Just curious if I can use one of those heat gun devices to detect inadequately sized battery cables and connection points in my solar system?I'm only getting 15 minutes of run time on my 1200watt microwave on high before the low voltage sensor kicks in.Running 4 GC batteries (440 amps), 2000 watt full sine wave inverter with 700watts solar.My thought is to run the microwave on high and check each battery cable in the system to see which ones might be undersized by the amount of heat they give off.Is this a valid test?Ron W.

I measure voltage drop across terminals and cables under load.

Chris Bryant wrote:I measure voltage drop across terminals and cables under load.This would only test the capacity of the entire system. The OP is looking for a bad connection or undersized wire based on heat built up.As long as you take temp readings before and then after a big load on he system, such as a microwave, undersized wiring or bad connections could be isolated.

What size are the cables? Are they ALL of the same size? Innter connects large also? I dont invert my heavy loads but do run number 2 on all the battery stuff and number 4 on solar in and out. What size cable to the inverter? How far is the inverter from the battery? I would run 2/0 or 3/0 to that inverter if it's within a few feet of the battery.If I was inverting to 2000 watts I would also run heavier than number 2 on my batteries. With the system loaded you can use a digital meter to look for voltage drop of individual conductors. You may be losing more than you like and not generate a lot of heat. Volt meter is going to be more accurate than a temp reading. If you have several poor connection points or under sizing in general you can get a total resistance that will hurt you but not see a lot of heat at any one point.If you had one very bad connection point such as a loose cable it would show as hot, it may even be too hot to touch, it may even start to smoke and melt.It's extremely important to have all the wiring sized large enough or you are penalized forever. My solar should basically be ok with 6 gauge but I ran 4. 520 watts with about 3 feet from the solar control to batts and 12 feet from solar control to combiner box.You dont want any push in type fuse holders in your solar system either. No crimp plier terminal ends, hyd crimped ends and bare strand into terminal strips with set screws not yellow crimp on ends.

edatlanta wrote:Chris Bryant wrote:I measure voltage drop across terminals and cables under load.This would only test the capacity of the entire system. The OP is looking for a bad connection or undersized wire based on heat built up.No, this tests each cable and each connection. Why guess using an IR gun when you can *directly* measure the loss with an accurate meter. That's how I measured and found bad crimps- which were heating up- put a couple hundred amps load, and put a volt meter across every connection- not the entire system.Bad crimp- got hot:That was wrapped in elecrical tape.The OP is not going to find a bad connection on the solar side with a heat gun, but he could with a volt meter.

Chris Bryant wrote:edatlanta wrote:Chris Bryant wrote:I measure voltage drop across terminals and cables under load.This would only test the capacity of the entire system. The OP is looking for a bad connection or undersized wire based on heat built up.No, this tests each cable and each connection. Why guess using an IR gun when you can *directly* measure the loss with an accurate meter. That's how I measured and found bad crimps- which were heating up- put a couple hundred amps load, and put a volt meter across every connection- not the entire system.Bad crimp- got hot:That was wrapped in elecrical tape.The OP is not going to find a bad connection on the solar side with a heat gun, but he could with a volt meter.There you go!! Excellent example of how to not do it. A guy at a solar store was trying to sell my friend a hammer crimper. I told him I can do a better field crimp with a pair of vise grips. I bought a hydraulic crimp 16 ton on ebay for $36.00. Nothing to brag about compared to the $1,800 one I had at work but it gets the job done for us do it yerselfers. Under heavy loads I have seen several hammer crimps burn up.

Will laser heat sensor find inadequate battery cables?

33 Replies

pianotuna
Nomad III
Nov 24, 2015
Hi,

It is not so much the higher voltage of a 12 volt jar. It is that there are, for the same amp-hour capacity, twice as many cells, so the load per cell is 50% of what it is with 6 volt jars.

2oldman wrote:
15 minutes of MW is going to be a struggle even with 6 batteries. Higher voltage may help, but that's still a whopping load.
pianotuna
Nomad III
Nov 24, 2015
Hi Mex,

Thanks for explaining how to check for voltage drop across terminals.
JiminDenver
Explorer II
Nov 24, 2015
My IR gun would pick up anything that would be noticeably hot to the touch and it does help to be closer.

When we talk of running a microwave we say to use four 6v because while the Ah's may be there, the internal resistance will keep you from using it with just two. Four will do it but at the amount of run time you are talking, I wonder if you run into the same issue.

Using the solar to assist the bank can help keep the bank up but small wiring between the bank and the inverter is adding resistance itself. You may want to see if those wires are getting warmer while you run it because as the heat builds up, so does the resistance.

I have had our MW run 12 minutes nuking four large taters and three more minutes wouldn't have been a issue. Then again we have a little more solar, 50% more bank in 12v AGM that puke when you nuke and much larger wiring everywhere.
2oldman
Explorer II
Nov 23, 2015
rjsurfer wrote:
Michael Angelos Lasagna With Meat Sauce, frozen, 32 oz's.Cooks 15 to 17 minutes on high.Real good too....
I'll bet.

15 minutes of MW is going to be a struggle even with 6 batteries. Higher voltage may help, but that's still a whopping load.
MEXICOWANDERER
Explorer
Nov 23, 2015
Sorry Oldman, I was assssssuming he was using a Harboring Fright grade IR gun. Love to have a thermal imaging gun BTW.
rjsurfer
Explorer
Nov 23, 2015
2oldman wrote:
MrWizard wrote:
15 minutes, are you baking a turkey ?
x2. Please, OP, why do you need that much time on an MW?

No turkey, Michael Angelos Lasagna With Meat Sauce, frozen, 32 oz's.

Cooks 15 to 17 minutes on high.

Real good too....

http://www.michaelangelos.com/product.php?productID=1

Ron W.
2oldman
Explorer II
Nov 23, 2015
MEXICOWANDERER wrote:
An IR gun needs to be ONCE INCH NO GREATER distance from a small part to be probed.
that depends on the meter. Mine focuses 2 red laser dots, at about 8"
MEXICOWANDERER
Explorer
Nov 23, 2015
Multimeter set to TWO VOLTS DIRECT CURRENT

Fully Charge Batteries

Start microwaveon high

At each connection such as the battery lead post to battery cable clamp

Put the POSITIVE RED meter probe close side to the battery

Put the negative side on the ADJOINING terminal, post, nut, stud, etc.

RIGHT NEXT TO EACH OTHER

Keeping in mind the meter decimal point what do you read?

WRITE DOWN A LIST of junctions tested and voltage ALL the numbers on paper.

TRANSCRIBE the list of parts and numbers to a separate post on this forum.

The last thing written down is a separate test, stab both lead battery posts with the meter set to 20 volts.

SET THE METER KNOB TO TWELVE VOLTS DC

Then RUN RUN RUN

And stab both terminal POSTS (not the the lugs nor the nuts) going into the inverter. THE THREADED BOLTS THE STUDS THEMSELVES

Write that figure down and include it in your post.

This is the ONLY meaning SINGLE SOLITARY way you are going to find your problem without replacing a whole bunch of stuff.

An IR gun needs to be ONCE INCH NO GREATER distance from a small part to be probed.
RJCorazza
Explorer
Nov 23, 2015
A 2000w inverter should have a minimum of 1/0 cable to the battery with a short 3' run. With welding cable (flexible) 2/0 and larger is relatively easy to work with, and will allow slightly longer runs.
I have no idea how much heat would be generated at those loads with a x.x volt drop, but I do know the actual voltage drop can be accurately measured and expressed as a percentage.
jeomelia
Explorer
Nov 23, 2015
Chris is one of the top rv gurus, listen to him!