[PUP] Energy resource management ( was PPM in general - what should it be ?)

[John Marshall]

Arild,
	Once a week, I leave the genset running until the entire bank (I've  
got all 12 8D's in parallel when I do this) is fully charged. That  
takes a few hours longer than the usual ~80% charge. I gives me a  
chance to fully fill the water tank and run bed linen and towels and  
the like through the washer and dryer. I do this even if I've been  
underway a fair bit, as the alternator on my John Deere isn't as smart  
about charging as my Xantrex. The process is just a lot quicker if the  
engine alternator has the bank mostly charged.

	One of these days I'm going to switch out the alternator with a  
Balmar or similar that has an external smart charger that optimally  
handles Lifeline AGM's, and that would eliminate the need for the long  
genset run. We never sit at anchor for more than a week without moving.

	And a couple of times a year, I Condition my AGM's (Lifeline's term  
for what is called Equalization on flooded cells) by holding the bank  
at 31.2v for 8 hours to recover any lost capacity. That's tricky as  
all the other 24v loads and lights need to be turned off for that  
period.

John

	

On Dec 7, 2008, at 1:46 PM, 2elnav at netbistro.com wrote:

> John Marshall wrote
>> We cook with propane, and rarely fire up the electric oven, although
>> we do microwave a bit.
>>
>> In warmish weather, our major current drain is refrigeration. In
>> winter, in the PNW with short days and heating needs, lights and
>> heating dominate.
>
>
> REPLY
> Once we get past the obvious issues of sea keeping ability, hull  
> strength
> and integrity; the biggest ongoing issue facing all cruising boats  
> is how
> to manage the available energy resources. This ranges from the most  
> fuel
> efficient cruising speed to getting the maximum return on genset run  
> time.
>
> When fuel was cheap and refueling stations plentiful, it was not as  
> much
> of an issue. The new reality seems to be, fuel is getting much more
> expensive and many of the smaller fuel docks may not continue to  
> stay in
> business.
>
> It has for a long time been considered a given that you stop the  
> generator
> when the battery is recharged to about 80% of full charge. Once you  
> get
> into the later stages of absorbtion and float charge, the  genset is  
> no
> longer efficient in terms of amp hour output for fuel consumed input.
>
> I do not propose to question thi, but the one thing about this  
> practice
> that is a downside is the fact not all of the lead sulfate is reversed
> back to lead and lead oxide during each charge cycle. The remaining  
> 15% -
> 20% remains as lead sulfate and the longer it remains so, the harder  
> it is
> to reverse. The accumulation of lead sulfate will eventually lead to
> battery failure. Even periodic equalization will not totally remove  
> the
> most stubborn remnants. And frequent equalization has its own issues  
> in
> terms of damage to the battery.
> Boats that frequently tie up to shore power can overcome this  
> because the
> duration on shore power will enable the charger to complete the float
> stage and hopefully reverse all of the accumulated lead sulfate. But  
> what
> about cruisers who routinely stay at anchor for days on end, then  
> make a
> short hop to another anchorage?
>
> The float stage must be maintained for several hours to remove the  
> last
> vestiges of lead sulfate. Battery engineers make the assumption that  
> the
> charging regime is done without simultaneously depleting the same  
> battery
> bank with an ongoing load. Unfortunately this is the norm for cruising
> boats.
> One solution might be to split the house bank and bring one half up to
> float charge with wind or solar panels while the other half is used to
> support hotel load on board. This may or may not be workable,  
> depending on
> how big the hotel load is.
> Has anyone developed a good routine?
>
> best regards
> Arild
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