Dewalt Interface Board Mount

Hello! Well, I am FINALLY building something for MY E-Bike kit!

Previously I was building things for my father's kit or working on making a 24v pocket bike motor for my GT, but that became too difficult to justify, and I decided to start concentrating on my geared motor kit that is almost here.

I am using kfong's interface boards to use Dewalt 28volt batteries while still in their case, but I wanted to have a "lego" attachment on the bottom of each battery, in other words, a battery mount that will mimic the tools that these batteries were designed to plug into attached to the bottom of each battery so I can chain them together.

I decided to use black ABS (1/4" for the main parts of the mount) instead of lexan, and using a variation of Kin's design, I will have a 1/16th inch piece of ABS glued to the bottom of the entire circuit board (with holes drilled to allow space for the electrodes of the resisters and such) which will also be glued to the main mount, solidly attaching the circuit board to the mount.

Here is the link to where Kin shows his battery mounting tray:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=10986&start=45

I am using 28 volt batteries, so the dimensions are 5 x 3.5" for the "blank" that I started with, then I made a master patterns to duplicate for the rest. I don't have much automated tools, so forgive the crude hand-cut mounts.




Note in the third picture (above) that there is a channel cut into the bottom of the mount, this is for a rib that is on the battery's "deck" just below where the interface board attaches on the battery. On a 36 volt, there are 2 of these ribs.

I've used standard ABS pipe glue from the hardware store to bond the pieces or ABS, but I will be using super glue to bond the 1/16th inch thick piece of ABS to the circuit board initially, and if it doesn't hold up, I might go silicone so as to have a bond that isn't impossible to break if I need to take off the board and repair it.

Another great trick with ABS plastic is to get MEK (methyl ethyl ketone) and use it to create a glue with scraps of ABS plastic. Be aware, MEK is EXTREAMLY volatile solvent, so treat it with respect, it can also do a number drying out/burning your skin, gloves strongly recommended.

I have measured from the "deck" of the battery's mounting surface to the top 9/16ths inch so, I will also be putting a piece of 1/16th inch thick ABS as a third layer on top of the two 1/4 inch thick pieces to make it the right hight. Also, if you look on the side of the battery there is a "step" in the grove that attaches to the mount. This step is also 1/16th inch thick where I will be placing a small strip of ABS on the mount to make this a very snug mount.




Once I have the masters done of each part of the mounts (and the 1/16th inch sheet :wink: ) I will glue it altogether and sand down the edges so they match and round out the corners. I'm not sure exactly how I want to mount these to the bottom of the batteries yet, I am hoping that the Dewalt battery cases are also ABS, so that I can just glue these to the bottom with the same glue, if not I can just use gorilla glue to put them on.

The hope is that I will be able to use the battery cases themselves as a "stressed member" in lieu of a full battery box. If all works as planned, this will also allow me to create custom configurations of the batteries to fit inside the frame triangle with minimal mounting hardware, and if I want to add some more packs, I can just plug a few more on.

*** NOTE *** I also wanted to mention I have the male connectors soldiered on the opposite side as normal to make more clearance between the interface board and the mount below.

That is a good built. However, I figured another way to save space while finding a good place to put my batteries. See below:

Nice! Did you use the lights that go with the batteries as the mounts?

Yes, I have used two flashlight holders to mount the batteries by trimming the inside of the cases and bolt to onto the rack aluminum frame. I also have two other flashight holders into the bags.

More pics of my progress, got my first mount finished today, and I'm pleased with the results, so now just 7 more to go


Here you can see the first of the batteries "lego-ed" together.


Soon I will have mounts on each end that will attach to the frame on top and below to keep them secure.

More pics, still working (tonight as I post this) on the fourth and fifth mounts, but here is an update:


As you might notice I decided to beef-up the mount a bit, instead of adding back pieces later I discovered it's not as difficult to just glue together a bigger piece on and carve out the space for the circuit board, so now I will have less difficulty clamping things together, (no little pieces to move around on me) and I will have a stronger mount altogether.

Ok, got the pack 95% done! More pics:








Now I just need to decide on how I am going to finish the "hangers" on top to beef their strength, and add a fourth one that will go down to the bottom to hold mounts for the other 4 batteries (ten total).

