Diagnosing an electrical problem!

Hey everybody,

Been out putting this machine through its paces in preparation for a full month of work in February.

Tonight I was driving along and all electrical went dead, then came back, came back, dead, etc. Lights & other electrical loads turn off and the brake engages, bringing me to a stop. Then, without rhyme or reason, electrical comes back and I can drive again as the break disengages.

I think I have an open somewhere. Fuses aren't being blown. Tightened up the battery connections - problem persists. I've got about 500 watts of lighting on this machine. Maybe I'm cooking a main wire to the 12V power bar with excessive loads - not sure.

My approach is to trace the power from battery to the power panel in the front of the machine. Tomorrow when it fails I'll check it with a multi-meter at various places I can access.

Anyone have a better way to diagnose this little problem? My six-year-old is ready to help!

Thanks -

kgracey said:

Hey everybody,

Been out putting this machine through its paces in preparation for a full month of work in February.
Anyone have a better way to diagnose this little problem? My six-year-old is ready to help!

Thanks -

Click to expand...

KGracey,

Well if you are going to start tracing an open short, start at "A" the Battery and go thru "Z". Bouncing all over the wiring will more often than not eat up a lot of time and not find the short/open wire.

You said it dies totally and all? Then you know it isn't a bad battery terminal itself, if the engine was running and you remove the battery terminal, the Alt/Gen would supply the power to keep running. So you look at the first common spot that the battery and Charging system come together.

Since I don't know your machine, I will assume that the Starter terminals are the first place the power is split off to the system from the battery, that is normally where the Charging system is connected. So follow the Positive battery term. down to the starter to ensure that there is no other relays in the system. You may have something as simple as the terminal is loose.

Once the wiring system splits off to the fuse block, there may be some loose terminals in that line also. Just keep following the wires and check all the connections, by the sounds of it, you have a loose wire not a direct short to ground. But my guess by what you said it the open is going to be common to the charging system and Battery.

After checking between the battery, starter and fuse block really closely and if no issues are found, then keep going one step at a time down the harness.

You stated that you had a lot of driving lights, you may have a main automatic reseting circuit breaker that is "Popping" and then resets after a few min's, It may appear that if that was the case, it will be the main "Big" breaker that is about 80 amps or so in the main wiring harness before the battery and Charging system.

Since I don't know what kind of a "Rig" you are talking about, I am just giving you some generic ideas to work with, if you let me know more about the unit, I can be a bit more site specific.

Good Luck,

Mark

Mark,

Fantastic advice. I'll start in daylight tomorrow and trace it from the battery to the power bar.

The machine is a BR-302HD hydrostatic. Best I can tell the electrical looks pretty basic, like this:

Battery => Starter
Battery => Big Breaker => Power Bar
Alternator <=> Battery

All of the electrical that shuts off is also switched from the main panel (and "power bar") overhead in the cab.

I wasn't aware that there is likely a breaker. This could be cause for the problem - and I can test that out by lowering electrical loads (fewer lights) and observing if the same reset occurs. I'm going to head outside and look for the breaker now. . .but what's strange is that there's little consistency to load vs. shutdown in my view.

It doesn't seem that it could be an "open", to me. If it were, I may not see this intermittent power on and off.

So, it's got to be either a breaker overload or a loose fitting, like you hinted towards.

I'll head back outside in this awesome storm to see what I can find!

Thanks again - Ken

kgracey said:

Mark,


So, it's got to be either a breaker overload or a loose fitting, like you hinted towards.

I'll head back outside in this awesome storm to see what I can find!

Thanks again - Ken

Click to expand...

One other thing, if you don't seem to have a large load and it "Pops", then you may have a direct short that is popping the breaker with wire grounding while bouncing down the trail, that would be a totally different problem to look for and the breaker is doing it's job.

If it was a short from the different accessories, then the local smaller fuses would blow and that would be easy to find, so I would guess that the short (if you don't find a loose wire connection) is just after the big breaker, before the fuse panel...

Good luck.

ck your ground to the dash had this problem when bouncing along dash lost ground and shut everything off also ck starter solenoid that cables are tight

Hey all,

I think I found the problem.

