What would you do?

[JohnM]

grizzzman » Fri Dec 23, 2016 11:25 am

If you don't mind my asking? How often do use you're gen-set?

To be honest the the Gen set has been fired up in anger, twice in the last 3 years, both times when we were camped out, once when we had almost a week of constant rain, and another time following three days of rain, The Cod were on the bite and I didn't want to move on, It was doubtful whether we could get out any way, until it dried out a bit.
I usually fire up the gen set every couple of months and put it on some sort of load, just to make sure it is working.

[grizzzman]

Thanks for you're response John M

[grizzzman]

Been busy repairing the patio roof ready for Christmas so been off the air for a few days. We had the big white elephant the NBN installed yesterday, still isn't up and running, would have been a good thing if this govt had installed the system the way it was designed but the botched up mess they have now will cost a fortune to fix, but that is another story.

Properly designed from multiple cells in parallel, strapped and properly condition charged/balanced before their first use and quality cells will remain in balance. Balancing becomes an issue with 24v system and even more with 48v systems, 12v systems don't suffer the problems so a full time active balancing system whether wasting energy or transferring energy from the high cell to the low cell is not really needed. The cells will stay in balance without any form of balancer fitted.... unless there is a problem, then the balancer will hide the problem. Basically, if a 12v system requires a balancer to remain in balance and would go out of balance without it, the is a problem with the system that needs to be identified and fixed.

T1 Terry

Glad that you are getting ready for Christmas Internet? Problems suck I understand balancing but am unclear about conditioning?

Thanks

The conditioning is to make cells made for electric vehicle use suit long cycle life house battery use. Even though they are the same cells the use intended is at opposite ends of the scale, EV use requires big amps (up to 500 amps per 100Ah capacity) discharge to near empty and fully recharged at a controlled rate, the trade off is cycle life but still far better than the lead acid alternative.
On the other side house batteries only require relatively small discharge rates (50 amps per 100Ah is usually about the max) a varied recharge rate generally from solar, no requirement to return to 100% recharged and very rarely 100% capacity discharged often floating between 60% and 90% capacity even during the day charging period. Without conditioning the cells the cycle life will not be much better than EV use, although the high current isn't an issue that made them past their use by date for EV use so still have some life remaining as house batteries they have still suffered seriously depleted capacity. The death by internal build up between the plates causing a shorted cell is still there so cycle life is reduced even though the cells never saw high current discharge use. This is the problem the "experts" with lead acid battery interests are using to put down lithium batteries as a replacement for lead acid. Sadly there will be quite a few cases of exactly that happening because those jumping on the band wagon to sell lithium systems haven't done the hard yards in research but merely skimmed the surface and think they know all there is to know about.
Condition charging was first used for satellite and space use, although there is some dispute regarding the chemistry of the Mars Rover lithium cells, these were condition charged and are still operating after 11 yrs even though they went through a full shut down deep discharge when the solar panels were covered in dust. They recharged, turned back on and away it went again.

T1 Terry

So conditioning helps to stop/slow down the formation of dendrite's causing shorting/loss of capacity and life of the cell? It was interesting reading about the Mars Rover lithium cells. Seems that cold does not need to be an issue with lithium with the right electrolyte.

Thanks Terry

[native pepper]

These two pdfs will tell you what you want to know about the rovers batteries, read about them to see what and how NASA used them compared to what we use, they are li-ion and not lifepo4. Certainly have proved the technology and just love the way they kept them heated.

https://trs.jpl.nasa.gov/bitstream/hand ... sequence=1

http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

[T1 Terry]

In Jay Whiteacre's LiFeP04 talk while still at Carnegie Melon university from quite few yrs back he mentions actually freezing cells in liquid nitrogen and defrosting them to see the effect, apparently none. There is mention vaguely regarding the condition charging and his involvement in the Mars Rover missions..... it sure sounds like he is talking about LiFeP04 cells from A123, but some other mob has claimed it is their lithium cells being used in these expedition vehicles, who knows who is telling the truth, but Jay Whiteacre certainly has some very big name backers for his Aquion venture and I doubt they would have accepted anything said by him on face value

[T1 Terry]

These two pdfs will tell you what you want to know about the rovers batteries, read about them to see what and how NASA used them compared to what we use, they are li-ion and not lifepo4. Certainly have proved the technology and just love the way they kept them heated.

https://trs.jpl.nasa.gov/bitstream/hand ... sequence=1

http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

Still unsure about that part NP, they do give a chemical composition for the low temp electrolyte used but I didn't see a composition for the anode and cathode materials used, but I might have missed that bit. The fact that the cell voltages and cell numbers to create the 28v pack match the characteristics of LiFeP04 cells rather than any of the other lithium chemistries that fall under the generic Li-ion label lends quite a bit of weight to the argument for them being LiFeP04 and not against.

T1 Terry

[native pepper]

Was basing my assumption on this bit, in the second pdf. "each battery was discharged to about 25% depth of discharge per battery during launch, with lowest cell voltages being 3.82 V." So thought that was to high for lifepo4 and must be some fancy li-ion construction

After reading them again, the 3.82v may be 3.28v as that sounds like to me to be somewhere near 25% DOD and a typo, which I jumped on. But they keep the cells between 4.1v and 3 volts, which is what most of us use isn't it. Nice to know NASA use the same voltage parameters and their systems have survived over a decade on freezing Mars and how ever many months in space. The panels must be really efficient, even by todays retail standards, as must be the charging system.

Actually got more out of reading those to pdf's about the Mars missions and conditions there, than all the articles they produce in the media. Also confirmed our approach as being the right direction. After more than a decade of faultless operation in unlivable environmental and extreme conditions, with charging regimes that range from low to zero for very long times, lifepo4 looks better and better for the long term.

[T1 Terry]

The extreme cold allows the higher charging voltages as they can actually pump the heat out of the battery compartment. I doubt they still charge the cells that hard though, the battery was only designed to last for a very short period, as a section of Nasa has control of the Mars rovers they would have altered the charging regime to increase the battery cycle life. They lost the other Rover as they let the battery voltage drop too low and the system shut down, no way of pressing the button to turn it back on, they didn't make the same mistake with the second Rover
At least we have access to the reset button, so the same basic fail safe method works just fine

T1 Terry

[grizzzman]

How do you decide when the DC to DC charger needs to be cut off? Or for that matter back on? Using voltage? Counting amp hours?

Thanks

[BruceS]

Combination of many things.
Cut off if total V is too low V.
Cut off if cell V is too low.
Cut off if total V is too high.
Cut off if cell V is too high.
Counting Ahr is more for state of charge. (SOC)