Question on alternator upgrade

[Gvannin]

Hey all i have a 2017 gmc savana about to start my build.  I plan to run a fridge and lights and a fan. With 2 deep cycle house batteries. No solar.
Question is do i need to upgrade my alternator?? Or will factory alt. Do??

 

[Almost There]

Other than using the alternator when driving how do you plan on keeping those house batteries charged.

There is no need to upgrade the alternator but you will need to put in a Continuous Duty Solenoid to keep the house usage from draining back to the engine battery leaving you with no start situations. I put a switch on the dash so I could have control of when my house batteries were being charged.

It's important to note that it takes 5 to 7 hours of driving time to fully charge any house batteries that have been deeply discharged Like keeping the fridge running. Unless you plan to be plugged in to shore power and install a properly sized battery charger those house batteries are doomed to an early death with just using the alternator for charging.

 

[Gvannin]

Ok thanks. Ya reason being i live in b.c where solar isnt the best as it rains alot . So what is my best options to a succesful elctrical setup?

 

[Spaceman Spiff]

Hey all i have a 2017 gmc savana about to start my build.  I plan to run a fridge and lights and a fan. With 2 deep cycle house batteries. No solar.
Question is do i need to upgrade my alternator?? Or will factory alt. Do??

 . . . Ya reason being i live in b.c where solar isnt the best as it rains alot . So what is my best options to a succesful elctrical setup?

The stock alternator should be fine, but you will need to have big, fat wires going to the house batteries.  

Even with minimal draw on your batteries you will need to drive 2 - 3 hours a day to get them back to full.  It takes that long to get from 80% to 100%.  You will most likely discharge to 60% - 70% daily, meaning more drive time.  And alternators don't like to be run without airflow from driving; they tend to overheat, so you shouldn't just idle for a few hours.

Without solar your best bet is a small generator and battery charger.

I camp under heavy forest canopy a lot (Northern Minnesota).  I get enough out of my 200W of solar to do the absorption phase (80-100%), even on rainy days.  I use a 1000W inverter/generator and 35A charger to get to 80% in early AM and let solar finish.

 

[Doubleone]

I'd recommend a dual battery isolator set up to separate the start battery from the house batteries.  That will keep you from draining the start battery while parked and automatically allow the alternator to charge both while the engine is running.  The alternator will provide a basic charge to the house batteries but not a full charge because deep cycle batteries like a long slow charge.  I recall a good article or some threads on battery chemistry and charging somewhere on the site that explains it well.  For proper house battery charging you'd need a dedicated charger and a power source like solar with a charge controller, or a generator/shore power with a power converter.  Power converters convert AC power to 12v so you don't discharge the house battery while plugged in and also functions as a charger.  Wire size depends on the distance and voltage you expect at the end of the run.  Voltage drop for 90amps of 12 volts at the end of a 20 feet run can be 2-5% loss depending on wire size.  Larger wire has less loss.  I'd estimate about a 1 or 2 gauge copper wire for 20 feet run would work.  Go up one size if using copper clad aluminum wire.

 

[highdesertranger]

yep like everyone is saying the alternator alone won't cut it. it doesn't matter what alternator you have. highdesertranger

 

[bullfrog]

It bothers me that people don't understand alternators in vehicles have a life span and the more you use them the quicker they wear out . Deep cell batteries as I understand it don't do well either with high charge rates which vehicle alternators are regulated to provide I believe. Do the new 120 volt smart chargers or the inverter generators provide 2 or 3 stage charging that a solar controller does?

 

[John61CT]

Everything has a lifespan.

Alternators are pretty cheap to fix / replace compared to their utility.

No, many deep cycle batteries are much **better** off with high current charge rates, and certainly not harmed by them.

It is the alternator that needs protecting from very high-CAR bank chemistries.

And intelligent staged charging regulation is available for all charge source types.

However many modern vehicles would need to use a DCDC charger rather than fitting an external VR.

 

[Ticklebellly]

Will the standard Alternator, do?   Yes.

Maybe getting up to speed on the benefits of a Solar setup would be time well spent.   Lots of the Solar oriented posts also talk about Alt only charging of house batteries as well expanded charging options integrating a DC to DC charging setup using inputs from both Alternator and Solar.

