Powered Up Rechargeable Battery Mod

[bogieman]

I am quite new to Lego trains having bought my first sets in September of last year. Right away I decided the AAA batteries are not a great power source due to their cost and the difficulty to change them so I went searching for another option. I discovered that Dewalt made a power screwdriver, a clever gyroscopic one at that, that had a lithium ion battery that would provide the right voltage and fit within the 6 wide locomotives. It's an "8V MAX", really 7.2, which seemed would be okay since at top speed, the trains go too fast anyway. I bought a screwdriver kit with battery and charger and a flashlight that uses the same battery on ebay to try it out. Once it seemed it would fit within a 4 wide brick space I bought another charger on ebay to get the battery socket from. I since bought several chargers for $17-20. each. The batteries are $40. and up for a Dewalt battery but Amazon sells several compatible batteries in the $13-15. range. The Dewalt battery is listed as 8.0 Wh, the competitors list theirs as 1500 mAh, probably stretching the truth.

Here's what the battery, screwdriver, flashlight, and charger look like:

IMG_20190208_171051 by David Goding, on Flickr

The Maersk locomotive was the most difficult so far to fit. I made the long hood removable to make the battery change easy. The battery socket is removed from a charger and the bottom filed flat and smooth. The back side of a 4k6 trap door hinge plate was milled smooth to mount the battery socket. A pair of small holes were drilled into the bottom of the hub for the wires that are soldered to the + and - battery contacts that feed the hub electronics.

IMG_20190208_174543 by David Goding, on Flickr

I added a 4 amp fast blow fuse and socket in the bottom battery position just in case there was a short internally in the hub, I had to mill part of the rib inside the box to fit:

IMG_20190122_180702 by David Goding, on Flickr

I lengthed the long hood by 3 studs and made it a rigid assembly that mates with 4 studs on the locomotive, two on top of the hub, two on underframe that engage the end structure. The underframe length is not altered but the long hood is one stud closer to the end handrail. I changed the radiator inlets to align with the cooling fans and altered the dynamic brake to look better in my opinion. The pushbutton for the power switch somewhat resembles the carbody vent between the DB and radiator fans.

IMG_20190208_174615 by David Goding, on Flickr

The width of the hub and the plugs posed a problem solved by placing the cables where the traction motor blower housing on the left side and a panel on the right allowed room for the plugs but I did have to shave a bit off the rib on the panel and file some of of the side of the plug in the A socket.

IMG_20190208_174754 by David Goding, on Flickr

IMG_20190208_174834 by David Goding, on Flickr

While I was at it, I added LED's for the headlights and ditch lights. The ditch lights required drilling horizontally between the plates at the end to route the wires but the lights are in there original Lego position. For the headlights, I used a 1x3 plate with a 1x1 centered below it and 1x2 vertically on top of them. I think the number boards look better without the black slopes beneath them. Those were glued to a 1x2 brick and holes drilled thru for the LED's. I used the Lego Powered Up light cable but cut the original LED's off and soldered on 3mm bright white ones.

IMG_20190208_175308_1 by David Goding, on Flickr

Here's the finished product:

IMG_20190208_174450 by David Goding, on Flickr

I ran some back-to-back tests on this setup comparing the life of AAA batteries, the Dewalt battery and the Shentec battery. I set a 10 car train running on a level track a speed 6 in each case: the AAA's lasted 101 minutes, the Dewalt 115, and the Shentec 109 so they all seem to be comparable in capacity.

Overall, I am very happy with the results. I only wish the original owner of the Maersk set put the stickers on better. I've bought a set of replacements though.

If anyone is interested, I can post pictures of the other locomotives I've modded.

Dave

[XG BC]

looks really cool ive had the same problems with pf but i switched to 9v conductive rails instead.

XG BC

[Roadmonkeytj]

What a fine looking mod...  I wonder if a different brand of battery would last longer...  My Bosh drill batteries last quite a while...  A regulator would need used as they are 18v but run to me would definitely be longer.    Perhaps shedding the skin would save space on the deWalts?

We always want to see trains around here!

PS.  I love that you call the parts by their actual use/function lol

[1963maniac]

Pardon me but, why wouldn't you just use rechargeable Lego 9v batteries? This seems like a lot of extra work!

[pirzyk]

Am I correct in saying you only have one PUP train motor?  Looks like you are using the second socket for the LEDs.

[bogieman]

1 hour ago, 1963maniac said:

Pardon me but, why wouldn't you just use rechargeable Lego 9v batteries? This seems like a lot of extra work!

As far as I know, there is no Lego option for Powered Up, the only Lego rechargeable is for Power Functions and the cost is $100. for two not including the charger. The cost of what I am doing is about $44. for a charger (for its socket) and two batteries. Plus it is really easy to remove and replace the battery and drop in a Dewalt charger.

12 minutes ago, pirzyk said:

Am I correct in saying you only have one PUP train motor?  Looks like you are using the second socket for the LEDs.

I have two powered trucks on all my locomotives but I use one Powered Up truck and splice a Power Functions truck into the motor leads on the PUP truck with a reversible plug/socket to get polarity correct. This only uses one hub socket and both run all the time. I had no problem mixing the PF and PUP trucks on the hub on 6 locomotives so far. At $14. for the PF trucks direct from Lego including axles and wheels, they are a bargain in my opinion.

For lights, on some of my locos I have used terminals 3 & 4 on the hub B socket which are VCC (+3.3V) and ground, on all the time, with 3.3V white LED's. This leaves the headlights on any time the hub is powered on, which has the advantage of reminding me which locos are active.

[TrainDragon]

Thanks for sharing, this is nice!

