came across a local source for 8volt flooded lead acid batteries, deep cycle
that were brought in from korea as a second line for use in golf carts.
they weigh in at about 65lbs each and seem to be of good quality.
they are rated at 165amp/hrs and i got a set of 6 of them to put together a 48volt string
for the test lab.
at 60 bucks each i figured why not give them a try, the life expectancy is about 1200 cycles to 50%
DOD which would be great if i get that out of them.
now i get to see how import korean batteries stack up against other batteries made in this hemisphere.
last piece of the puzzle has now come together.
bob g
Hi Bob,
Is there a web site to look at them?
Henry
i am looking for a web site for them, so far no luck, but i would like to make a report
i went out and put a voltmeter on them, and was very surprised to find them sitting at 20%
SOC,,, that is horrible!
when i picked them up i was told they had been charged properly and the specific gravity
was 1.275... bullshit!
these things never saw a charger, and if they had checked the specific gravity they would have found
the electrolyte to be nearly pure water... wouldn't even tingle my fingers!
i decided to throw a carbon pile on them, they call will deliver 150amps no problem, so maybe, maybe
they can be recovered? maybe not? it looks like i have a real project ahead of me reconditioning these cells to get them anywhere near their rated capacity. then who know's how many cycles they are good for.
i am pissed off at both the supplier for obviously lying to me, and at myself for not taking a meter to check the condition of charge myself before i committed to buy them.
lesson learned and let it be a lesson to everyone here,,, don't ever take a suppliers word for anything relating to a battery.... verify the state of charge yourself, and verify the specific gravity of each cell before you commit to buy a battery , especially a set of batteries.
batteries sitting around nearly dead will have the sulfation crystallize and harden, which makes it a very difficult process to convert the sulfation back to acid in the electrolyte.
i think i am most pissed off at myself, i knew better!
also i will not recommend this supplier to anyone here or elsewhere, however i won't say anything bad about them by name, until i can determine what i have is bad and if they will stand behind the warrantee without a bunch of hoops and bullshit.
not at all happy with this purchase, however i will suck it up and see if they charge up, with the specific gravity coming up to spec (which would indicate that the sulfation did not harden to the point that it was not fully converted back to acid) if i can't get the specific gravity back to spec, they will hear from me.
darn it all.
bob g
Bob, how are you intending to bring the batteries back ?
The reason I am asking is because I have a couple of 4D batteries that are only a year old and they are below 50% capacity when using normal 3 stage charging. I have looked for a portable charger to do (true) equalization without success. These batteries were also at about 20% SOC when I got them (house bank on a sail boat)
I have not yet purchased a specific gravity tester - is a cheap Canadian Tire unit (or similar) good enough for monitoring batteries or should one buy something better in which case a recommendation would be appreciated.
Sorry if this ends up hijacking your thread .....
bob g,
if this was a corporate outfit
we would flog you with a verbal warning ;D
Randall
believe me i am flogging myself bigtime and will really get flogged trying to get these things recovered
Jens
currently i have them attached to an apc ups, it will charge up to about 54volts, which would normally be adequate to maintain the bank until i was ready to use them, had they been in good shape to start with..
now i am using this to at least get some charge back into them.
my next move and this because i don't have my trigen set back up yet, is to get some sort of system built up that can get the bank up over 60volts to equalize the batteries, and do multiple cycles and equalizations until i can get the specific gravity back up to spec.
if that doesn't get the job done, i will tip over the cells into a vat and drain them, refill them with fresh distilled water and then put 60plus volts on them over time to see if i can further break down the sulfation crystals. fresh water and higher voltages will over time break down more of the crystals than would otherwise break down in electrolyte. i may have to add something to the water to get it to conduct
which i hate to do. as the crystals break down the specific gravity of the water will increase to a point that it will not go any higher... then i will drain the water, flush them and add fresh electrolyte.
the only other alternative i can think of is to just put them on a equlization source and let them sit there cooking for perhaps a week or more, cycling on and off as they get hot, letting them cool and adding water as needed.
it always takes herculean efforts to recover cells (if they can be at all) once they have been allowed to sit
and have the sulfation harden and crystallize.
maybe i will get lucky and they will recharge up and be ok without a huge effort, but if i had to bet, my bet would be this is not the case.
i am not big on the desulphator scheme, mainly because they break the sulfation crystals loose from the plates instead of converting them back to acid... this just adds crap to the bottom of the cells, or causes shorted plates and does nothing to bring the specific gravity back up to where it ought to be.
at this point i think i will do the recharge, see what i have, make an assessment and then call the supplier
and ask to have them swapped out for something useful.
it just seems so unnecessary
especially given they have the knowledge, the equipment, and experience to know better.
bob g
Bob,
I must be missing something here. If these batteries were sold to you as new, why are you fooling around? Just take 'em back and demand restitution.
Quote from: Jens on August 30, 2012, 03:00:02 AM
Bob, how are you intending to bring the batteries back ?
The reason I am asking is because I have a couple of 4D batteries that are only a year old and they are below 50% capacity when using normal 3 stage charging. I have looked for a portable charger to do (true) equalization without success. These batteries were also at about 20% SOC when I got them (house bank on a sail boat)
I have not yet purchased a specific gravity tester - is a cheap Canadian Tire unit (or similar) good enough for monitoring batteries or should one buy something better in which case a recommendation would be appreciated.
Sorry if this ends up hijacking your thread .....
I'd recommend that you get a hydrometer similar to this:
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7001145_0361128149
It is designed for testing batteries, works in the range that is needed, and has a built in thermometer to do the temperature correction, and the components are not destroyed by battery acid. It's cost is low enough that it doesn't make sense to use anything less.
Bummer about the batteries Bob. But perhaps now is the time to try a desulfator and see for your self how they work. I used a 12v telco agm battery that woiuld not take a charge for 2 months. When a desulfator was added it started taking a charge and after a month was load tested at 90%. I used this battery for 2 years with a PV panel attached in an RV that was lived in and the battery was heavily cycled. It was still going strong when the trailer went away.
This is the one I use on my battery bank: http://www.ebay.com/itm/YAMAHA-CLUB-CAR-GOLF-48V-BATTERY-DESULFATOR-48-VOLT-/220732894456 (http://www.ebay.com/itm/YAMAHA-CLUB-CAR-GOLF-48V-BATTERY-DESULFATOR-48-VOLT-/220732894456) and I'm not seeing any reduction in performance in the bank since Nov 2007.
Quote from: Thob on August 30, 2012, 08:36:19 AM
I'd recommend that you get a hydrometer similar to this:
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7001145_0361128149
It is designed for testing batteries, works in the range that is needed, and has a built in thermometer to do the temperature correction, and the components are not destroyed by battery acid. It's cost is low enough that it doesn't make sense to use anything less.
Thanks, I will see if I can find it locally at Napa.
Quote from: Tom on August 30, 2012, 10:38:40 AM
This is the one I use on my battery bank: http://www.ebay.com/itm/YAMAHA-CLUB-CAR-GOLF-48V-BATTERY-DESULFATOR-48-VOLT-/220732894456 (http://www.ebay.com/itm/YAMAHA-CLUB-CAR-GOLF-48V-BATTERY-DESULFATOR-48-VOLT-/220732894456) and I'm not seeing any reduction in performance in the bank since Nov 2007.
Is there anyone else that can confirm that pulse desulfators work ? Do they also equalize or do they just desulfate? Do they run continuous for as long as they are set up ? Does one need to watch it like an equalizer or does it just do it's thing in the background ?
a bit of an update and my take on desulphators
first of all, i misread the charts for 8volt batteries, an 8.0volt reading equates to about a
50% state of charge, rather than nearly depleted.
it was late, i was tired, and medicated, so i was wrong about them being nearly flat
however it still didn't make sense how they could be at 50% if they were just transferred
to the distributor from the warehouse two days prior, and then presumably fully charged and tested
as near as i can tell it appears they did fully recharge them, then tested their capacity down to 50%
where they found one that did not pass, brought in a replacement and then gave me a call to come pick them up... apparently they did not recharge after the capacity test, thinking i would install them in a golf cart, put it on a charger anyway before heading to the course for 18 holes.
to be fair i never told them they were for a golf cart and they would have no reason to think that i might have another use for the batteries.
anyway, before i freak out i should get some sleep, which thankfully i was able to do before calling them, it also gave me time to charge the bank and see that they appear to be responding as they should.
so i will retest capacity myself, to about 30% state of charge at the 20 hr rate, just to make sure they are good to go, and to have numbers to put in the log for each cell.
now here is my take on desulphators
i spent many years researching these things, read every double blind test, every independent lab report
and place most weight with sandia labs testing over those tests performed by those that sell them and those that have bought them.
there is no evidence that supports they work any better at recovering a battery than simply placing them on a charger capable of equalization voltage and leaving it there long enough to actually do something.
the one thing they do seem to do, is allow a badly sulfated battery that will not accept a charge to start to take a little charge when other smart chargers simply will not start to charge the battery... however a dumb charger will given enough time generally do as well given enough time.
there is also no good understanding as to what the desulfator really does to the hard sulfation crystals,
i have seen no evidence or qualified report illustrating that the crystals are broken down and the acid if returned to the electrolyte, rather than simply dislodging the crystal and allowing it to slough off the plates.
while sloughing off sulfation allows the battery to regain some capacity it does nothing to get the specific gravity back to spec, it also removes plate active material and it is lost forever, the result is reduced cell life.
as for desulphators and agm batteries, good agm batteries will almost always come back to life and recover to near rated capacity given a long controlled recharge. i have 6 agm six volt batteries that sat inside a locked shipping container through last summers intense heat (30 odd days of triple digits) and only removed from the containers intense heat last fall... i just got them out for recharge last week
they were all dead, bad, bad bad, on me!
i simply removed the caps, which we are told never to do, and added 6cc of distilled water, and put them on a charger for about 4 days, at 3amps and 7.5volts... slowly they came back, and all are near peak rated capacity now.
from my research agm's built to some sort of european standard (which most are) can be recovered by this method, then slowly drained to dead, attach a shorting cable overnight, then repeat the process a half dozen times or so,, the result is each extreme cycle the capacity increases.
flooded lead cells don't work that way, never want to kill them dead, much less do so intentionally, then apply a shorting strap overnight and do it repeatedly!
anyway getting back to desulphators, there is no reason to go out and buy one or to use one in normal use of flooded batteries, further i would not recommend the use of one until all recommended methods are exhausted, that means attaching a charger with amp limiting and high enough voltage to get into the equalization range for the battery being charged (15-16volts for a 12 volt battery) and give it enough time to do its work.
i would then go the extra mile and if i still was not getting the results i want, as evidenced by specific gravity not returning to spec, i would then drain the battery, refill with fresh distilled water and put it back on the charger for days if necessary while monitoring the waters specific gravity to rise and stabilize. given enough time, limited amperage and enough voltage, the crystals are more likely to dissolve in fresh distilled water than they are in acid. a rise in specific gravity of the water will be evidence that the crystals are being converted and broken down like they should be without being dislodged and without undue sloughing of the plate materials... after the spec gravity of the water peaks
and does not rise for 3 hours then i would drain the batteries and replace the electrolyte with fresh electrolyte of the correct new specs as stated by the manufacture.
this is a hell of a lot of work, not practical for the average diy'er if he has a 2 ton forklift battery, but certainly practical for batteries in the sub 100 lb class. of course it goes without saying there are safety concerns with working with acid, proper disposal of the old electrolyte and all that entails, however for
expensive batteries one should probably consider first doing no harm before trying other methods.
