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Topic: Alternator size upgrade (Read 822 times) previous topic - next topic

Alternator size upgrade

All this discussion on Solar vs generator vs added battery capacity is fantastic but it has my head spinning on what direction I need to go.
My personal opinion is that ALL are the answer, its like picking the right tool for the job at hand.
I will start with increased battery capacity and build from there. To go further will require the Freedom inverter to be upgraded to a more efficient modern design ( can't complain about the 22 years of service the original has provided)
With more battery capacity I think I will need more charging power, while the coach is under way. I don't see myself sitting for hours with the generator on, charging batteries.

You that have upgraded your alternator to a larger size, HOW is that working out for you?
Any "if I had to do it over again" thoughts?
Also, I like Bretts "do away with the isolator" idea. I like K.I.S.S.
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: Alternator size upgrade

Reply #1 –
"Proper" alternator size had to do with a lot of factors:

Planned driving time/frequency when dry camping.  A standard 160 amp alternator is just fine for charging if you are driving for several hours.

If running the main engine/alternator while not driving, you really want to minimize run time.  So, that starts with AGM batteries with lower internal resistance so that they can safely accept a charge faster. It means oversized wiring for minimal voltage loss at high amp charge rates.  It would benefit from removal of a diode-based isolator (that turns some of that precious electricity into heat). It may mean a smart regulator and good monitoring system.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Alternator size upgrade

Reply #2 –
Quote from: Lon and Cheryl –
You that have upgraded your alternator to a larger size, HOW is that working out for you?
Any "if I had to do it over again" thoughts?
Also, I like Bretts "do away with the isolator" idea. I like K.I.S.S.
In our ex-U300 with the DD 6V92 I upgraded from the stock 160 amp L-N to a 300 amp Delco brushless alternator, along with the wiring and isolator. I made my own cables and crimped my own terminal lugs. It worked like a charm, faster charging after boondocking, and helped to support running the inverter to power the fridge on AC while driving.

300 amp Delco 40si alternator/isolator/cabling upgrade

Roger Engdahl has also recently upgraded his alternator, maybe he will chime in.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Alternator size upgrade

Reply #3 –
I never thought my 160 amp alternator charged batteries as much as they should have or kept up with loads while driving (AC or heat, headlights etc.) And rebuilding it was going to be about $300.  With Peter Flemming's encouragement and help I found a new 240 amp Delco Brushless alternator for just over $600, installed that and a smart three battery bank Sterling no-diode isolater.  I made all of my own bigger cables.  Get the right tools and do it right.  It doesn't take many to start costing less than having them made for you.  So far this works great.  Start battery voltage while driving is almost 1 volt more than it used to be.  House batteries are much closer to 100% after a days drive even with running lots of things as we go.

Make sure your batteries are good.    Have your alternator tested.  Be sure the FT connections to the LN alternator are in good working order.  Clean every battery connection and cable common posts, put on some anti-corrosion protection and tighten all the connections.  If everything is in cood condition then you can start looking at which parts make the best sense to fix. This is like many things, it is hard to be any better than the worst link.

This summer I am adding 4 L16 400 amphr 6v batteries to add another 800 amp hrs to the mix and a Sterling alternator to battery charger.  This adds the smarts to the alternator voltage regulator side of things.  All for a fraction of the cost of solar.  The three L16s are on there own and have their own pure sine wave inverter for the refrigerator and entertainment bits.  A Sterling smart charger does the L16s and the start batteries.  I would really like to add a Victron Inverter/Charger for all of the new technology they add but my old one is still working.

All of this is directed at how we use our coach.  Someday maybe some solar but it is hard to justify today.

Delco 40si 240 Amp Alternator, Sterling ProSplitR Installation
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Alternator size upgrade

Reply #4 –
Quote from: Roger & Susan in Home2 –
House batteries are much closer to 100% after a days drive even with running lots of things as we go.
Roger,
 
What is charging your house batteries while you drive?
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Alternator size upgrade

Reply #5 –
240 amp Delco via Sterling zero voltage drop isolator.

If you have an isolator and an alternator then your house batteries get charged from one side of the isolator and the engine batteries from the other.  Since the sense wire to the alternator comes from the engine batteries and these get recharged quickly the alternator senses that and the voltage goes down which means There is less to push charge into the house batteries.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Alternator size upgrade

Reply #6 –
Another brushless option besides Delco is a Canadian company Dixie-Electric that manufactures high capacity DelStar alternators (I called and verified - made in Canada not China). They make direct replacements for the Delco 40si and Delco 55si with remote sense, and both with a J-180 mount option. The DelStars actually have higher idle and running amperage ratings than the Delcos.

Delco 40si replacement
D100-17102 J-180 Alternator

Delco 55si replacement
D100-18101 J-180 Alternator

They sell through US distributors. For a self-installed purchase the warranty is 1 year.

Also I see Sterling Power has a new alternator-to-battery charger that can handle 400 amps, and also functions as an isolator
400 amp alternator to battery charger

I think the Delco 40si 320 amp or DelStar 350 amp and the Sterling 400 amp alternator-to-battery charger might be an awesome combination for an upgraded house battery system.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Alternator size upgrade

Reply #7 –
Delcos are far superior in build, output and durability.  Leece Neville/Prestolite is a crude beast by comparison but they are also very easy to rebuild.  Basically WW2 era style internals, the output post is a 3/8" galvanized carriage bolt secured to the diode block.  Dead simple and cheap to replace diodes, brushes, bearings.  Parts are readily available.  Were I changing one, however, the replacement would be a Delco, one time and you're done. 
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS
 

Re: Alternator size upgrade

Reply #8 –
Has anyone ever investigated whether or not there are holes in casting under the alternator that will accommodate a pad mount unit? Since a serpentine belt with a belt tensioner is used, I wonder if the J180 long hinge is the only option. I know that Cummins engines use the pad mount in some applications, so I would think the blocks would all have the same castings... just curious at this point, as it seems there are more available deals on the pad mount versions of the Delco 40Si.
Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson