blank autohlem bidata screen - again

[portvasgo]

This problem started sometime ago, and thanks everyone for the good advice, however I am still having problems with a blank display on an autohelm bidata screen. To recap, I have a very simple electric set up on our Hunter 23. One leisure battery topped up by the engine (outboard) and a small solar panel. I have a single screen autohelm Bidata screen that shows speed and depth readouts. This has now gone completely blank on two occasions. Following the advice given last time, I have used my multimeter (First time I’ve’ used one!) and this showed a charge to the back of the screen of 9.6v. I checked the reading between the battery terminals and the same reading was given. I therefore suspect the battery is not ’very well’. Last I had this problem, I charged the battery, connected back up and the bidata screen worked. My question is this.
1. Although the reading on the battery was low, the lights, and VHF seemed to come on ok, but not the bidata screen. Do these screens just shut down if the voltage drops below a certain level? The screen was not fading or anything like that. It was working fine during the day, I switched it off and then a few hours later wanted to check depth but when I switched it on – nothing!
2. On bringing the battery back home and charging it, it came to full power on my charger after only 30 minutes or so. The last time I had the problem it did the same. The last time I had no multimeter and assumed the battery was nearly fully charged before charging and was not the problem. But this time, knowing it was reading 9.6v before I started, does this mean there is a problem with the battery. ie not holding charge?

Your thoughts to help a novice would be most welcome, they were last time. Hopefully, I am beginning to narrow the choices down, and learning all the time!

 

[oldsaltoz]

G'day Cuddy,

Sounds like the battery is on the blink. How is the water level in each cell?

A cheap Hydrometer will indicate what each cells charge state is, so if one has gone this inexpensive item will tell you, confirming your suspicions.

I doubt a battery would go from 9.5 volts to 12 in 30 minutes, did you take a reading with your meter and was the charger disconnected at the time?

I hope this helps

Avagoodweekend......

 

[Bilgediver]

You have one duff cell in your battery....Check the fluid with a hydrometer and I bet the cell nearest the plus mark is lower than the rest and drops first as soon as you apply load...


The reason for this is shown in your letter...you charg with the outboard and a solar cell. I suspect you never manage to get up to equalisation voltage of 14.4 which is very important with leisure batteries.

You might recover the battery with one of those zappers advertised in the magazines however if you buy a new battery and want it to last then get a charger which isn t full of fancy cutouts and voltage limiters and will pump in at 14.4 volts at least.

The normal Halfords cheepies aren t too good with leisure batteries but someone here recently mentioned he had seen 3 stage chargers at HAlfords which were cheaper than the marina priced items.

 

[portvasgo]

Thanks for the replies.

I set up and charged the battery overnight, actually about 18hrs. The reading under charge was 13.2v, straight after disconnection, it was 13.1v. 18hrs later it was reading 12.4. Tomorrow I am going back onto the boat and I will reconnect the battery and see if the bidata screen comes on, and how long it lasts!

Thanks for all the replies trying to help me sort whether my battery is ‘past it’, I have a feeling that it may well be on the way out. It came with the boat, and I’ve had the boat 4yrs.

I have another question, if my battery is ‘past it’ would this cause the bidata screen to suddenly cut off in the way it did? The VHF and lights were still working, although I did not leave the lights on long, and I had no way of checking the strength of signal on the VHF. The screen just went from ‘working’ to ‘nothing’, is this how these screens behave, ie they need a certain amount of voltage to work, and below that voltage, they just cut off completely without warning?

Thanks again, although I would love to get this sorted out (don’t mind being without the trip, but don’ like being without the depth reading), it really is quite interesting trying to narrow down the problem, I just wish I had more expertise.