I'm thinking that I might actually get everything I need from the 8 (two still in the mail) I have now, making it a 52 volt battery with 9 AH's, weighing 16lbs. 8)

LI-ghtcycle, I really like your ideas! Rather than using the flashlight holder, I think using your brackets do save more weight & space. I wanna be your follower. Do you know where I can buy the circuit boards and positive your homemade brackets? My original think for the next upgrade would still be focusing on the 10 miles range but faster speed. I think to do a 2S3P setup or 2S4P if the power is not enough again wind resistance. But I also want to save weight by not using the seatpost rack and bag. I also want to save more weight by replacing the saddle & seatpost with lighter ones. I have calculated I save about 4 pounds this way. But I need to put the batteries in the triangle frame. Or I can put them in front with the front fork rack & panniers. What do you think?

Nice job lI-ghtcycle. It looks like the packs are not removable or am I not seeing this correctly? How are the packs leggoed on? If you intend to leave the packs permanently on the bike, then you will need to verify that the BMS actually shuts down and still not drain the batteries after a day or two of full discharge. I usually charge my pack after a ride and leave them off till I need them again, so I don’t have to worry about this.

When you plug the batteries into my interface board, my board turns on the enable pin on the pack. This powers up the internal BMS, the BMS is like a small computer, but it requires power to run. It turns off the pack when the batteries hit low voltage. This works great but some of the older designs still drained the batteries because the processor required power to run. If you were to leave the pack discharge after a run and it was an older design, then the next day the packs would be totally discharged due to the small amount of charge left in the pack being used up by the internal BMS. I think the newer design totally puts the micro into very low power mode or sleep mode. This isn’t a problem if you charge right away.

Another issue is if you leave the packs on the bike for the winter of non use. The processor will eventually drain the packs. That’s why I don’t recommend leaving the batteries on the bike for long term unless you know it's a newer design, but I have not found a good way to test the packs if they are a new design without constant monitoring.

A solution to your setup is to cut the enable line and use just the 15amp fused connection. This will bypass the BMS, but then you will lose the benefits of the battery cutoff and protection. Also how are you charging the packs if they are permanently installed?

I think I see what you are doing now. The mounting setup is permanent only to the back of the battery. You can still slide the pack off, but don't you still have to deal with the wires or am I still not seeing this clearly?

lyen said:

LI-ghtcycle, I really like your ideas! Rather than using the flashlight holder, I think using your brackets do save more weight & space. I wanna be your follower. Do you know where I can buy the circuit boards and positive your homemade brackets? My original think for the next upgrade would still be focusing on the 10 miles range but faster speed. I think to do a 2S3P setup or 2S4P if the power is not enough again wind resistance. But I also want to save weight by not using the seatpost rack and bag. I also want to save more weight by replacing the saddle & seatpost with lighter ones. I have calculated I save about 4 pounds this way. But I need to put the batteries in the triangle frame. Or I can put them in front with the front fork rack & panniers. What do you think?

Click to expand...

Oops! Missed your post somehow last night, might have been I was having too much fun testing out my E-Bike in the dark! :lol: 8)

First off, the circuit boards are not my own creation, that honor goes to Kin Fong, (kfong here on ES) he inspired my own mounts. I just made a card-board template the size and shape of my triangle, and then set my batteries on it in different ways and determined the best way to stuff the maximum amount of Dewalt 28 volt batteries.

The basics of my design are this: 1/4 inch thick ABS plastic, (I started with a 30 x 50 inch sheet) and cut it into 5" wide strips on my table saw. Be careful to use a good sharp panel/plywood blade (lots of small teeth close together) and try to push it through at a good steady rate, not too fast or too slow, too fast will chip the edges, too slow will melt the plastic.

The basic sized piece I cut the grooves out of is 5 x 3 inches, and from there I just try and keep things square, but it's not really crucial, just remember if it's a bit large, it can be sanded down later and too small just means weaker.

I bought another sheet of 3/32 thick ABS to make the layers of starting from the "deck" of the Dewalt battery and used two 1/4 inch thick pieces then the 3/32 inch thick ABS on next, before the final piece that will be the full 5 inches with the cut-out for the locking "dog" on the end of the battery.

I don't really have any "plans" or specs per say, I simply made one of each piece fit after doing my best to match the grooves of the mount on the Dewalt battery and then used them as templates to make copies, but this is very inaccurate, and requires much adjusting of each copy, sanding/filling because even when you use a knife edge to scribe the master pattern onto a blank, it's not going to be exactly the same. I was trained to be a pattern maker, so I build things with same methods I would have used to make a wooden pattern for a metal casting, but I have mostly hand tools and no CNC machine to make things accurate.

