Traxide SC 80 cut out

[landoman]

I have a traxide SC80 DB system installed with standard Denpfender OEM battery and optima yellow top as second battery

On the weekend trip I was checking my battery voltages after running my fridge for a night and a day and a night and the voltage on my main battery had dropped to 11.89 v

The SC 80 green light was on but not flashing so looks like it never cut out at 12 volts ..........is there a fault here in that my SC 80 is not cutting out and how do I check if it's working properly ...should it be flashing when cut out ?

My car had no problems starting at the 11.89 volts but I'm a bit concerned that if it's not isolated it might drop even lower to a point I can't start my car

Thanks

[alien]

If the light was still on the batteries are still conected.
11?89 vs 12?00 for the cut out could be in the gauge used.
If in doubt ring Tim, I rang him recently on another issuee and as always he was happy to help.

[landoman]

If the light was still on the batteries are still conected.
11?89 vs 12?00 for the cut out could be in the gauge used.
If in doubt ring Tim, I rang him recently on another issuee and as always he was happy to help.

So the light goes out when the bartteries are disconnected ......not flashing ?

[alien]

So the light goes out when the bartteries are disconnected ......not flashing ?

When the light is on the batteries are conected.
Flashing indicates they are isolated from each other.

I normily get 2 days with the fridge on with cool ambiant temperatures before the isolator cuts out(I use the USI160 unit).
I'd try running the 2nd battery down a little more to a slightly lower voltage to confirm yours is cutting out.
As I've said talk direct to Tim as his after sales service is excellent.
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[landoman]

Thanks mate .....much obliged .....I'll turn on my fridge and run my optima right down and see what happens .....I should get a flashing SC 80 when it cuts out
......will that flashing keep up until I boost my cranking battery above 12 v

Didn't want to call Tim until I was sure of what I'm talking about so appreciate the help in clarifying my understanding ......

Also I have been told that to run your battery down to 12 v or lower is very bad for its life expectancy .........any thoughts on this ?

[austastar]

Hi,
Your fridge should have some smarts to prevent it over discharging the battery.
Cheers

Sent from my GT-N5110 using AULRO mobile app

[drivesafe]

Hi Landoman, your SC80 should have cut-out at 12.0v and I have them calibrated to somewhere between 12.0v and 12.07v.

With your cranking battery down to 11.89v at the battery, did you measure the auxiliary battery voltage at the battery?

Also, when it is convenient for you to do some tests, day or evening, give me a call and I will talk you though the tests and we can find out what is going on.

[drivesafe]

Also I have been told that to run your battery down to 12 v or lower is very bad for its life expectancy .........any thoughts on this ?

One more point, unless you are cycling a cranking type battery down to 11.9v every day, or unless you regularly cycle one below 11.75v, you will not effect the life span of a cranking battery.

Before the availability of Deep Cycle batteries, cranking battery were used as auxiliary batteries, and not abused, they gave pretty good usage as an auxiliary battery.

A lot more to it but this is the basics for getting good use from a cranking battery as an auxiliary power supply.

[landoman]

One more point, unless you are cycling a cranking type battery down to 11.9v every day, or unless you regularly cycle one below 11.75v, you will not effect the life span of a cranking battery.

Before the availability of Deep Cycle batteries, cranking battery were used as auxiliary batteries, and not abused, they gave pretty good usage as an auxiliary battery.

A lot more to it but this is the basics for getting good use from a cranking battery as an auxiliary power supply.

Thanks Tim

If I remember rightly both cranking and second battery were at 11.89 v and the green light on the SC 80 was light up
and not flashing ........

I have now plugged in my fridge ( its the only thing I run off the second battery )

I will run it to see if the SC 80 cuts out and at what voltage .....

The only other thing drawing on my DBS is my UHF radio ..This is hard wired to my Cranking battery so that I can always have use of it even if my second battery is run down .

Will give you a call after I check the voltages in the next few days

[landoman]

Thanks Tim

If I remember rightly both cranking and second battery were at 11.89 v and the green light on the SC 80 was light up
and not flashing ........

I have now plugged in my fridge ( its the only thing I run off the second battery )

I will run it to see if the SC 80 cuts out and at what voltage .....

The only other thing drawing on my DBS is my UHF radio ..This is hard wired to my Cranking battery so that I can always have use of it even if my second battery is run down .

Will give you a call after I check the voltages in the next few days


Hi Tim

Well checked all the wiring was intact on the system then I ran my fridge and ran the batteries down......the SC 80 cut out ( flashing green light ) At 12.1 v ....good

I then turned on the engine and put some charge in the system to 12.34 v
and I ran the fridge again until the voltage dropped and again the SC 80 cut out at 12.1v with green flashing light ....good .....all working as it should

So I cannot explain why it failed to cut out on the weekend and let my cranking battery fall to 11.89v

1) It was an extremely hot day .......could this have affected it ?
2) I used the same volt meter to measure on both days so it's not the voltmeter
3) By moving it around to check the wiring did I inadvertently fix a loose wire ?
4) could I have a fault in it that caused it to not cut out .....and if so how would I check other than above

My SC 80 is about 12 months old and used on a defender and this is the first time this ever happened and I have driven it across Australia and over very harsh terrain

I also used another SC 80 for 4 years on a discovery with out problem so I have great confidence in the system ....just would like to understand what might have happened in this instance .

