easy ways to make a power supply charge lithium

[Matt Gruber]

Now i'm charging easily, but it is a manual system. I have to switch out the load tester to keep the amps up.
But it wasn't so easy at first

got my first limn tuesday and promptly blew 2 fuses

i put a spool of hookup wire in series and the amps came way down.
that was fine for my 2.5a ps, BUT
not enough for my 25a ps.
so i hooked my variable load tester in series and can set it for whatever start up amps i want.
just a temporary solution so i can charge as i learn.
so post your ideas, there must be plenty more! Mainly stuff you had lying around that worked, or cheap to make circuits, etc.

 

[Hillhater]

OK ..I will bite..... what is a "limn". ??
guessing that it some form of Lithium battery ( type, capacity, voltage , brand, etc ???)... i would suggest you get a suitable charger.... before you blow something else up. :wink:

 

[heathyoung]

That would probably be lithium manganese.

You need a current limited power supply / AKA constant current - you either adjust the voltage output based on load to keep the current under limits, or you adjust the voltage another way (eg. with a buck supply) Using a resistor to limit the power is not a good solution, as you have discovered.

 

[Matt Gruber]

buy a new unit? What fun is that?
.
i have a 0-60min timer. old school type. my plan is to use it to kick out the current limiting load tester so i won't have to watch it and do it manually. it will be fail safe. if the timer dies, it just takes longer to charge.
will use relays as i plan to use 3 or 4 switch psu's to charge my yet to be determined pack. Can't buy a CC PSU until i know how many volts the pack will be. Not sure if the LVC will kick in too early. So i'm using what i have for now, and if it continues to work out, i won't need a new CC PSU.

 

[dnmun]

why would there be a LVC if you don't use a BMS? if you rent your house you should do all this stuff outside on the concrete in the carport. you can be cavalier about reality if it is your house and let the insurance company decide how negligent you were. if you burn down an apartment building and someone is killed you can be held for negligent manslaughter.

 

[Matt Gruber]

controller has LVC that i've not verified yet.
research li'mn and see if you can find any fires. my search found no fires, that is why i picked them. Makita could not have a high amp circular saw jam in a 2x8 and burst into flames. So they picked a non-flammable battery. Pretty cool, HUH?
how can you have 11173 posts and not know about safe cells?

 

[dnmun]

because i had a careless tenant like you who thought they knew everything and they caught my house on fire charging lipo in cans just like you. it kinda sealed my resolve to never rent to pretentious and ignorant guys again. it will be up to the property owner to sue you for the damages and up to the DA if they wanna charge you with negligent homicide if it kills someone.

 

[dmwahl]

Makita could not have a high amp circular saw jam in a 2x8 and burst into flames. So they picked a non-flammable battery. Pretty cool, HUH?
how can you have 11173 posts and not know about safe cells?

There's a big difference between shorting out a battery pack and massively overcharging cells by charging them with an uncontrolled 25A power supply.

 

[Matt Gruber]

finished charging 6 used makita packs, and removed all dubious cells. The more i do this, the easier it gets.
now i'll wait a week and see how the voltage holds up.
25 amps would be too high, that is why my load tester is in the circuit, to reduce amps to a worry-free level. Today it did not exceed 3.2 amps. Maybe some day i'll need a quick recharge, then i'll press a button and speed up the charge, but NEVER to 25A!.
With my current limiting circuit, there is no problem. i just tried 8p and charged at 3.2 amps max. I think they will last longer with a slow charge. But even my 2a ps needs 5 minutes before being fully engaged. The idea is to avoid overloading the ps, that could make it overheat and quickly fail. Safety is my #1 concern, that is why i did not buy lico or lipo etc. too risky for me!

