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I have a couple of questions for connecting a charger to the batteries in a portable. I'm a noob.
Would it just be something like this?
I'm not sure which way to face the polarity of the charger.
If that poorly drawn schematic is correct, then would I be able to power the load while charging if I close that switch, since the charger would put out the same volts as the battery would (making the battery just charge slower)?
And if it did work like that, would the charger power the load, then have the rest of the available current that the charger can supply go to the battery?
Basically yes to the whole post with a few conditions.
Yes that diagram is correct. The charger over powers the battery with a higher voltage and forces electricity back into the positive. Just make sure the max voltage of the charger won't fry the load. Now if you want to charge the battery and half the load on at the same time, then you have to make sure that the charger can supply more amperage than the load takes. You may want 200 more mA of charging current to make sure the charger doesn't fry, of course this is relative to the size of the load. The extra 200 mA charging current would work for an N64p for example. If you don't have enough current to power the load you can expect a fried charger.
Now if you want to charge the battery while the load is on then the charger will have to have more current then the load.
Say I have and n64p, the console it self with an expansion pak draws about 1200-1300 mA. So if I want to charge the battery and play the n64 at the same time, then I need to get a charger that's about 1400 mA of current or more. But if the charger is only that much higher then the load, then you'd only charge the battery with 100 mA per hour. So it would take a very long time to charge.
So here's a summary.
1. That schematic is correct, just make sure that the charger voltage won't fry the load. Although if the charger is enough to fry the load, then the battery will fry it too.
2. If you want to play and charge at the same time, your charger needs more current then the system is drawing.
So, for clarification, If that n64p draws 1300mA, and my charger supplies 1300mA (although you would want more, to make sure that the charger doesn't fry, but this is just theoretically), then the batteries would just not charge at all?
On a side note (not that I would do this, I'm just curious), if the charger only supplies 1200mA, and there was still some charge in the battery, would the load also draw 100mA of current from the battery in addition to the 1200mA from the charger?
Theoretically yes, the battery would charge and wouldn't drain if you had a charger of equal value.
I haven't done it before, but I would assume that it would take equal amount of amperage from the battery and charger. Like 650 from the batter and 650 from the charger, until the battery dies. While the battery is dying and it's voltage drops then the amperage would slowly start to draw more from the charger, then when the battery dies the charger would start to fry.
We weren't really talking about the capacity of the battery, just if a charger can power the load and charge the battery. And since most cameras don't need much power the charger can take the load of the camera and charge it, loosing the need for a high power charger.
hailrazer wrote:For lithium's it is different.
Like the camcorder batteries are 2000mAh and the charger is 300mA.
So yea they work a little differently.
Another question
Say, if the charger is rated to charge at 2A, and my load draws 1.5A, would the charger fry the load once the battery is fully charged?
Also, does anyone know where I can get a 7.4v lithium charger that's around 2A?
Not it wouldn't, it would just charge the battery and when it's fully charged the current would not force in 2A.
And as for finding a charger that strong, I don't think you're going to find it. Normally people don't need a charger that big for a battery that small. Even battery space's chargers for li-ion and li-pol only go up to 1.5A
So let me make sure I got this right. I'm getting ready to make my first portable, a PS1P out of an SCPH-9001, and I want to have my batteries able to charge inside the case (call me lazy).
The PS1P mobo should draw 7.2-8.4v. Using 5 AAs that would give me about 7.5v. So with Ni-Mh or Ni-Cd batteries I'd just need any old PSU that gives about 8 volts and more Ma then the whole system ends up drawing? No need for additional circuitry to ensure I don't overcharge the batteries if I leave them plugged in overnight? Would this also work the same with Li-Ion?
Think! I refuse to have a battle of wits with an unarmed opponent.
