbine goes up to 300W I'd expect the controller to push around 20A tops on a 12V system, if the controller is 80% efficient. (300W / 12V) x 0.8 = 20A Using the 'amps divided by three' rule of thumb to get cable size that gives 6.666mm 220A/3 = 6.666mm 2Since that's juuuust over 6mm 2 which is a standard size I'd go for that, plenty on Ebay just look for 'trirated cable'. That said if 10mm 2 is just a little more and you can connect it just as easily, why not go for that. Would have thought you're looking at about £12ish for 3m red and 3m black 10mm 2 on Ebay. That'll give about 0.25V drop if the round trip distance is 5m meters, which is acceptable for a charge source I feel. (cue expert argument)  Onto the cable between turbine and controller: For the cable between controller and turbine I'd expect voltage drop is much less of an issue, so I'd go for 4mm 2 solar cable which is weatherproof and fairly robust and rated up to 55A. But ensure it's clipped on a surface and not installed in a bundle or in insulation. As above if the next size up of 6mm 2 is not much dearer then I'd go for that, say £10ish for 10m of 6mm 2 solar cable on Ebay? ETA: If you're a bit unsure about how best to make crimp connections, why not start a new topic as I'm sure it would help a number of peeps and so it's best not to bury it in another topic. |
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Post by tonyqj on Nov 17, 2016 11:27:15 GMT
That'll give about 0.25V drop if the round trip distance is 5m meters, which is acceptable for a charge source I feel (cue nitpicking experts Nitpicker 1 reporting for duty! If OP has a Trojan (which I believe he has) and if the controller isn't adjustable (by which I DO NOT mean a 'wet' battery preset) then he'll already be charging around 0.4V lower than Trojan recommend. Adding another 0.2-0.3V to that is just going to make matters worse. I'd cable it for 0.1V drop as absolute maximum. In other words 25mm 2. |
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