Hi all there seems to be a lot of interest in bat banks.
So I thought I would give a little real life story, of the last week.
I am the marine electrician/designer of a rehab of a 1962 15 meter Baguetto (http://photos.imageevent.com/studio413/bassante/large/bagietto.jpg).
My part of the job is a top down demo/rewire...of the electrical systems on board.(http://photos.imageevent.com/studio413/bassante/small/wireway.jpg)
I installed a new house bat bank(3 interstate 8-d 12v/720amphr) in July of this year.
Now on to the puke. The owner was at the boat in late December with the canvas guy, they changed the shore power cord from the port to the starboard entrance(what they didn't do is rotate the deck switch from port to starboard), then they managed to leave on, one of the distributed panel, dc power(http://photos.imageevent.com/studio413/bassante/small/dcbuss.jpg) switches for the aft stateroom, along with the breakers for about 15 amps worth of lights. He didn't return to the boat till late January, and noticed that the house bank was dead. I showed back up 2 days ago when parts landed, and he said, by the way you did something wrong bc the batteries are all dead.
As the story goes 720 amp bank with a load of 15 amps will go dead after about 62.42 (Peukerts Law) hours(or 2.6 days) with no charge(don't forget to factor temp), well we exceed that by about 38 days with no charge. With labor and parts that's about $2k USD. Everyone knows if you leave a dead battery uncharged for any amount of time it's a goner....not to mention that there was a 15 amp load(lights) that wouldn't let the bat recover....anything. So the bank is dead, $2k puked
Or is it?
Now for the Outback trap. I installed an FX2512 inverter /w bat charge the, inverter/charger drops out at 10.5 volts, and bc they programed it so it can't be grid tied without a dc side it won't come back online until it sees a dc buss voltage of greater than 11 volts for ten minutes. That means you better have an auxiliary charge source in some cases if you want to get the outback, back online(even to use as a battery charger).
So I brought in my portable shore charger, hit the bank with 10 amps for 24 hrs, then I hit again with 20 amps for 24 hrs. I energized the outback and up she came. After 24hr rest period I ran the spg on all the cells, they ranged between 1.10 and 1.225 at 12.8 volts, now that's a dead battery...no matter what the voltage says(it's called surface charge).
I then hit the bank with a 15.8 v equalize...now the spg after a 24hr rest on all cells is between 1.25 and 1.26....I recognize this as a surface charge. So I disconnect the string into individual 12 v bats, I set up a Peukert discharge of 12 amps on bat 1, within in one hour the voltage drops to 12.3, Peukert says I have 20 hrs to hit a voltage of 10.5, that's not going to happen, so I recharge to full, and hit it with another eq this time 16 volts, after 24 hrs rest I have a bat voltage of 12.9, and an spg of near 1.3...maybe things are looking good, wrong. I set up a factory spec load of 12 amps, she pukes out at 141amps/10.5v drawn in about 8 hrs, well below any respectable bank/bat. So now, I have the bat on a 10 amp recharge, when she hits voltage...I'll hit her again with a 16 amp eq, and another load test. If one bat can't pass this, then the whole bank goes to recycle and a new group of bats will be installed.
I'll let you know
Lloyd
check out this mag switch, that I rebuilt, it runs the auto-start for the gen, when there is a demand for high voltage that the inverter can't supply. (http://photos.imageevent.com/studio413/bassante/websize/magswitch.jpg)
These are the voltage regs, for the reinstalled dynamos (http://photos.imageevent.com/studio413/bassante/websize/regulators.jpg)
Nice job on the wiring! Lots of time invested and it shows.
Her power, Professor you'll love this twin supercharged 8v71 jimmys.
She cruises @35 knots, top speed 50 knots...just think all the 55 drums of diesel thrown overboard.
Lloyd
The next project is a 23 Meter big sister built 1962, for the Prince of Saude Arabia. She was sunk after a complete restore in 2000, she hit a reef(off Italy) at 35 knots ripped her quarter stern from just forward the shaft log. She had brand new v12 Manns from the 2000 restore(less then 1 month)...the new owner bought her in Italy had hers shipped to Seattle. They floated her with plywood scabs, she is on the ways nearing a rebuild of the under-waters at Jensens. New 12 cyl CRM's(http://photos.imageevent.com/studio413/bassante/websize/crmdiesel.jpg) just landed in crates from Italy. The engine builder was the original OEM for the boat when she was new, they sent all of the original drawings/engineering. The crates came with all the v-drives oil/water reactors("heat exchangers as we know em") fuel/oil filters, and oil/waterpumps.
twins mind you
something tells me that it's going to turn faster than 650 rpm, not sure i like that. ::) lol.
Scott R.
Quote from: Lloyd on February 14, 2010, 12:23:43 AM
Hi all there seems to be a lot of interest in bat banks.
So I thought I would give a little real life story, of the last week.
I am the marine electrician/designer of a rehab of a 1962 15 meter Baguetto
Years ago a 3 month old aluminum hulled 56 footer was found on the bottom at the marina across the street from my house one morning. They tried to pump it out but all they got was big boiling cauldron and the boat just sat there. The finally removed the roof of the covered slip and brought in a barge with a crane to raise it. It seems that an engine had fallen through the bottom of the boat.
At the slip across the dock from it the shore power cord was in the salt water bubbling merrily away. 5 other boats nearby had serious electrolyses problems. The worst part was that the owner of the aluminum boat had not had time to take the boat out for it's first cruise and because of that, he had stalled on getting his boat insured. Total loss.
Quote from: rbodell on February 14, 2010, 08:30:52 AM
Quote from: Lloyd on February 14, 2010, 12:23:43 AM
Hi all there seems to be a lot of interest in bat banks.
So I thought I would give a little real life story, of the last week.
I am the marine electrician/designer of a rehab of a 1962 15 meter Baguetto
Years ago a 3 month old aluminum hulled 56 footer was found on the bottom at the marina across the street from my house one morning. They tried to pump it out but all they got was big boiling cauldron and the boat just sat there. The finally removed the roof of the covered slip and brought in a barge with a crane to raise it. It seems that an engine had fallen through the bottom of the boat.
At the slip across the dock from it the shore power cord was in the salt water bubbling merrily away. 5 other boats nearby had serious electrolyses problems. The worst part was that the owner of the aluminum boat had not had time to take the boat out for it's first cruise and because of that, he had stalled on getting his boat insured. Total loss.
That is hardly news to those that realize a boat is just a euphemism for a depression in the water into which one pours lots of money.
Quote from: rcavictim on February 14, 2010, 01:25:52 AM
Nice job on the wiring! Lots of time invested and it shows.
Thanks
You should have seen the owner when I started the job. The first thing I did was to grab my big wire cutters and proceed to cut every wire in the boat out. He was like how are you going to know where to put everything back? He said, he thought that we should replace one wire at a time.
I approach these jobs as a kinda of art form. On a boat you don't have much real estate to work with, so each wire way has to be well though out. On this boat all of those "silver(alum)wire clamps, are all hand made to fit the wire way, by me. When the boat was originally built the factory pre-designed/made all the clamps so the installer could look at the plans, and order this many or that many of each clamp he needed.
With so many new systems on board the original wire ways didn't work...so it was a complete new layout.
The whole regulator assembly didn't exist, it had been converted to modern alts. When he was at the factory buying the sistership, he found new old stock, so we went back with the original Bosch 12 v 80 amp dynamos, and regs(which are paralleling) for the 12 volt house bank. Then we changed the start back to 24v, and added some rebuilt dynamos and regs.
Lloyd
i can relate to your wiring job as to how the owner reacted
years ago, at the ripe old age of 19 my boss assigned me to repair the wiring in a trade in truck
it was hopeless, and i figured it easier to strip it to the bone and start over from scratch.
you should have seen the look on my bosses face when he saw the pile or wire on the floor, and the dash stripped to the firewall.
:)
i can still hear his voice in my head
"I hope the hell you know how to put that all back together again"
and my answer
"it didn't work when i started!"
(somehow that was not a comforting comment to him)
bob g
Quote from: lowspeedlife on February 14, 2010, 07:00:01 AM
something tells me that it's going to turn faster than 650 rpm, not sure i like that. ::) lol.
Scott R.
Scott,
maybe you'll like my friends boat engine better
(http://www.mvdeerleap.com/images/0792.jpg)
He's got a pair of really nice Gardners, they turn slow.
(http://www.mvdeerleap.com/images/port_eng.jpg)
I was hoping that he had the new pics of his engine room online.
http://www.mvdeerleap.com/engine.htm
Here is a big side shot http://lh3.ggpht.com/_NMqUqexRT-w/SOQo7smMy_I/AAAAAAAAAeM/bnbzZXg5wpA/IMG_3496.JPG
Lloyd
So what would a person do with a boat like this besides pay through the nose for insurance, docking fees, maintenance, etc., plus not be able to take it out anywhere for fear of pirates and being killed? Just wondering aloud.
This coming from someone who firmly believes that one should not go out in public wearing a watch that is worth more than your hand.
Quote from: mobile_bob on February 14, 2010, 01:21:38 PM
"I hope the hell you know how to put that all back together again"
and my answer
"it didn't work when i started!"
LOL - brilliant response...
Quote from: rcavictim on February 14, 2010, 05:36:40 PM
So what would a person do with a boat like this besides pay through the nose for insurance, docking fees, maintenance, etc., plus not be able to take it out anywhere for fear of pirates and being killed? Just wondering aloud.
well, I don't know where that boat is, but in American waters, piracy is pretty much a thing of the past. In the middle east and Africa, large ships and tankers are the prize. Drug smugglers want fast boats and boats that are inconspicuous and carry heavy cargos like fishing boats. This boat would probably be recognized all over the world.
Of course that isn't guaranteed, but I think that would be one of the last ones to be taken by pirates. All that aside, weather, fire, and miscalculations in navigation would be way up on the danger scale above pirates.
Quote from: rcavictim on February 14, 2010, 05:36:40 PM
So what would a person do with a boat like this besides pay through the nose for insurance, docking fees, maintenance, etc., plus not be able to take it out anywhere for fear of pirates and being killed? Just wondering aloud.
This coming from someone who firmly believes that one should not go out in public wearing a watch that is worth more than your hand.
Fear of pirates ? Or being killed? This sounds like somthing my 78 year mother in law would come up with.
Anyways, This is not a merchant ship. It can be armed.
And what to do with the boat? Have fun going out looking for pirates and take care of them. Just Kidding ;D
Very nice boat. I love seeing old boats getting a second life.
Henry
Yea not much fear of Pirates in the NW.
Slim, does most of the work near 80% himself, he also restores little chris crafts as business.
They live on the boat from about April - October, usually sometime by early May, they head north to Alaska. They gather fish and sea food along the way. He's got a big smoker on board, and a couple of large freezers. They put away enough to last them the year. He owns a boat house that it lives in during the off season, his annual mooring is likely cheaper than mine.
Him and his wife are the most down to earth people, you'd think them just ordinary joes.
He's one of those guys that can find a deal anywhere he looks...and about as frugal as any off grider I know. Hell the boat only burns less 12 gals an hour at a cruise speed of 11 knots, I think the engines only spin at 600-700 rpm, with some monster wheels.
What's even more amazing is he and his wife have run the boat by themselves, but usually the have changing crews of friends and family all along the way...who dbl as deck hands. They like us spen about 1 out 30 days tied to a dock the rest the time it's on the hook...no mooring fees.
Lloyd
In the engine picture it looks like the person that did the pipe fitting and sweating the copper tubing had a few hours of experiance. He did a very nice job. Everything was kept neat.
Henry
Boy Henry,
I wish Slim would get the new engine room pics on his web site. It's like going into a surgery center, all the bulkheads are sheathed in mirror polished SS, and the amount of 90/10 copper pluming for sea cooling is all polished, anything made of brass/bronze/copper/SS is all polished.
And talk about design order. Some real pre-thought went along with all the polishing...I love to see well executed machine spaces.
I think I'll email him and have him send me a pic, I can post of the ER.
I am going to bet the fittings are brazed instead of sweat fit, as electrolysis is a big issue in marine installations.
Lloyd
I would love to see more of the work. I was a plumber and pipe fitter for 8 years and I know good work when I see it. I can't see the fittings up close but it looks like they were all wiped nicely before everything was polished. If you can get more pictures please post them.
Henry
Quote from: Lloyd on February 14, 2010, 12:23:43 AM
Hi all there seems to be a lot of interest in bat banks.
So I thought I would give a little real life story, of the last week.
I then hit the bank with a 15.8 v equalize...now the spg after a 24hr rest on all cells is between 1.25 and 1.26....I recognize this as a surface charge. So I disconnect the string into individual 12 v bats, I set up a Peukert discharge of 12 amps on bat 1, within in one hour the voltage drops to 12.3, Peukert says I have 20 hrs to hit a voltage of 10.5, that's not going to happen, so I recharge to full, and hit it with another eq this time 16 volts, after 24 hrs rest I have a bat voltage of 12.9, and an spg of near 1.3...maybe things are looking good, wrong. I set up a factory spec load of 12 amps, she pukes out at 141amps/10.5v drawn in about 8 hrs, well below any respectable bank/bat. So now, I have the bat on a 10 amp recharge, when she hits voltage...I'll hit her again with a 16 amp eq, and another load test. If one bat can't pass this, then the whole bank goes to recycle and a new group of bats will be installed.
I'll let you know
Lloyd
I ran another Peukert load "12 amp" test on a single 240 amphr bat from the string. Starting voltage is 12.9, spg is 1.3, this after a 24hr rest from the last eq. I energized the load with in seconds the bat voltage dropped to 12.23, after 15 minutes w/load the voltage recovered to 12.32. I dropped the load after 1 hour, the voltage was 12.1 after 15 min. rest, the bat recovered back to 12.57. This shows the bat has a huge internal resistance. I turned the charger back on after she came upto float I hit her with a 16v eq, for 1.5 hrs.
Ran the same load test as previous, this time I let it go until the outback dropped out(the load was only connected thru the OB). The OB dropped out after 141 amphr's in 13 hrs. The spg was 1.10 on all cells, and the resting voltage was 11.3, these measurements were taken after 1 hr. I chraged and eq again.
Final test started after 48 hrs. This time I am using close to a c/25 load, which according to Peukert, I should have 158.34 amphrs available, the OB should drop out after 3.3 hrs, the load is 48 amps. Starting from a float voltage of 13.6, After connecting the load, the bat voltage drops to 12.35, after 1 hr the voltage is 12.1, 49 minutes later the voltage is down to 11.46, then in 30 min the voltage is 11.01, After another 15 min the OB drops out at a voltage of 10.5. I leave the load going for another 15 mins, and the voltage drops to 9.5. It is time to disconnect, Test starting at 1:00pm and ending at 3:30 pm=2.5 hrs, total of 109 amphrs draw from the bank. After 15 mins the voltage recovered to 11.2.
This bank is effectively junk for its intended use as a deep-cycle bank for inverter loads. So it's going to the scrap heap for recycle.
A one time owner fopa on a brand new bank that should have lasted at least 5-7 years if maintained. Bat banks are unforgiving for any mismanagement.
Lloyd
Perhaps the system design should have added a low voltage battery cutoff and warning piezo alarm, as humans are prone to these types of mistakes.
There is little loss penalty now for a low voltage cutoff, as mosfet on resistance is becoming so fabulously low.
Cheap insurance for an expensive battery bank.
Hi Bruce,
I begged the owner for a low voltage cut-out for the main dc bus. His answer, it didn't have one to begin with so I don't think it needs it now. His reason every boat has it's start up shut down procedure. He's not laughing now. He thinks the batteries were bad to begin with...he is beside himself going on that there is just know way that a bank could be so unforgiving. Looking for some else to blame.
It's been a battle from the beginning just adding the ABYC required safety devices, ie fuses where they didn't exist. On more than one occasion I offered him to hire another electrician, and I would drop out. I just won't risk his and his families life, nor my insurance, to take a short cut.
Lloyd
Pity he didn't take your advice on the low voltage cut out, Lloyd. Some people can't be helped.
I have to try and idiot-proof everything that I use- I'm way beyond absent minded now. After smoking my house badly and risking a fire more than a dozen times, I finally installed a relay and mechanical timer on the electric stove. It now turns itself off if I don't check on it or wander out into my shop or get busy in my office. This most simple project improved my life greatly. I'm going to have to do the same for my off grid place with the propane stove.
Yea Bruce,
I am a big believer in idiot proof...it 's very few people that can do a full check list every time the start and stop...much as a pilot is required to do. Accidents happen closer to home bc we become complacent in the things we do every day. Which in no short order will, be one of those accidents close to home.
My first house I bought, I almost burned her to the ground...came home from work tired set a pan of oil on the stove...woke on the couch to a glowing orange flame in the kitchen. I went in and had flames from the top of the stove to the ceiling...9ft ceilings. As a scared fool I grabbed the pan and took it outside...thereby splashing flaming grease all the way to the door. It's a pure wonder I didn't splash it on me..do you think I had a fire extinguisher...no way...22 year old'ss don't think that far ahead.
As far the propane look into the marine shut-off valve, you can locate it next to the stove and it shuts off the tank at the tank.
