Batteries - Need small battery with high Voltage and high Current


#1

Can someone please help me to find a battery similar size to a 9v battery and with 9v but a higher current than a 9v battery. Around the current value of a 6v lantern battery. I have started looking but so far I’ve had no real luck.

Putting 2 9v batteries in series only increases the voltage to 18v but does not change the current.
And having a 6v or 2 6v (12v) lantern batteries is way too big to fit into a small pocket

I am therefore stuck on how to power the lights. I was able to make my circuit work but it required 2 6v lantern batteries in series as it supplied a large enough v and a high current, but the size I need is around 2 9v batteries.

Is there another battery that I could potentially use? Maybe rechargeable? I am going through batteries really quickly as the lights just draw way too much current so the rechargeable option may be best.

I have looked at:
PHOTO/ELEC 6V LITHIUM BATTERY DL223AB - 1400

ZNTER S19 9V 400mAh USB Rechargeable 9V Lipo Battery

Ultra Lithium 245 Battery - 1470

But then I also saw:
http://www.ebay.com.au/itm/9-6V-2400mAh-Ni-cd-Rechargeable-Battery-Pack-Main-Charger-Tamiya-Connector-/351493675070?var=&hash=item51d6a7d83e:m:mqRByrDNHXhHyVkLOeYTa6Q
Which are designed for remote control toys? But could this work?
But I’m not sure.

Background: I need to power 3 8x8 RGB Matrix (Not all at the same time), I have a 5v Regulator to supply a constant voltage (7805). I have tried 9v batteries but they drop in voltage really quickly.
I have learnt that placing 2 9v batteries in series only increases the v to 18v but the current stays the same.

If you can help can you please direct me in a direction where I can get the battery and if it is rechargeable, somewhere to get the charger from too.

Thanks


#2

You’re using a linear regulator to drop the voltage to 5V, anything above that will be burned off as heat.

Can you change the regulator to a switching regulator? That would be much more efficient (usually around 85 to 90%) and won’t get as warm.

As for batteries; I would suggest a 2S1P lithium polymer battery pack. That will supply a nominal 7.4 v (8.4 when fully charged) and you can but whatever capacity you need to achieve the run time you want.

Do you know what sort of current draw you have?


#3

How long have the batteries run for?

Did you use alkaline or carbon zinc 9V batteries?

You might also place the 9V batteries in parallel, that will double the current and capacity (different things), without doubling the voltage.

But even 9V alkaline batteries are not really suited to this task, unless you want it to run for a few seconds only.

You should use a switcher rather than a 7805 to avoid wasting power. As @CaffeineAU says.

You haven’t said how much current you draw, please do, but if it is under 500mA then use

https://littlebirdelectronics.com.au/products/pololu-5v-500ma-step-down-voltage-regulator-d24v5f5

Since you want 5V, you might remove the 7805 and use a 5V phone charger pack, available at supermarkets; these contain a 3.2V to 5V step up switching regulator and one or more 18650 or similar lithium polymer batteries. They have their own charge regulator too. With careful management, these things can last way longer than their printed limitations.


#4

I agree with the above - you most likely want to switch to a 2S1P Lithium pack and a step-down regulator, although you may need a higher current version than the linked one. For charging, you need a lithium charger that can handle a 2S pack, whereas most only do single cells (ie. USB chargers).
Example products (not enough info to be sure this suits you):
https://littlebirdelectronics.com.au/products/7-4v-lipo-2200mah-battery-arduino-power-jack
https://littlebirdelectronics.com.au/products/7-4v-lipo-battery-charger
https://littlebirdelectronics.com.au/products/pololu-5v-2-5a-step-down-voltage-regulator-d24v25f5