Spotlight: a suggestion about battery and lamp

[Adriano]

Hi, I'm sorry my inexperience, I'd like to have a suggestion.
I have just made a spotlight for my videocamera. The battery is a 2000 mAh 14,8 volts and the lamp is 12 volts 20 watt. When The battery is not able to switch on the light. If I put together two batteries it is ok, the light lit up.
I have no problem to assemble two batteries bt I'd like to know if the lamp will be able to consume all the battery capacity.
thanks for your suggestion,
Adriano

PS. The battery is Li-ion 18650 pack TENERGY

 

[TigerhawkT3]

2Ah is a little low for an 18650, but not really a problem. It sounds like each batt pack is 4x18650 in series, and you've made two of them. You don't give many details about the bulb (in theory, it should draw less than 2A when driven by a 12V source), so I don't know if overdriving it like this is pushing the current too far for the cells' protection circuits. For 18650s, you'll probably want to keep it at under 4A. I'm guessing that when you say you "put together two batteries," you mean in parallel, right? It must be, because I doubt you could drive many 12V bulbs at around 30V without instaflashing them.

If the assumptions in the above paragraph are correct, you might be able to successfully drive the bulb with a battery consisting of only 3x18650.

You don't want to overdischarge Li-Ions ("consume all the battery capacity"), as that will damage them. Recharge them when the light grows dim or when the protection circuits kick in.

I hope some of this helped in some way.

 

[Adriano]

2Ah is a little low for an 18650, but not really a problem. It sounds like each batt pack is 4x18650 in series, and you've made two of them. You don't give many details about the bulb (in theory, it should draw less than 2A when driven by a 12V source), so I don't know if overdriving it like this is pushing the current too far for the cells' protection circuits. For 18650s, you'll probably want to keep it at under 4A. I'm guessing that when you say you "put together two batteries," you mean in parallel, right? It must be, because I doubt you could drive many 12V bulbs at around 30V without instaflashing them.

If the assumptions in the above paragraph are correct, you might be able to successfully drive the bulb with a battery consisting of only 3x18650.

You don't want to overdischarge Li-Ions ("consume all the battery capacity"), as that will damage them. Recharge them when the light grows dim or when the protection circuits kick in.

I hope some of this helped in some way.

Thanks a lot for your precious suggestions. I now give you more details about the bulb.
It is an OSRAM 12v - G4 Halostar 64425 - clear 2000 h

Yes they are 4x18650 in series and I have have assembled them in parallel.
By 20 watt bulb I want more light and therefore I have made this battery pack. But I hope the bulb works fine with it.
thanks ... again!

 

[Adriano]

"But I hope the bulb works fine with it. " ERROR!

I'm sorry: But I hope the battery pack works fine with the bulb. RIGHT

 

[TigerhawkT3]

Well, it looks (from AWR's Hotrater) like, even at a full 4.2V/cell, that setup should only draw around 2A. If you have access to a multimeter, try taking voltage and amperage readings off the 4s2p (both 4-cell batteries connected in parallel) pack and post them.

If you don't mind keeping the batteries in parallel, you could try something like the 62138, which has a lot more output (but uses more power).

 

[Adriano]

Well, it looks (from AWR's Hotrater) like, even at a full 4.2V/cell, that setup should only draw around 2A. If you have access to a multimeter, try taking voltage and amperage readings off the 4s2p (both 4-cell batteries connected in parallel) pack and post them.

If you don't mind keeping the batteries in parallel, you could try something like the 62138, which has a lot more output (but uses more power).

I'm sorry I am not able to use a multimeter. With the data I have just given you, can you tell me if that battery pack works perfunctorily fine with OSRAM 12v - G4 Halostar 64425 bulb?
thanks