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  1. #1
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    Li-Ion / Li-Po discharge when not in use

    Charged up my relatively new batteries last week post ride (one for bar, one for helmet), and haven't been used since then. Going for a ride tonight so just a quick check and connected the charger to each. The Li-Po, already fully charged. The Li-Ion however needed about 15 minutes of charge to top up.

    Is this typical?

    (batteries are kept in the house, disconnected).

    Just wondering about the Li-Ion as it died on the ride last week though was just under the expected run time for medium power with the lights/battery combo I've got (2.5ish hours) and I'd had it on medium more than previous rides, rarely on full power, though I do still set it to low or off when stopped. It was also 0C temperature. The Li-Po however was showing still over 50% remaining. Both using medium power, though the Li-Po is also 3300mAh whereas the Li-Ion is 2600.

    Previous rides I'd leave the battery after ride and charge them up only the night before. Perhaps this is a better way to do it anyway.

  2. #2
    I ride a Swarf
    Reputation: Stuart B's Avatar
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    What are you using to charge them? If you charge a battery and the leave it to settle and then put it back on charge it will probably take a while before the charger terminates again.

    sent from my phone, apologies for any typos.
    What exactly is a rigid hard tail?

  3. #3
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    Charger that comes with the lights/batteries. They're Four4th lights and batteries (local UK light manufacturer. Good quality stuff), and the charger is designed for them.

    Think it's probably okay, it's just that the Li-Po when plugged into the charger said it didn't need a charge, but the Li-Ion needed about 15 mins. Just wondered if Li-Ion tends to drain more when unused than Li-Po. Or not.

  4. #4
    I ride a Swarf
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    Are you using the same charger for lipo and li ion? As I understand it Lipo has a slightly higher nominal voltage than li ion, so the charger may think that it needed a bit more charge even though it was full.
    What exactly is a rigid hard tail?

  5. #5
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    In general the Li-po and Li-ion should have minimal discharge factors especially when compared to other types such as Nimh or nicd. Realistically you should not have to top off a topped off battery within the same month, sometimes much much longer. I'll agree with the above and say that it is likely the charger's 'smarts' that is in question since you are switching it around.

    If you meter-check the voltage when you charge it before, then let it settle(like 15 mins post-charge) note it. If the voltage is generally the same, or really close then the charger was simply topping off. Compare the post-charge voltage to the voltage you get prior to the next "sitting" period and if it is still the same then discharge was not an issue.
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  6. #6
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    Thanks. I've got a charger for each supplied with the lights, though they're identical.

    I don't think it's really an issue, just I was curious as to the difference.

  7. #7
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    Both li-xxx do not self discharge if they are good! But you need to store them charged to around 3.8V - they retain 50% of charge in this state and don't cause stress/oxidation on electrodes. Protection PCB has some small draw, so if that went bad, it might drain the cells. Temperature also causes cells to drop the charge, li-xxx like warm temps - so you need to put the cells somewhere else perhaps.

  8. #8
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    Another thing that I was thinking about is the charging process. But this is the same for li-ion and li-po, at the 50% of the charging time the cells are charged to about 80% of capacity and the last 50% of the time is spent for those rest 20%. So as Stuart B said, it could be the charger logic (if the chargers are different for both li-ion and li-po) that needs time to recognize the cells are fully charged.

  9. #9
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    Over-discharging a LiPo battery will cause irreparable damage and may cause battery failure. To prevent over-discharging, only use Traxxas Power cell LiPo batteries with an electronic speed control (ESC) that has a low-voltage detection system or alarm.

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