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Changing/ Adding Alternator

Thinking of upgrading my alternator... Thinking of going with the continuous duty 275-320amp range (if I can find a good deal).

What are your thoughts in keeping the original alternator for the start batteries and adding another for the house.. Keep in mind this will charge the Lithiums only as I drive..

Separating the lithium from the chassis batteries is a little challenging but not impossible.. getting a good charge at night while I drive and I also have added the A/C to the inverter and can run it off the batteries with no issues and I think the alternator will help in keeping a charge while in use and driving.

Ideas?

Re: Changing/ Adding Alternator

Reply #1 –
Mounting the alternator might be the bigger challenge. I personally would like to just put on a better and easier to replace alternator doing away with the Duvac.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Changing/ Adding Alternator

Reply #2 –
I would also go with a bigger single alternator.  I just did away with my isolator/combiner, and use my boost solenoid to combine both banks when needed. I just monitor lithium SOC and only combine when needed.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Changing/ Adding Alternator

Reply #3 –
Boost solenoid requires 3 amps to hold it together.  Never designed for continuous use.  Gets physically hot. 

A combiner consumes no power after engaging
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Changing/ Adding Alternator

Reply #4 –
Quote from: Caflashbob –
Boost solenoid requires 3 amps to hold it together.  Never designed for continuous use.  Gets physically hot. 

A combiner consumes no power after engaging
Actually replaced the boost solenoid itself with a latching type, so does not get hot or use power, a normal combiner will not work with two different battery types.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Changing/ Adding Alternator

Reply #5 –
Quote from: Caflashbob –
Boost solenoid requires 3 amps to hold it together.  Never designed for continuous use.  Gets physically hot. 

A combiner consumes no power after engaging
A "Ford starter style" boost solenoid isn't intended for continuous use, but there is a solenoid with that same form that is wound for continuous use.  Yes I gained that little bit of knowledge the hard way.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Changing/ Adding Alternator

Reply #6 –
Actually Foretravel must have found that if you use their battery selections that the  two different battery types they used can be combined or isolated without issues.

Mk gels and optima red tops either through an isolator or a combiner work great.

My high volume guru electrical buddy said the same thing when I asked him the same question.

Two separate alternators both being temp compensated from a BTMS at each bank would be the best.

Hot engine battery can need down to 13 volts to prevent overcharging.

As that is not easy to do the red tops ability to dissipate heat and take overcharging from their design made them Foretravels choice for every Unicoach ever made.  Yes a few years were yellow tops for whatever reason.

Red tops can take heat and overcharging well.  Mk gels can take incorrect charge rates and deeper discharges and never need equalizing. 

DaveS's use of lithium batteries that can take much increased charging amps is a different use


"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Changing/ Adding Alternator

Reply #7 –
Quote from: Caflashbob –
Actually Foretravel must have found that if you use their battery selections that the  two different battery types they used can be combined or isolated without issues.

Mk gels and optima red tops either through an isolator or a combiner work great.

My high volume g
Quote from: Caflashbob –
Actually Foretravel must have found that if you use their battery selections that the  two different battery types they used can be combined or isolated without issues.

Mk gels and optima red tops either through an isolator or a combiner work great.

My high volume guru electrical buddy said the same thing when I asked him the same question.

Two separate alternators both being temp compensated from a BTMS at each bank would be the best.

Hot engine battery can need down to 13 volts to prevent overcharging.

As that is not easy to do the red tops ability to dissipate heat and take overcharging from their design made them Foretravels choice for every Unicoach ever made.  Yes a few years were yellow tops for whatever reason.

Red tops can take heat and overcharging well.  Mk gels can take incorrect charge rates and deeper discharges and never need equalizing. 




uru electrical buddy said the same thing when I asked him the same question.

Two separate alternators both being temp compensated from a BTMS at each bank would be the best.

Hot engine battery can need down to 13 volts to prevent overcharging.

As that is not easy to do the red tops ability to dissipate heat and take overcharging from their design made them Foretravels choice for every Unicoach ever made.  Yes a few years were yellow tops for whatever reason.

Red tops can take heat and overcharging well.  Mk gels can take incorrect charge rates and deeper discharges and never need equalizing. 




