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Newby Lipo question

smokey125smokey125 Club Members Posts: 4
I'm starting to get back into model flying after years away from the hobby. When I was last regularly involved Lipo's didn't exist in the hobby.

As something to do with the kids, I've got a couple of the small cheap shop models for them to use/crash prior to getting my older/better stuff updated.

Both of these have single cell lipo's. Both charge the battery via a plug on the model, both batteries have a small PCB as part of the battery.

My question is, are these PCB's part of the charging/control system of the model or a normal part of the Lipo battery? Having not used them before I have nothing to compare them with.

Comments

  • WTWUKWTWUK CornwallClub Members Posts: 13,160 ✭✭✭
    Likely to be safety circuits to protect the LiPo's from being over discharged - something that is fatal to LiPo cells.
  • SootySooty Christchurch NZClub Members Posts: 6,110 ✭✭✭
    And often fatal to the model when the PCBs stop providing the batteries life-giving current. image
  • smokey125smokey125 Club Members Posts: 4
    Thanks for the replies.
  • Clark06000Clark06000 Antibes, FranceClub Members Posts: 851 ✭✭
    This small protective circuit has several functions:

    - limiting the discharge current, depending on its specs.

    - stopping the discharge at a safe level (about 3.2v/cell),

    - limiting the charge current, also depending on its specs.

    - limit the charge voltage (about 4.3v/cell).

    So this helps to have a long lipo cell life (one circuit per cell). clark060002016-07-06 23:30:18
  • smokey125smokey125 Club Members Posts: 4
    Ok thanks for that.

    A couple more questions, I assume that modern radio gear and changers are cleaver enough to protect the batteries so a "normal" model doesn't need this type of protection circuit? Could you charge a battery with one of these circuits on it with a normal Lipo charger or would it interfere with the charging program?
  • Clark06000Clark06000 Antibes, FranceClub Members Posts: 851 ✭✭
    I would say that the lipos fitted inside Txs are most of the time NOT protected by such a small circuit... Don't forget to switch off your TX. Also not seen some of them inside rc running or flying models!

    - No problem using a such protected lipo for charging it BUT limit the charge current below the spec! i.e: 1C, try 1 amp for a 1000mah battery.

    - If battery in the (small) model, be sure the discharge amps are below the cuicuit amps spec limit or it will cut off and may die: crashed model!

    Some more expensive protective devices (bigger!) are coming on the market and can cut up to 30amps and more.... Not your application I guess!clark060002016-07-07 20:57:04
  • __Evan__Evan Club Members Posts: 1,122
    [quote=smokey125]A couple more questions, I assume that modern radio gear and changers are cleaver enough to protect the batteries so a "normal" model doesn't need this type of protection circuit?Modern chargers are smart enough, but it never hurts to have a backup. You can charge a protected battery in a standard charger; it won't notice any difference.



    Planes/quadrotors/helicopters tend to have a low-battery warning (eg. beeping, reducing power, etc) but they will not forcefully protect the battery. This is generally a good thing; I'd prefer to totally ruin a LiPo by using every last bit of its power to make a safe landing than to protect the LiPo but crash the plane.

  • DaithiDaithi Belfast,IrelandClub Members Posts: 8,708 ✭✭✭
    For the 'plane, use Lipos - but for a transmitter. LiFe is better (that doesn't have the discharge/storage problems that a LiPo does). It's heavier (power per weight than a LiPo) so it's not the best idea for a receiver
  • smokey125smokey125 Club Members Posts: 4
    Thank you for all the help. Charged the battery from one model no problem. Despite the circuit the one in the second model appears to be dead. I'll replace it and see how things go. At least I can see what the batteries are doing when I charge them from a proper charger.

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