Many thanks

[drivesafe]

Hi again Landoman, temperature is not a major factor with the Cut-Out level as the unit will always be quite warm because the relays are powered up.

If you had a loose wire, the SC80 will actually fail-safe, it will cut-out at a higher voltage.

I have no idea what would cause it to cut-out at a lower voltage on one day then work perfectly.

If the SC80 was faulty, it would, one would expect, stay faulty.

I can only recommend you keep an eye on the voltage levels and see if the situation repeats it self.

Sorry I can't be of more help, but that is a strange one, and I suspect it is going to be something other than the isolator, but ?

[landoman]

Hi again Landoman, temperature is not a major factor with the Cut-Out level as the unit will always be quite warm because the relays are powered up.

If you had a loose wire, the SC80 will actually fail-safe, it will cut-out at a higher voltage.

I have no idea what would cause it to cut-out at a lower voltage on one day then work perfectly.

If the SC80 was faulty, it would, one would expect, stay faulty.

I can only recommend you keep an eye on the voltage levels and see if the situation repeats it self.

Sorry I can't be of more help, but that is a strange one, and I suspect it is going to be something other than the isolator, but ?

Thanks Tim .......if it fails to cut out when the voltage on the cranking is below 12 volts then it would very much appear not to have tripped ........anyway I'll keep an eye on it and sees how it goes .....very strange ??

[vnx205]

I understand that you would like to know exactly what is going on.

However, I'm not sure that 11.89 volts is a worry. When the previous battery in my Defender was on its last legs, I measured the voltage at 10.5 and was able to start the engine - just.

It was pleasantly warm weather at the time. It would have managed it if it was cool. :)

[landoman]

I understand that you would like to know exactly what is going on.

However, I'm not sure that 11.89 volts is a worry. When the previous battery in my Defender was on its last legs, I measured the voltage at 10.5 and was able to start the engine - just.

It was pleasantly warm weather at the time. It would have managed it if it was cool. :)

Thanks good to know .......guess my concern was that while the voltage had dropped below set cut out volts ( 12) the SC 80 did not isolate the cranker

......I keep an eye on it to see if the issue recurs

[vnx205]

While I did manage to start with just 10.5 volts, if this chart is accurate then it seems that really is the limit.

I think Tim has posted something similar a few times in the past.

https://www.aulro.com/afvb/

I am certainly not suggesting that relying on a battery with a low SOC is a good idea.

I remember being astonished the first time I saw Tim's chart at how much a battery is already down by the time it gets to 12V.

As I said, I understand that you want to know what is going on. While 11.9 volts may not be a problem, the question is how much lower would it let the battery get if the cut out is not doing its job.

[landoman]

While I did manage to start with just 10.5 volts, if this chart is accurate then it seems that really is the limit.

I think Tim has posted something similar a few times in the past.

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fwww.marxrv.com%2F12volt%2Fvoltchar t1.gif&f=1

I am certainly not suggesting that relying on a battery with a low SOC is a good idea.

I remember being astonished the first time I saw Tim's chart at how much a battery is already down by the time it gets to 12V.

As I said, I understand that you want to know what is going on. While 11.9 volts may not be a problem, the question is how much lower would it let the battery get if the cut out is not doing its job.

Precisely ......that was the crux of the matter ......if I had not checked it and found the voltage below the cut out .....and the the two batteries still connected with the SC 80 not tripped then My cranker would have reached too low to start ....
I'll monitor it to see if this incident repeats ......

Ps ....excellent chart ...good to know you can start your motor on 50 %
.......some people have argued with me that not possible .....but appears it is

[drivesafe]

Hi vnx and landoman, that chart has been around for decades and with good reason.

The GREEN area is the section of the battery that is able to meet the CCA rate of a battery.

Most people are unaware that the CCA rating of a battery is maintained by a battery till it is discharged down below 40% of it's SoC ( 11.9v ).

So with landoman's SC80 not tripping at 12.0v, he was still within or close enough to his CCA rating and would have no problems starting his motor.

But this does not explain the strange one time low voltage????

BTW, I have tested quite a few new and newish vehicles, not just Land Rovers, and all started with batteries as low as 11.5v.

My TDV8 RR ( when it was running ) could be started with a cold motor, using a battery discharged down to 11.5v.

But at 11.3v, I could not turn the motor over.

[karlz]

...

My TDV8 RR ( when it was running ) ....

I really did want one of those at one stage.

Anyway, I love the explanations of how your gizmo works. I also have one in my Defender (ex Disco 4).

No issues so far, all works as normal.

I do have a big battery in the cargo area and I get at least 5 days use of the Engel starting the motor.

[Blknight.aus]

in one of the early units if you had the condition where you had good connections to the main battery and earth, the traxide to earth, ignition source and aux battery but the aux battery had a bad connection to earth with no alternate earth path for the aux battery through the load it would do some funny things when the main battery was more discharged than the aux battery.