[TG] [TG11] A65 Battery alarm

[Rich1982]

Hey, need some help. recently purchased a new boat with a RM A65 with DSM25. Everything works perfect other than the unit keeps alarming saying battery low alarm. Managed to get Battery readout on screen and its bouncing from 12.6 down to 9.5 volts.
I have checked both my batteries and they are fine. also had a multimeter on power supply to unit which remains steady at 12.4 volts. also done a factory reset. Still have the alarm.

Any help would be appreciated.

cheers

[Tom - Raymarine - Moderator]

Hello Rich,

There are two possibilities here:

1. You have a high-resistance connection somewhere between your battery and the A65/DSM25's power supply, so that whilst you have good battery voltage, you don't have good supply voltage reaching the display. This sort of thing is extremely common on boats where you have a very harsh, corrosive environment with lots of vibration to create loose contacts and brittle breaks in flexing cables and connectors. Don't place too much reliance on a multimeter's voltage measurement: the DSM25 will draw brief bursts of current as it recharges its reservoir capacitors and these brief bursts will tend to produce correspondingly brief dips in supply voltage that are too short for the slow sampling rate on a multimeter to pick up. We very often see poor power supplies that look fine on a multimeter.

2. You have a hardware fault in the display where it's no longer able to measure the voltage accurately.

A good way to test for (1) is to connect a small load (incandescent nav-light globe, small 12V motor etc.) into the sockets on the end of the display or DSM's power cable, and then measure the voltage at that point under load. If the multimeter shows >12V and the motor/globe work strongly then your supply is indeed fine (at the time of measurement) and the problem is the electronics. If on the other hand you measure low voltage or the globe is dim or motor slow then your supply is bad despite the previous multimeter measurement.

If the problem is the A65 then I'm afraid it's time for replacement: that product was introduced in 2006 and retired 2009 and can't now be repaired. An Axiom 7 DV or Axiom 7 RV can re-use the same transducer via an adaptor cable (A80484 for Axiom 7 DV, A80488 or A80491 for Axiom 7 RV), has a similar screen-size but is 15 years later in technology design. You can see details of the Axiom range here.

Regards,
Tom