having said and done all that, if i still could not get the battery back to reasonable condition, i would then give the desulphator a go, figuring i have nothing to lose, and also figuring if it works the loss of plate material is an acceptable tradeoff.... if that didn't work then i would as a last resort ...
use edta or some other magic potion, figuring that i am poisoning an otherwise useless battery so if it comes back with the use of this crap, maybe i can get some use out of it.
no way on earth would i use a desulphator or edta on an expensive battery to recover it without first checking with the manufactures engineering department.
i would also never use either as some sort of preventative measure on an otherwise normally operating battery over the course of its life. i have heard of folks buying and using desulphators and adding edta or some other elixor to their battery banks because they have heard some bullshit about that extending the lifespan of their investment... bullcrap!
one day, perhaps after the first of next year, when i get the somrad lab built and in operation, one of the things i plan on doing is this
i plan on buying a new 6 volt golf cart battery, only because it is reasonable in price, i will fully charge it, drain it, cut it apart into separate cells, taking each cell to do testing on.
i will put each in a glass jar and suspend it, refill with electrolyte, then apply a load, drain them dead
watch what happens with the formation of sulfation and crystals, then use each method of recovery
after which do an autopsy of each cell to see just what happens to the crystals and what happens to the plate materials.
so far i know of no such test having been done, and if it has i know of no such published reported results of such a test.
we have lots of anecdotal evidence pro and con, and we have batteries of all conditions being reported on, which is a huge set of multivariables, the results of which are about worthless.
nothing would please me more than seeing a positive and negative plate suspended in electrolyte in a glass jar where i could see if the crystals are being broken down electrically and dissolve or simply being blown off the plates and falling into the bottom of the jar.
i am left to wonder why we have not seen pictures or video clips of such a test proving what actually happens to these crystals, the lack of such should lead us to conclude that the technology might not do what it claims or it might work but reduce the lifespan of the battery.
bob g
Thanks Bob for that thorough write-up. I too am leery of these desulfators and I would much rather buy a charger that allows for equalization. Unfortunately, these things are difficult to find. Having said that, West Marine has the ProNautic 12V 50A charger for sale at $449 and they have a promotion going that would give me $50 off that price if they had them in stock which they don't :( .... I have emailed them to see if they would like to do the deal even though it is not an in-stock item.
Simple sustained charging at modest current, voltage limited to something at or approaching equalization (or at least above bulk charge voltage), has always worked for me.
Like BobG, I also view the pulsed desulfators with some technical skepticism. All technical skepticism could be quashed by the sort of photographic evidence that Bob suggests, without huge expense, and you have to wonder why that isn't presented.
I love my 120VDC system with cheap Walmart 12V marine batteries, using individual battery shunt regulators. (A scheme developed my Manzanita Power for electric cars with AGM batteries.) There's virtually no water loss, no need for protracted equalization, and a premature death in the 3rd year can be replaced without having to worry about age matching. (My 2 battery losses were both due to prototype hardware failures due to corrosion on unsealed boards with too fine a clearance around traces.) At the end of 4 years, the charge efficiency was noticeably poor, so I retired the whole set when I had a cell loss last fall. I'm too lazy to work hard to save an aged $67 battery. Twice a year I check all the cells SG, and add water. I'm ready to go to once a year now; I'm not adding hardly any water, and have had almost no variation in water consumption between cells or batteries. I do mini-equalization charges (2 hours) monthly. The Manazanita Power approach to charging long series strings is a real winner in my book. I realize I'm well outside the mainstream with 120VDC, but someday this will be much more common, unless the battery technology picture changes.
Hey BruceM you are now the 2nd fellow i know using a home brew 120VDC set up.
Any interest in taking this off on a thread of it's own so some of us can quiz you about the nitty gritty realities if using this on a daily basis?
Then you could control the content and tone.
Thinking about the battery set up to go with for the lights, maybe universal small hand held tools in my solo small shop, the chicken house and greenhouse.