Lloyd
I came to this thread late via reference to one of the pictures. Please pardon the tardy response.
A client of mine had a similar experience. His boat arrived in the Phillipines with a delivery crew. Someone left several circuits energized and the boat was hauled for dry storage for 3 months before anyone came to look at it again. Needless to say the 1000 amp hour battery bank was flat. These were 2V AGM cells made in China so quality was definitely a question mark. Because I design my systems to handle a dead ship restart I could send instructions to the surveyor on how to get the vessel going from a dead ship condition even when no shore power was available. 24 hours later I got an email reporting that everything was back to normal. One year or so later the vessel is back in the Phillipines still with the original bank going fine. At least the owner is not complaining even when he runs the air conditioner over night on the inverter system. Something to be said for AGM technology.
I have had similar revival experiences with other brands of AGM batteries left for dead over extended periods of time. I am not saying they never suffer any damage but in many cases the worst problem is sulfation and Pulsetech technology does a good job of recovering sulfated batteries. Nano pulser is another brand and it is sold by Boat Electric in Seattle.
I would highly recommend installing pulse desulfators on any battery bank left sitting unused for periods of time.
I have heard less than sterling product use reports about one brand called Battry Mind(er) but generally the technology seem to work as claimed. Why else are there so many clone products available now that the original patent has expired. More than a few people must have had positive experiences leading them to consider copying the product.
regards
Elnav
odd thing is, there is precious little scientific method testing to support the use of a pulse charger
in my experience, a careful recharge with a good charger, given enough time will recover the cells as well
as the pulse units do.
i recently killed a couple of agm's, don't ask how, but suffice it to say i was sick
it took about a week of charging, and discharge cycles to get the batteries back to better than 95% capacity
that using a standard charger set at 10amps, alternating to 2amps at a rate of 14.8 volts
agm's generally are much more forgiving to this sort of abuse, do this to a flooded cell and you will be crying alligator
tears for a very long time.
lots of folks swear by the pulse chargers, but i have yet to read a comprehensive report on testing in a controlled
3rd party lab such as sandia labs (and yes i am aware that they have tested the technology)
bob g
I must confess that when I first heard of it my initial reaction was "snake oil!" As luck would have it, someone I knew said he had a sample in his desk drawer left by a sales rep but he didn't have any interest in testing it. He gave it to me to try and despite my intial scepticism it really did work. I was working for Xantrex at the time so had lots of 'dead', abused and sulfated batteries to test with. The initial tests proved promising enough that Xantrex authorized me to buy more samples and set up a test program. The idea being we might licence the technology for inclusion in our own chargers.
Unfortunately at about this time, senior management had a corporate policy revision and decided instead to disband the marine division as a separate entity. My work and much of the marine directed activity got terminated.
I carried on by myself but was unable to fund a rigorous 'scientific study' and can thus only report anecdotal evidence. I suspect this technology is regarded by the battery manufacturers and the industry as a whole as a potential threat to sales of replacement of sulfated batteries so who else has an interest in promoting the technology.?
In the past four years I have begun to see a few charger manufactures include 'pulsing' in their advertising literature. Considering the technology was originally made for the US Army it probably has some credibility. It was granted some patent papers.
WWW.pulsetech.com was the original company but now there are about six brand names on the market.
Lloyd
a few questions
what type of charger do you use, you say that you hit it with 10 amps and then 20amps for 24 hours, is this selectable from your charger and is it at a contastant voltage ?
what make or model do you use.
"I then hit the bank with a 15.8 v equalize...now the spg after a 24hr rest on all cells is between 1.25 and 1.26....I recognize this as a surface charge. So I disconnect the string into individual 12 v bats, I set up a Peukert discharge of 12 amps on bat 1, within in one hour the voltage drops to 12.3, Peukert says I have 20 hrs to hit a voltage of 10.5, that's not going to happen, so I recharge to full, and hit it with another eq this time 16 volts, after 24 hrs rest I have a bat voltage of 12.9, and an spg of near 1.3...maybe things are looking good, wrong. I set up a factory spec load of 12 amps, she pukes out at 141amps/10.5v drawn in about 8 hrs, well below any respectable bank/bat. So now, I have the bat on a 10 amp recharge, when she hits voltage...I'll hit her again with a 16 amp eq, and another load test. If one bat can't pass this, then the whole bank goes to recycle and a new group of bats will be installed."
so you can select the output/ charge voltage as well ?