This time, I kept the power budget low, using only about 100W of 500W of lighting. Did everything else the same - plowed snow, drove up and down hills, played like a kid, etc.

No power outtage.

Increased the power budget - turned it all on!

Power out!

Must be the breaker. I'll confirm tomorrow when I can see enough to take some power measurements.

Went back to 100W or so - no power outtage.

Must be the breaker.

Thanks for all the help.

Ken

Sounds like they are running everything through one breaker which is a big No No! Thats how cats catch on fire. I'm having the same issue on 2 of my cats which will be corrected soon. Also it looked like they installed bad manufactured wire at the factory on my Super Imp. I ran a new wire harness I built to my lights using 10 gauge wire. Next I will wire in two relays.

Snowcat Operations said:

Sounds like they are running everything through one breaker which is a big No No! Thats how cats catch on fire. I'm having the same issue on 2 of my cats which will be corrected soon. Also it looked like they installed bad manufactured wire at the factory on my Super Imp. I ran a new wire harness I built to my lights using 10 gauge wire. Next I will wire in two relays.

Click to expand...

Running the main power though one breaker isn't bad. What is bad is that the factory designed the load for that machine with the equipment that came with it.

Over time, people add radio's, lights etc. What happens the load exceeds the wire size and breaker size and that is when you start to have problems. When installing accessories, it is a good idea to run a second harness off the battery system with a fused line for that to isolate the systems.

Lights can be run off a relay that shuts off when you turn off the key, but draws the main power supply for the lights off the battery through a fuzed wiring system that doesn't affect the main breaker directly.

The other downside to adding all of the new stuff is that the charging system can't maintain the load and the battery slowly dies or burns out the charging system that is running at 110% all the time. So a bigger charging system may be needed and the wire coming from it may need to be larger also...

I am no electrical wizz by ANY means. I like the idea of the relay. Thats my next step as well. Fogteneder if to much draw is put on a breaker will it flip or just create the problem he is describing? It sounds like its a problem with the breaker. Either its getting really hot and malfunctions or...???? BUT I am just guessing at best.

Snowcat Operations said:

I am no electrical wizz by ANY means. I like the idea of the relay. Thats my next step as well. Fogteneder if to much draw is put on a breaker will it flip or just create the problem he is describing? It sounds like its a problem with the breaker. Either its getting really hot and malfunctions or...???? BUT I am just guessing at best.

Click to expand...

Sounds like the lights draw too much and the breaker does it's job and "Pops".

You can install a relay and hook it to the light switch that turns on the relay, but the power to run the lights themselves comes directly from the battery and a fused link so the main breaker is bypassed and not overloaded. But when you turn off the light switch, it secures all the lights at one time without adding more switches to the panel.

To turn on and off the relay by the light switch only draws a fraction of an amp so the main breaker doesnt' even notice that added draw, Power for the lights through the relay is drawn directly off the battery via a wire of the correct size with a fuse for the correct amp load.

Just make sure that the charging system can handle the load also, or your battery will slowly go dead because it is putting out less than the system is replacing...

At 500 watts you create a 41.6 amp load on that breaker and would need at least a #8 size wire to carry that amperage. Size your breaker and wire according to your load or spit your load across two breakers like someone else already said.

Kgracey, did you add anything to the cat, or just use what was there? If all the loads were there before you got it, it may handle them O.K. the way it is. You may have the main circuit breaker starting to fail. Use an amp clamp to see what it is pulling at full load. If it is less than the C.B. rating, and it still trips, then the C.B. is going bad. (for instance, a 50 amp C.B. that trips at 30 amps). If the system truly is pulling more than the C.B. is rated for, re-engineer the system to handle what you need. Create a second bus with its own circuit breaker for just the accessories.

Something that will up the amp draw, will be excessive corrosion on the terminals, that will cause your breakers to "Pop" also. So go though and do a good check of all those connections.

Or even a dead short in one of your lighting circits that may be wired in, but with no fuse and is wired directly to the Main Braker....

One way to see if you have a short in your system is to turn everything off. Then with you key in your pocket disconnect the battery ground. Touch the ground cable to the ground lug on the battery. If you get a spark you have a short somwhere in the system.

I learned that trick from BobP.