Regards
Well I guess I'll be the forum guinea pig for the desulfator. The one I have is the same as linked. It runs full time off of the battery power. The first deslufator I had came with an attached solar panel and with instructions for mount on tanks and missile launchers, I guess the military wants to start when needed. If the military has determined that they are effective that's good enough for me. I don't believe they cause lead to slough off, but cause the sulfate crystal to go back into solution. When run continuously the crystals that form are supposed to be smaller and go back into solution easier during charging improving charge efficiency. I'm running one on my $8K battery bank so we'll see how it goes 10 years from now when the bank starts to reach the end of it's life.
Tom
i meant no disrespect to your posting or use of a desulfator
i only related that i haven't as of this date came across a white paper that supports their use
based on real world testing with supporting documentation.
not saying it doesn't exist, or that it can't work, only that i am not aware of such documentation
as of yet.
if you or anyone has or comes across a link to information or testing of desulfators please feel free to post it so we can take a hard look.
bob g
Steve U. OK, I'll start a new thread on 120VDC, but suspect we might have a better exchange by phone. There is understandably more interest on this forum for more mainstream off grid power systems with off shelf hardware and support.
QuoteIf the military has determined that they are effective that's good enough for me.
Well that's one of us. As a reformed user of military equipment and decision making I just can't let these blanket statements float by. And gentlemen, stuff does float downstream!
Casey
There may be technical merit to the pulsing desulfators, but the use of same by some DOD group is meaningless. I used to select and order stuff (computers, boards, tools, test equipment) for an AF research lab. Several hundred thousand $ a year, often more for big projects. My choices were based on what I thought looked cool or useful in glossy advertizements. Or just a whim. No one else scrutinized my selections. Many DOD groups have a similarly high degree of autonomy in what they buy to support their mission. Claims of a product's use by some DOD group is the common marketing practice of many hucksters. I chuckle every time I read such a claim.
Well perhaps that is a naive opinion on my part. They have could have been purchased because they were made by someone's brother in-law. The Pulse tech web side does reference 2 university studies that were requested by the military though the way they report the results is a bit sketchy.
Quote from: LowGear on August 31, 2012, 11:45:03 AM
QuoteIf the military has determined that they are effective that's good enough for me.
Well that's one of us. As a reformed user of military equipment and decision making I just can't let these blanket statements float by. And gentlemen, stuff does float downstream!
Casey
Gotta agree with Casey on this also:) I don't doubt their use, but they were probably sourced as one of their main features is that they, being solar powered, will keep the battery floated on vehicles that spend more time parked than in operation...
I ordered a ProNautic 50 amp charger today. Delivery would probably be in 3 - 4 weeks as it is currently out of stock.
well it looks like the batteries are probably going to be fine
i still need to pickup my new temp compensated hydrometer to verify the specific gravity
at full charge, but for now as far as i can tell they seem to be doing fine.
after recharging them up to as near full charge as i can tell with a digital voltmeter (which is only
good at telling state of charge on batteries of known good condition) i placed a 325watt load on the bank
via the apc ups unit i used to charge them with.
so at a measured efficiency of ~86% and a measured load of 280watts AC, then 280 / .86 = 325 watts
from the batteries.
the batteries carried the load for a bit over 5 hours and the batteries dropped to a bit over 80% SOC
as measured by the digital voltmeter,, (again with the same qualification above) so 325 x 5hrs = ~ 1.6kw/hrs.
that is a bit under what the bank is rated at, however i have not ran through enough cycles to break them in yet and i have not verified that they started out as fully recharged as tested with a hydrometer
rather than a voltmeter.
they appear to be in good enough condition that i won't be raising a bitch with the supplier especially given the deep discount i got on the set.
i think when it is all said and done, broken in fully, and tested with a hydrometer my bet is they will be
very close to spec, so i am happy with them.
for future reference the model number of these batteries is gc8-890 which as far as i can tell
they are , gc = golf cart deep cycle, 8= 8volt, 890 =190amp hours 20 hour rate.
