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

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  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 30978
    • Albion

    #101
    Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

    post a photo of the battery markings so i can look for the spec.

    Comment

    • eccerr0r
      Solder Sloth
      • Nov 2012
      • 8696
      • USA

      #102
      Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

      The battery appears to be wrapped and no real good markings visible on it. I suspect it should be just as good as both vacuums have similar runtimes (~7.5 minutes) and initial battery capacities (3.6V@1.3Ah vs 3.6V@1.5Ah).

      Heck the motor is about the same size too.

      Well I put it together with some damage, the plastic seems to have gotten very brittle over the years. With the battery charged to 4.2V it seems that the charger has cut off. Have to see if it charges correctly after it's discharged a bit.

      The vacuum cleaner really SUCKS now!!! Even compared with the original NiCd cells, then again the original NiCds were quite used up.

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30978
        • Albion

        #103
        Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

        well you mention 10A, i would be surprised if the cell was rated above 4A
        most small ones arent.

        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8696
          • USA

          #104
          Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

          We'll see how long it lasts and if it goes up in smoke. I don't know what protection this thing really has.

          7.5 minutes is ⅛ hour, which is an immense load. 1.5Ah / ⅛h = 12A (in the "new" vacuum. The old battery in the old vacuum was 1.3Ah/⅛h = 10.4A) I suspect the Li-ion may last a few more seconds in the old vacuum due to 200mAh higher capacity...

          Comment

          • Dannyx
            CertifiedAxhole
            • Aug 2016
            • 3912
            • Romania

            #105
            Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

            At least yours was intended to run on LiIon from the factory Vac still hasn't returned...guess he got lucky this time or the cells were of better quality and resisted the abuse better
            Wattevah...

            Comment

            • eccerr0r
              Solder Sloth
              • Nov 2012
              • 8696
              • USA

              #106
              Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

              Eh no... I'm saving my _old_ vacuum cleaner that came with NiCd cells...
              Now my _old_ vacuum has a single Li-ion cell and it sucks once again!

              Comment

              • Dannyx
                CertifiedAxhole
                • Aug 2016
                • 3912
                • Romania

                #107
                Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                Interesting, so you did what my super skilled buddy tried to do here for *ahem* research purposes Do not try this at home kids
                Wattevah...

                Comment

                • eccerr0r
                  Solder Sloth
                  • Nov 2012
                  • 8696
                  • USA

                  #108
                  Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                  Well, not exactly. I transplanted the power system from a seemingly working vacuum that theoretically was designed properly to the old one.

                  I wanted the wet/dry system of the older vacuum, hence sacrificing the newer one.

                  Comment

                  • Dannyx
                    CertifiedAxhole
                    • Aug 2016
                    • 3912
                    • Romania

                    #109
                    Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                    Must admit I haven't seen a BATTERY operated wet/dry vac...what brand might this be ? Sounds pretty "power hungry", at least by directly comparing it with a mains-unit - a Karcher - I use at home which is 3000w
                    Wattevah...

                    Comment

                    • eccerr0r
                      Solder Sloth
                      • Nov 2012
                      • 8696
                      • USA

                      #110
                      Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                      It's an old Hoover, and yes 10A...though only at 3.6V = 36 watts.
                      Only good for small spills but sometimes that's what you need. Anything bigger I need to use the shop vac.

                      Comment

                      • eccerr0r
                        Solder Sloth
                        • Nov 2012
                        • 8696
                        • USA

                        #111
                        Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                        The thing I wonder is if I can use the old charger... after all, what is this circuit board for if it doesn't appear to have overdischarge cutoff (since it appears to hook the + and - directly to the output/motor)?

                        Must be some charge controller?

                        If so, then the old NiCd charger should work

                        I should test this outside my house somewhere away flammables...

                        NOPE. Forgot, the charger is AC. This won't work :\
                        Last edited by eccerr0r; 03-23-2019, 12:18 AM.

                        Comment

                        • eccerr0r
                          Solder Sloth
                          • Nov 2012
                          • 8696
                          • USA

                          #112
                          Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                          Well, looks like that circuit board is indeed a charge protection board and will cut off power when the battery is fully charged.

                          The weird thing is that the original wall wart for the li-ion cell appears to be 15V @ 150mA. I have a suspicion that the original wall wart which didn't come with the vacuum has a fairly high impedance for a power supply, else the charger would dissipate way too much power while charging the extremely low impedance of the battery.

                          Suspecting the wall wart is a CC PSU versus a CV/CC PSU most Li-ion chargers are. Very weird indeed.

                          Comment

                          • stj
                            Great Sage 齊天大聖
                            • Dec 2009
                            • 30978
                            • Albion

                            #113
                            Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                            there's a lot of shit sold to the public.

                            there are some very nice led flashlights from china worth getting but being cautious with.
                            they have a charging connector on them - NOT usb.
                            here is one - ignore the Lumens bullshit.
                            https://www.aliexpress.com/item/4200...818422476.html

                            and this is even better:
                            https://www.aliexpress.com/item/LED-...867214598.html

                            now here's the catch.
                            the charge-port goes directly to the battery contacts,
                            and the only thing in the car charger is a fucking resistor!!!
                            (well 2 if you include the one for the led)
                            btw, *never* buy these with the battery - it's a slavage job with no protection circuit - even if the label says otherwise.
                            Last edited by stj; 03-24-2019, 03:17 AM.

                            Comment

                            • Dannyx
                              CertifiedAxhole
                              • Aug 2016
                              • 3912
                              • Romania

                              #114
                              Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                              Originally posted by eccerr0r
                              Suspecting the wall wart is a CC PSU versus a CV/CC PSU most Li-ion chargers are. Very weird indeed.
                              I think I encountered this setup with a Braun epilator a while back: someone brought it in for repair and the wall-wart was dead. It was sealed VERY tightly - not only was the case virtually impossible to crack without destroying it, but the insides were also completely sealed in hard wax, so there was no way any sane human being would service that at component level, made most sense to replace it entirely. I thought, no problem, I'll just dig through my box of wall warts and find one with identical voltage and maybe higher current for the nice lady.

