question

fokke jongerden avatar image
fokke jongerden asked

Cyrix-ct does not work

When the cyrixct is connected with with the 86 pin to the minus of the battery, the relais stays closed and no current is going through. When the engine is running the voltage is abive 14,5v but it stays closed. When i do not connect the minus pin 86 to the battery the relais switches and stays open, but it does not close when the voltage is low and when the engine stops. Does anyone know if the cyrix-ct is broken or do i do something wrong?

Cyrix Battery Combiner
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I think you misunderstood the function of the cyrix.

The cyrix close if voltage is over 13-13.8V(with intelligent trend detection) on one side and open if voltage is under 11-12.8V(with intelligent trend detection).


cyrix-ct.jpg (53.1 KiB)
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David avatar image
David answered ·

Your description of what is happening makes full sense.

If Pin 86 is not connected to ground, then the Cyrix-CT will NEVER switch on (close) regardless of the engine voltage.

If Pin 86 is connected to ground, then it will operate as per the table posted by M.Lange, which it sounds like it is doing.


What is it you are expecting to happen?


One thing to note: If either side of the Cyrix-CT has a very low voltage (I cannot recall the value), then it will not switch on (close). So if testing the function, it is important to have a voltage (so a battery basically) connected on both sides. Other VSRs do not have this need as they are simple relays.


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fokke jongerden avatar image fokke jongerden commented ·

Tank you for your answer.

The thing is, I have the feeling it does not charge my secondary battery when the engine is running. I have a solar panel as well, which works, but I have the feeling that I don't get any charging from the engine when running.

I may be using the wrong words for explaining. But when I did not connect pin 86 to ground the cyrix did let through current. When I connected pin 86 to ground. It stopped. And I thought this is strange, but maybe I just don't understand. When testing I did not put a voltage on both sides. So that could be a problem. But with a voltage on both sides I don't now how I could test if it works...


My idea was that when the engine is running the voltage is high and the cyrix-ct switches on and let's through the current to the secondary battery. When the engine stops, the voltage level drops en the cyrix will switch off and stop current flowing from one to the other battery

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David avatar image David fokke jongerden commented ·

If Pin 86 is not connected to ground, the relay just should not work at all, so what you are seeing sounds strange.

Are you possibly mixing up Pin 86 - Ground; and Pin 85 - Start Assist

If Pin 86 is connected to ground, and Bolt 30 is at 14.5V like in your example, then the relay should close (and pins 30 and 87 internally connect together).

(just to clarify terms in case of any mixups - ON = Closed = LED On; OFF = Open = LED Off)

Try this test.

DO NOT start the engine.

A) Connect Pin 86 to ground; Connect Bolt 30 to the starter battery; Connect Bolt 87 to Bolt 30 (this makes sure there is a voltage on both sides).

The Relay should be open as the voltage will not be high enough for it to close.

Now with a wire on Pin 85 (Start Assist), tap that onto Bolt 30 for a second. This should turn on the relay for 30 seconds (and LED will come on)


B) Now leave the wire in pin 85 connected to Pin 30 and the relay will stay on and the LED will stay on. Now pull the lead on Pin 86 off and the relay should instantly go off (and LED off).


C) Finally reconnect Pin 86; disconnect Pin 85; and with Bolt 30 and Bolt 87 connected together you should see the relay still open (LED off). Start the engine and watch for the LED coming on very quickly (as long as your alternator is working, of course!)


If tests A, B & C all work as expected, your Cyrix-CT Battery Combiner Relay is working I would say. If one test does not work as expected, there would seem to be an issue I think.

If tests are good ,then at least the Cyrix should be eliminated from the troubleshooting if a charging problem still exists.

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