Bob, look at OP's question, and my signature and you will see why your methods will not work.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Changing/ Adding Alternator

Reply #8 –
With lithium you ARE in new territory. 

"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Changing/ Adding Alternator

Reply #9 –
 I added one Delco alt just the way that you describe. Works fine as hoped , runs my resi fridge .  I removed the dash AC compressor as it  was problematic . And fit the alt in the same belt slot.

Re: Changing/ Adding Alternator

Reply #10 –
Quote from: jcus –
Actually replaced the boost solenoid itself with a latching type, so does not get hot or use power, a normal combiner will not work with two different battery types.
Latching solenoids are the ticket. Use zero juice either open or closed. Exactly like the VW headlight latching solenoid many of our coaches use for the 12V water pump. Not expensive either.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Changing/ Adding Alternator

Reply #11 –
High output alternator has come before IRC they are very hard on belts. Has anyone used the PTO for anything?
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Changing/ Adding Alternator

Reply #12 –
All Greyhounds had direct drive 300 amp brushless oil cooled alternators. My bus conversion had one. PT0 also ran the radiator fan. No belts on any kind on the engine.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Changing/ Adding Alternator

Reply #13 –
I separated the alternator charge circuit from the engine power/starter circuit. This allows me to charge a small 35AH AGM lead battery which runs an inverter which runs a charger that intelligently charges the 13.2V 400AH lithium start/coach backup battery. So while the engine is running, this charges the 13.2V 400AH lithium start/backup battery at whatever current I want.

The 13.2V 400AH lithium battery is a backup for my 48V 180AH lithium - solar house charging system.

While the engine is running, the engine, coach and toad lights draw about 40Amps at night and only about 10 amps during the day. I would not buy a massive alternator because of the massive wire gauge required, the stress on the belts and pulley and lower MPG.

I would rather recommend a Sunpower solar upgrade.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Changing/ Adding Alternator

Reply #14 –
My smart battery isolator switches any amp input be it the charger or alternator back and forth between the start battery and house battery bank based on voltage. Once start battery is at peak volts, it switches to charge house batteries. Once start battery falls below the threshold voltage it again charges. Not quite sure, but it seems logical that the alternator has no idea the convertor is now charging on shore power. Don't know if the OP BMS can accommodate. My isolator is only rated for 200 amps.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Changing/ Adding Alternator

Reply #15 –
Quote from: Old phart phred –
My smart battery isolator switches any amp input be it the charger or alternator back and forth between the start battery and house battery bank based on voltage. Once start battery is at peak volts, it switches to charge house batteries. Once start battery falls below the threshold voltage it again charges. Not quite sure, but it seems logical that the alternator has no idea the convertor is now charging on shore power. Don't know if the OP BMS can accommodate. My isolator is only rated for 200 amps.

I bought a Victron 200 amp isolator. I had thought of increasing my alternator to a 240 amp or above unit. I called Allen at Bay Marine ( he sold me my Victron equipment) and asked about my isolator not being rated to over 200amps.
He advised me that probably it would be extremely rare to actually see 240amps come out of the alternator and if it did it might only be temporary, the Victron would have no problem.
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Changing/ Adding Alternator

Reply #16 –
Quote from: DavidS –
Thinking of upgrading my alternator... Thinking of going with the continuous duty 275-320amp range (if I can find a good deal).

What are your thoughts in keeping the original alternator for the start batteries and adding another for the house.. Keep in mind this will charge the Lithiums only as I drive..

Separating the lithium from the chassis batteries is a little challenging but not impossible.. getting a good charge at night while I drive and I also have added the A/C to the inverter and can run it off the batteries with no issues and I think the alternator will help in keeping a charge while in use and driving.

Ideas?
David,

What is driving your requirement for an upgraded alternator? (probably running your ACs on the road)

I am about to go "Lithium" as well and was interested in what kind of issues you have run into.

Guy
2000 U320 4010 WTFE #5609
2017 Ford Explorer toad
Current RVSA Certified RV Technician
Previous 2001 Forest River Windsong 340

Re: Changing/ Adding Alternator

Reply #17 –
Using AC on the road is one but it does work as of now on the road.. I added a li-bim 225 but figured if I get a constant use alternator with massive amps it will be able to charge the lithium and not burn up.