Engine Alternator use:

Topic: Engine Alternator use: (Read 2061 times) previous topic - next topic

Engine Alternator use:

August 28, 2015, 02:19:23 pm

John S, you said "prevent overtaxing the alternator. It is not made to recharge but to maintain" in the "Refrigerator Fire" post.
I have heard this mentioned by others also, but do not agree with this statement!
I run my refer from the inverter when travelling all the time and have not experienced failures.
The alternator is a mechanical/electrical device which will wear out even if the available electrical energy is not used.
The alternator will impose a HP load on the engine which is directly related to the amps being supplied, and the alternator will also run hotter with increasing load. However, even with high loads (i.e. 50% of capacity) an alternator will provide trouble free electrical current for years. When an alternator requires repairs, shops are readily available at reasonable cost.

Feedback please, particularly from those who disagree with my belief on alternators.

Re: Engine Alternator use:

Reply #1 – August 28, 2015, 02:53:57 pm

@Wyatt I'm with you on this one. The only real downside to using the alternator in this fashion is the heat issue. The Powerline in a lot (most?) rigs is almost totally enclosed and can build heat. One of the reasons I replaced mine with a Delco Remy 24si. It has much better ventilation to dissipate the heat. IMHO the heat would only be an issue at the extremes of operation such as trying to charge the house batteries after dry camping via engine alternator only. Much better to run generator to bring up the house batteries if they are depleted. This can even be done while on the road, don't need to wait on batteries before leaving.

see ya
ken

Re: Engine Alternator use:

Reply #2 – August 28, 2015, 04:18:10 pm

It has to do with design. It may put out 180amps, but if it isn't designed to put out 180amps continuously, it will overheat and life will be shortened. Continuous duty alternators (I had one in my old transit bus that ran huge 24volt fans for the A/C condensor) are MASSIVE.

Re: Engine Alternator use:

Reply #3 – August 28, 2015, 04:23:55 pm

So...when running the genset and engine at the same time, is there a priority as to which charges the house batteries? Does the converter get 120 VAC from the genset to then charge the house batteries overriding the 12 VDC from the alternator?

Re: Engine Alternator use:

Reply #4 – August 28, 2015, 04:31:31 pm

Hmmm Good question Peter. I just assumed it did. Hopefully someone with actual knowledge will chime in...

see ya
ken

Re: Engine Alternator use:

Reply #5 – August 28, 2015, 04:34:30 pm

The device set for the higher voltage will to the majority of the charging, unless battery voltage is below the voltage of the second device.

So, when first turned on, the generator/inverter-charger in bulk mode may be higher than the alternator/regulator voltage and would do most of the heavy lifting. But once the inverter-charger reaches float mode, the alternator voltage will likely be higher and do most of the remaining lifting.

Re: Engine Alternator use:

Reply #6 – August 28, 2015, 04:47:48 pm

Here is one way to find out, add some Ammeters and Voltmeters at strategic locations. Just keep your eyes on the road while driving.

DC 0 300V 200A Shunt Voltage Current Panel Meter Digital LED Voltmeter...

This one is rated at 200A, which should do the trick. Rather inexpensive, and 50A, 100A models are even less.

Put one on each charging source and you will know exactly how the work is being shared.

Re: Engine Alternator use:

Reply #7 – August 28, 2015, 05:42:04 pm

Quote from: P. Wyatt Sabourin – August 28, 2015, 02:19:23 pm

John S, you said "prevent overtaxing the alternator. It is not made to recharge but to maintain" in the "Refrigerator Fire" post.
I have heard this mentioned by others also, but do not agree with this statement!
I run my refer from the inverter when travelling all the time and have not experienced failures.
...
However, even with high loads (i.e. 50% of capacity) an alternator will provide trouble free electrical current for years.

I upgraded to a 250 amp 28si alternator and 250 amp isolator right after I bought my coach. I also run my refer on the inverter while under way. With headlights on, inverter on, and juice to run the Detroit and Allison electronics, I estimate the alternator is running at about 100 amps down the road. Not any problems for many miles.

