| Author |
Message |
Fred Mc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 7:11 pm: | |
I am making some changes to my 17 year old conversion (GM PD4106) and want to add house batteries, After reading many posts I think I want to use separate house batteries that are charged from the bus alternator(DN50)at the same time as the starting batteries. Xantrex has a device called the Pathmaker that seems to facilitate this. It combines the house and starting batteries for charging but separates them for discharge. I don't want or need an inverter at this time.
My other option seems to be to use a separate single wire GM alternator monuted to the engine somewhere.
Any comments on this plan would be appreciated.
Thanks
Fred Mc GM PD4106 |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 7:36 pm: | |
Fred,
I'll assume you don't have the bus air conditioning system anymore. And I don't know how much of the original electrical system is left in your bus but all you need was there to run the big blowers of the HVAC system. There was a 150 amp or so circuit breaker, a heavy solenoid switch and a relay connected to the 'r' terminal of the alternator. These were all connected to allow power to the blowers, through the circuit breaker, only when the alternator was delivering power. By simply taking the wire that used to go to the blower motors and connecting it to the house battery + and leaving the heat/off/ac switch in either heat or ac position you'll charge the house with the DN50 and the house battery will be isolated if the alternator isn't 'putting out'.
I've done it this way in my bus & it works fine. I do have a SW2512MC inverter wwich powers my air conditioners off of the house battery and the DN50 while I'm driving.
Regards
Jerry 4107 1120 |
Earl-8-Ky
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 10:05 pm: | |
Fred I use a one wire GM alt. on my MCI MC8 to charge the house batts. I used a low amp alt on the advice on the NAPA auto parts store. He talked me into it. The best reason he gave me is that it would not boil the water out of the house batts. He was right.I wonder if the power from the DN50 alt would be thru a regulator. You may over charge the house batts. Just something to think about. |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 11:15 pm: | |
Earl,
Are you in Kentucky? I'm in Science Hill Ky,about 60 miles south of Lexington.
The DN50 on Fred's 4106 has a regulator & it's adjustable. It should be set to deliver 13.7 +/-.2 volts, measured at the coach battery, to maintain the coach battery charge. At this setting it'll properly charge the house battery as well. The 4106 is a 12 volt coach so using the coach alterntor is easy, safe and practicle. Unlike most automotive alternators the oil cooled gear driven DN50 on GM busses is designed to deliver the full rated 300 amps continuously 24/7/365. And the regulator, when properly set, keeps water loss to a minimum.
Regards
Jerry 4107 1120 |
david anderson (Davidanderson)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 28, 2005 - 12:05 am: | |
Fred,
Call Dick Wright at Wrico. He engineered my system after I described what I wanted. Reasonable prices and wonderful service and very proactive in the bus conversion community. 541-744-4333 in Eugene Oregon.
David Anderson |
Fred Mc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 28, 2005 - 1:58 am: | |
Jerry,my concern in having both banks of batteries charged thru the bus system is that one of the banks may charge at a different rate that the other. So if, for example, the house batteries charge slower than the starting batteries, the starting batteries will over charge and boil out the water. Am I correct in this or perhaps I just don't understand how the charging works"?
I certainly understand that the alternator has plenty of capacity.
Thanks
Fred Mc.
Fred |
Fred Mc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 28, 2005 - 2:04 am: | |
Jerry again,in your post suggesting I use the circuit for the blowers(which I still have but am going to remove)will the DN50 alternator work the same as for the starting batteries through the regulator i.e.stop charging the house batteries when they have a full charge. If not, perhaps one could add a second regulator.
Thanks
Fred Mc. |
Jack Gregg (Jackinkc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 28, 2005 - 9:28 pm: | |
I have a pathmaker. It works great for me. I don’t use it so much to charge the house batteries as to allow me to run the A/C off the alternator while on the road. Basically it is a battery isolator that works in both directions. It connects the two systems as long as the batteries with the higher voltage don’t drop below a certain level (say 12.5 or 25).
It seems like it would not allow the starter batteries to overcharge because excess charge on those batteries would go to the house batteries until the house batteries are up to charge at which time the alternator would quit charging. The pathmaker can not give a three stage charge; it just lets the alternator charge the house batteries after the starter batteries are up to voltage.
Jack |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 29, 2005 - 5:49 pm: | |
Fred,
The alternator and it's regulator make a constant voltage source at the regulator's voltage if the load is less than 300 amps at that voltage. How much charge each connected battery gets is determined by it's state of charge and capacity. If two batteries of different capacities are connected in parallel, the higher capacity battery at the same state of charge will draw more curent than the lower capacity battery.
But there isn't any risk of over charging either battery if the regulator is set properly. I'll try to explain why. A battery's state of charge determines it's output voltage. When it is fully charged it will be about 12.7 volts. It takes about an additional volt of charging voltage before any current will flow(due to the rather complex electrochemical process involved) so at 13.7 volts of charging voltage a fully charged battery is taking no more charge and will not boil out any water. But a half charged battery has an open circuit output voltage of about 12.0 volts. The internal resistance of an 8D sized battery is about .005 ohm. The half charged battery will draw .7volts/.005ohms = 140 amps from that 13.7 volt regulated source (the DN50). and as it is charged the charging curent will drop. A higher capacity house battery will have a lower resistance than the 8D ( my bank of 4 ea L16's is about .002 ohm).
So the more discharged battery will be charged first and once they are at equal % of capacity the higher capacity will be charged with more amp hours per hour, but both will gain equal % of capacity per hour, approximately.
Regards
Jerry 4107 1120 |
Fred Mc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 29, 2005 - 9:07 pm: | |
Thanks Jerry. That explains it for me.
You also mentioned that you charge your house batteries from the former blower motor circuit. Does this not have to go through the voltage regulator or does the regulator control all the voltage coming from the alternator no matter what circuit you tie into.
Thanks
Fred Mc. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 30, 2005 - 6:09 am: | |
The nice heavy wiring up foward to the blower motors is fine to charge the House set with.
It is regulated and will charge just as the starts get charged.
IF you are concerned with rapid recharges a better 3 stage V reg might be in order, but if your rides are 4 or 5 hours that last elusive 10% will finally get pushed in.
Simplest controll is to use a solenoid (the ones that ran the blowers would be just fine) and use the ACC terminal of a key switch to energise the solenoid.
Your RV would be as seamless (no thinking required) as every RV made in the last 40-50 years.
KISS
FAST FRED |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 30, 2005 - 8:39 am: | |
Fred, In general, all charging current comes directly from the alternator, controlled by the voltage regulator.
Richard |
Steve Zona (Highwayrunner)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 30, 2005 - 3:32 pm: | |
Okay, I actually understand all of the above, but how would you accomplish anything like this with twenty four volt bus start batts, and twelve volt house batts, of course I love the idea of using the wire from the now removed blower motors, but how do I get that voltage down to 12 volts? |
Jack Gregg (Jackinkc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 30, 2005 - 5:34 pm: | |
. . . how do I get that voltage down to 12 volts?
.
search the archives for "equalizer" you will find plenty of stuff about having 12 & 24 volts at the same time. |