Dewalt Battery power box

[dbrose]

Using my pole trimmer trimming trees and also my sawzall with pruning blade, I was always running inside to switch out batteries. So I came up with and idea to charge my tool batteries via solar and getting a second use out of all the batteries I have. Instead of using a 12v lithium battery, why not use these tool batteries?
Here is what I have come up with so far: a powerbox using Dewalt 20v tool batteries. I already use Dewalt tools and have many batteries. Milwaulkee and others can be used the same, although I am not sure how many manufacturers make a 12v car charger. But as long as the batteries are charged in the factory charger periodically to balance the cells internally is kind of what I'm thinking.


Doubling as a battery charging station. Going to add four more Power Dock battery mounts. I found these on etsy.

Will be adding also 12v post connector, a 24v suitcase solar panel setup with solar charger.
I have the 12v step down converter installed for the 12v and USB outlets.
Dewalt and Milwaulkee make a 12v car charger for their batteries so using two of these battery chargers, the batteries can be rotated through the external charger for cell balancing. I number my batteries so i know what batteries have been balanced and if one goes bad it's easier to locate later.

Wiring is the typical battery wiring that Will shows in his battery banks, all in parallel (2 banks of 4 when I'm done, may go 4 banks of 2, but 8 batteries total).
As a battery charging station I decided to also have a couple USB and 12v battery chargers for charging AAA up to D cell batteries and 9v. Found batteries and compatible chargers on https://power.tenergy.com/
I have a 400 watt inverter that don't plan to mount, just have post mounts externally.
Also have a marine type fuse box similar to what Will uses in his 12v projects.
This tool box has a tray on top to store various items.
So this is my first project powerbox and I'm thinking it can be used for camping, power outages, fishing, hunting or other outdoor activities.
It's been a fun project and what I have done up to this point all works very well.

 

[Mike Jordan]

The tool batts balance internally. None of them have external balance leads to connect to the charger. So i don't think that is an issue. I have been trying to figure out solar charging 20v batts. No SCC come in a 20v version. The go from 12-24v

What are you doing to solar charge these batts?

 

[dbrose]

Hey Mike,
Still a work in progress. I don't have the solar done yet. Planning to try 24v solar into solar charger. The 20v batteries should take up to 28v charging so 24v should be well within range. Can't remember where I saw that now, I was going through the same questions then found out I was well within the range of the batteries. The question is will the solar charger over-charge like you are asking? Going to research Solar Chargers to see if any can be programmed as such with a maximum battery voltage setting. I have not researched that yet. That's also why I'm adding 4 more batteries to absorb and lower overall wattage/voltage. Maybe someone has suggestions or input.
As a power station though, it's really great so far.
I do plan to use two of the 12v car chargers Dewalt makes into the 12v cigarette lighter style outlet. I thought internal balancing only works when connected using the factory charger using all the ports, that's why I'm thinking I need to cycle them through the factory charger. I could be wrong though.

 

[David in nh]

is there a low voltage cut off in the battery ,? will you damage battery by running it low ? i thought it was in the tool in dewalt stuff ?
i did the same thing using ryobi but those have built in low power cut off ,

 

[Mike Jordan]

Hey Mike,
Still a work in progress. I don't have the solar done yet. Planning to try 24v solar into solar charger. The 20v batteries should take up to 28v charging so 24v should be well within range. Can't remember where I saw that now, I was going through the same questions then found out I was well within the range of the batteries. The question is will the solar charger over-charge like you are asking? Going to research Solar Chargers to see if any can be programmed as such with a maximum battery voltage setting. I have not researched that yet. That's also why I'm adding 4 more batteries to absorb and lower overall wattage/voltage. Maybe someone has suggestions or input.
As a power station though, it's really great so far.
I do plan to use two of the 12v car chargers Dewalt makes into the 12v cigarette lighter style outlet. I thought internal balancing only works when connected using the factory charger using all the ports, that's why I'm thinking I need to cycle them through the factory charger. I could be wrong though.

I have researched this to analysis paralysis. But I am certainly not the expert. I don't think you can charge those batts with a 24v SCC without over charging. (also see the last paragraph) You need to control the charge. So far the only SCC I found that would work is the Victrons, as they are highly customizable and you can adjust the voltage. I just don't want to dedicate the amount of dollars the Vics cost, to solar charging a tool batt power station. Even with a whollotta tool batts you don't have as much watt capacity as a a smaller set of prizmatic cells. Its just more cost effective to charge the tool batts from another solar power station

The tool batts are all 5s. So to have balancing done elsewhere, you would need 6 contacts, plus the +/- contacts for power. None of the tool batts have that many contacts.

But... you need to know what those other contacts do. I live in the Ryobi ecosystem, so I do not know anything about the dewalt. The Ryobi you can DIScharge all day with just the +/- contacts. But you can not charge them without the other contacts. One of the Ryobi contacts is a temp sensor. The the batts will not accept a charge without the charger reporting back an acceptable temp reading first. With the Ryobi you can bypass that, by jumping a diode from the temp contact on the batt to the + contact of the batt. I would guess you will find a similar scenario with the dewalt

 

[Symbioquine]

Related, I wrote up a small review of some of those adapters I found on Amazon in case it is helpful to folks: https://symbioquine.net/2021-12-03-dewalt-diy-adapters