Lithium facts in practice

[Grandad]

............ a lot of city folk from Aus, think they know everything and we are backward and know nothing. So happy to not hear from him, city people seem to be living some where in space these days.

Oh, ain't that the truth? So glad to hear someone else say it. Thought maybe I was just turning into a grumpy old man.

Jim

[native pepper]

That's about right NP, the only reason to go above or below the cell voltages is to clear the memory effect. That requires a great deal of control and watching them like a hawk so they do not get damaged due to run away voltages at cell level either end.
Could you measure the voltage between the cell negative and the outer case and the cell positive and outer case of each cell?

T1 Terry

1.87v for the positive side and 1.67v negative side on my portable pack which is in an aluminium housing with 12mm ply down the sides. Bus, .02v positive .03v negative, still in aluminium but has ply down sides and underneath the cells between the aluminium and cells. House pack, is zero as it's not in an aluminium box, but in a wooden cupboard, not strapped just sits there.

Checked if there was any voltage between the inverter and pack housing in the bus and zero. Thanks for that little test, will clean up the portable as it is covered in possum shit and other junk sitting in my workshop, then do it again and see what I get. Probably should keep the tops of the cells clean, but as it always holds its energy levels over many months, haven't bothered.

Have trouble with possums, they love the veggie oil dregs and create havoc in my oil room. Have trapped lots and released them a many klms away in the forest, but they just keep on coming, must have some sort of bush telegraph that says go here, free junk food to get addicted to.

[native pepper]

............ a lot of city folk from Aus, think they know everything and we are backward and know nothing. So happy to not hear from him, city people seem to be living some where in space these days.

Oh, ain't that the truth? So glad to hear someone else say it. Thought maybe I was just turning into a grumpy old man.

Jim

Nah not grumpy, just see the reality.

[T1 Terry]

Interesting, some of the DIY EV people have seen rather high voltages at times between the battery box and the vehicle chassis, certainly enough to know about it when getting linked up between the two. It seems the problem gets worse when under high load tripping safety circuits designed to protect against a battery to chassis fault. Their answer was to wrap each cell in the BBQ sheet material so they were isolated from each other and the battery box. That of course then affects the cell cooling capability so the other method is to leave them in their plastic baskets, room then becomes the issue.
Of course, these battery packs are much higher voltage, between 270vdc and 750vdc depending on the set up.

T1 Terry

[native pepper]

Interesting, some of the DIY EV people have seen rather high voltages at times between the battery box and the vehicle chassis, certainly enough to know about it when getting linked up between the two. It seems the problem gets worse when under high load tripping safety circuits designed to protect against a battery to chassis fault. Their answer was to wrap each cell in the BBQ sheet material so they were isolated from each other and the battery box. That of course then affects the cell cooling capability so the other method is to leave them in their plastic baskets, room then becomes the issue.
Of course, these battery packs are much higher voltage, between 270vdc and 750vdc depending on the set up.

T1 Terry

I'll try it with the portable pack when it's being used, to see if that makes a difference to the voltage, have noticed when it's in use and have checked the cell voltage, sometimes get very high voltages on the pack. Once it was over 14.8v which freaked me out, so stopped it and it reverted to 13.3v as it settled and it was only driving a small veggie oil pump. My P pack has now dropped to 13v for the first time in it's history, will now experience how it performs under 13v.

[Mrcoolabah1au]

What is ncm lithium on read on one of the American web site

[T1 Terry]

Electric vehicle stuff, not really suited to house batteries. They have a faster charge rate and discharge rate than LiFeP04 as well as being lighter, but the cycle life is as yet unknown. They are smaller in cell size but heat issues and outer case isolation issues are yet to be determined. They need a few yrs to prove themselves in an electric vehicle situation before they could be considered for a house battery. The other concern of course is the "goes bang" factor, only LiFe and LTO chemistries don't go bang if things go wrong.

T1 Terry

[Mrcoolabah1au]

Thank you just what I thought rubbish as yet to be tested

[T1 Terry]

Not necessarily rubbish Wayne, but yet to prove itself. It has really only been commercially available in Aust for around 8 mths and there are very few DIY EV's actually installing and using them. Most are either still on their Winston or CALB cells or have opted to try Tesla cell packs or Leaf cell packs. There are a few who have gone with the aluminium case Winston cells, but they too are still in the "proving themselves" stage. They have issues themselves, the outer case can develop a voltage and must be insulated from the next cell in series as well as isolated from the vehicle body or it sets off the voltage leakage safety relay and the battery is isolated from the rest of the system until the fault can be fixed. Not only that, the boot up the arm from a static discharge shock you sometimes get with nylon seat covers is nothing to the one you could get touching two different parts of the body at the same time, not nice at all.

[Mrcoolabah1au]

Yes think I will stick to Winston while I got someone to service them when the time come or any update or upgrades