Re: Engine Alternator use:

Reply #8 – August 28, 2015, 06:17:46 pm

You can run your fridge underway with the alternator. It will keep up with the draw, especially in the day but if you have gone overnight, you will have a deeper discharge on the house batteries and it will cause the alternator to run constantly and it will burn up faster. James Triana did a session on this at the grandvention one year. Also they covered it in Ladies Driving school. Your stock alternator is not designed to recharge your house battery bank after a night of discharging. IF they are fully charged then the alternator will maintain the charge. I think there was even a Motorcader magazine article on it as well. I think you would need a second alternator or a bigger one and a bigger isolator before you could recharge the batteries.

Re: Engine Alternator use:

Reply #9 – August 28, 2015, 06:20:39 pm

Also the new IHs have 340 amp alternators or some huge number so they can run the AC while they are running down the road off an inverter. We have 180 amp on the 320 and I think it is a 160 amp on the 270.

Re: Engine Alternator use:

Reply #10 – August 28, 2015, 06:28:16 pm

Here is a link to the alternator site.

Prestolite - Leece Neville

It says in there that An alternator can become damaged if it operates too long at excessive temperatures.
They go over dirt and lack of air flow but over charging also causes high heat and if it has to replace lots of amp hours, first from the start drain and then the house batteries, it will not shut off and it will not cool down.

Re: Engine Alternator use:

Reply #11 – August 28, 2015, 06:34:14 pm

So running down the batteries at night running a residential refer might benefit from a heavier duty Alternator designed for the deeper discharge on a regular basis?

Re: Engine Alternator use:

Reply #12 – August 28, 2015, 06:54:38 pm

Most auto alternators at rated amp load will only provide about 10 volt output. Even the ones provided on our coach's, yes making lots of heat too.
There are units that will do 250 or more amp load at 14.5VDC, you would not want to pay the price for it. Nor could you fit it on my 320, ISM500. Weight & physical size would be the issue

Re: Engine Alternator use:

Reply #13 – August 28, 2015, 09:31:50 pm

If the sensing wire is hooked up on the engine battery side of the isolator then the alternator voltage regulator shouldn't be able to see the voltage in the house batteries due to the door being shut in the isolator. If this is the case then it seems like if you run your coach batteries low during the night then crank up and move in the morning all the charge your coach batteries will be getting will be the dregs (like a trickle charge) after your cranking batteries get full. If this is the case then your coach batteries can be low at your next stop if you aren't traveling a long distance. If this is not the case then how does the alternator voltage regulator see the house battery voltage unless you equalize your battery system through the "Boost" then the voltage regulator will see a need to get up and go?

Pamela & Mike

Re: Engine Alternator use:

Reply #14 – August 28, 2015, 10:15:19 pm

The easiest way to explain the isolator is to compare electricity to water. The isolator has one (water) input and has two (water) outputs to fill 2 buckets - 1 (chassis battery) and 2 (house batteries). It doesn't care what it is filling, but the input has to keep up with the combined flow of the 2 outputs. More water will flow to the bucket that has the lowest water.

The sense wire is connected to measure bucket 1.

So, say bucket 1 is almost full, but needs a little more water. So the alternator supplies some water to top off bucket 1, but to top off bucket 1, it also has to fill bucket 2, which is low and takes almost all the water.

The sense wire tells the alternator to increase water output to try to top off bucket 1, but the water still continues to mostly flow to bucket 2. This increase continues to the max output of the alternator (water), and bucket 2 continues to get most of the water until it reaches the level of bucket 1.

Then when the alternator can finally make progress filling bucket 1 (and also bucket 2), the sense wire then detects this, and when bucket 1 (and bucket 2) are both topped off, the sense wire then says "both buckets are full".

So the isolator will always try to equalize the batteries, giving the lower bank more charge current until full charge is reached in both banks.

Re: Engine Alternator use:

Reply #15 – August 28, 2015, 10:34:46 pm

The fridge does not use most of my power. Two C paps and lights and blower motors on the heaters and water pump and TV and dvr and computers and charging cell phones. Dual alternators might be an idea to help it out but really a bit of bulk charge will help you save your alternator.

Re: Engine Alternator use:

Reply #16 – August 28, 2015, 10:53:05 pm

My "stock" 1991 coach 12 volt setup (160 amp alternator and 160 amp isolator) was adequate for the coach intended use back in the day, and no doubt was chosen to meet the necessary price point at the time in 1991.

