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Messages - Guy_Incognito

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241
Everything else / Re: Battery de-sulphater
« on: September 15, 2006, 04:47:02 PM »
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funny how some folks want to live offgrid, not be bothered by outside folks, but also don't want to fuss with taking care of something that takes care of them, namely
their batteries.

I think battery maintenance interferes with their mellow hippy lifestyle routine a bit. But some of the local system designs are a bit awkward for them as well. Eg. 1000Ah of cells + a crappy 3kVA genset to charge via a 60A battery charger. = 8 hours of running to pull up from 50% charge + another 4 hours or so of moderate equalisation. No self-respecting hippy trying to commune with nature is going to have a 3000rpm genny running for that length of time  ;)



242
Everything else / Re: Battery de-sulphater
« on: September 15, 2006, 10:39:50 AM »
"So a hundred bucks or so for a bit of extra life out of your $5000 set of batteries is a pretty good deal."

maybe!  maybe not!
do they sell these desulfators? or sell the plans for them?
if so i am very suspicious of their report.

Aha! I've stumbled upon your pet rant it seems.  ;D
They don't sell the desulfators. They give way the plans for a basic desulphator. They are a privately-funded rainforest research station.

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can you link directly to their article?
i really don't want to spend half the night trying to find it only to find what i usually find in these desulfator reports, that is poor science.

I gave you my reasons for not linking, but it's on that site I indicated. Look for yourself in the archives.

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sulfation that has crystalized and hardened will form crystalls of differing sizes and mass, each of which would have to have a different frequency to get them to vibrate, that is if they could vibrate at all in a liquid bath, which would dampen them.

where a desulfator might have validity is in its ability to pulse higher voltages than normally used for equalization for very short durations, thus avoiding heat buildup.. maybe,, theoretical at best.

They have a few photos of plates under an electron microscope, but they state that the hows and whys are purely theoretical. That's why they tested them, silly. They were looking for hard data and the end result. Whether it actually twangs the crystals to shrink them, or little moon men are attracted to it and sneak in at night to file the sulphate crystals down for you, it doesn't matter in the end if the thing works, no?

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so far i have seen no report, (and i have read many dozens over the years) that illustrate the mechanism of a desulfator working any better than careful charge regiimes and routine equalization, as far as good batteries go.

This is principally an area where "careful charge regimes" are not used. All the RAPS in use there are run by average people, who don't give a damn about equalisation or what-not. They just want their lights to work. This is a test of desulhpators in real-world, hit and miss use. They noted that there were some improvements in entire packs simply because people were aware that "technical people" were watching them, and they were then obliged to look after them a bit better. Putting the desulphator across half a bank allows them to take issues like that into account though.

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if at the end the researcher was to retest the capacity of the two groups and found the desulfator group clearly of more capacity then maybe i would get on board,, until then no way.

They measured each cell's internal conductance monthly. This is a (but not "the") principle indicator of remaining plate life and general capacity. It's a bit hard to come up to someone - who volunteered - and say "Hey, I'm going to cycle your pack and interrupt your next couple of days power usage, so I can get some numbers for my report". Especially the kind of people living in that region. They prefer to be left alone.

The ones in the desuplhator group consistently indicated a higher conductance than the ones run normally. Well, that's what the scatter plot of 40 sets of cells in the report indicates anyway. The bulk of the samples were in the "better" section of the plot.

But hell, I'm going for a nickel-iron set in my RAPS, so sulphation can take a flying leap.  ;)





243
Everything else / Re: Battery de-sulphater
« on: September 15, 2006, 02:55:17 AM »
I've got a report here on the trial use of desulphators in power systems in the Daintree region in Australia in 2003.
It was done by a research station at Cape Tribulation. While they mainly look at flora and fauna in the region, they also experiment with remote area power systems a fair bit. The whole region (about 350 homes in a 30km stretch along the coast) is off-grid. This is where my 6/1 is going, to supplement the solar array for my new house in the cloudy monsoon season.

(The report's online, but I won't link to it - they ask for a donation to their research station for it. If you're interested, go looking at http://www.austrop.org.au/)

Anyway, they fitted their own design of desulphators to one 12V half of a 24V system and run for 24 months or so, with conductance measurements every month on each half of the bank. Fitting them this way ensures most of the extraneous issues with charging/discharging are nullified as each half of the entire 24V string gets the same charge/dischare currents. The conductance measurements accurately determine the amount of plate capacity left in each cell. About 40 or so systems were used in the trial, so there was a reasonably large sample size.

