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Message |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 155
Registered: 7-2005
Posted From: 152.20.216.103
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 26, 2007 - 3:59 pm: | |
I posted this on the other forum and thought I'd try here, too. I've got a 200 amp cont. duty solenoid to combine the house batteries with the start batteries. I can manually connect the two banks, if the start batteries are dead. Normally, I'd like the solenoid to be activated when the alternator is charging. I assume this means when the 'not gen' light is out. Is there a place to pick up 24v+ from the A/C breaker/termnial box in the front bay? Also, I have a Intellitec latching disconnect solenoid so I don't have to use the manual disconnect switch in the battery compartment. I want this to be disabled when the off-run switch is switched on to keep from disconnecting the start batteries when the alternator is charging. Is there a terminal thats hot when in the 'run' position in the A/C breaker/terminal box? Thanks for any help. |
Len Silva (Lsilva)
Registered Member
Username: Lsilva
Post Number: 93
Registered: 12-2000
Posted From: 71.30.254.255
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 26, 2007 - 4:17 pm: | |
David, You really need some documentation on your bus including schematics. Projects like this are so much simpler when you have the info instead of trusting others who may or may not be correct.
I'm sure there is a charging indicator in your bus but lacking that, you could use an oil or fuel pressure switch. It won't know if you are charging but it will know that the engine is running.
FWIW,
Len |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 156
Registered: 7-2005
Posted From: 152.20.216.103
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 26, 2007 - 4:28 pm: | |
Len,
I've got all the manuals for my '8 including wiring diagrams. I've not been able to find the info I need there. I've read a post from another user that did this, and I was hoping it wouldn't be a big deal to do. The HVAC in MC-8's won't turn on 'til the 'not gen' light is off, so I know that there is some interconnection, most likely in the breaker / junction box in the first bay.I suppose I'll just have to connect the start batteries back up, crank it up, and go to it with a multimeter. Thanks, though.
David |
Don Evans (Doninwa)
Registered Member
Username: Doninwa
Post Number: 19
Registered: 1-2007
Posted From: 65.61.96.82
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 26, 2007 - 10:48 pm: | |
David,
I'm not sure I follow everything, but sounds like you have a solenoid between the start batteries and the engine/alternator. If so, that would make me nervous. Even a momentary disconnect while running can be disastrous for the alternator and regulator. With out the batteries in the circuit the voltage goes through the roof and can damage anything still connected to the alternator.
Also, if the solenoid fails to connect and anything is direct connected to the batteries, possibly through the bank connect switch, when you hit start it will try to pull start current through that other circuit. A sure way to find out if everything is properly fused!
There is probably something I am missing here. If so, please disregard. Just trying to prevent unwanted smoke.
Good luck
Don |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 157
Registered: 7-2005
Posted From: 71.77.196.175
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 12:01 am: | |
Don,
It's a latching solenoid; apply a momentary current to the coil and it engages; reverse the polarity and apply to the coil and it disengages (disconnects). The reason I want to find a convenient connection that is hot when the run switch is on is to use a NC relay to prevent the disconnect solenoid from being activated. The second solenoid simply bridges both sets of 24v battery banks. This allows the house batteries to charge when the alternator is charging or to jump start if the start batteries die.
David |
Tom Caffrey (Pvcces)
Registered Member
Username: Pvcces
Post Number: 1059
Registered: 5-2001
Posted From: 65.74.64.138
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 12:31 am: | |
David, we have a GM, but I think you have some comparable circuitry, so I'll tell you how ours works.
Because, of two needs, the manufacturers came up with a common scheme. One, they didn't want to take a chance that the starter might be accidentally engaged with the engine running and two, they didn't want the heating system to be on if there was no output from the alternator.
They did this on our coach by unsing one relay that is pulled in by about 6 volts. It is driven by the relay terminal on the alternator, which puts out about half the charge voltage.
When it is released, the starter will operate. As soon as the generator starts putting out power, it pulls in the relay, which disables the starter and enables the HVAC system.
This same relay can provide the signal to turn on your battery combining relay whenever the generator is providing power to the HVAC. The good thing about this setup is that you don't have to remember to turn the relay off.
Then, if you add a switch to energize the relay from the house power, you can turn it on when you want to give the starting system a boost. I would stick to a mometary only switch for this purpose.
You can buy an already built combiner control to run your relay with more features if you get a Pathmaker and it's remote switch from Xantrex. That's what we have.
HTH and good luck.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 158
Registered: 7-2005
Posted From: 152.20.216.103
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 9:25 am: | |
Tom, I think the 'field' connection voltage is what you're referring to. I believe it's half the output voltage, which will be 12 volts on my 24 volt system. I'll have to use a small, 12 volt Bosch-type relay to activate my combiner solenoid (24 volt coil). I'd forgotten about using the field option. Now that I'm thinking about that, I believe there's a small relay in the HCAC control box that connects to the field. I hate when (I think) I've figured out something while I'm at work and can't check it! Thanks for the memory jog.
David |
Chris Peters (Chris_85_rts)
Registered Member
Username: Chris_85_rts
Post Number: 9
Registered: 11-2006
Posted From: 66.194.150.45
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 9:27 am: | |
Is there any concern here that connecting a good battery to a dead battery could draw much more than 200A, depending on the state of the dead battery? |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 159
Registered: 7-2005
Posted From: 152.20.216.103
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 11:39 am: | |
Chris,
Not really. I have volt meters on both battery banks and the original manual disconnect is still installed between the start batteries and the latching disconnect. If the house batteries go bad (shorted cell, etc), I just put the combiner switch in the center (off). I used a DPDT switch to allow combine (emer. starting), off, and auto combining (when the alternator is charging). The big disconnect, and it is physically very big, handles surges of something like 1000 amps for several seconds.
David |
doug yes (Dougg)
Registered Member
Username: Dougg
Post Number: 10
Registered: 1-2007
Posted From: 4.235.248.226
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 8:51 pm: | |
David,
Where did you get your Intellitec latching disconnect solenoid and what was the cost? |
Tom Caffrey (Pvcces)
Registered Member
Username: Pvcces
Post Number: 1060
Registered: 5-2001
Posted From: 65.74.64.138
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 10:04 pm: | |
David, what I was talking about was the RELAY terminal, not the FIELD terminal. You do not want to connect anything to the field terminal other than the voltage regulator.
The voltage at the field terminal varies all the way from near zero to the system voltage; the relay terminal only goes to about half of the system voltage, and it only turns on the safety relay after revving up the engine.
Once the generator is putting out power, the relay will usually stay energized.
The safety relay is located in the electrical compartment in our bus.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |
David (Davidinwilmnc)
Registered Member
Username: Davidinwilmnc
Post Number: 160
Registered: 7-2005
Posted From: 71.77.196.175
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 11:35 pm: | |
Doug,
I found the solenoid on ebay for about $45 new (a very good price). I'd look there first. I saw another not too long ago, but it was around $80. Tom, I'll investigate the relay situation with my multimeter. Thanks.
David |