# How to test a SMART split charge relay



## philals (Oct 24, 2012)

Hi, thanks for all the help. I have been reading the forums and they have been able to answer almost all of my questions.

I have installed a SMART switch charge relay. There is no voltage change on the leisure battery when I turn on the engine. This leads me to think that the relay is faulty or that it's smart and recognises that my (new) leisure battery is fully charged. There is also no voltage change when I disconnect the battery terminals and put my voltage tester on the disconnected terminals.

Is there any way to test my smart split charge relay without draining my leisure battery and hoping that it charges it back up.

I do hear it click when I turn on the engine so I know current is getting to it

Any help would be great.


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## Firefox (Oct 24, 2012)

The reading for a fully charged battery should be about 12.9v. This should go up to 14.0 to 14.5 v when the engine is connected. It may take 10 secs for the relay to kick in.

If it doesn't the relay is faulty or you wired it wrong. What exact readings are you getting ?

Check the leisure battery earth. Check you have multi meter on volts DC not volts AC. Check you are getting good contacts on the probes.

If all else fails there is an adjustment screw on the smart relay.


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## philals (Oct 24, 2012)

Thanks very much for the information.

Update: the reason why it was not working was that we had not installed one of the fuses in the fuse holder. 

However we are having problems with the relay.

When everything is all connected the leisure battery is reading ~13v. We start the car and the voltage spikes to ~15v. After we turn off the engine it returns to ~13v. This seems fine as it shows the battery will be charged. However, once we take the terminals of the leisure battery the terminals still read ~13v telling us there is still a complete circuit with the starter battery.

Thanks for the tip about the screw adjuster I'll check it out in the morning.


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## Firefox (Oct 24, 2012)

Your readings are all normal apart from 15v is a little bit high for constant alternator output.

The battery will be charged at 12.9 /13v

When you take the terminals off (assuming there was no load) (accessories connected to the leisure battery) the reading across the battery will still be 13v.

You may find it goes down to 12.8 or 12.9 v when the battery has had time to rest after being charged.


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## philals (Oct 24, 2012)

Firefox said:


> Your readings are all normal apart from 15v is a little bit high for constant alternator output.
> 
> The battery will be charged at 12.9 /13v
> 
> ...



Thanks for the reply. 

The voltage was across the terminals which were connected to the leisure battery and now disconnected. If the engine is off the relay should disconnect them from the start battery. This is where I have my problem.

Hopefully adjusting the screw will help. They are both new batteries which may have a higer voltage than the screw is set at.

Cheers.


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## n brown (Oct 24, 2012)

i have found adjusting the little screw means you turn it totally anti clockwise,to the left.start engine,turn clockwise,to the right while listening for the click,when you hear the click,turn a little more.this is a where its abit funny.the only way to see if you have it right is-turn off engine-listen for a click as the relay responds,this may take a little while[vague  i know]restart engine listen for click-you're away!


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