Solenoid Project - Page 1
Forum section: electronics / beginners

author: skeletor1030
author_rank: Newbie
timestamp: March 19, 2025, 06:35:13 pm
content: Hello,I have a few questions about a project I'm trying to do. My end goal is to power a linear actuator with a battery to flick some dice. A list of the parts I am using are below. The actuator requires 12V to and says it has a load current of 460mA. My plan was to use a 9V battery and use a boost converter to get to, and maintain, the 12V needed. When I test the voltage of the battery before I connect it to the converter, I have 8.5V. As soon as I connect it to the converter, the voltage reads 3.2V. When I adjust the voltage to 12V on the converter, I cannot trigger the actuator. I have to adjust the output voltage to around 26V to get the actuator to trigger and stay activated.My questions are:Why do I have to boost the voltage to 26V to trigger the actuator?I know 9V batteries have high internal resistances, is it a bad fit for this project?Why is the voltage dropping to 3.2V just when connected to the boost converter?Equipment:https://www.amazon.com/dp/B0B4DFJTHX?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1https://www.amazon.com/dp/B07BNHR4HW?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

author: BeBuLamar
author_rank: Super Contributor
timestamp: March 19, 2025, 10:27:10 pm
content: I think your 9V battery doesn't have sufficient current to power the circuit. Try first to supply the solenoid with a 12V power source with good current capacity. Next try to run it with the converter powered by a 9V supply with good current capacity. I think in both case it would work but the 9V battery won't work.

author: skeletor1030
author_rank: Newbie
timestamp: March 19, 2025, 11:01:21 pm
content: Thanks for the reply. That is a good point, because I have tested with a 12V power supply and that works as expected. I'll test with 9V next to make sure that works. I thought I would have enough current from a lithium 9V battery but I guess not.

author: tooki
author_rank: Super Contributor
timestamp: March 20, 2025, 06:27:07 am
content: I found a datasheet for Varta’s 9V lithium (https://www.farnell.com/datasheets/3627082.pdf) and it lists a sustained current of 600mA and maximum pulsed current of 1A. That could very well be too little for your boost converter when the solenoid pulls its initial slurp of current.With that said, have you checked how your 12V solenoid behaves on 9V directly? It would not surprise me if it just worked. (But of course you’d want to test this across the battery’s entire discharge curve, since the voltage will continue to drop.) Many solenoids I’ve played with work just fine on half their rated voltage.

author: skeletor1030
author_rank: Newbie
timestamp: March 20, 2025, 04:10:54 pm
content: Quote from: tooki on March 20, 2025, 06:27:07 amI had found something similar for my battery that said 1000mA on the pulse as well and I thought that would be enough. How wrong I was. I tried it with the 9V battery without stepping it up to no avail, but for some reason I never thought to try it with a power supply. I am happy to say that you are correct, it works great at 9V as well. The interesting thing is, the power supply says it has an output of 1,000mA and it triggers it just fine at 9V. I guess I'm just not getting the current out of the battery I hoped.

author: tooki
author_rank: Super Contributor
timestamp: March 22, 2025, 10:38:04 am
content: See what happens if you use the solenoid on the 9V battery directly, but with a beefy capacitor (like 1000uF or more) in parallel with the battery.

author: MarkT
author_rank: Frequent Contributor
timestamp: March 23, 2025, 11:46:11 am
content: Quote from: skeletor1030 on March 19, 2025, 11:01:21 pm"9V" lithium batterys are only 7.4V (2 x 3.7), probably not enough voltage for a 12V solenoid. Use two of them in series perhaps, you'll have 15V or so.

author: BeBuLamar
author_rank: Super Contributor
timestamp: March 23, 2025, 12:01:14 pm
content: Quote from: MarkT on March 23, 2025, 11:46:11 amI don't think the voltage is the isssue but rather current capacity.

author: tooki
author_rank: Super Contributor
timestamp: March 23, 2025, 07:01:56 pm
content: Quote from: MarkT on March 23, 2025, 11:46:11 amNot lithium-ion. Lithium. As in lithium primary cells. Their actual voltages are actuallyhigherthan most alkaline cells. The battery whose datasheet I linked above has a nominal voltage of 9V.Here’s another from energizer:https://data.energizer.com/pdfs/l522.pdfAgain, nominal 9V.

author: tooki
author_rank: Super Contributor
timestamp: March 23, 2025, 07:10:41 pm
content: Quote from: BeBuLamar on March 23, 2025, 12:01:14 pmExactly. That’s why I suggested trying a capacitor in parallel, to see if an initial surge current is enough to get it to pull (and then be happy with a reduced holding current.)