Directly replacing NiMh cells with Li-Ion cells - bad idea ?

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

chinese SZN's
nothing wrong with SZN's, but the asshole i got these from had soldered to them and damaged a couple of the insulator rings.
so i was suspecting problems from the start!
out of 6, i'm down to 3 - just testing.
2 had case damage, one tried to go thermonuclear.
the other 3 charged o.k. - now i wait a few days to see if they hold.
if they do then i'll do a discharge test to check capacity.
i'm not confident though - i think they guy fucked them when he soldered to them.

[momaka]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

i suspect this is the type of repair shop that would re-use the solder if they could.

But then they can advertise they are an Eco/Earth-friendly shop.

[eccerr0r]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Then there's the irony of reusing lead solder for being eco-friendly :o

Sigh. I wish it were easy to make all the waste solder I have back into wire, I sure would reuse this solder for noncritical uses... solder is solder, just need flux!

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

you can put it in a solder-pot for tinning wires.

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Just purchased new cells for my colleague...even higher capacity, even higher price...this is going well - at this rate he'll get fired These are pink "Unicell"...cells with a rating of 4200mAh apparently - that's what the chap at the store told me.
The vac says 14.4v on it, so we can work this out: 4 3.7v cells would indeed add up to 14.8v.

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

you dont have a Liitokala Lii-500-Engineer there do you?
you should if using lion batteries, they cost under 20€

then you could analyse them, because you know damned well the highest capacity yet acheived is 3600mAh

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Pfft...the joint barely has enough light fixtures Ancient fluorescent sh!ts that buzz my brains out the whole 9 hours continuously (! !) so a device like that would be completely superfluous and would only see use just this once probably...if that Though I'll probably get one myself, why not - good idea

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

they are very handy.
https://lygte-info.dk/review/Review%...-500%20UK.html

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Wa-wait - what's that I hear behind me ? It's the sound of the vac trying to come back to life with the new cells but not charging...followed by my super skilled colleague's obligatory "f-s" and *insert whatever curse word you can think of here*

So once again, it appears to run, but the LED on the dock doesn't light to indicate it's charging....could be because the higher voltage of such cells indicates the unit doesn't require charging...there's 4 terminals on the back of the handheld portion, so GND, VCC, NTC (?) and SENSE (?)...just a hunch...

I just about heard him mutter "15v" when measuring the voltage on the batteries, because that's another thing that's really "cute" about this guy: he mutters all his thoughts, so you can follow along at your desk and go head to head in fixing something - not very good at keeping secrets Aaanyway

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

maybe the charger is fucked from last time.

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

I snapped some pics of the thing today. Here's the batteries I got this time that my boy put in and also a close-up of the IC that's in there...had to do it rather on the sly so unfortunately the model is not visible, but the point is it HAS some pretty advanced tech in there. It probably handles charging and motor speed control. It's an Electrolux ErgoRapid or something like that, forgot to mention for anyone who might be interested...at least that's what it says on the outer case - I don't know the exact model because I didn't bother.

The green Samsung cell is what he attempted to use the first time when it failed.

I actually got it wrong: the charge circuit is built into the handheld part, as you can see, but the LED I was talking about is at the top of the handle which you use for converting it into an upright vac for the floor. This whole apparatus then slips into a dock which does nothing but connect the wall adapter to the handheld portion which has the 4 metal shims I mentioned and handles the charging internally. The LED on the handle now comes on as well when docked...apparently, according to him, someone had been inside before they brought it back in and they had messed up some wires or something along those lines. Either way, it looks like the problem's solved - at least partially...we'll see how long it lasts this time.

[budm]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

So the charging Voltage for 4 cells is about 16V, is that the charger putting out? He should also monitor the charging current.
https://batteryuniversity.com/learn/..._with_voltages

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

that chip looks like a charge controller - there is no way in hell it will touch those cells!!

the green cells arent bad - lets not speak about the ultra(fire) ones!

[momaka]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Either way, it looks like the problem's solved - at least partially...we'll see how long until it catches fire and burns down the customer's house.

FIFY!

lets not speak about the ultra(fire) ones!

BTW, I just saw it in the news today... a second person here in the US died from those vape pens / e-cigs. Apparently battery exploded and shrapnel cut an artery in his neck. Not that anything like that might happen with this vacuum cleaner, as the customer won't be wearing it in their pocket or have it near their face. But still, it goes to show that Lithium batteries can be dangerous if not designed to charge/discharge properly or are of poor quality.

... because that's another thing that's really "cute" about this guy: he mutters all his thoughts, so you can follow along at your desk and go head to head in fixing something

I think that's an age-related thing. My grandmother often does it too.
Heck, even I've done it a few times if I didn't talk to anyone for an entire week.

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Best case scenario, the controller will just shut off or act in some way to prevent catastrophic failure...

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

The wall adapter puts out 20v at 200mA. I just had a peek for curiosity's sake and I also heard him saying the pack reached around 16v or thereabouts and the LED was still on and apparently charging - probably in "trickle charge" specific to NiMhs....not sure if LiIons like to be trickle-charged. I've read they're topped up to full capacity (let's assume 100%), then the charge is cut off entirely and they're only topped up as necessary (let's say when they fall back to 90% or less), while NiMhs are kept on the charger even when full, at least based on some online resources and I imagine this may vary with charger design. This one looks pretty smart...

[stj]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

too bad we cant see the number on the chip.

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

too bad we cant see the number on the chip.

Should I seize another opportunity to sneak a peek at it, I'll post back undoubtedly.

[sam_sam_sam]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

Why are you playing with fire

Just put in a BSM board for the right battery voltage and right type of battery and use right type of charger

And be done with it and be safe about it

I think you like to play with fire

[Dannyx]

Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

It's not my project since I know this stuff fairly well. Tell that to my super stubborn workmate and see what happens