my hope is these turn out to be as good as any other typical battery of this type and capacity, and my supplier can source and supply more of these for a lower cost than the USBattery he sells most of. he told me he brought in two sets of these, one went to a golf cart the other to me for inverter use in testing.
he figures the golf cart set will probably get average attention given most golf carts and probably be lucky if they make two years, but is thinking with better attention given by me in my lab they ought to last at least 4 years, and maybe more if i do as i say and limit the cycles to something less than 50% DOD. he is convinced if they are maintained properly, recharged properly and cycled no more than 50% they will last 4 years. that is a nice target to shoot for.
we shall see
i would be nice however to come across an alternative battery that could give good service for our use, and do it for less up front cost. it is hard for me to get my head around how this is possible to do given they are built in korea, shipped half way around the world, warehoused and redistributed and sell for less than batteries built here in the states?
i thought maybe they cut corners, by using less lead? but they weigh within a lb of the trojan equivalent. so it would appear they didn't skimp on lead, and it is hard to see how they could cut lead weight and not add the difference in plastic case? the case looks to be adequate in thickness but not overly so.
who knows, just glad i got a string to work with.
this weekend after fully recharging them, testing the specific gravity to verify full charge, i plan on another capacity test this time with approx 850 watts of resistance heater load. that ought to stretch them a bit and get the pores in the plates opened up!
bob g
I am glad to hear that all is well ! I am puzzled about the 8V thing - you talk about normal electrolyte and you talk about lead plates so how is it that these things are 8V each. Further, are golf carts running at 48V because 48V seems to be the only point where these things would fit properly. Why would they even make an 8V battery seeing they cut themselves out of the 12V, 24V and 36V market.
Colour me puzzled !
What hydrometer are you buying ?
just as the 6 volts have three two volt cells in a common case, 12 volts have six two volt cells in a common
case the 8 volts have 4 two volt cells in a common case.
yes it puts them out of the 12 and 36volt usage but 3 of them work in a 24 and of course 6 will work in a 48volt system.
i can only speculate that they take up a bit less foot print in a golf cart and 48 volts probably make a bit more hp when it comes to powering motors?
i will post the specs on the hydrometer when i get it, hopefully later today, if not it will be tuesday
labor day weekend is a big thing around here, 3 days of celebrations
bob g
back with an update on the 8volt golf cart deep cycle batteries
did a few shallow cycles down to ~70% SOC and back up to full charge
then topped off the electrolyte with distilled water, and put them back on the charger
for several days at ~4amps @ 54.4vdc, while waiting to get a decent hydrometer
the one i had leaked so badly it was just a mess
after looking at a few at my local napa he finally ordered me in a very expensive unit (his words)
and i waited for it to come in,,, it did and i picked it up for the princely sum of $9.79 including tax... no wonder the crap they sell is so cheaply made, if a decent one cost less than 10 bucks one really doesn't even want to think about a cheaper priced unit... i really would like to have gotten one priced at 30 or more dollars but apparently they can't get one that good or the sales dude would have died rather than order it.
anyway it works, has a built in thermometer and the temp compensation chart all in a nice unit.
while it drips a bit it is usable.
i checked the batteries, each cell and they all come in at 1.275 plus 2 for temp compensation, meaning they are all at 1.277 which is what they should be at full charge.
so the voltage is correct for each battery, all within a couple hundredths of a volt and all the cells electrolyte specific gravity are spot on, so...
it looks like these are all ok, and will do what is expected of them.
it looks like i will have to take back half of the ugly things i was thinking about the dealer!
lol :)
seriously i am happy with the purchase, at 60 bucks each, plus a 20 dollar core charge each
i got six 8volt 190amp/hr batteries that are true deep cycle, and in good condition.
for my intended use, which is more of a buffer bank than a deep cycling proposition, i think with good care and maintenance i can get at least 6 years out of them.
i am thinking of setting up a regime where they will be used to no more than perhaps the top 20% for the most part (6 out of 7 days) and down to 50% state of charge on the 7th day.
