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jaybeegee 02-17-2013 04:23 AM

Battery alarm troubleshooting
 
Any advice on why my Beta Marine BD722 Battery/Engine Alarm is remaining on after I start the engine?

Came up to the boat over the weekend and did a routine engine start. Apply heat for 10sec, key turned, buzzer comes on with low oil light alarm + battery + temperature all on, start engine and alarms remains on with the batter light on (oil and temp off)!

All wiring seems to be in place! But I noticed that if I use the battery selector switch (1 or 2 or both or off) the alarm goes off when the switch is in the off position but remains on in the 1 or 2 or both modes.

Thanks in advance!

I seem to be on a roll as this last few months has been one thing going wrong
after an other!


Jay

PorFin 02-17-2013 01:30 PM

re: Battery alarm troubleshooting
 
If you turned your battery selector switch off while the engine was running, you'd better check the diodes on your alternator -- they may very well be fried.

jaybeegee 02-17-2013 02:33 PM

Re: Battery alarm troubleshooting
 
Yes I realise now that was not a clever thing for me to do!

Are alternators and diodes something that would typically be repaired?

hellosailor 02-17-2013 02:35 PM

Re: Battery alarm troubleshooting
 
jb, go to WallyWorld or Target and spend $20 on a digital multimeter. Put it on the 20VDC setting and test your actual voltage, engine on/off.

That's the only way you'll find out if the problem is in the alarm, or your battery/alternator are dying. Unless you want to just wait to see what dies.

jaybeegee 02-17-2013 03:11 PM

Re: Battery alarm troubleshooting
 
thanks for that.

Yes I have sourced a digital multimeter and get a 12v reading on both batteries and around 13v when I connected the electric battery charger using the shore supply.

hellosailor 02-17-2013 03:13 PM

Re: Battery alarm troubleshooting
 
A battery that has rested should read around 12.6 when fresh. "12" would be more than half dead. A charger (or alternator) typically would put out 13.8-14.4 in bulk mode, and "13" would be way too low.

Stu Jackson 02-18-2013 12:38 PM

Re: Battery alarm troubleshooting
 
Quote:

Originally Posted by jaybeegee (Post 991304)
Yes I realise now that was not a clever thing for me to do!

Are alternators and diodes something that would typically be repaired?

It all depends on how it's wired. If your alternator output goes through the C post of your 1-2-B switch, perhaps, but sometimes if the batteries have been full and the regulator was not being "requested" to maximize alternator output, the alternator diodes might survive. Only YOU can tell, by firing up the engine and measuring alternator output voltage.

You might want to consider these articles:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

hellosailor 02-18-2013 01:44 PM

Re: Battery alarm troubleshooting
 
An alternator consists of a heavy metal frame, which more or less lasts forever, and a batch of cosumable parts. Wire windings, bearings, diodes, sometimes the internal regulator, etc.

Everything in the alternator can be replaced, so the alternator can be rebuilt (which means fixed) or remanufactured (which means stripped down and rebuilt 100% to original specs). Sometimes it is cheaper to simply buy a whole rebuilt/reman'd alternator, with a warranty, than it is to gamble on whether some shop is really qualified and going to charge any less to fix yours, IF it needs fixing.

It really pays to learn how to diagnose them yourself, since there has also always been a thriving community of "see? Your alternator's bad!" thieves around. As well as the nice men who spray the whole thing shiny silver when they've fixed it, which actually guarantees it will burn out again (gee, I don't know why) right after the warranty. All it takes is one extra coat of paint on the new diodes, and they WILL overheat and blow out early. All sorts of little tricks to keep the business repeating.

Best adice I ever heard about alternators, is to look in the shop. If it is a greasy mess? Walk away. Yes, it is a dirty business, and someone who is doing a good job will also usually keep their shop fairly neat.

jaybeegee 02-18-2013 03:38 PM

Re: Battery alarm troubleshooting
 
Quote:

Originally Posted by hellosailor (Post 991321)
A battery that has rested should read around 12.6 when fresh. "12" would be more than half dead. A charger (or alternator) typically would put out 13.8-14.4 in bulk mode, and "13" would be way too low.

thanks for this. I have checked my battery readings and with the engine off I got a 13 and no change registered with the engine on under load!

jaybeegee 02-18-2013 03:49 PM

Re: Battery alarm troubleshooting
 
thanks for all the tips! I have now removed the alternator which seemed to be the source of the problem as there was no charge the wiring in place. I take your point about all the cowboys around - I am hopeful that the electrician I will go to will be genuine as I am sending the part via a common friend!


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