Driving an LED panel off two 18V cordless drill batteries

Forums › Home Workshop DIY › Driving an LED panel off two 18V cordless drill batteries

tehgerbil

1110 posts

Uber Geek
+1 received by user: 884

ID Verified

Subscriber

#298945 29-Jul-2022 13:14

Good afternoon DIY'ers

I've got multiple 18V B&D battery packs, and this LED MCPCB which I think was originally from a streetlamp assembly.

My intentions are to 3D print a body for LED panel, battery packs and a carrying mechanism perhaps with a tripod mount.

There's no practical purpose other than vanquishing the dark momentarily and I mean momentarily - This thing gets ~HOT~.

My question is do I need to worry about circuits for varying the voltage or will a basic mechanical pot be adequate?

Would love to hear from anyone who's utilised power tool battery packs for DIY projects for any gotchas I need to be aware of.

Thanks for looking!

Scott3

4176 posts

Uber Geek
+1 received by user: 2990

Trusted

Lifetime subscriber

#2947829 29-Jul-2022 13:36

Process is as follows:

work out the voltage requirements and current draw of the panel (assume you will be curring out whatever AC conversion was in the streetlight, and feeding it direct with DC?)
Get hardware to do a voltage conversion from your battery voltage to the required voltage. If this is an increase, you must use a DC to DC, if it is a decrease, you could use an appropriately sized resistor. Strongly recommend going for a DC - DC as it is more efficient.
Buy (or 3d print) a battery holder. i.e. https://www.aliexpress.com/item/1005004017400893.html?
Work out if the power tool brand has under-voltage protection in the tool or battery. If it is in the tool (I think it will be as this is the case for Dewalt, another Stanley black and decker brand, you will need to provision this). For example: https://www.aliexpress.com/item/1005003785049716.html?spm=a2g0o.productlist.0.0.134c6169lvSWl3& (check that it holds its setting's when powered off)
Wire and package everything.

If you skip 4th step, be careful not to ever run your batteries flat, as it can damage them.

Example of a DC - DC. You will need to select an appropriate sized one.

https://surplustronics.co.nz/products/11064-dc-to-dc-step-up-step-down-converter-buck-boost-

tehgerbil

1110 posts

Uber Geek
+1 received by user: 884

ID Verified

Subscriber

#2947834 29-Jul-2022 13:48

Legend! That's the advice I'm after cheers!

Scott3

4176 posts

Uber Geek
+1 received by user: 2990

Trusted

Lifetime subscriber

#2947840 29-Jul-2022 13:53

Could include a switch too (or just remove the battery to turn it off).

If you go the switch route, put it on the battery side of the electrical gear. (due to no load drain from the DC-DC etc.)

tehgerbil

1110 posts

Uber Geek
+1 received by user: 884

ID Verified

Subscriber

#2947920 29-Jul-2022 14:37

Scott3:

Example of a DC - DC. You will need to select an appropriate sized one.

https://surplustronics.co.nz/products/11064-dc-to-dc-step-up-step-down-converter-buck-boost-

https://www.banggood.com/Geekcreit-DC-6-40V-To-1_2-36V-300W-20A-Constant-Current-Adjustable-Buck-Converter-Step-Down-Module-Board-p-1203369.html?cur_warehouse=HK&rmmds=search

Something like this seems to fit both bills, it does say low voltage shut off protection - That's done through controlling the current?

richms

29097 posts

Uber Geek
+1 received by user: 10206

Trusted

Lifetime subscriber

#2947942 29-Jul-2022 15:28

Before you build all this, look on aliexpress for a premade one with a car spotlight style thing on a battery clip, they are cheap as.

Also black and decker have no protection on the + and - pins, but they do have some smarts that will brick it from charging if it gets over discharged. you can bring it back up on a hobby charger but the real charger will not deal with the pack again. Terrible design. I have some black and decker tools and no batteries if you want to pick them up.

Richard rich.ms

pih

666 posts

Ultimate Geek
+1 received by user: 359

Lifetime subscriber

#2948043 29-Jul-2022 17:49

Can't see the panel and it's not clear whether this panel is just a bank/COB of LEDs, or if it has a built in driver. But if it's the former you'll want to find out the nominal current draw and use a matching constant current driver of appropriate size. Again, I don't know what we're looking at here, but if it's substantial then an inline resistor most likely won't cut it. And get a heat sink, heat destroys LEDs.

Lego

Shop now for Lego sets and other gifts (affiliate link).

Scott3

4176 posts

Uber Geek
+1 received by user: 2990

Trusted

Lifetime subscriber

#2948046 29-Jul-2022 17:59

tehgerbil:

https://www.banggood.com/Geekcreit-DC-6-40V-To-1_2-36V-300W-20A-Constant-Current-Adjustable-Buck-Converter-Step-Down-Module-Board-p-1203369.html?cur_warehouse=HK&rmmds=search

Something like this seems to fit both bills, it does say low voltage shut off protection - That's done through controlling the current?

Note that is a Buck converter, not a buck boost.

Means it is only good for decreasing the voltage, So OP would need to verify they need to step down, rather than step up.

neb

11294 posts

Uber Geek
+1 received by user: 10018

Trusted

Lifetime subscriber

#2948078 29-Jul-2022 20:58

Scott3:
Process is as follows:

The tl;dr version is: Get an LED driver and put it between your power source and the LED panel. Whatever you do, don't just hook a high-current battery pack up to the panel.

tehgerbil

1110 posts

Uber Geek
+1 received by user: 884

ID Verified

Subscriber

#2949239 1-Aug-2022 15:12

richms:

Before you build all this, look on aliexpress for a premade one with a car spotlight style thing on a battery clip, they are cheap as.

Also black and decker have no protection on the + and - pins, but they do have some smarts that will brick it from charging if it gets over discharged. you can bring it back up on a hobby charger but the real charger will not deal with the pack again. Terrible design. I have some black and decker tools and no batteries if you want to pick them up.

Thank you, that's a good idea. I think the panel needs a minimum of 36V.

I'll avoid playing around until I get a voltage cutoff, don't want to brick the packs!

Re. Skins - Yes please! May I pm you?

richms

29097 posts

Uber Geek
+1 received by user: 10206

Trusted

Lifetime subscriber

#2949315 1-Aug-2022 16:06

PM me, will be some time till I can go thru the boxes and find them, but I think theres a drill/driver and something with changable heads on it that I got a router end for.

Richard rich.ms

tehgerbil

1110 posts

Uber Geek
+1 received by user: 884

ID Verified

Subscriber

#2959660 26-Aug-2022 09:14

richms:

PM me, will be some time till I can go thru the boxes and find them, but I think theres a drill/driver and something with changable heads on it that I got a router end for.

Sorry for the delay, thank you. I've actually managed to find a Jobmate 36V battery pack for a few bob. I am unable to find anything online about it regarding protection, may I ask if you know more please?

Apple TV

Stream your favourite shows now on Apple TV (affiliate link).

neb

11294 posts

Uber Geek
+1 received by user: 10018

Trusted

Lifetime subscriber

#2959961 26-Aug-2022 18:58

tehgerbil: Sorry for the delay, thank you. I've actually managed to find a Jobmate 36V battery pack for a few bob. I am unable to find anything online about it regarding protection, may I ask if you know more please?

Since Jobmate is Mitre 10's ultra-budget in-house brand, my guess is that the answer would be "what protection?".

Can you crack open the case and post a photo of any circuitry inside?