 

[Matt Gruber]

turns out it was much easier than i expected! ended up using my 1979 10amp 24v truck charger!
no need for any current limiting! it loves LIMN. it is 10 amps at 29v, and tapers to 2 amps at 37.7v, perfect for my 9s pack.
I'll have to watch it as it is DUMB, but it charges fast enough so that is not a problem for me.
Too bad i wasted time fooling with 6 switching psu's that i had lying around. They suck. If everything isn't perfect, they shut off

 

[Matt Gruber]

Well
looks like i may go 10s instead of 9s. this is why i didn't buy a charger. not being sure of the final set-up.
So that cool antique truck charger won't work, as it is down to 0.24a at 42v.
BUT i've got 6, 2.4a wall power supplies, 15vac, 2 can be wired in series thru a 6 amp bridge, and it charges at 2a tapering to .6a.
also have a 16.5vac, and 16vac 2.4a are $9.25. Transformers can be wired in series for any combo that works well.
Good thing the Konions limn have a great reputation for self balancing. i don't intend to do over 60% DOD, so that will help lots.
So i don't expect to need a new charger, as long as the self balancing is as reported. Will watch/time each and every charge, and it will NEVER charge when i'm asleep!(fire hazard with any charger)

 

[yuyuyak]

I agree they are PROBABLY safer, but please don't get too complacent about them.

Konion battery fires:
http://www.candlepowerforums.com/vb/showthread.php?262234-TK-Monster-Explosion
http://endless-sphere.com/forums/viewtopic.php?f=7&t=46280

Hmm, there's one more here at ES, I think it's by gestalt.

 

[Matt Gruber]

Yak
you inspired me to do a test.
1st i shorted a Konion V cell. it barely got warm and the internal fuse blew.
Them i removed the + terminal(the fuse is under it) and hammered a screw into the cell!
it started to smoke and i put it outside just in case.
no fire.
So now we need to do a comparison test.
I have a half gallon of gasoline. What would you suggest?
.
If i buy another car and sell the ebike, will i be safer?
Everyday cars catch fire, thousands every year, and many people die. Is this better?
I do appreciate the links, at least you found something i missed! The 1st was not a V cell. The 2nd wasn't really a fire. But, good try!

 

[yuyuyak]

Again, I agree they are PROBABLY safer.
Still, do you commonly leave a 1/2 gallon of gasoline in your living room?
That's the difference. There is no argument, just the simple fact that a lot of energy in one place is probably going to be something to be respected, barring some miracle storage device unknown currently.
I just accidentally drilled into a Konion today, a little smoke, hiss & bubbles, that was it.
As far as the fires, well, the flashlight incident, although I would call it operator error, as the fellow SHOULD have known those batteries were iffy, but humans make errors, I think I've even made a few. The other documented reference certainly appeared to be our old friend the nickel strip cutting into the insulation on the positive end. But again, it happens.
But by far, the most interesting one is the one I couldn't find the link for either, but it's here somewhere. It goes approximately like this:
I believe it's by gestalt, his brother had a homemade pack of Konions. Was sitting on a wooden shelf for two weeks, not charging, nothing. Suddenly burst into flames. Fortunately brother's roommate was there, tossed it outside, pack was hosed. And part of the shelf too.
Nobody knows what caused it. The important fact is it happened, whatever the cause. So yeah, I'm not saying hide under the bed for the rest of your life, just respect a lot of power in a small package.
Dogman says it best: never leave your batteries anywhere you wouldn't start a campfire. Mine live outside, in a cleared area, protected from rain, they don't mind at all. Even the Konions.

 

[Matt Gruber]

google "causes of house fires"
laptop fires don't make the top 10 list, and laptop cells are WAY more dangerous than Konions!
Even so, i do keep my cells away from flammable items.
Lets see who can match my safety program:
I even installed a 15 minute timer on my stove burner! A top cause of fires is leaving on a burner by mistake. Who else has a timer on a burner? So how can anyone lecture me on fire safety?
And i unplug even the toaster when not in use! Anything plugged in can start a fire.
And i have a fire extinguisher in the house, and never charge when i'm asleep. And i don't run the HVAC when i'm asleep(house heater is #2 cause of fires) No gas heat! i use a heat pump.
and of course i don't smoke or light candles.
So i invite es members to match my fire prevention methods!
Many people do in fact keep many gallons of gas in their house! They have an attached garage with a car in it! A fire waiting to happen!
My garage contains my cars and ev's and is 50 feet behind my house, totally detached.
So now you all see the secret to my success! Great safety program that i bet no one here can match!