rectifier tosted?

[kazek]

greetings.i found today that my 25 amp full wave bridge recrifier has burned connections same as issolating tape it was wrapped in.took tke boat for a long run today at WOT and at one point tach stopped working,so i thought that plug got loose.then i see battery gauge is steady at 12v.so after getting back home (managed to keep engine running)i found the insulation tape on rectifier burned.what would caused that?

 

[oldman570]

Re: rectifier tosted?

Better check the water in the battery as it could be low. Bad connections from the battery to the rectifier will cause trouble also. JMO
oldman570

 

[Texasmark]

Re: rectifier tosted?

Most rectifiers are made to recharge a charged battery, not to charge a discharged battery. Reason being they are not heat sunk adequately to dissipate the heat that comes the long high current charging. So think about that and what you subjected your charger to and you might have your answer. 12v is basically a discharged battery. 12.75 measured after at least 24 hours from being charged (stabilization) is what I use for a full battery. While charging varies with charge needed but when battery is near full will be up near 14.5.

Mark

 

[kazek]

Re: rectifier tosted?

it was a while when i used charger on battery last.i use the boat often and didint had this problem.i will pull battery out,check water in it and charge it.i hope this helps.i was using fishfinder and running motor at minimum rpm for a period of time.motor is 1975 merc 850.thanx

 

[Chris1956]

Re: rectifier tosted?

if you have a good battery and the wiring is good, you should no issue with that charging system, as it is maybe 9A at most. Make sure the rectifer is good. A 25A bridge sounds like the Radio shack brand. If so, you have a clean ground on the -DC connection, right? You have bolted it to the front cowling support? it will need a heatsink.....

 

[kazek]

Re: rectifier tosted?

connections at rectifier were are tight and clean.can't say that about battery connection.i could unscrew nuts by hand,thanks merc850,added some water also.battery was discharged and is charging now.chriss.... and texas......i get ur point now that i need a heatsink(did not have that before,just wrapped in the tape.thanks for a lesson.i will post back at closest opportunity if its all good

 

[Chris1956]

Re: rectifier tosted?

Ditch the wingnuts and get some nylon lock nuts in stainless steel. BTW I have never seen the stator blow out the $5 Radio Shack rectifier, but it sure can blow the $50 merc ones.

 

[kazek]

Re: rectifier tosted?

i see.thanks.yes its radio shack rectifier.is the testing for it is the same as for merc rectifier?

 

[Chris1956]

Re: rectifier tosted?

yes, testing is the same.

 

[Texasmark]

Re: rectifier tosted?

connections at rectifier were are tight and clean.can't say that about battery connection.i could unscrew nuts by hand,thanks merc850,added some water also.battery was discharged and is charging now.chriss.... and texas......i get ur point now that i need a heatsink(did not have that before,just wrapped in the tape.thanks for a lesson.i will post back at closest opportunity if its all good

I use white thermal grease between my rectifier and the plate to which it is mounted. Helps the thermal conductively immensely....RS has that too.

Mark

 

[kazek]

Re: rectifier tosted?

just as i thought...rectifier is burned.i got new rectifier 25amp 200v.just finnished testing and numbers differ from mercury manual.there is opposite readings.....no conductivity with red lead to ground and blk to ac.i have flow opposite way thou.no conductivity between ac terminals.conductivity with red lead to positive terminal and ac but no flow other way.is this a good rec..?it flows one way only but opposite direction than genue merc manual and other post that i have read.i am comfused.should i still try it on motor?

 

[Chris1956]

Re: rectifier tosted?

The rectifier is likely fine. The interpreter of the test got it backwards. Are you using a digital meter to test diodes? They can be tricky.

 

[kazek]

Re: rectifier tosted?

I checked with both digital and analog.same readings.power flows only one way ,so i took the boat for a test ride with new rectifier.it works.i peaking at 17 volts at wot.is it possible to charge two batteries with this rectifier and how connections to be made ?

 

[Texasmark]

Re: rectifier tosted?

On testing continuity, it depends upon how the meter mfgr. mounted the battery. If installed reverse polarity from the person making the manual the readings on diodes will be reversed. Normal.

Glad you got it working.

Mark

 

[oldman570]

Re: rectifier tosted?

Yes there is a switch that will allow the system to charge multiple battries. They can be bought at dealers or online. I do not recommed them as they vary often add to the confusion when things go wrong with the electrical system. JMo2
Oldman570

 

[Chris1956]

Re: rectifier tosted?

That charging system is not real robust. It is about 9 Amps at WOT, less at part throttle. I am not sure it will charge two batteries with any real benefit.

 

[kazek]

Re: rectifier tosted?

ok, thanks guys for directing me in right direction.