it would appear that the lifespan is dramatically higher in shallow cycling, however electrolyte stratification can be a problem, so my thinking is to go ahead and take them down to half tank once a week or maybe extend that to once every two weeks to stir up the electrolyte and open up more plate pores in the process.
in any event they will be very closely monitored for any signs of changes, and the regime altered to keep the batteries in peak condition. the idea being those lessons learned and procedures developed can then be applied to a more expensive battery set, and have some idea how best to utilize the investment.
bob g
Hi Guy's
don't forget some of us still use some 32v stuff and 4x8v still works for us. In my EV the 12v acc batt died while shopping so needed a new batt there and then ( controller works off the 12v batt ) so went beck into dept store and could only get standard auto batt, so bought the cheapest one I could $79.00 later , get home and order another deep cycle batt but also put 12v desulfator on the little one I just put in there. That was 4yrs ago and the little batts still in there and going fine it gets charged when the main pack is charged and runs all 12v items in the car, lights wipers radio etc. I do sometimes get home in the dark with dim lights and a buzzing instead of a radio- so a very run down batt but it charges back up again and still seems happy.
Just saying that I to do like the desulfators and run them on all lead acid batts here ;D
Out of curiosity what are you guys paying for Trojan T104's $360.00 each here.
Ian
Quote from: mobile_bob on September 12, 2012, 08:02:11 PM
after looking at a few at my local napa he finally ordered me in a very expensive unit (his words)
and i waited for it to come in,,, it did and i picked it up for the princely sum of $9.79 including tax...
no wonder the crap they sell is so cheaply made, if a decent one cost less than 10 bucks one really doesn't even want to think about a cheaper priced unit... i really would like to have gotten one priced at 30 or more dollars but apparently they can't get one that good or the sales dude would have died rather than order it.
anyway it works, has a built in thermometer and the temp compensation chart all in a nice unit.
while it drips a bit it is usable.
That same unit (presumably) costs $19.99 plus tax up here in the not so frozen north. If you are feeling badly about how cheap yours was, I can sell you one for a mere 29.99 :) BTW, be vely vely carefull about the thermometer. It is like ultra fragile and if you push on it by accident it will break (the 29.99 high precision unit that I offered above does not have a broken thermometer by the way - it has a custom shorter thermometer to be able to reach into smaller confined spaces)
Although it did the job, I find these specific gravity measurements to be very frustrating and highly misleading as to the accuracy and precision attainable.
I am glad the batteries worked out for you and 60 bucks is a steal !
thanks Jens
i too find the hydrometer to be very tedious to get accurate results with, however it is able to do
so if you are very careful with it.
is it as easy as a cheap digital voltmeter is at measuring voltage? hell no!
but it beats anything i have so far at measuring specific gravity.
i am going to keep looking to see if i can find a better one, i know that they used to make
very good, high quality hydrometers, but that was maybe 40 years ago since i last saw one.
at least this one will work well enough to get a baseline and determine if the cells could be charged up to full and give me some assurance that they are not heavily sulfated.
i would still like to do about a 3 hour equalization on the string, just to make sure they are as good as can be from the start, however i am not seeing anything that tells me that is needed right now, so maybe that will wait until i can get my charging system up and running so that i have a tightly controlled equalization capability.
the thought also comes to me that maybe i would like another string of these batteries to alternate between, an A and a B set. that would allow me to be much more careful with the batteries in use, and in charging, and allow for a 24 hour rest before a string would be put back into service,, this would allow for better accuracy using voltage as an indicator of true state of charge between service intervals.
failing that, i think i will at least call and get one more battery to match this set, to use as a spare, and rotate it into the string on a weekly basis, sort of like a spare tire in the trunk. this would allow me to take out a weak sister if one pops up and give me time to do some remedial work on it before putting it back in the lineup. i think that would be very beneficial, in that i could probably correct a problem before it got to the point of being very hard or impossible to correct.
