Wire size short/long run

JDCAVE said:

...The reason for 4/0 is because of the length of the cable run to the inverter charger and the associated voltage drop when under large loading. Since the current cable size is 2/0, I asked if the connectors between batteries could remain at 2/0 since the current between the individual batteries would be considerably less than that of the mail cables to the inverter charger. He indicated that while that could be done, he urged best practice would be to switch everything over to 4/0 all the way to the inverter charger...

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Jim: We went 4/0 from the negative and positive of the battery bank to the inverter as per the manufacturer. I would have had a difficult time with the battery posts if I had done all the interconnecting with 4/0 because of the lug thickness. Check your post type and height. After 7 years with a 2800 watt invertor, the 2/0 interconnecting cables has worked with no issues.

side note: Our T-105's had ELPT (embedded low profile) posts. If our batteries had the EHPT (embedded high profile) posts, I would have been OK.

psneeld said:

OK....how do YOU base what wire size to use on a run?

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Use the tables to determine a minimum wire size. Use a voltage drop calculator to see if you need to go larger, not to try to get away with smaller.

QB said:

Use the tables to determine a minimum wire size. Use a voltage drop calculator to see if you need to go larger, not to try to get away with smaller.

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Right...so we all use the same tables...not sure what your point was to Kevin.

caltexflanc said:

What's the old saying? "The nice thing about banging your head against a wall is that it feels so good when you stop!"

Not so, current, which is measured in amperes, will be the same all across all the battery-related cables.

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Clearly my electrician agrees with you!

Larry I'm not sure what posts I have. Probably the low ones I think. I guess I'll cross that bridge when I get to it!

For now I have the 2/0 cabling, but we need to do the load tests to see what the voltage drop is with higher inverter loads. I've only run the microwave occasionally and for a maximum of 3 minutes at a time. It's a 1000 watt model I believe so we haven't gone to the full potential of the inverter. The cables remain cool with the full charger load.


Jim
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Guys this is not really worth arguing to me.

No, I generally would not choose to use a smaller size inter cell jumper than my load cables.

I reserve the right to do so, simply because from a technical standpoint I can.

I am an old man and have spent a lifetime making a living thinking about among other things wire size and battery banks so I'm not too worried about my decisions in this area.

For the laymen out there... Use a wire size table. That way you will always get the right size cable for the job.

To keep the heat down on those terminals , you might consider using copper nuts ,

as their ampacity is far better than SS.

Harder to find tho,,,,