If you have any more specific questions, please let me know, I could try making some plans with specs from my master pattern pieces, but it's not really going to be more than an educated guess, and your going to have to adjust also if your using 36 volt batteries, as they are slightly longer, so these mounts won't directly attach to 36 volts, but could be with slight modification.

I am also going to beef-up the top "hangers" going to be doing that today, and I will do some tests on my "favorite" 7% hill to see how well this geared motor performs, and if I'm REALLY feeling dangerous, I'll open up the motor and put in my temp gauge. :lol:

I'm so happy with the way it's operating that I'm reluctant to do anything to it.

What a HUGE difference from my father's DD motor, I am beginning to think he got one of the early 9C motors in his Amped Bikes kit built by Golden Motor, it's heavier than the current crop of DD motors from Amped Bikes (about 19 lbs, so double the weight of my geared motor! ) the newer DD motors from Amped Bikes are 14 lbs.

kfong said:

Nice job lI-ghtcycle. It looks like the packs are not removable or am I not seeing this correctly? How are the packs leggoed on? If you intend to leave the packs permanently on the bike, then you will need to verify that the BMS actually shuts down and still not drain the batteries after a day or two of full discharge. I usually charge my pack after a ride and leave them off till I need them again, so I don’t have to worry about this.

When you plug the batteries into my interface board, my board turns on the enable pin on the pack. This powers up the internal BMS, the BMS is like a small computer, but it requires power to run. It turns off the pack when the batteries hit low voltage. This works great but some of the older designs still drained the batteries because the processor required power to run. If you were to leave the pack discharge after a run and it was an older design, then the next day the packs would be totally discharged due to the small amount of charge left in the pack being used up by the internal BMS. I think the newer design totally puts the micro into very low power mode or sleep mode. This isn’t a problem if you charge right away.

Another issue is if you leave the packs on the bike for the winter of non use. The processor will eventually drain the packs. That’s why I don’t recommend leaving the batteries on the bike for long term unless you know it's a newer design, but I have not found a good way to test the packs if they are a new design without constant monitoring.

A solution to your setup is to cut the enable line and use just the 15amp fused connection. This will bypass the BMS, but then you will lose the benefits of the battery cutoff and protection. Also how are you charging the packs if they are permanently installed?

Click to expand...

kfong said:

I think I see what you are doing now. The mounting setup is permanent only to the back of the battery. You can still slide the pack off, but don't you still have to deal with the wires or am I still not seeing this clearly?

Click to expand...

Thanks kfong! I'm going to show pics of the batteries being charged, and thank you for reminding me of the fact that the boards can drain the batteries! I thought I was having some real trouble the other day because one of the batteries just sitting in the garage was drained down to 20 volts!

I have left batteries plugged into the boards on a regular basis, and I think it's only one maybe two of the boards that are the older style, and self discharged a bit.

You are correct, each battery (with a couple exceptions) has a mount glued to it's bottom, and some are double mounts, some have the hanger attached, therefore, I had to modify my charger to accept the larger bottom piece. This is very easily done by sawing off the end (I opened it up first making sure there weren't any wires in the "handle" end of the charger) and gluing on new "feet" to replace the ones on the part that was sawed off, so the charger sits level. You might also need to have the charger on the edge of a table this way, because you will have the wires right there, and I'm very careful not to stress them any more than necessary.

New pics to come soon! Going to be a while, need to make the hinged locking "arm" to help beef-up and secure the top hangers. Also, when I get my two additional batteries, I will be building a 4th hanger mount that might contain up to three battery mounts on it's bottom- glued plate. These multiple battery mounts have to be used sparingly or in places where a battery just below the battery with the mount glued is not needed, since batteries above and below the battery that has multiple battery mounts will not allow for another battery glued to that mount. This is not ideal, but I haven't thought of a better way to incorporate the frame hangers/mounts and multiple glued batteries. MAYBE with highly modified Dewalt chargers (cut down and glued together as tight as my batteries are side to side) I might be able to have multiple batteries glued to the same base mount.

You could create horizontal battery trays similar to your setup but you keep the batteries intact and just slide the pack in sideways, using the dewalt locking tabs to hold the packs secure. Same setup as yours but the packs now just slide in. I'm sure your setup is stiffer since they are interlocked, but if the packs are close together they would be somewhat secure as well, and you would have the packs in their original form. That's what I thought I pictured when I first saw the photos. You can use 1/4" aluminum plates connecting to the top and bottom tube and just screw mount the holders to them, I think that will take the stress better. In anycase, I'm glad it's working out for you.

kfong said:

You could create horizontal battery trays similar to your setup but you keep the batteries intact and just slide the pack in sideways, using the dewalt locking tabs to hold the packs secure. Same setup as yours but the packs now just slide in. I'm sure your setup is stiffer since they are interlocked, but if the packs are close together they would be somewhat secure as well, and you would have the packs in their original form. That's what I thought I pictured when I first saw the photos. You can use 1/4" aluminum plates connecting to the top and bottom tube and just screw mount the holders to them, I think that will take the stress better. In anycase, I'm glad it's working out for you.