 

35 minutes ago, bogieman said:

I have two powered trucks on all my locomotives but I use one Powered Up truck and splice a Power Functions truck into the motor leads on the PUP truck with a reversible plug/socket to get polarity correct. This only uses one hub socket and both run all the time. I had no problem mixing the PF and PUP trucks on the hub on 6 locomotives so far.

This is interesting.  When I tried the same thing (mixing PF and PUP motors tied to the same source), they did not spin at the same speed.  Especially at low speeds, 1-2 clicks, where the PF motors don't even bother to spin.  You can see it in this short video I uploaded here.  I tested multiple motors with the same result.  Are you not seeing a similar effect?

 

[bogieman]

3 hours ago, TrainDragon said:

Thanks for sharing, this is nice!

 

This is interesting.  When I tried the same thing (mixing PF and PUP motors tied to the same source), they did not spin at the same speed.  Especially at low speeds, 1-2 clicks, where the PF motors don't even bother to spin.  You can see it in this short video I uploaded here.  I tested multiple motors with the same result.  Are you not seeing a similar effect?

 

Thanks. I am not seeing that on the locos I've converted. I just tested four of them under no load conditions at throttle step 1. You can see in the videos they all start and spin about the same speed:

VID_20190209_130429 by David Goding, on Flickr

VID_20190209_130403 by David Goding, on Flickr

VID_20190209_130514 by David Goding, on Flickr

VID_20190209_130329 by David Goding, on Flickr

These are some of the other locomotives I've converted to use the Dewalt battery:

VID_20190209_130622 by David Goding, on Flickr

Dave

[LEGO Train 12 Volts]

Nice MOD ...is the locomotive heavy?

[bogieman]

18 minutes ago, LEGO Train 12 Volts said:

Nice MOD ...is the locomotive heavy?

Good question, so I weighed the parts. Six Duracell Alkaline AAA batteries weigh 67g. The Dewalt battery weighs 80g and the Shentec 76g. The socket and wires add 12g so the net increase is about 25g, not too much. I'm actually thinking of adding more weight as I get a lot of wheel slip with a 10+ car train on the 4% grade on my layout.

Dave

[LEGO Train 12 Volts]

Wow you've right ...not too much

Thanks for the info! 

[Giottist]

Please have a look here. There is another suitable solution for rechargable batteries ...

[bogieman]

1 hour ago, Giottist said:

Please have a look here. There is another suitable solution for rechargable batteries ...

Agreed. I did see that thread but I didn't like the battery solutions that put the batteries inside the hub since it requires the hub to be removed from the loco and then opened up to replace the batteries. With the power tool battery, it's in a nice commercial package, cheap, easily charged, and easy to remove and replace.

But it does take up more space which can be hard to fit. On the 60197 locomotive, I replaced the 6x24 base with a 6x28 while adding a front powered truck, both of which I think make it look better anyway.

Dave

[dr_spock]

Clever MOD.  I've seen those types of batteries MOD to use in Airsoft pellet guns.  People custom 3D printed gun stocks to hold the tool battery and used spades for electrical contacts.

[Wabbajack]

I have actually tried something similar. I got two 18650 Li-ion batteries with 3200 mAh capacity and did only a proof of concept. Next step was a better BMS with balancing and the SBrick for bluetooth, but I somehow stopped working on it and started collecting modular buildings...

Also, my train has 2 PF motors, both on one connector and one has reversed polarity (i switched the cables inside the motor, not with the bulky reverser).

https://drive.google.com/file/d/1KpNMJNVKyhZrp9fCNMgJQh2TSmakUEcPrw/view?usp=sharing

Edited February 10, 2019 by Wabbajack
I do not really know how to add google drive video...

[zephyr1934]

Great idea and thanks for sharing!

[Roadmonkeytj]

@bogieman

So your splicing 2 pf motors onto a pup plug or your splicing a single pf motor into a pup motors wiring? 

[bogieman]

10 hours ago, Roadmonkeytj said:

@bogieman

So your splicing 2 pf motors onto a pup plug or your splicing a single pf motor into a pup motors wiring? 

I just took the PUP motor and spliced the PF motor into the motor wires about 2 inches from the plug. I used a connector that I could plug in reversibly so I could reverse the polarity to get the direction correct.

[bn77]

Just signed up to this forum, so I don't have the ability to PM, @bogieman can you share more details/information on the connections inside the battery compartment?  Your original post you uploaded images of the fuse side however I'm interested to see the connections on the other side of the battery compartment to the hub terminals itself and/or if you've improved this technique in the past year?  Having just started in on the trains and spent a load of money on builds for engines/rolling stock I'm looking to save some money on batteries long term and your solution here with the rechargeable tool batteries may be my solution.

 

[bogieman]

I simply soldered wires to the battery holder battery terminal side on the + & - terminals that contact the hub electronics so no mod is done to the hub (except the battery holder) other than drilling a pair of small holes for the wires to pass thru. Here's a shot of the other side of the battery holder:

Note the wires coming from the DeWalt battery socket go into the bottom of the hub thru two small holes then the red connects to the fuse and the other side from the fuse is seen coming thru a hole to solder to the positive terminal where the AAA battery contacted, the black goes straight to the spring terminal where it's soldered to the negative battery terminal. Although I removed all the other battery contacts, they just pull out and I've saved them so I could undo this mod in the future.

Here's a view from of the installation with the battery removed:

Even though the DeWalt battery is 8V Max, really more like 7.2V, it powers two train motors fast enough to derail a heavy 8-wide train in R56 curves, so there is no need for higher voltage in my application.

Dave

[bn77]

@bogieman thank you sir!  Great info, much appreciated.  Now I gotta go find a deal on the charger/batteries on amazon