Power tool battery as auxiliary battery

I’ve been thinking a lot about doing a second battery setup mainly to power lights when the truck is not running and not drain the main starter battery but buying another battery setup for the twice a year fishing trip I take doesn’t seem worth the money. I’ve seen a lot of videos online of people using portable power tool batteries like DEWALT in trailers to power lights was wondering if anyone has done this in the Tacoma. The footprint is small they would fit easily behind the rear seats or under the rear seats.

 

You would have to figure out some kind of charge controller if you were to do such a setup, you can't just hook up a lithium ion battery to a vehicle electrical system.

 

Yea I totally agree or make some kind of cutover so that you can only activate or use the battery while the cars off. Here’s a little video of a trailer setup with the led lights. https://youtube.com/shorts/wVku2Q8q1Fw?si=J0H3qvBN_O7L7O6L

 

looks a lot like the parts i used for my powered tool box with a bluetooth stereo, tape light, and usb charging.

setup separately from the vehicle, it's extremely easy. main considerations is that any 18v battery typically runs somewhere between 16-22v depending on cell condition and charge voltage. so you require either equipment that can accept a variable input voltage, or a 12v regulator with sufficient output for the intended load.

 

I have a 40V-MAX 4.0 Ah Kobalt battery from an electric lawn mower I no longer have (long story ...). Mower was $250, battery still is $160 . Lowes has a Kobalt inverter (https://www.lowes.com/pd/Kobalt-Gen4-300-Watt-Portable-Power-Station/5013697329) I just used today to power an electric hedge trimmer and it worked fine for 30 minutes, only 50% down. Also tested it and it ran a 40 in TV for hours 2 hours 40 minutes.

 

I just finished installing a 20v Dewalt battery step down inverter to power bed lights and camp lights.

Very useful and I keep the parasitic draw away from the starter battery.

And I have TONs of Dewalt batteries so I just swap it out and recharge at home.

Mellif DC Power Adapter Compatible with 20V Battery, 20V to 12V Step Down Voltage Converter, 180W Inverter Automatic Buck Converter Regulator for Golf Cart Led Strip Light (Tool Only)

https://www.amazon.ca/dp/B0BSTYV6ND?ref=ppx_pop_mob_ap_share

 

Interesting ... basic DC inverter that needs a few more connections to handle grounded plugs (I assume). But leverages the many batteries you have.

Mine is a power block with 3-prong plug, USBs. For $100 I leverage a $160 battery I still have.

I like "leveraging" solutions!

 

Well it only goes to hot and ground back to the inverter, I isolated every wire, every connection away from touching or even running the metal body. Since that is a separate current.
I’m very afraid of the two circuits meeting and shorting the ECU or anything electrical on the equipment side of things.

as for inverter for my heated blanket though I went with this.

https://a.co/d/6UphgFA

 

I went the same route with the red brand. A $4 USB powered LED to light my canopy and one of these cables to run a 12v fan via the USB-PD port: https://www.adafruit.com/product/5450

 

Can yall post some pics of your setup? Im wondering if some kind of dc to dc charger would work with those 20v batteries. Many of them are able to handle anywhere from 12-40v dc in or out and alot of them auto detect the battery type. Im not a electrical engineer so idk exactly what type of dc to dc converter/charger would work but im sure something exists that can take that 20v and make it chargeable and available to use in the 12v cars system as like a aux battery. To me it just feels like a good cheaper way for you to have aux power when you have tons of those extra batteries lying around like the dewalts and the makitas etc.. This is a cool subject to think about tho!

 

I think dewalt does have 12v battery system.. Maybe something like this with a dc to dc charger would probably work in a car without needing a converter and the off brand batteries on Amazon are cheap..

$45 TENMOER 2 Pack 6.0Ah Compatible with Dewalt 12V 6.0Ah Battery Replacement for Dewalt 12V Batteries DCB127 DCD701F2

https://www.amazon.com/dp/B09YTZL1H4

 

If I were to do this I'd run two completely separate systems and have two batteries on hand. Just use a normal 120v charger plugged into the factory inverter.

 

I dunno… off brand batteries have a bad reputation for a reason. Do you really want to risk torching your vehicle with a lithium ion fire and then having insurance fork you because they discover you had some hillbilly sh!t wired in?

There are some dewalt brand (and off brand, of course) thingies that use 20v batteries and output both 12v and usb. Add a bit of led strip lighting with a plug on the end, charge your batteries on a real dewalt charger and boom: you’re lit.

 

Far better to keep the systems isolated.

 

This. Milwaukee makes a car charger that I assume would be more efficient than running one off of the inverter (just because dc to dc) but of course it’s overpriced so I haven’t picked one up yet. Don’t have an inverter on my first gen though