But, to meet the 12 volt demands in my current setup with a little reserve, I upgraded the 12 volt system - 250 amp alternator and 250 amp isolator. High output alternators and isolators available now are efficient, run cool, and are relatively inexpensive.

Re: Engine Alternator use:

Reply #17 – August 28, 2015, 11:57:02 pm

People with gas refrigerators have a different situation than people with electric refrigerators. If you have a gas refrigerator it's unlikely you'll deeply discharge your battery overnight, or at least I've never been able to, even after running the gas furnace for a while in cold weather. I never start my genset to charge my battery before driving away in the morning. My alternator produces a much higher voltage and amperage than the charger so my batteries are all fully charged very quickly when driving. I have a 160 amp Leece Neville and a single 8D flooded cell coach battery and I do just fine traveling all over the country. I do this all the time and it's never been a problem. Running the genset takes twice as long to charge the batteries. The genset is expensive to overhaul and it's a waste of fuel unless it's really needed. The alternator is a cheap little thing by comparison that's inexpensively rebuilt at an alternator shop, and you can rebuild it yourself if it's an AC/Delco. I've done a bunch of them over the years, some for as little as $5 in parts, although that was many years ago and it probably costs more now. If you're trying to run a residential electric refrigerator you should probably stay plugged in at a commercial campground, just saying. Boondocking is for gas refrigerators unless you're prepared to do extremely expensive electrical upgrades and still have drastically less endurance than an old coach like mine with a gas refrigerator. I fill my propane tank once a year. I can run my refrigerator on gas six months between fillups according to my calculations... This information is coming from someone who seldom has time to write on here because I'm always too busy traveling. I've got half a dozen national parks to write about just from the past couple of months. I haven't even gotten my slide film developed yet because I just barely got a mailing address!

Re: Engine Alternator use:

Reply #18 – August 29, 2015, 12:10:32 am

Please excuse my limited information but I do not know for sure how the alternator and freedom 25 inverter/charger in our coach works.

My understanding is that you should charge batteries at a max of 20% of their CCA ratings which matches the way Foretravel engineered the coaches electrical system.

My three 8g8d's have roughly 675 amp hour capacity so a max charge into them would be the 130 amps the freedom 25 is designed for and the magnum 2812 also has a max 130 amp rating.

The alternator while rated for 160 amp seems to be correct at roughly the same charge rate as the charger built in to the freedom 25.

Especially as it has only bulk charge versus the acceptance and float programmed into the freedoms charger.

My question is that if I add a larger high output charger will it try to overcharge the batteries?

I have seen countless grey batteries with bulging cases from overcharging it seems long ago.

Will a higher output alternator than the nominal 160 amp one from Foretravel try to input more power into the battery than it can accept which will damage the batteries over time?

I understand if you are smart enough to divert any extra DC power over the charger to battery needs as it occurs it's posdible to not overcharge the batteries capacity but that would have to occur in real time?

In other words load the alternator not to overcharge the batteries? Good luck.

Enough instrumentation it could be done I am sure but using the refer on inverter power might be required?p

What happens when the refers thermostat switches the input off when it reaches its low temp shutoff point then?

Just looking for info. Will a higher amp output alternator try to overcharge the house batteries?

Tell me how the system works? If extra amps hurts nothing why did Foretravel not put a higher output alternator on the coach?

And the matching output of the charger and alternator to the three gel batteries that our coach came with is why I am asking these questions.

Does the alternator simply reduce its DC output if its overcharging the batteries?

Re: Engine Alternator use:

Reply #19 – August 29, 2015, 12:42:47 am

Caflashbob:

Excellent questions. The thing to remember is alternators with a lower or higher amp capacity will have a similar voltage setpoint. So no overcharging will occur once the voltage set point is reached, but a higher amperage alternator will be able to recharge a battery bank faster, or, handle a higher continuous load.

Compared to say 20 years ago, higher amperage alternators/isolators are available now for less money due to advances in technology. I think the RV manufacturers supply what the market will bear at the time...and what is competitive with SOBs...

