Strange voltage readings

[rob2]

What a marvellous day, yesterday! Warm, breezy and smooth water!

As I had a new lady as crew, I didn't want to make an issue of this. My 503 windgen was whirring away as usual, but when I switched the HRDX controller to read the two battery voltages, they showed around 4.7V. As the instruments and radio fired up without problems, I tried the engine - the starter ran at normal speed, although the engine started so willingly it was not much of a test.

I shall return with a multimeter to try and see what's happening, but I wondered if anyone recognises the symptoms? Always good to have a few ideas as a guide when troubleshooting.

Rob.

P.S. Good day? Even the outboard on the tender started first pull - and that's a first!

 

[rob2]

Phoned Marlec and they suggested that I should check the gen output off load - if there's a voltage then its working. Also suggested a poor connection somewhere in the wiring causing an attenuating resistance and voltage drop. As its showing the same false reading on both batteries, I'll be checking the negative connection tomorrow!

Rob.

 

[mattnj]

very low battery fluid levels gave me these symptoms last year

 

[rob2]

Hmmm...don't you just hate intermittent faults! Yesterday, the controller was indicating around 12.3V on both batteries and a meter check on the terminals showed around 12.7V - correct for blocking diodes. I checked the battery levels as suggested and wiggled all the connections, but couldn't get it to repeat the false readings!

I guess it'll just haunt me forever unless I get a repeat performance... On the plus side, everything still worked fine when the readings were off.

Rob.

 

[jfkal]

Hmmm...don't you just hate intermittent faults! Yesterday, the controller was indicating around 12.3V on both batteries and a meter check on the terminals showed around 12.7V - correct for blocking diodes. I checked the battery levels as suggested and wiggled all the connections, but couldn't get it to repeat the false readings!

I guess it'll just haunt me forever unless I get a repeat performance... On the plus side, everything still worked fine when the readings were off.

Rob.

Re tighten all connection. Bin the meter and relax.

 

[dhippey]

Sounds like a poor connection somewhere in the monitoring circuit.
No easy answer, just if it happens again I think this is the area to look.

Regards,
David H.

Have you heard about my project this summer? Check out www.eventoftheyear.co.uk​

 

[nealeb]

I get this symptom very regularly. The battery monitor typically shows 12.whatever for one battery and anything between 1 and 12V for the other. I know that in my case it's a poor connection in the cheap car-type fuseholder I use in the monitoring cable so it's certainly worth checking connections if everything else indicates that the system is otherwise OK.

 

[CSFenwick]

Hmmm...don't you just hate intermittent faults! Yesterday, the controller was indicating around 12.3V on both batteries and a meter check on the terminals showed around 12.7V - correct for blocking diodes. I checked the battery levels as suggested and wiggled all the connections, but couldn't get it to repeat the false readings!

I guess it'll just haunt me forever unless I get a repeat performance... On the plus side, everything still worked fine when the readings were off.

Rob.

Do you have a splitting diode between the wind-gen and the batteries?

 

[rob2]

No, no splitting diode, there are two separate outputs from the controller wired one to each battery. I suspect the controller has independant blocking diodes on each output as it has the facility to accept a solar input and the diodes will protect one good battery against discharge to a defective one, as well.

Rob.