Wires Overheating

[Cheechako]

Wow, making hot water with an inverter? Huge draw. I would never do that. I find an engine heat exchanger through the hot water heater keeps water warm enough to shower for 24 hours.

[GILow]

Originally Posted by Cj115

No it wasn’t a typo, I do have a 200ah 12v battery bank. The batteries are silicon dioxide batteries and aside from the heat there don’t seem to be too many problems on that front. Heating the water uses about 36ah of battery power - Only 18% of my battery capacity. I have 3X 100 W solar panels and the system is connected to the alternator. Why would this pose a problem? I’m not trying to heat the whole lake here

Ok, so it sounds like you are heating maybe less than ten litres (2 gal US) then?

And yes, the lead crystal batteries will cope according to the literature. Impressive stuff.

The solar and alternator are not really relevant unless each is putting out full power at the moment you are heating the water, and even then, all they would do is protect the batteries from some of the load, they’d have no effect on the inverter wiring.

Well, as others have mentioned, it is time to check for voltage across those cable runs and components.

My quick check says the cable should be ok, just, but maybe it is sub-standard wire or nonsensical labelling. I’d get a set of callipers on it check the diameter of the copper core bundles is at least close to 10 mm.

And look closely at that fuse system. The fuse may be adequate but the fuse holder sounds like it really is at its maximum limit. Once this stuff has heated badly it is often impossible to get good conduction though it again. I’d want a fuse body rated for at least 500 amps if I were going to run 200 amps through it for a long time. (More than a few seconds). Still with a 250 amp fuse of course.

Good luck, let us know the sorts of voltage drop you are recording over those cables and fuse body, I think we’d all like to know.

[Sternwake]

I bet you could pull that ring terminal off of the 2/0 cable with not much effort, due to undercrimping, and incredible point source heating is occurring right there. If the crimp on the switch just below is of equal quality......

If the ANL fuse has been getting so hot you can't touch it, I would have a back up ready to replace it.

I'm not sure what is going on with the cable to its right. Is that a Butt splice 1 cm away from the ring terminal?

The Inverter came with its own cables? The parallel cable with dual ring terminals with 'Yong' on the heatshrink?

I was once offered some cables such as these by an owner who chose not to employ them. They were the thinnest ring terminals I have ever seen, and the cables were suspiciously light. They were copper clad aluminum and when we peeled off the heatshrink, they were the type of ring terminal where one is supposed to fold the wings over then into the cable, then perhaps put in a Hex crimper. It appeared to have been done with Pliers and no further crimping pressure applied. Could move the wires and see the stranding move on the other side of the 'crimp'.

Also there appears to be thin stranded wire with brown insulation crushed under the nut holding down the ring terminal. NO way that nut is able to apply the correct torque to ring terminal and fuse holder with stranded wire wound under the nut. That thin brown wire, if it has to go there, needs its own proper size ring terminal .


I think A Mainesail Linky on how to properly make battery cables is justified and that brown wire should not be attached there.


https://marinehowto.com/making-your-own-battery-cables/

Pay attention to his review of the harbor fright hydraulic crimper at the end. While arguably that is the worst one on the market, and they have since improved their die sizes, and might be 'acceptable' on 4AWG cables, it really is a Piece of junk. I own it, I regret it, I just got the FTZ crimpers he recommends, as I have no less than 24 2/0 lugs to crimp in the near future.

Even if I were to grind proper size Harbor fright crimper Dies to do 2/0 cable, it is an awkward tool that I have little to no faith in, and takes an inordinate amount of time to achieve a visually acceptable crimp, but could also be an undercrimp. Tons of effort, poor result, wastes wire/cable and Lugs time effort and emotion.

[mlydon]

One more recommendation, besides fixing your wiring.....downgrade the coil in your tank to a 700 watt unit. While it will take longer to heat up, it will use the same amount of energy at the tank (amps x volts= Watts).
As the current demand is theoretically halved at the battery, efficiency will increase (the batteries are rated 100ah at a 20hr RATE - capacity decreases as rate increases). Next, the reduced load will reduce voltage drop at the battery( batteries have a resistance) reducing the current required (more volts x less amps = same watts) at the load.
Finally, the voltage drop at your heater (mostly at the inverter, actually, where DC ends) is a function of ohms law, just like the battery - voltage drop = current x resistance - decrease the current and the voltage drop decreases, increasing voltage seen at the inverter, and thus further decreasing the current required to meet your wattage requirement.

So adding these all up, you’ll decrease your total current draw off the battery by significantly MORE that 50% and increase your available storage capacity while not burning your boat down ;-)

Matt