At the end of the trial, the cells with the desulphator had a definite measurable improvement over the cells without, particularly on gel-cells. So a hundred bucks or so for a bit of extra life out of your $5000 set of batteries is a pretty good deal.

244
Listeroid Engines / Re: 6/1 and generator setup
« on: September 14, 2006, 08:11:42 AM »
Well, it's going in when I build a house and builders will be looking after the house slab and other concrete pours, etc etc. - so laziness on my part is not really an issue...

I've done the search and read a fair few posts on the holy block of concrete as a means of vibration dampening and ... I still don't know. There's two questions I have to ask :

1. A ton of concrete will dampen the local movement of the engine, but isn't the same energy transferred outside that block to the surrounding dirt regardless? You've got a certain amount of reciprocating mass thrashing about in your engine and that's where the energy comes from. Whether it gets transmitted through a ton of concrete before being further transmitted through the surrounding soil is a moot issue. I would have thought that the larger block in fact increases the coupling between your thrashing masses and the ground around it.

2. There's talk that bearing/component longevity is increased when bolted to the holy block of concrete and thrashing is reduced to a minimum. Say you've got (shrugs) 5kN of force at a particular instant trying to push your engine block into the dirt and 5kN of force pulling up into the air a half-cycle later. Bolted to a relatively immobile block of concrete, wouldn't that stress all the internal components more than if it was bolted to a flexible mount that moved a little in the downwards direction, then moved a little in the upwards direction? If we take it to the extreme and it was floating in space (or suspended on springs) - there surely would be a lot less internal stress between the block and the reciprocating mass when the whole lot can thrash about as it wants?

This is why I was looking at some sort of rubbery/springy mount that absorbs the energy in one part of the cycle and gives it back later on. Sure, it'll thrash about a bit, but the peak forces transmitted to the ground are then reduced.  I know, the manual says - big cube of concrete. But that was the factory-decreed catch-all solution from nearly a century ago, before there were things like special-purpose rubber dampeners tuned to low frequencies.

But I've plenty of time to play with the system before it goes in "for real", so I might just make the frame and if it's no good, embed it on site in the cube on concrete when the rest of the place gets built.

245
Listeroid Engines / 6/1 and generator setup
« on: September 14, 2006, 01:27:34 AM »
I'm slowly working my way towards getting a jkson 6/1 and a 5kW ST head for it. It'll be used in an off-grid setup to top up batteries once a week or so, with solar making up the most of the charging capacity. Charge time from flat of the battery storage should be about 8 to 10 hours of full load (3kW) on the 6/1, but I don't expect it to be completely flat all the time... just half the year in monsoon season  ::) . I'm using new nickel-iron cells as - while inefficient - they're immune to discharge damage. I expect the system will be used and abused lots.

Anyway, going through the math involved it seems I need a 250mm diameter pulley on the generator to get 1500RPM and 50Hz at aroundabout 620-650rpm. I'm not completely sure of the flywheel size of the jkson engines - 23.5" ?

So, rough gameplan is :

- Source a 250mm, 8 groove poly-v pulley with a bush to suit the 38mm shaft

- Find a suitably-sized belt and bung the 6/1 and genny together on a solid frame

- Possibly get a small tensioner on the frame as opposed to stuffing around with a slide of some sort for the genny, as I'm sure to screw that up. :D - the pulley mob also stock some nice stepped tensioners that also serve as belt trackers.

- Mount frame with fairly solid rubber mounts bolted to a concrete pad. (Fairly solid as in rated at 500kg each rubber mount. It won't be all that flexy. Hopefully)

- Run cooling pipes to a fairly thin tall rectangular cooling tank and let it thermosyphon away. Dimensions guessed at 100cm long by 150cm high x 10cm wide or so - just want plenty of surface area for convective cooling, right? Anyone good with the calcs for this? Ambient is about 20 - 30 degrees C year round. There'll be a heat exchanger in there somewhere to boost my solar hot water system, as when it's cloudy I'll be needing to run the genny to charge the system up anyway.

Anyone see any showstoppers in this?

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