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Old 27-09-2020, 16:58   #1
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Wires Overheating

Hey!

I’m having a problem with my electrical system I was hoping to get some help with.

So I have 2x 12v 100ah batteries powering all my electronics - one of which is a 2000W inverter that I use to power a 1440W hot water tank. When the water tank is heating up, some of battery wire connections get warm - and one wire gets extremely hot. As well, the 250a ANL fuse I have gets extremely hot. Here is how things are wired and how they get hot:

Battery - 2x 2AWG (warm) - 250a ANL Fuse (scalding hot) - 2/0AWG (very hot) - 275A battery isolator switch - 2/0AWG (warm) - 250A bus bar (warm) - 2x 4AWG (neutral) - Inverter.

The warm wires are slightly concerning as I don’t think they should be getting hot, but the “very hot” 2/0 wire is extremely concerning. It got so hot that it melted off the heat shrink tubing. The ANL fuse gets so hot that I can’t even touch it. I’m not sure if it’s a problem with the wire - or perhaps the wire is just dissipating the heat from the extremely hot fuse. I can send some photos if needed.

Any help is greatly appreciated!!
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Old 27-09-2020, 17:10   #2
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Re: Wires Overheating

Quote:
Originally Posted by Cj115 View Post
Hey!

I’m having a problem with my electrical system I was hoping to get some help with.

So I have 2x 12v 100ah batteries powering all my electronics - one of which is a 2000W inverter that I use to power a 1440W hot water tank. When the water tank is heating up, some of battery wire connections get warm - >>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>

It is rare that people use an inverter to make hot water, it is usually done on shorepower. Your modest battery bank would not support that load.
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Old 27-09-2020, 17:49   #3
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Re: Wires Overheating

Make sure all your connections are tight, your terminals are tight, no corrosion, and use dialectic grease on all. (Relatively) Loose connections, cause reduced conductivity, leading all that current to travel through less area....heating up.

Also agree that 200ah of battery is insufficient for that load - you’re pulling close to 1C - depending on the batteries, of course.

Last - inverters are not efficient - your 1400 watt load is likely 200 amps @ 12 volts. Run the motor to heat the tank. You’ll be running it a long time to recharge those batteries anyway.

Matt

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Old 27-09-2020, 17:52   #4
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Re: Wires Overheating

May I suggest running parallel wires. That may lessen the load per wire, in theory.

Also, may I suggest reading this: https://www.altestore.com/howto/reco...-or-fuses-a62/


If it is true, you are way undersized.


Try this tool: Circuit Wizard - Blue Sea Systems
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Old 27-09-2020, 19:27   #5
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Re: Wires Overheating

Hot wires means too much current. Your are risking a fire! Thx-Ace
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Old 27-09-2020, 19:37   #6
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Wires Overheating

That is an insanely small battery bank to be running that kind of load. Frankly I am surprised it has enough stored energy to heat the wires, let alone the water.

Even if the OP eliminates the wiring problem, the voltage sag from the load will cause all kinds of problems including killing the battery bank through excessive sustained current draw and subsequent discharge below the threshold available to the battery chemistry.

Plus, as the voltage sags, the inverter will draw progressively higher current to sustain output, meaning a need for heavier wires to the inverter.

It is time for the OP to start again and reconsider their setup from the start. A little reading around CF will point them in the right direction.
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Old 27-09-2020, 19:48   #7
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Re: Wires Overheating

@GILow


The OP probably meant two 1000 Ah batteries not 100 Ah. Still not huge but a 10x difference. As for current draw, still way to much. I would look at stepping up to a 24V system or getting much bigger batteries, alernator/charging system, etc.



3000W over a sustained period is quite a draw.
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Old 27-09-2020, 20:01   #8
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Re: Wires Overheating

That's a very large load. Depending on run length your wire size may or may not be appropriate. However I suspect that the real cause of the problem is that the battery bank is under-sized. What's the voltage drop at the batteries under that load? The wattage of the heater is more or less constant, so any voltage drop = more current. More current = more heat. The wires might be correct for the load calculated at 12V nominal but under-sized when the voltage drop under load is considered.
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Old 27-09-2020, 20:05   #9
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Re: Wires Overheating

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@GILow


The OP probably meant two 1000 Ah batteries not 100 Ah. Still not huge but a 10x difference. As for current draw, still way to much. I would look at stepping up to a 24V system or getting much bigger batteries, alernator/charging system, etc.



3000W over a sustained period is quite a draw.
I doubt it. An 8D Lifeline AGM is 255Ah. Does anyone make 1000Ah batteries?!,
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Old 27-09-2020, 21:23   #10
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Re: Wires Overheating

Replace the heating element in your hot water tank with a 12V element to avoid using the inverter, increase the size of your battery bank (and add as much solar as possible). Check the wire connections, measure the Amps and then rewire accordingly (up one notch ?).
Use hot water only when the motor is running. Usually the water gets preheated in the motor and your alternator might help as well to provide lots of Amps.


-Richard
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Old 27-09-2020, 22:12   #11
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Re: Wires Overheating

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@GILow


The OP probably meant two 1000 Ah batteries not 100 Ah. Still not huge but a 10x difference. As for current draw, still way to much. I would look at stepping up to a 24V system or getting much bigger batteries, alernator/charging system, etc.



3000W over a sustained period is quite a draw.
Umm... I don't think I'd want to lift a 1000AH battery, even if it were Lithium.

I'd be HUGELY surprised it that's what the OP meant.

But then, sometimes I am hugely surprised I made it out of bed in the morning.
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Old 27-09-2020, 22:14   #12
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Re: Wires Overheating

Actually, I suppose they might have typo-ed and also meant to say that they had EIGHT of these...

https://www.evworks.com.au/winston-b...ah-lifepo4-cel

In which case, yeah, I wouldn't expect voltage sag.

But then I also wouldn't park my boat too close to theirs.
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Old 27-09-2020, 22:16   #13
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Re: Wires Overheating

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... Does anyone make 1000Ah batteries?!,
As it turns out, yes, but these are only 3 volts.

https://www.evworks.com.au/winston-b...ah-lifepo4-cel

Who'd a thunk it?
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Old 27-09-2020, 22:18   #14
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Re: Wires Overheating

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...

3000W over a sustained period is quite a draw.
Aside from your somewhat oddly optimistic battery bank interpretation... where did 3000 W come from? The OP was talking about 1440 W.

TWO water heaters perhaps?
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Old 27-09-2020, 22:21   #15
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Re: Wires Overheating

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Replace the heating element in your hot water tank with a 12V element to avoid using the inverter, increase the size of your battery bank (and add as much solar as possible). Check the wire connections, measure the Amps and then rewire accordingly...
This is such good advice it should be in a signature.
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