Oral B Electric Toothbrush- Nimh Vs Li-Ion

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  skid on 02/01/2021 - 13:12

  Li-ion lasts around 300 to 500 charge cycles.

  Eneloops (NiMH) advertise 1000 to 2000 charge cycles.

  Li-ion tends to need more frequent charges (each Li-ion cycle lasts around a third of a NiMH cycle).

  NiMH has a higher rate of self-discharge.

  Gut feeling would say go with Li-ion as it is "newer" tech, but practically, NiMH wins on every count.

  IMO

  • 

    JimB on 02/01/2021 - 16:15

    Perfect answer I'm looking for.

    Higher rate of discharge isn't an issue, because I'm likely to charge it often.

    Unlike a phone, I don't really care that it can run X days between charges. I would leave the toothbrush on the charging base whether I charge it or not.

    To extend the lifespan of NiMH, better to leave it on charge all the time or should I run down the battery between charges?

    I'm happy to pay extra for Li-ion if it provides better real world lifespan, but this doesn't seem the case.

    • 

      avoidfullprice on 02/01/2021 - 17:27

      If both toothbrush batteries are of the same capacity (Wh), then I would imagine the NiMH version would have longer lifespan.. however, given li-ion has a bit higher specific energy (W/kg) and efficiency, the li-ion toothbrush would be a bit lighter to hold. If both weigh similar, then the lifespan of the two product would not just be based on charge cycles of the chemistry. So both might just last about the same in years… And your decision might just come down to $$ and the features2.

      Found this on the web - are they the two models you talked about?

      https://www.electricteeth.com/au/oral-b-pro-500-vs-pro-2-200…

      Disclaimer: not an expert, just my thoughts.

      • 

        JimB on 02/01/2021 - 21:32

        +1

        Yes, those are the 2 I'm looking at.

        The 500 and 700 are exactly the same.

        The 500/700 are light enough so not a consideration.

        I think I'll save my money and get the 700 if the battery life is the same or better.

        In terms of features, all I want for it to do is oscillate. Not even sure what pulsation really does.

        Even the most basic of electric toothbrushes cleans infinitely better than manual toothbrushes.

      • 

        skid on 02/01/2021 - 22:14

        What you're saying makes sense in theory but I haven't found it to be the case in real life. Maybe the difference in weight between the chemistries is getting dwarfed by the rest of the toothbrush? Can you think of any other explanations?

        • 

          avoidfullprice on 02/01/2021 - 22:51

          @skid: Not in toothbrush I'm afraid. I haven't swapped too many e-toothbrush myself. I notice a big difference when I compared my old NiMH laptop battery pack to my newer Li-ion laptop battery pack.

          I don't expect the two toothbrush models use the same amount of power to begin with, and the battery capacity is unknown to me, so I wouldn't even know if one lifespan is more or less than the other. I don't think the lifespan differs purely because one uses li-ion.

          I would say from a bargainers perspective, lower annualised $ per replacement would be ideal. But each will have different experience and some will like more powerful motor than the other.

          I'm glad OP didn't ask which one is best, but rather looked at the lifespan angle. It is refreshing on this forum.

    • 

      skid on 02/01/2021 - 22:11

      You should run down the battery; extending the time between charge cycles.

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  frondono on 02/01/2021 - 14:03

  +1

  I think the 2000 series might be like double the oscillations per minute of the 500/700?

  • 

    JimB on 02/01/2021 - 16:08

    Yes, you're correct. But in the real world is it going to be twice as good? Unlikely as you get to a point of diminishing returns.

    • 

      avoidfullprice on 02/01/2021 - 16:44

      Twice the oscillation rate may allow the brush to spend less time per teeth to get the same effective, like washing dishes.

      Probably won't improve the time along the teeth gaps.

• 

  JimB on 02/01/2021 - 21:03

  +1

  Actually, there's little difference in oscillation. Pulsation is double, but what exactly does Pulsation do?

  As per above review-

  The Pro 500 has a motor that is capable of 8,800 oscillations and 20,000 pulsations, but the 2000’s motor is capable of 9,900 oscillations and 45,000 pulsations.

  "Ultimately I believe even in clinical conditions, the results would be inconclusive or not considered clinically significant."

  Just like dishwashing tablets, I believe there's little cleaning benefit of more expensive one, just marketing- powerball, max in one, all in one, quantum etc.

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  mymilkynipples on 02/01/2021 - 21:14

  I bought the Smart 7000 as it has a better motor and more oscillations than the 2000 series. It definitely feels much better in my opinion and is noticeably stronger.

  • 

    JimB on 02/01/2021 - 21:47

    Thanks for sharing.

    So you upgraded from the 2000 to 7000?

    • 

      mymilkynipples on 02/01/2021 - 21:54

      Yes, my gf also has the genius 9000 and it is pretty similar to the smart7000 minus some features and the travel case powerbank.

      • 

        JimB on 02/01/2021 - 22:17

        Hmmm something to think about

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  Sickman on 02/01/2021 - 22:41

  I went from the Vitality to the 2000. I much prefer my 2000, I will never go back to the Vitality which has 7,800 oscillations so just 1000 less than you 500. Very noticeable stronger faster brushing than the Vitality, I can take the 2000 on a 2 week holiday and it still has charge at the end. Battery life has been good for the 18 months I have had it.
  The quote by Skid at the top about battery cycles is not quite that simple. The Li-ion battery has higher capacity and voltage than the Ni-MH so the number of full capacity battery cycles required will be significantly less when compared to a Ni-MH.
  Just get the 2000.

  • 

    JimB on 02/01/2021 - 23:01

    I also had the Vitality 10-15 years ago.

    The 500 is also infinitely better.

    I'll consider getting the 2000 if the total battery lifespan is better. Such a waste for the environment they are disposable when the battery dies.

• 

  davoid on 23/08/2023 - 16:03

  I just bought an Oral B Vitality Precision Clean and it has a NiMH with a capacity of 1500 mAh (from what I can gather from online searching of 'type 3709'). The battery is rated for 2 mins twice a day for 5 days.

  I noticed that the Oral B Vitality Cross Action is rated for 8 days, so I guess that it has a 2400 mAh NiMH.

  These two brushes are the same price. So it'd be worth getting the Cross Action for battery longevity.

  1500 mAh rated for 5 days = 75 mA per minute.
  2400 mAh rated for 8 days = 75 mA per minute.

  2 mins. is 150 mAh, and 10% depth of discharge equals approx. 5000 cycles for the 1500 mah, and approx. 8000 cycles for the 2400 mah.

  5000 cycles at two per day is 2500 divided by 365 days = 6 years, 10 months.
  8000 cycles at two per day is 4000 divided by 365 days = 10 years, 11 months.

  These are just theoretical estimates of course, but for the same price brush, the Cross Action battery should last about 40% longer.

  The 'Floss Action' and 'Pro White' models also have the larger battery.

  As for my purchase, all I can say is: d'oh!