Solar panel connections keep breaking

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timmmay

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#261460 29-Nov-2019 06:58

I have a small 60W or 80W solar panel which I use to keep a few 30AH batteries topped up. It sits inside a garage window where it gets enough light, so everything is inside and not exposed to the weather.

The problem I'm having is the wires into the controller keep breaking, every 3-6 months. Each time I cut the cable back, cut off about half the strands as it's too thick to fit into the controller, tin the connection with solder, and screw them back into the little controller.

The cables are wedged into a shed bench so that there is minimal pressure onto the connection. The controller isn't fixed in place and doesn't move. The cables might get bumped a couple of times a month but are generally out of the way.

Any suggestions how to make a more reliable, longer lasting connection?

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#2362506 29-Nov-2019 07:10

Stick the cable under one of the batteries 、I’m guessing it’s the weight of the cables running down the side of the bench which are pulling on the connection , which is only a few strands

timmmay

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#2362518 29-Nov-2019 07:35

The cables don't pull on the controller, as the controller isn't fixed in place. If the cables were pulling on the controller it'd fall off. But I might try that to keep them more steady thanks.

nzkc

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#2362520 29-Nov-2019 07:51

Maybe they move a little when the area heats up (during the day) and cools down (during the night) from expansion and contraction. Over time that could cause some wear - though I would have thought it would take longer than a few months. Guess it would depend on the temperature swing.

So I'm thinking maybe fixing the box and tacking the cables to the wall/bench might actually help that.

Other than that - maybe the connectors are tightened too much which cracks the strands.

chevrolux

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#2362524 29-Nov-2019 08:06

I would hazard a guess and say don't tin the wire. You are making it solid and therefore more susceptible to movement.

If you want to screw down on something solid, perhaps consider a crimp on the end instead?

Oh and a second for terminals too tight - especially with stranded wire.

timmmay

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#2362564 29-Nov-2019 08:57

I can try not tinning the wire. Part of the reason I do it is because otherwise it's really difficult to get into the controller, I can see if a crimp will work thanks.

Bung

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#2362668 29-Nov-2019 09:52

Tinned stranded wire under screw terminals is unreliable. The solder tends to spread leaving the screw loose. In the case of mains wiring this is specifically not allowed.

trig42

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#2362672 29-Nov-2019 09:57

Can you get a choc-block connector, put the solar panel cables into one side, then a couple of thinner gauge cables into the other, then into the controller?

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shk292

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#2362708 29-Nov-2019 10:35

By cutting half the strands and tinning the thin tip you’re creating a perfect stress concentration where the wire suddenly gets smaller and less flexible. As above, don’t tin. Is it possible to use thinner wires?

timmmay

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#2362741 29-Nov-2019 11:21

A connector block then thinner cables is a good idea, thanks @trig42. Agree with what everyone else is saying too. For now I think after poking around it's mostly the strain on it, so I'll give that a go first, then circle back to other options if they don't fully work. Thanks all :)

elpenguino

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#2363133 29-Nov-2019 20:11

Movement is a certain death for wires. If you insist on such an adhoc installation you need some kind of strain relief in the form of a clamp etc.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

timmmay

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#2363137 29-Nov-2019 20:16

elpenguino:
Movement is a certain death for wires. If you insist on such an adhoc installation you need some kind of strain relief in the form of a clamp etc.

How would I make it less adhoc? I understand the electrical parts but have no experience with the physical parts.

This is a simple system to keep batteries charged, sitting on a bench in my shed.

Jase2985

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#2363163 29-Nov-2019 20:41

take a piece of 4x2, mount the charger controller to the timber, then clamp the cable to it so it cant possibly move.

buy your problem is your cable is to big for the controller. get the right sized cable and you will likely have less problems.

richms

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#2363164 29-Nov-2019 20:41

If you must have wires that are too thick, then get a barrier strip, and crimp on some fork terminals, then take some smaller wires from the barrier strip to the charge controller. Put ferrules on the thinner wires if you feel that will make it easier to get them into the terminals, but they need a specific crimper to do a good job.

Do not solder any flexible cable ever as it will break where the solder ends, and it will not fit in a terminal properly. Soldering terminals onto wires is something that old people do who distrust crimps because their only experience with them has been on old British cars put together by drunken Englishmen with no care at all.

Richard rich.ms

elpenguino

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#2363169 29-Nov-2019 20:54

timmmay:
elpenguino:

Movement is a certain death for wires. If you insist on such an adhoc installation you need some kind of strain relief in the form of a clamp etc.

How would I make it less adhoc? I understand the electrical parts but have no experience with the physical parts.

This is a simple system to keep batteries charged, sitting on a bench in my shed.

Youve got a good looking wall there. Mount the charger on the wall then as mentioned clamp the wires to the wall also.

All the comments about soldering(not) and wire sizes are all good advice but if you simply permanently mount everything you should reduce a lot of your problems.

You could use saddle clamps, p clamps or those cable ties with a little screw eye etc.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

Ge0rge

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#2363188 29-Nov-2019 21:40

richms:

....

Do not solder any flexible cable ever as it will break where the solder ends, and it will not fit in a terminal properly....

It will only break if you don't provide adequate strain relief, apply too much heat during the process, allow solder to track under the insulation or don't clean the flux off afterwards. Soldered joints can be extremely reliable if done correctly - I certainly wouldn't write it off by saying "don't do it ever".

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