 

[bullfrog]

So in my case I like to drive several hours (about 4 hours) a day off road in my 4x4 should I install an isolation relay with heavy cable to my 2 deep cycle batteries from my camper trailer? Would a higher output alternator help shorten charge times? I could see swapping out batteries every couple of days would get old but maybe with Anderson plugs and some quick release mounts this might prevent having to mount larger amounts of solar or having a generator. Is it possible to have some type of state of charge meter built in the circuit so I would know if they were getting fully charged or would the vehicles amp meter surfice? I know solar is the way to go but if you lack space to mount additional solar panels or don't want to baby sit a generator would this be a good alternative? I currently use Ryobi 18 volt fans and lights and use the vehicle charger for those with no problems but with the addition of a freezer and a little solar I can see needing an easy way on cloudy days to bring the batteries up to full charge. Would maybe a small Ryobi propane generator and sitting around be better? Thanks in advance for your opinions.

 

[Doubleone]

It bothers me that people don't understand alternators in vehicles have a life span and the more you use them the quicker they wear out .  Deep cell batteries as I understand it don't do well either with high charge rates which vehicle alternators are regulated to provide I believe.  Do the new 120 volt smart chargers or the inverter generators provide 2 or 3 stage charging that a solar controller does?

Bullfrog, I 100% agree.  Alternators are sized to provide for the needs of just the vehicle, not the house.  And, mechanical objects all have an expiration date... from the moment it's running, it's wearing out.  But it can work in a pinch, I just wouldn't want to rely on it as the sole charge method, hence the suggestions for solar/generator/shore power. 

I've used the alternator on my Class C on occasion to charge the house batteries while on the road.  I have a switch set up with a continuous duty solenoid for emergency jump starting (works both ways).  I once needed to use the alternator for a couple days before I could replace a failed power converter.  I'd get on the road for a few minutes to let the start battery recover first, then hit the switch to give the house some juice.  I did it that way so the alternator wouldn't strain to charge all batteries at the same time.  It's not the ideal situation, but deep cycle batteries can take a high rate for a surface charge up to about 70-80%, but then they need a long (24-48hrs) low rate charge to reach full capacity.  Using at anything less than full charge shortens life of the batteries too.

I'd also highly recommend a smart charger or controller!  Not all of the power converters come with it.  One of the best purchases I've made was a smart controller (3 step) for my power inverter.  Before, I needed to add water to the batteries every week or two.  With the smart controller my house batteries are always fully charged plus I need to add only a minimal amount of water every six months.  It also works as a maintainer, with a float charge but waking up every week for a brief high rate to stir the electrolyte.  I can't speak highly enough of it...  It just works and keeping up the batteries is no longer a chore.

 

[Doubleone]

Hey, just saw that 900 watt Royobi propane generator.  It's kinda neat in it's own way.  Thinking out loud... my gut says 900w seems low.  You could let it run continuously, but then refueling and longevity become an issue.  I'd feel better going with about a 2000w in a gasoline or dual-fuel version (redundancy is a good thing).  2000w is still small enough to carry around.   Gasoline has a higher power density and is available everywhere.  I just think it'd be less hassle than propane.  Plus, a 2000w could easily run a small microwave but a 700w continuous/ 900w peak would strain.

 

[bullfrog]

I have had a lot of different RVs over the years and always had a problem with over charging and having to refill the cells while on shore power. On a sealed battery how can I monitoring the state of charge while charging? I like the idea of using a little solar with a controller ( as I understand the controller limits the charge) to top off deep cycle batteries but seems to me without huge amounts of panels you will eventually be in a situation (clouds, shade or rain) where you need an outside source to bring them up and not over charge them, especially with the batteries I have. Using an alternator, old style generator or charger doesn't seem like a very good idea with out some type of controller or monitoring device. I'm a little confussed when you said "inverter" did you mean converter and was the smart controller a seperate device that could be wired in or was it made into the unit?

 

[John61CT]

A basic ammeter will also tell you when 100% Full is reached, in fact that is the most precise measure.

 

[John61CT]

Big advantage of propane is not dealing with stale ethanol issues, clogging the carb etc.

Gasoline is fine if you use it every week / month, propane best if it sits

 

[Ticklebellly]

Would a higher output alternator help shorten charge times? 

Higher output voltage or larger capacity rating?   An alternator putting out 14.2 volts will charge at an instantaneous rate, no matter what the rated capacity of the alternator.

 

[John61CT]

Higher output means current, amps.

> An alternator putting out 14.2 volts will charge at an instantaneous rate

Please clarify what you mean by this.

 

[highdesertranger]

> An alternator putting out 14.2 volts will charge at an instantaneous rate

I also find that sentence confusing. hey John would it help if we threw in some abbreviations? just funnin you.

highdesertranger

 

[John61CT]

ROFL HDR

 

[bonvanroulez]

It is the alternator that needs protecting from very high-CAR bank chemistries.

CAR?  No amount of googling comes up with any meaning in context. I'm stumped. Is it in this list?

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