Click to expand...

Yes, I agree, however the main reason for the orientation of the batteries I chose was maximum amount of batteries fit into the triangle. If I had them going horizontally, I couldn't quite fit 5 batteries along the top tube.

Horizontally I might be able to have more wiggle room in the sense that I might end up with more room as in more batteries on the third tier down, however, my main idea was to make the battery cases themselves stressed members of the battery "case"

I'm going to look and see if I can't trim down a charger so that I could have 2+ batteries shoulder to shoulder and squeeze in individual chargers in that small space.

Here are some more pics to show how the batteries separate and go into the charger:

LI-ghtcycle, very nice work. The innovation shown by ES members is amazing. After seeing how Kfong used the adapters he prepared, I would have never thought of another arrangement. Even more impressive that this work was apparently done with relatively simple hand tools. If I was starting over, I think that I would try the Kfong adapter approach. Thanks for sharing your work. Rich

Thanks Rich! 8)

I'm very pleased with the results so far, and my Amped Bikes geared motor is a very nice change from my father's DD motor, very efficient, climbs well so far (I'm still breaking in batteries and such, so not flogging it hard yet ) with light throttle going up a 5-7% grade over a mile or so.

Also got caught in the rain, (only my second real trip on the bike!) so I've officially tested the battery mounts in the rain! :lol:

No ill effects other than maybe some moisture inside the cheap digital thermometer, but looks like it should dry out.

I'm really amazed how much power and distance I have so far, even going up a long steep hill! Only used about 1 AH of my 5.4 AH battery capacity, for about 4-5 miles (I actually went 13 miles, but I calculate I only used the throttle about 30% of the time), so maybe I will be just fine with 8 total 28V packs once they get here.

LI-ghtcycle: My 36's have "79 Wh" printed on the black side of the battery.

I'm assuming that means "Capacity=79 watt-hours".
viz:

Is there anything like that on your 28's?

PeteCress said:

LI-ghtcycle: My 36's have "79 Wh" printed on the black side of the battery.

I'm assuming that means "Capacity=79 watt-hours".
viz:

Is there anything like that on your 28's?

Click to expand...

Hmm, I'm about to charge my pack so I'll take a look, and yes that is about right for the capacity for the 36V, so I am sure that is the rated watts per battery.

***EDIT ... I checked and I don't have anything like that on the back of my 28V, but mine are 2007 date coded, look on the opposite side of your 36V and see what the date is, I have a feeling that might be something they started doing on either the 36V in general or just the later dated ones.

LI-ghtcycle said:

... look on the opposite side of your 36V and see what the date is...

Click to expand...

I'm seeing "2009 12-U0"

So the dewalt packs are 36v nominal and 2.19 AH each one? I had always thought they had more capacity.
-Mike

In truth they are only 33V nominal, and they are supposed to have 2.3 AH of capacity, but lets face it, they always advertise the most optimistic performance ratings to sell, thus giving the surface charge as the rated voltage, i.e. 36V. :wink:

That's far below what I thought these packs were capable of... So even 4 of them in parallel works out to 33v nominal and about 9AH?
I had considered these for a customers folding bike build, he is a general contractor and as such I figured sticking to what he already knows would make things easier but I need 20AH of capacity and higher voltage so I guess it's back to LiPo.

Thanks!
-Mike

LI-ghtcycle said:

In truth they are only 33V nominal, and they are supposed to have 2.3 AH of capacity, but lets face it, they always advertise the most optimistic performance ratings to sell, thus giving the surface charge as the rated voltage, i.e. 36V. :wink:

Click to expand...

I'm getting 2.0-2.1 AH out of them in 40-ish weather.

Funny thing is that the CA says I'm only getting 60-61 watt hours (compared to the 79 that's printed on the battery). i.e. I'm getting almost all the amp hours, but significantly less watt hours.

mwkeefer said:

So even 4 of them in parallel works out to 33v nominal and about 9AH?

Click to expand...

More like 8Ah if I read what was said before correctly.