                              The original was 6v at (I think) 200mA. Before that however, I wanted to make sure the device itself runs fine and the internal battery isn't shot, so I cut the dedicated plug off the original dead adapter, stripped the ends, hooked up some alligator clips to my bench supply and applied 6v: to my surprise the current shot up to the supply's maximum 1.5a capacity and entered OC protection...what gives ? Great, I thought, the thing's busted as well.

                              However, next I tried slowly increasing the voltage from 0v to keep the current below the supply's limit to see what happens: again, much to my surprise, it didn't behave like a dead-short would, i.e. the current didn't remain constant indefinitely, but instead begin to drop...almost....like a....battery getting.....charged...OOOOOHH I see: so the adapter is a CC supply and adjusts the voltage up/down based on the current. My supply at the time only did CV, so I had to manually increase the voltage when the current dropped. The charge LED was also on, so I let it sit for around an hour and then tried it out: it worked...my colleague and I even tried it on the hairs on our arms...you know, for testing purposes ....hurts like a Mo-fo BTW...yeah, we did a lot of stupid sh!t back at my old shop...those were the days I'd like to take a moment to thank all the ladies out there for putting themselves through pain to make themselves more attractive for us

                              So this meant my idea with the replacement adapter went down the drain, since they're all CV and my colleague ended up contacting the local Braun dealer and ordering an original wall-wart. Imagine getting a 3a+ supply and hooking it up to the device (like I originally planned): instant dead cell I'd say and possibly some smoke, UNLESS the device had OC protection inside of it as well. I DID find an adapter which did 5v at 200mA, so the "CC" was merely the supply's limit and not an active current sensing...it worked this way as well, but we figured the best way was to go with the original one rather than half-assing something like this.
                              Wattevah...

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 30978
                                • Albion

                                #115
                                Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                never bodge something that either comes into contact with the user, or gets used in a bathroom!!

                                Comment

                                • sam_sam_sam
                                  Badcaps Legend
                                  • Jul 2011
                                  • 6033
                                  • USA

                                  #116
                                  Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                  Originally posted by stj
                                  and this is even better:
                                  https://www.aliexpress.com/item/LED-...867214598.html

                                  now here's the catch.
                                  the charge-port goes directly to the battery contacts,
                                  and the only thing in the car charger is a fucking resistor!!!
                                  ( real SHIT I seen this so many times )

                                  (well 2 if you include the one for the led) ( O really how are they doing the brightness control )
                                  btw, *never* buy these with the battery - it's a slavage job with no protection circuit - even if the label says otherwise. ( are trying hurt someone with this crap)
                                  First of all

                                  Are these worth buying meaning are LED modules any good and do they last

                                  What is the quality of these LED module on a scale of One to Ten one meaning shit and ten meaning very good quality

                                  Second of all

                                  With a good quality battery what is the run time

                                  Third of all

                                  I would not use a shite battery in the first place not using it every day
                                  I would also not use the charging controller that comes with it I have good quality charging controller for this I would just use the connectors on it
                                  Last edited by sam_sam_sam; 03-24-2019, 07:15 AM.

                                  Comment

                                  • stj
                                    Great Sage 齊天大聖
                                    • Dec 2009
                                    • 30978
                                    • Albion

                                    #117
                                    Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                    the first one with the teeth is 5/10, the led is so-so for a T6 or clone.
                                    still good output, but others are better.
                                    i was thinking of changing the led before i even got it - maybe to InfraRed.

                                    the second is really good - 9/10.
                                    i would say 10/10 if it had usb and a charge controller in it.

                                    the thing about those lights with the tubular socket, they are very solid construction - real nice.
                                    just let down by the charge cable - i made a new cable that terminates into one of these.
                                    https://www.aliexpress.com/item/10pc...948825580.html

                                    i think i'll get one of these next - infact i know i will - just waiting for the price to drop a touch.
                                    https://www.aliexpress.com/wholesale...pocketman+1315



                                    ah yes, your questions.
                                    the controller on the first one is the usual 3pin + parallel resistors - i replaced it.
                                    the second i didnt try to strip.

                                    they all generally drive the main led at around 1A so calculate runtime yourself.
                                    i dont know if i metered the current for the cob-ring on the second.
                                    Last edited by stj; 03-24-2019, 08:14 AM.

                                    Comment

                                    • eccerr0r
                                      Solder Sloth
                                      • Nov 2012
                                      • 8696
                                      • USA

                                      #118
                                      Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                      I should make my vacuum USB charged, screw these special wall warts

                                      Comment

                                      • sam_sam_sam
                                        Badcaps Legend
                                        • Jul 2011
                                        • 6033
                                        • USA

                                        #119
                                        Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                        Originally posted by stj
                                        the second is really good - 9/10.
                                        i would say 10/10 if it had usb and a charge controller in it.

                                        https://www.aliexpress.com/item/LED-...867214598.html
                                        I just bought two kits so I have the power supply cord to charge it

                                        Now I will have to buy some more Panasonic batteries that have protection boards on them

                                        Thanks for sharing this

                                        Comment

                                        • Dannyx
                                          CertifiedAxhole
                                          • Aug 2016
                                          • 3912
                                          • Romania

                                          #120
                                          Re: Directly replacing NiMh cells with Li-Ion cells - bad idea ?

                                          Talk about coincidence: this just popped up in my subscriptions NOW
                                          Wattevah...

                                          Comment

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