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Battery Post Heat

J

jor_tucson

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RV install with 1K watts and 2.2K inverter

Another rudimentary question. My Giandel inverter works great and my 2/0 cables are just barely warm but the end of the battery post is pretty hot @137 degrees F. I have a fuse mounted on the battery post as shown in the photo. Is it normal for that point to be at this temp? Thanks.
jor
1.jpeg2.jpeg
 
I have MRBF on all 4 of my batteries and they do not get hot.

Double check the cable crimps and the torque. Mount the inverter lug onto the fuse first, the bus bar cable second, And mount the small lug (is that power for a victron shunt?) directly on top of the MRBF fuse holder since that small cable has a built in fuse holder.

But honestly, I would prefer to land all cables on the bus bar and only one connection on the MRBF.

OK, I just realized you have the fuse holder on top of a lug. That is no good. Put the fuse holder on the battery first. Put the parallel battery lug on top of the fuse holder.
 
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How much current are you pushing through that fuse, and what amperage rating is the fuse? Fuses will and do dissipate heat and the amount of heat will increase as you get closer to drawing its rated value. That's how fuses work.
 
Thanks guys for this excellent info. I'll make those changes. The fuse is 250a. So far, I've used an inductive burner, tea kettle and a blender. The most amps I think were 135 or so.
 
OK. I made the suggested changes.
* Fuse on battery post
* Followed by battery lug
* Followed by inverter lug
* Followed by bus bar cable
* Followed by Victron power cable

I ran a tea kettle on it for awhile at about 134 amps. The post still got hot @ 125F. The cables are not getting hot.

Two questions:
1. I can move the Victron power cable to the bus bar. But in order to get to one cable on the battery, is it permissible to cable the inverter to the bus bar rather than directly to battery as the inverter instructions indicate?
2. Would I be better of with a different kind of fuse, a breaker for example or an inline fuse?
Thanks.
jorIMG_3399.jpeg
 
Last edited:
I wouldn't worry about the double tap much myself, the contact the lug to lug contact is probably not making the heat it's the fuse.
 
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the contact the lug to lug contact is probably not making the heat it's the fuse.


I'm sure that's the case as the cables are not hot. As suggested, I'm going to cable the inverter directly to the bus bar but should I get a different kind of fuse to avoid this heat?
Click to expand...
 
I believe that the heat is due to the multiple connections, rather than the fuse itself.
I count 6 at that location.
 
Fuses do tend to get warm under heavy load.
All those joints on that post will concentrate the heat in one place.

Its very nice to have a big copper buss to bring your connections too
It also helps to dissipate heat

If you have a good clean flat copper on copper connection it should not corrode or loosen up with heat cycles

But dissimilar metals will expand and contract different and sometimes this is trouble.
Most people here are probably familiar with aluminum copper connection problems.

Copper on copper is best, if possible get some Naval brass bolts and fastener to reduce that expansion and contraction difference.


Today we don't " fit connections "
When I started out I would cut and punch my own bus work to fit the job.
I was supposed to fit the joints, that meant draw filing for a clean connection.
As years went by this went away....

Most bus and bolt on lugs today are plated to improve the connections prevent corrosion.

You may use some copper to copper joint compound ( I do this when I have to connect new cable to an old copper bus that turned black )
Its just something I do and I find it happens in places like the sewage plant ( I spend a lot of time in the sewage plant when I am bad, thats where I got my tagline I am " #1 at #2 " )
 
What brand model is the fuse/fuse holder?

You can test for a bad cable crimp by removing the fuse holder and just attaching the cables directly to the battery and then making tea.

If it still gets hot, it's probably a bad crimp. You can further isolate by attaching one cable at a time then loading.
 
As long as your wires and bus bars are rated for the amps you want to put through them, putting everything on the bus bars would be the best solution. Here is how I did mine. I am adding 2 more batteries and all 4 of the battery connections will land on the bus bars. I just haven't decided if I will double up the battery lugs or get bigger bus bars.
Bus Bars.jpg
 
More great information. Thanks a million. I'm going to get all but one cables on the bus bar. The fuse holder, btw, is BlueSea. I'll do the crimp-test as suggested and try that copper joint compound. Maybe I'll replace my busses with the type shown in the phots (nice and clean setup). Anyhow, thanks to you all. I'll post later. Gotta buy a little more 2/0 red cable. Everyone have a great Saturday!
jor
 
I had the mrbf on my setup in the beginning. They started getting noticably warm over 100a. I've swapped to class t fuse and that's warm. But neither were anywhere near scalding. Bus bar will be safer in your config as stacking connections causes a few issues. (Improper torque, less contact area) And also less to have on a single point of failure.
 
jor_tucson said:
RV install with 1K watts and 2.2K inverter

Another rudimentary question. My Giandel inverter works great and my 2/0 cables are just barely warm but the end of the battery post is pretty hot @137 degrees F. I have a fuse mounted on the battery post as shown in the photo. Is it normal for that point to be at this temp? Thanks.
jor
View attachment 203752View attachment 203753
Click to expand...
Goodness gracious, …… get a high quality buss bar with several extra posts for future connections…get rid of all those stacked lugs…
J.
 
Its not a code requirement or anything, but rather than mount that sort of stuff to a combustible surface get a sheet of Glastic or phenolic board.

If you know any electricians that do industrial work its pretty easy to get a few small pieces of it from scrap electrical equipment where it is used as a.
The idea is if your connections get hot they don;t have to get hot enough to set fire to wood they just need to get hot enough to pyrolize the wood.
Overtime this reaction cooks the to wood to char.
Char is far more easily ignited than wood ever was..

Pyrolysis Prevention to Avoid House Fires

chimneykings.com chimneykings.com

You can get glastic in sheets or shapes to make what ever you like as a barrier between your project and wood construction material.

Alternately in Canada it used to be a code requirement to mount residential electrical equipment ( servicebox ) with some gypsum board behind it.
This is no longer code but I always like the idea and still do it myself

If you use some recycled phenolic be aware old stuff made before lets say?
1985?
it make contain Asbestos as a reinforcement material to make the brittle plastic more shock resistant.
Other more modern version of the product will use glass or canvas
 
jor_tucson said:
More great information. Thanks a million. I'm going to get all but one cables on the bus bar. The fuse holder, btw, is BlueSea. I'll do the crimp-test as suggested and try that copper joint compound. Maybe I'll replace my busses with the type shown in the phots (nice and clean setup). Anyhow, thanks to you all. I'll post later. Gotta buy a little more 2/0 red cable. Everyone have a great Saturday!
jor
Click to expand...

Glad to hear it's Blue Sea.

I bet you have a cable crimp that needs a bit more crimping or re-crimped or perhaps (as others suggested) the multiple cables stacked is causing the issue.

Also, torque and torque some more.

Proper torque is indicated by the inability to rotate the terminals when a good amount of side force is applied.
 
You can get a 2 terminal MRBF fuse. Stacking the lugs will cause you issues with these.

www.westmarine.com

MRBF 2 Terminal Stud Fuse Block | West Marine

Check out our MRBF 2 Terminal Stud Fuse Block and more from West Marine!
www.westmarine.com www.westmarine.com

In some instances I have put a pure copper 1mm thick washer on top, then the lug. Polish first

In all cases I use no-ox-id grease on all the contact points to prevent corrosion.
 
That smaller gauge voltage sensing wire can be moved to another battery terminal.
 
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