Hi,
I'm looking for some help to design a power supply for a LED lamp (24V strip led) able to charge a battery pack to make it portable to.
Lamp use 2.3m of strip led for a total 28W at 24V (1,2A).
I need the lamps on during charging time and once removed from power supply stay on for 3 hours.
anyone know any board for the task?
I thought to use a standard power supply (like meanwell GS60A24) to power a charging board and a step-up converter on its output to reach the 24V for the strip.
Is correct to use a power supply able to give at least 2 time the current needed for the strip (strip+battery charging) ?
Because of the portable I wish use Lithium battery, do I have to use any board to protect them from total discharge and temperature?

Thanks guys

 

Boosting from a 4.3V (max) lithium pack to 24V will be troublesome. 1.2A at 24V is almost 6A (and that's at fully charged without any alterations from efficiency loss)

You may have to put several batteries in series to get above your intended 24V then regulate it down. Remember every battery has a range of voltage so if you use a LiPo (or similar) it's going to range from 4.3V (fully charged) down to 3.1v (when discharged). This varies from pack to pack so you'll have to rely on the information from the manufacturer.

Alternatively, you can cut the strip into several pieces so you can run them at lower, more manageable, voltages.

Typically, most battery packs have a PCM circuit to help prevent over-discharge and temperature protection. You would have to look at the pack you're going to use to confirm.

 

thanks Jared for reply me

Maybe a battery pack like this ? Then a charger like this.
Could I connect the dc/dc convert in parallel with the battery pack?

 

Yes, those will definitely both work for your situation.

Bear in mind that the battery will range from about 26V down to about 22V. As long as that range is ok for your lights you should be good to go. Otherwise you may need a buck/boost to regulate the voltage consistently to your 24V. I was thinking you could use a boost with 100% duty cycle but it won't help regulate the higher voltage when fully charged.

The only other thing to worry about is the charger. It's rated to 2A so if your LEDs run at 1.2A it should still be able to charge the battery, although slower than normal.

Finally, the pack seems to have the right capacity which will yield you your 3(ish) hours of use.

As for a power supply, yes you technically connect it in parallel. The positive lead going to the positive of the power supply, negative of the power supply going to the negative lead on the battery. Then connect the outputs of the power supply to the LEDs.

 

many thanks again Jared.
Getting that charger will take too long for me so I found this product by meanwell here at local store. It's a battery charger 27.2 V dc output, 120W (enough for lamp on and charger) and have a 2 stage (cc+cv) charging curve... looks great to me.

Could someone suggest me where to buy battery pack? I'm having some difficult to find any, or better, to distinguish the good and the bad one! I need a Lithium ion 7S pack with charging management and around 4800mAh, any suggestion to have no problems? Which are most important safety aspects when choosing a Lithium ion battery?
Thanks

 

I bought some cheap LiFePo4 packs a while back for an e-bike. I think it was either on eBay or some other source. Doing a quick google search there are a few companies out there that make higher voltage battery packs. I bet if you check out the sites that sell products for E-Bikes you'll be much closer to what you're looking for. These packs are not cheap by any stretch of the imagination though..