Lloyd. you charge up the bank and then when it has reached full voltage you hit it with a 16 amp equalisation charge ?
the reason i am asking these questions is that i was given a battery bank, where it has not been charged for a few months but the batteries are reading from 11.8 to 12.3 volts,
what would you recommend to test them out, should i charge them at a low rate, 1 amp for a long time or at a higher current rate, 20 amps until the reach their voltage.
they are 12 volt 65ah deep cycle batteries
step by step what would you do ?
regards
Loon
Quote from: loonogs on July 07, 2010, 05:15:35 AM
Lloyd
a few questions
what type of charger do you use, you say that you hit it with 10 amps and then 20amps for 24 hours, is this selectable from your charger and is it at a contastant voltage ?
what make or model do you use.
I have a military shore charger, that I use when working with a bat bank. I can select the voltage from 1volt to 48 volts in 1 tenth increments, and amperage's in in increments of 1 amp up to a max of 40 amps. It has a time selection with a 24 hr clock, and a temp correction sensor.
A very low discharged bat will not take high amperage very fast in the beginning, it will heat up and shed, especially if its sulphated badly, the shedding can cause thermal runaway.
Quote"I then hit the bank with a 15.8 v equalize...now the spg after a 24hr rest on all cells is between 1.25 and 1.26....I recognize this as a surface charge. So I disconnect the string into individual 12 v bats, I set up a Peukert discharge of 12 amps on bat 1, within in one hour the voltage drops to 12.3, Peukert says I have 20 hrs to hit a voltage of 10.5, that's not going to happen, so I recharge to full, and hit it with another eq this time 16 volts, after 24 hrs rest I have a bat voltage of 12.9, and an spg of near 1.3...maybe things are looking good, wrong. I set up a factory spec load of 12 amps, she pukes out at 141amps/10.5v drawn in about 8 hrs, well below any respectable bank/bat. So now, I have the bat on a 10 amp recharge, when she hits voltage...I'll hit her again with a 16 amp eq, and another load test. If one bat can't pass this, then the whole bank goes to recycle and a new group of bats will be installed."
so you can select the output/ charge voltage as well ?
Yes, as stated above
QuoteLloyd. you charge up the bank and then when it has reached full voltage you hit it with a 16 amp equalisation charge ?
the reason i am asking these questions is that i was given a battery bank, where it has not been charged for a few months but the batteries are reading from 11.8 to 12.3 volts,
what would you recommend to test them out, should i charge them at a low rate, 1 amp for a long time or at a higher current rate, 20 amps until the reach their voltage.
they are 12 volt 65ah deep cycle batteries
Yes, always equalize after the bat is up to voltage, never when its under charged...other wise heat and thermal runaway, at the very least it will badly corrode the positive plates
Quotestep by step what would you do ?
regards
Loon
First I would make a matrix and number each bat/cell ie; B1C1, B1C2, B1C3....B2C1, B2C2...where b=bat, c=cell, then I would take spg of each cell, and voltage of each bat, and mark the matrix.
Then would choose the lowest bat in cell/voltage readings, hit it with about 4 amps until the the voltage quits rising. Take a spg/voltagereading, mark the matrix, then set up a 20 hr pukert discharge based on the manufacture ratings until voltage drops to 11.5, unloaded it, let it rest for at least 6 hrs, take a spg/voltage reading, mark the matrix, then charge at a 10 amp rate until the voltage quits rising, take a spg/voltage, mark the matrix.
Then I would run an EQ at the manufactures rated EQ voltage for a couple of hrs, let it rest for 24 hrs take a spg/voltage, mark the matrix, and repeat the above procedure. After the second cycle, I would then set up a 5 hr pukert discharge, and compare it to factory specs, if the bat last for 3 1/2 to 4 hrs I would recharge/eq....then run the same cycle on the rest of the bats in the group.
It's very important that each cell be with-in 15-20% of the other cells on spg at the start...if you have any cells that are wildly different, then watch like a hawk when charging, 1 or 2 very low cells on the spg as compared to the rest is an indication of possible short developing in that cell, which can cause a thermal runaway, and melt the bat in to a steaming pile of lead and gas clouds.
And if you can't get the worst of bats in the group to perform there is no reason to continue with the other bats...take em to the recycle and buy a fresh bank, and take care of it.
Lloyd
Lloyd
Lloyd,
thanks for the clear prompt reply
Regards
Philip