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Fried EXP2BUS was EXP2BUS and non-functioning alternator

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ixb(at)videotron.ca
Guest

Posted: Fri May 01, 2009 5:24 am Post subject: Fried EXP2BUS was EXP2BUS and non-functioning alternator

Yes.



On Fri, 2009-05-01 at 01:03 -0400, Mike Humphrey wrote:

[quote] 

 

 Ian,

 Did you install a 40amp breaker per the instructions between the alternator 

 and the EXP2bus?  The Master breaker is only designed for 35amp on the 

 board.

 

 Mike H

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ixb(at)videotron.ca
Guest

Posted: Fri May 01, 2009 5:42 am Post subject: Fried EXP2BUS was EXP2BUS and non-functioning alternator

Thanks Ed.  I'll check for any signs of high current.  I was able to

check the power at the alternator and the 12V is getting to the right

pin, the warning lamp lead is connected to the right place (and showing

about 1V, not sure if that's what you would expect to see the other side

of a 12V LED) but it "felt right".



Your fellow RVer probably read the bit in the EXP2BUS about removing the

on-board relay if he planned to go above 40 amps, but you have to

replace it with an external relay.  In the end I did install an external

relay, so I jumpered the connectors on the board per the installation

instructions from the EXP2BUS people.



 	  Quote: 	
		  From what you are saying, I should be able to see charging current.  Do

you folks normally see a high current after starting.  I'm only seeing
	


about two amps, and not sure if I should expect to see a lot more, when

the partially recharged battery is at about 12.0V.



Regards,

Ian



On Thu, 2009-04-30 at 18:48 -0400, Ed Anderson wrote:

[quote] 

 

 Hi Ian,

 

 While I do not have an EXP2bus, I did assist a fellow RVer who had one that

 was giving him problems.  The problem was the battery would not stay

 charged, charge it up and over night it would be dead.

 

 I had no experience with the EXP2bus, but did have a voltohm meter and got

 the schematics off the internet.  To make a long story short, at some point

 someone had blown/cooked the Exp2 on-board 40 amp (Master) relay.  More on

 how I think they did it - which is my real reason for addressing your

 question.

 

 When I first pulled the board I noticed that the solder coating on some of

 the copper traces on the board had gotten hot enough to melt and run off - a

 sure sign of excessive current flow.  I then found that the master on-board

 relay was missing from its socket and a heavy strip of copper bar had been

 solder across two of the relays socket pins.

 

 The addition of this jumper strip in lieu of the relay resulted in the

 battery remaining connected to the alternator B lead (and other board loads)

 even with the master switch off.  The reason is that when the board's master

 switch is on all it does is ground the circuit through this relay and causes

 it to close (or open if switch is off).

 

 So with no relay and the jumper installed,  there was no way to disconnect

 the load drain on the battery which as a consequence was drained overnight. 

 

 I looking over the EXP2 diagram it became clear that IF the board's master

 switch was left ON AND the "B" lead of the alternator was grounded (or the

 alternator somehow shorted out) that the path of current went from battery

 through board (melting the solder from the traces), through the relay

 (frying the 40 amp relay) and on to ground through the "B" lead.  Now, I was

 not there, so don't know if this happened, but it certainly would fry the

 board if it did.

 

 So make certain that if you work on the board or alternator to disconnect

 the battery OR at a minimum insure the Master switch is OFF.

 

 Now, I don't know if your board has a problem, but if I had and Exp2 board

 and my battery was not charging I would check the on-board relay.

 

 Ed

 

 Ed Anderson

 

 Rv-6A N494BW Rotary Powered

 

 Matthews, NC

 

 eanderson(at)carolina.rr.com

 

 http://www.andersonee.com

 

 http://www.dmack.net/mazda/index.html

 

 http://www.flyrotary.com/

 

 http://members.cox.net/rogersda/rotary/configs.htm#N494BW

 

 http://www.rotaryaviation.com/Rotorhead%20Truth.htm

 

 

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Ed Anderson

Joined: 10 Jan 2006
Posts: 475

Posted: Fri May 01, 2009 3:35 pm Post subject: Fried EXP2BUS was EXP2BUS and non-functioning alternator

Ok Ian,



Yes, you can remove and jump the relay positions provided you are using the

jumper provided by the EXP2 manufacture for that purpose.  Jumping it with a

wire (as in the case I mentioned) simply will not work.  I believe the

proper jumper has a diode in the circuit to prevent the battery from

draining back through the generator.



Good luck, that's all I can offer.



Ed



Ed Anderson



Rv-6A N494BW Rotary Powered



Matthews, NC



eanderson(at)carolina.rr.com



http://www.andersonee.com



http://www.dmack.net/mazda/index.html



http://www.flyrotary.com/



http://members.cox.net/rogersda/rotary/configs.htm#N494BW



http://www.rotaryaviation.com/Rotorhead%20Truth.htm

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_________________
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

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