Latern battery charging

[TotalMadness]

Hi,

I have a new LED lantern. In the manual it states the following:

This lantern can be recharged from a 12v DC source using the 12v DC power lead which is included. Do not use 12v DC charging system other than the one provided with the product.

This is just a cable that plugs into a car cigarette lighter and does not appear to have any voltage level control built in.

The lantern can also be charged from a 240v AC-12v DC source (not included).
Specification:
Input 230v 50Hz 60mA
Output 12v 400mA

The battery consists of 3 x AA batteries bound together making 3.5v.

My question is, if the battery is only 3.5v and the charge is 12v, why is it so high, and why do the batteries not blow up? The charge time is 3 hours.

Thanks

 

[k7elp60]

I think there is a resistor inside the lantern some where to limit the charge current.

 

[DerStrom8]

The battery consists of 3 x AA batteries bound together making 3.5v.

My question is, if the battery is only 3.5v and the charge is 12v, why is it so high, and why do the batteries not blow up? The charge time is 3 hours.

Thanks

First, 3 x AA batteries are not used. There may be three cells that are the same size as AAs, but are not AA batteries.

As k7elp60 said, there is probably a special charging circuit built into the lantern itself, which includes current limiting and probably a voltage regulator of some sort. This is the reason why the batteries don't "blow up."
Der Strom

 

[TotalMadness]

Actually, in the manual it states: "The battery in this lantern is a built in 4 pieces rechargeable 1.2v, 1200mAH, Ni-MH battery which is designed to last for approx 500 cycles". It is however only made up of 3. On the battery is written that it is 3.5v.

I guess you are both right. I guess it uses 12v because it's convenient to plug it into a cigarette lighter in the car or caravan to recharge it.

 

[crutschow]

First, 3 x AA batteries are not used. There may be three cells that are the same size as AAs, but are not AA batteries.

Why do you say they are not AAs? An AA battery is defined by its size. So if it's the same size as a AA then it's likely an AA.

 

[DerStrom8]

Why do you say they are not AAs? An AA battery is defined by its size. So if it's the same size as a AA then it's likely an AA.

Yes, you are right, crutschow. I guess I meant to say ordinary AAs, but I suppose that doesn't make much sense, either. I apologize. Don't mind me
Der Strom

 

[davenn]

The charger cct is most likely built into the lighter plug, its the usual thing that is done

Dave