Voltage regulator

[grandx]

Here's my story:<br />Replaced both my "wet cell batteries" this winter with Orbital "AGM" spiral wound batteries. <br /><br />Maybe it's just a coincidence, but now my engine occasionally charges over 16V, I have 1996 Merc 150's with and a Garmin 240 fishfinder which has a safety feature and shuts down automatically if supplied voltage exceeds 16 V. First two trips this summer I exceed 16 V and fishfinder shuts down now and then.<br /><br />Seems to me, quite a coincidence that when I replaced my batteries, my voltage regulators go out at the same time. Is there something I can do to determine the source of the problem, and what do I do to fix it?<br /><br />Thanks in advance,

 

[grandx]

Re: Voltage regulator

JB, Schematic, <br />How about some electrical advise? Have (2) engines with (2) new batteries, and both seem to be overcharging on occasions??? Very coincidental for the voltage regulaters to go out at the same time shortly after changing batteries, is there something with these new AGM's that may be causing it??? Your best guess will be fine at this point.

 

[grandx]

Re: Voltage regulator

bump to top, don't want to get lost on page 2.

 

[petryshyn]

Re: Voltage regulator

sounds like you have an unregulated charging system and batteries with a high internal resistance.<br /><br />Its the old story......either retrofit a regulator, or turn on lights and accessories to keep the voltage low. If you have a selector switch, run with both batteries selected. It may help keep the voltage down....

 

[grandx]

Re: Voltage regulator

Thanks for your input Schematic,<br /><br />A little more info:<br /><br />According to the dealer, both engines have (2) voltage regulators each, and 40 amp alternators. Regulars cost $156 each. Both batteries, Voltmeters are reading high. Can we explore the battery "High resistance" some more, tell me why this would cause regulators to allow more than 14.5 V? or maybe give me some advise on how to trouble shoot the regulators themselves. Could a bad connection cause this? Anyone feel free to jump in.<br /><br />Thanks again.

 

[Paul Moir]

Re: Voltage regulator

AGM batteries have very different charge characteristics than gells or wet lead acid. First determine if you are really putting 16v to the batteries by puting a meter on the battery terminals directly while running. <br />If you are charging them at 16v then they will live a quick life. It is safe to bulk charge them at 14.4v (not 14.6!), but only current limited and switched off as the battery reaches ~90% charge. The only 'simple' way to charge them safely is to float charge them at 13.6v (not 13.8), unless otherwise stated by the battery. This can be done indefinately and without current regulation.<br />AGM's are great batteries, but one caveate - they will only last ~300 charges if you completly discharge them, which is worse than some deep cycles. Try not to let them fall below a 50% charge (~12.2v) and they will last a very very long time.

 

[grandx]

Re: Voltage regulator

bump<br />thanks for the AGM advise. They are receiving 16 V, looking for how to stop charging them so high.

 

[AndyL]

Re: Voltage regulator

I may be on the wrong lead here but I had a similar problem on 1993 merc v6 which only manifested itself when I fitted a Furuno LS6000 fishfinder. The voltage cut off for this machine is 16.5 volts. All my other electronics can operate over higher voltage range so I don't know if the system was ever correct.<br />On my motor there are 2 voltage regulators and I had only one go down. To trace it I discommected one then ran the engine with an avo meter across the battery, If you have a steady 14.6V when the battery is fully charged it is probably OK. Reconnect that and then disconnect the other and perform the same test. Mine started outputting 17+Volts so I knew which was down. In UK the cost of a regulator is about £165 or $275 but we always get fleeced.<br />I am sure someone more technical may jump in and tell you a different way to test, but I just could not afford to replace both as my wife told me!!

 

[Joe Reeves]

Re: Voltage regulator

Grandx.... I hesitate to add anything here as my line of expertise is not with the Mercury engine line.... and I wouldn't know a AGM battery if I fell over it.<br /><br />However, in following this thread, I am reminded of a service bulletin of many years ago from OMC which stated in not so many words that using "Maintenance Free" batteries would affect the charging system for some reason, causing a excess voltage reading.<br /><br />I encountered this a few times, and in each case, replacing the maintenance free batteries with regular marine batteries cured the excess voltage problem.<br /><br />If those AGM batteries fall under the maintenance free label, I'd replace them momentarily just to see what happens.