Quote:
Originally Posted by Q Xopa
Agreed, most 'Large Frame/ Case' Alternators are rated to a max RPM of 7-8,000. Indeed I noticed the Ecotech max was 8,000 continuous and 10,000 transient.
Yes I think once you start wanting more than 100ish Amps continuously, it's more realistic from a reliability and heat perspective to be looking at a Large Case unit.
This is basically the next tier up from standard small case alternators.
However, as already been discussed, it's not the only thing needing upgrading at these levels. Ideally multi ribbed drive belt etc.
However this is obviously also going to cost more for all this good stuff. They are also quite large and weighty. So you have to have the space around your engine in the bay etc
Where does it end?
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Yes I am aware of all those facts like weight and quality and cost.
On the
cheap I would simply use 1
Honda or 2.
There is also a similar brand made in the
USA that cost half the
price then a
Honda and till now the feed back I have is happy customers.
Check it out
But I think here we want to talk about another dimension that we want to compare to the standard aproach of independants AC
generator.
And specially in LFP that needs a new aproach in my point of view.
LFP is a
game changer.
LFP due to the high amp discharge capacity is capable to handle loads that prior could only be handeled with AC generators.
This why I changed to look at a generator only as another component of the system.
It seems also some generator manufacturers are opening up to DC
charging.
Here for example is
http://polarpower.com/applications/marine/
They say:
The advantages of using a DC generator:
*Generator runtime is significantly reduced for comparable charge.
*A DC generator is smaller and lighter than a comparable AC generator.
*Less
fuel is used in
charging the
battery.
*Best is dual with
alternator 12v for house bank and generator for
propulsion 5kw
The disadvantages of using an AC generator:
*The AC generator takes longer to charge the
battery due to
current limits in the
inverter or battery
charger.
*Adding additional inverters or battery chargers increases system cost and takes up space while adding weight.
*The conversion of AC to DC consumes more
fuel due to power conversion losses in the inverter or battery charger.
*The AC generator is significantly larger and heavier than the DC generator.
Off course they are already focused on tomorrow and
electric propulsion. But since they have huge power demands I would say the more their arguments are valid for us.
Obviously it is different designing a new system than converting an existing one but when we look closer we are already on the way.
Most boaters today try to have a good size
solar system. The next step is LFP with more energy storing capacity and bigger consumers by using inverters. The only thing that is left to do is find a reliable DC source on the charging side to add on to
solar.
From this point on itīs only a question to satisfy the individual demand of each boater.
Now back to Polar Power. They are focused on a
boat with out main engine and all there is on the charging side is a generator. So they run the entire
boat including propulsion with one engine.
Is it safe ?
Well a
sail boat also has only one engine.
Is it safer with 2 engines ?
What happens if the main engine fails ?
Is the second engine of the gen make us live safer ?
So why not using the existing engine we already have and take max advantage with quality components instead of investing in
buying more problems ?
I believe at this point some interesting points of view have crystalized when asking .... What is a GOOD generator ??
Yes, there are some details besides the basic components that have to be watched.... specially on the price side but I would say besides the costs of LFP that has nothing to do directly with the basic question of a good gen I can see already very clear my advantages.
I take 2 EcoTech alternators that will cost some 2000$ that produce a huge amount of charging capacity with very low maintanance issues. Letīs give it another 1000$ +/- and what more is there that costs
money ?
Thatīs half the price of the typical AC gen with a lot less issues in all the aspects we analaysed till now.
Well letīs try and find the negative points of such a system.
I am still searching but I am kind of a handy man.
Of course for some itīs much simpler to go to the dealer and say I want an AC gen.
Yeah, that is a very negative point for some.
And if they can find a professional that can built them such a system we are talking about they get charged an arm and a leg.
What a petty