- My device requires ~4.5 V.
- I'm using 4 battery packs connected in parallel
- Each battery pack contains 3 metal-encased non-rechargeable alkaline AA batteries.
- I used voltmeter and verified that each battery pack individually provides ~4.5 V.
- I have also used voltmeter to verify that all battery packs are correctly connected in parallel.
- All the batteries are of the same nominal voltage, the same brand and product name (Varta Longlife).
- (It shouldn't matter here, but for completeness: The batteries are used as a backup to the main power supply, which supplies about 0.5V more than the batteries. Both the power supply and the batteries are connected via a Shottky diode [1N5822 40V/3A DO201] to prevent "charging" each other.)
The device runs fine on the battery packs, but sometimes, obviously when a load spike comes, the device suddenly switches off. I measured that the device, when connected to the power supply, draws 1.6 A during spikes. Normally it draws about 300-500 mA.
Question 1: Shall I keep adding more battery packs in parallel? Will it help or does it only increase the lifetime, but not max current/power?
Question 2: If I use a battery with higher mAh rating, will it help, or does it only increase the lifetime?
As a side note: I am also going to try top-notch lithium AA battery instead of alkaline to see if it handles the spikes.
EDIT: The backup is not supposed to be used much, just very rarely, during a power outage (which we haven't had in years).
UPDATE: I've tried the best lithium AA batteries on the market, replaced the alkaline batteries, and found out that they didn't handle the spikes, either. Moreover, they supply ~5.5V instead of the ~4.7V that the alkaline batteries do. So that's not nice, either, because that is higher voltage than that of the power supply. I'm thinking about using the capacitors or the suggested buck converter with 12 batteries in parallel. The thing is, I have no experience with capacitors and I don't even know what the circuit should look like. As for buck converter I don't know anything about them, either, and am a bit worried that they would introduce more complexity to the system, possibly increasing the chance of failure. So adding more battery packs in parallel, and changing to D-type batteries as some suggested, still seems to me to be the simplest (least complex) solution, which I feel capable of designing and building myself.
UPDATE 2: 4x3 D-type batteries (instead of the AA-type batteries I original used) did help and the device no longer shuts down during high-drain events.