in the end this is all to do research on, and it seems to me that if i am going to all the trouble to try and do accurate/repeatable testing, i might as well do as many facets of testing at the same time as is economically possible.
the goal now is to get this system fully functional before next cooling season, i want to have the trigen fully online and burning nat/gas before the need of heavy air conditioning hits again. these 300 dollar electric bills for this little place while manageable seem to me that i might be able to trim a bit off of.
with my luck however, by the time that comes around, natural gas prices will double or worse and make using it as an alternate (cheaper) fuel source not viable.
bob g
If you really want a good way to check SG try a Refractometer
http://www.extech.com/instruments/product.asp?catid=17&prodid=229
http://www.amazon.com/Extech-RF40-Battery-Coolant-Refractometer/dp/B00023RYR2
Quote from: mobile_bob on September 13, 2012, 02:07:13 AM
SNIP
with my luck however, by the time that comes around, natural gas prices will double or worse and make using it as an alternate (cheaper) fuel source not viable.
bob g
If you really think NG will cost that much more next year then hedge, buy some NG futures (http://www.cmegroup.com/trading/energy/natural-gas/natural-gas.html) expiring next summer.
Farmers sell commodities futures all the time to hedge their crops/meat production.
Quote from: squarebob on September 13, 2012, 06:10:58 AM
If you really want a good way to check SG try a Refractometer
http://www.extech.com/instruments/product.asp?catid=17&prodid=229
http://www.amazon.com/Extech-RF40-Battery-Coolant-Refractometer/dp/B00023RYR2
I have a Leica, that works great...
Quote from: mobile_bob on September 13, 2012, 02:07:13 AM
i am going to keep looking to see if i can find a better one, i know that they used to make
very good, high quality hydrometers, but that was maybe 40 years ago since i last saw one.
Try one of those new fangled digital jobs .....
Quote
the thought also comes to me that maybe i would like another string of these batteries to alternate between, an A and a B set.
Careful there Bob, next you will be talking bigger strings to improve life, more and more strings as backup and soon you have a giant room full of batteries - it creeps up on you, very sneaky !
8 volt batteries were commonly used as replacements for 6 volt batteries in old cars and tractors. Turn up the regulator a bit to charge at 8V, the lights burn brighter, the ignition has a hotter spark, and the starter cranks better. It might burn the points a littler sooner, however. But that was when there was a screw on the back of the generator that adjusted the "third brush" and you could easily turn it up. Maybe they still do that in some places?
Other than the convenience of multiple cells in one package for a car, I'd rather have individual 2V cells; especially in a stationary application like PV. It makes it so much easier to fiddle with and correct a single cell. I might even like 1.2V Ni Fe batteries better... except for the cost.
i won't be going with a much larger battery bank, at least for some time
as for nife (edison cells) i wouldn't take a set if they were the same cost as lead acid
the charging efficiency is dreadful on those things.
and contrary to folklore their lifespan is no better than a rolls surrette 5000 series.
(at least in the chinese cells, which to my knowledge are the only manufactures at this time)
bob g
Hmm, I thought the Edison cells lasted pretty much forever. When they die, one simply drains and replaces the electrolyte (lye solution).
I'm glad I didn't take the plunge!
Ron
If you had 2 banks, you could test one with a full time de-sulfator. :-*
Well, I guess I'm the lab rat for the edison cells. Mine are currently now using a lot of water, with very short absorb times. I don't know if that means the electrolyte is " carbonated " or what. Back to the vendors phone tree !
Any word from the vendor regarding your water use and short absorb times, Mike?
I'm a lot more optimistic about NIFE batteries than BobG. I just don't like the price, yet, and I'd love to hear more from off grid NIFE pioneers.
> Any word from the vendor regarding your water use and short absorb times, Mike?
Spoke with him yesterday, and he thinks I should roll back some of my charge voltage and time, so maybe I'll do that. I also ordered the carbonate test kit, and will see what shape the electrolyte is in.