Re: Engine Alternator use:

Reply #20 – August 29, 2015, 10:05:58 am

I removed the diode combiner and installed a Yandina Isolator. It's rated at 160amps. It's relay based, with no voltage drop.

There is a neat downside that is actually an upside to it though---if it is flowing a fair amount of current it gets warm and opens up to allow itself to cool off. This also allows the alternator to cool off!

Re: Engine Alternator use:

Reply #21 – August 29, 2015, 10:47:28 am

The slickest way to run roof A/C and residential refrig while driving, as well as recharging the depleted batteries through an onboard smart charger, is to bolt up a belt driven 120v generator to the main engine. Cruising sailboats (and powerboats) have been using them for decades. I haven't researched them recently, but I do remember that there were major advances in stabilizing output regardless of engine rpm's.

Re: Engine Alternator use:

Reply #22 – August 29, 2015, 10:52:45 am

I try to limit running my generator while going down the road to power the roof AC's.
My solution is the one Brad Metzger taught me years ago when I first met him. His solution is to simply take all his clothes off and drive naked. Says you can tolerate much more heat in the coach while driving that way.
Very creative guy that Brad.😎

Re: Engine Alternator use:

Reply #23 – August 29, 2015, 11:09:09 am

The dash A/C is on my spec sheet is 17,250 btu/hr. The roofs are 13,500 each. The problem is the dash has horrible ducting and doesn't let all the cooling typical get to the coach.

Crazy project, but I might try to add another evaporator in the future mid coach. If I can get a used dash HVAC unit, I can add heater core too for heat going down the road---since no aquahot.

Re: Engine Alternator use:

Reply #24 – August 29, 2015, 11:29:36 am

Can the charge rate from a larger than the 160 amp alternator I have into my three batteries exceed the batteries 20% of CCA limit?

How does the system work? Can you be below the set voltage on bulk charge and exceed the batteries design limits?

I understood you could and remember have seen many damaged batteries from this long ago.

But I may have a faulty memory?

I have set up a few coaches long ago with 120 volt alternators. 3 or 5,000 watts if memory serves me.

Yes the coach slowed down a bit.

My current research so far shows I guess is that if I'm going to try to improve the alternator charging of my battery bank some day that the same 160 amp alternator output that's in my coach now might be better to be a heavier duty unit designed for that continious output and/or locate a link 2000r or similar alternator control which then will have the same steps in the charging as the inverters do.

Bulk, acceptance and float.

Would seem to be necessary if the batteries are going to be more than 20% overnight running a residential refer to me.

Or have a much shorter battery life?

Would love to have a link 2000r setup if someone wants to sell one?

The MK battery engineer mentioned 10 year life from Foretravel owners already using their 8g8d's before the latest plate mounting mods that he said could potentially double the life cycles of the batteries.

I would bet the IH-45's 340 amp alternator uses a similar stepped output control to not fry the batteries.

Am I wrong? Can you bulk charge house batteries at more than the 20% rated input with a larger alternator than the batteries max charge rate input? Especially if it's bulk charge only as most here are?

Don't most boat batteries have the bulk, acceptance and float cycles in their systems to prevent gassing/damage?

Can I overdo the input charge amps damaging the batteries?

My gels I think on the inverter are set at 14.15 max. AGMS would I think be at 14.4?

Thinking of pulling my alternator for a preventive maintenance rebuild but adding a stepped charging controller and a continious duty unit is not out of the question for me if it helps over the long run.

I would think with 4 batteries for a residential refer install I would have a matching the batteries max charge rate input continious higher output alternator installed with a stepped power controller.

The original systems in the coach was not designed I think for the extra draws the system is now being subjected to.....

I had a battery guy 30 years ago show me his suburban with 400k miles and a fifteen year old battery under the hood.

Perfect maintenance and I think a stepped charging system he sold was how.

Never exceeding 20% discharge and going between 70-90% discharge seems to work ok with the stock Foretravel setup on the inverter/charger as the last 10% acceptance charge takes a lot of gen run time.

The freedom 25 manual mentions this.

Does the higher output alternators lower the amp output or just the voltage?

It's a system and I want to make sure I understand how it works and what mods are needed if the usage and loads change in the future.

Thanks

Bob

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