ST 4000+ - one for the sparkies?

[cardinal_mark]

The last couple of times we've used our auto-pilot the low battery alarm has started sounding after about 10 - 15 mins of use.

I checked the batteries (3 X 80 a/h) after the last alarm and found them to be fully charged. There's no guidance in the Raymarine manual so I am well and truly stumped.

If anyone has any ideas what might be causing it I'd be grateful to hear of them... Oh, by the way, do please keep it very basic, I'm more than a bit simple when it comes to 'electro- babble'!

Thanks in advance

Mark

 

[Phoenix of Hamble]

did you disconnect the autopilot before measuring voltage?

If yes, then it maybe that the batteries are tired, and disconnecting the load allows them to recover a decent voltage level, yet put a load on them, and they drop voltage levels dramatically....

If you didn't disconnect the AP, then i'd only be able to hazard a guess at perhaps checking the wiring to the AP, but that doesn't explain it happening after a short period of time rather than pretty much immediately.... so there's probably another explanation

 

[halcyon]

The auto-pilot checks the voltage at the auto-pilot.
Therefore if the batteries are ok, you are looking for a volt drop between batteries and auto-pilot.
Get a multi meter and next time the alarm sounds, check voltages from battery to auto-pilot, bad coonection somewhere. But check voltages at battery first to make sure you do have a volt drop, and it's not actually the battery voltage.

Brian

 

[simonfraser]

loose wire to the pilot which is only caused when the boat moves ?

 

[mikefleetwood]

Got a radar? Or using the VHF to TX? Both draw heavy current and can flatten a tired battery or cause voltage drop in inadequate wiring. Try measuring the voltages in different places with everything switched on.

 

[Phoenix of Hamble]

Also, check the fuse if it has one in the circuit.... can corrode in the holder....

 

[FullCircle]

Check the wire going into the unit. If it is a nice silvery solder colour, they have at least used the right cable, and connection should be good.
If it is copper colour, and shiny, you also probably have a good connection, but someone has cut corners and not used marine grade cable.
If the copper is dark green or black, you almost certainly will have a connection which wont sustain high current loads, but which may show 12v at no or little loads. This means the copper has oxidised, and it will affect the whole cable.
You may want to try running a loose cable then from the battery to the unit plug and trying it to see if it has an effect.
No amount of healthy batteries will overcome this defect!

 

[cardinal_mark]

Thanks guys... the one thing I did forget to mention is the batt's are brand new. So perhaps the dodgy connection theory might hold most water?

I'll check it over at the weekend... or maybe I'll just go for a nice sail and add it to the list!!!


Mark

 

[qetoo]

I believe the ST 4000 will also give a warning if it cannot hold the course for whatever reason, such as too much cross current. Are you getting the "beeping" warning?

Do you have the wheel-autopilot version or the tiller-arm version?
I have the wheel-autopilot version and will sometimes get the off-course warning (beeping).