----- All Answer about the Dewalt 36V battery and B M S ---

[Doctorbass]

Hi folks,

This is my first post. Been reading the site off and on for a while now and figured I'd throw in a couple cents. I built my 72(66)V pack about a year ago. Running a Crystalyte 5305 with a 20A controller. Purposely limited the controller ouput.

So I ran two packs for about 8 months before they started getting tired. About 1500 miles. Been primarily using two more packs since then. However I will occasionally still use the original set and seems like I can pull around 1800 or 1900maH before they dump on me. I pretty much abused that first set of batteries as often as possible trying to see just how much they could take. They took a lot.

I quit keeping written data after I figured out how hard I could push them. They fairly easily would take me five miles at an average of 16-18mph on relatively flat ground.

I see everyone talking about a 15A internal fuse and a probable 20A limit on the packs. According to my DB, I at least pull a surge of 25A on a regular basis as I still check the data daily. Haven't blown my controller or a pack yet. Don't know how long I could run at that rate but I do have my controller mounted to a nice little sheet of aluminum.

I notice you are also talking about mounting the packs. I'll show my solution in the photos I'm going to try to add.

I think it's great that you guys have advanced the uses of the packs since I built mine last year. I had fully planned to install 4 or 6 more packs to increase the range and/or torque but decided I just really didn't need either. Plus I really didn't want saddlebags which is why I built it this way in the first place.

So check out the pix and see what you think. Some of you may have seen these at the RC site before they pulled our thread or over at the Google Tidalforce forum.

John J

Hello and Welcome Jjackstone!

Welcome to the 5305 club.. :lol: we are 4 or 5 at least...

Your pack seems to be easy to use and congrat to you for the polyuretane holder :wink:

When i talk about 20A about the battery, i have been talking about the BMS current that i successfully tested.. but i did,nt try more than that because i have not higher load for that. the 20A is when you activate the BMS circuit with the center connector and some resistopr divider. The DC9360 pack have one POS and two NEG out. One is passing thru a 15A fuse and the next one have NO fuse.. but it is controlled with a 60A mosfet. in your case, you seems to directly use the NEG connector that pass thru the 15A fuse right?
otherwise, you could have bypassed the BMS and plugged rirectly to the cells tab to have max current.

You have a beast hub motor.. so why did you choose a 20A controller? is it stock? or do you consider to modify it to the IRFB4110 mosfet grade that allow you 50A+.. in this case you could discover that your 5305 can be like a monster!

Finally have you measured the voltage lost in your wires? the battery wires seems to be like 18 or 16 gauge... increasing to 12 or 10 gauge would increase significantly your power and efficiency and milleage..


Doc

 

[ngocthach1130]

What? You mean you can tap into the cell directly without opening the pack or going through the BMS? This is BS. I took so long to solder up wires from inside the battery then running it outside. I need to tap into the battery directly anyway, i want to pull massive amp for wheel popping fun.

Nice holder btw. Looked very easy to pop on battery and off. Too bad there's no space in my frame to fit something like that.

 

[jjackstone]

Hi Doc,
Thanks for the welcome. Let's see if I can answer some of your questions.

1. One is passing thru a 15A fuse and the next one have NO fuse.. but it is controlled with a 60A mosfet. in your case, you seems to directly use the NEG connector that pass thru the 15A fuse right?

I am using the negative tab furthest to the outside of the battery. I have to assume that it does not go through a 15A fuse or it should have popped a long time ago unless that fuse is a slow blow. But you seem to know the circuitry better so maybe my DrainBrain is reading transients.

2. You have a beast hub motor.. so why did you choose a 20A controller? is it stock? or do you consider to modify it to the IRFB4110 mosfet grade that allow you 50A+.. in this case you could discover that your 5305 can be like a monster!

I chose the low powered controller to purposely limit my speed. I rode motorcycles for years and while I do enjoy going fast, I feel that eventually the high powered mods that some are making will cost the entire e-bike community. I fear that we will become more regulated as our bikes become faster and more powerful. Don't get me wrong though, I really do like the mods you guys are doing and I may end up doing the same myself. As far as the motor goes I got it by luck as a rookie purchase. I wanted something that could push me around(I weigh just over 200 pounds) without a major strain. I saw that this motor was rated at 750W and figured it would be able to do the job. I didn't realize how powerful it really was until I started reading some of the posts here.

3. Finally have you measured the voltage lost in your wires? the battery wires seems to be like 18 or 16 gauge... increasing to 12 or 10 gauge would increase significantly your power and efficiency and milleage

The wire is actually 12ga stranded for the flexibility. Nice tip though, when I do a rebuild I'll try upping the gauge.

I've seen some of the posts on upgrading the controllers. Will the 20A controller upgrade ok to 50A? If it does I"ll have to probably buy a Cycle Analyst to handle the excess current.

Eventually and ideally what I and it seems like a lot of the members here would like to do is convert the Dewalt packs to standalone packs with their own chargers and BMS's. Future will tell.

JJ

 

[fechter]

The 20A controller you have will do 50A with 4110 FETs and a modified shunt. You can always make the limit adjustable, so you can go lower for normal use.

I can see why you limited the current running the stock battery packs.

I'm interested in the polyurethane casting material. What kind is that?
What is the consistency of the cured material? It looks like great stuff for making custom parts!


The wires from the controller to the motor are very long. There will be a lot of resistance loss in these. It would be better if the controller was closer to the motor so the wires could be shorter. For that kind of length, I'd recommend at least double 10ga. or 8ga. Current in the motor wires will be much higher than the current limit during acceleration.

 

[GGoodrum]

The problem I had with using the DeWalt packs directly is that I had a bad time with the DeWalt chargers. I had 8 packs mounted on a custom mount made from G10 material:

They too used the outer negative terminals, but with a 20s4p configuration, the total it would handle before the fuses would pop was 60A. At the time, the 7240 controller I had installed had a limit of around 38A.

Like I said, the big problem I had is that the packs were always going out of balance. I have four DeWalt chargers, and I tried all different combinations but nonetheless, the packs would get so far out of balance that a fw of them would show an error on the charger, and not charge. I'd have to use an RC charger to boost the overall pack voltage up to where the low cells were above the cutoff, and then the DeWalt chargers would take them again. I would leave the packs on for at least a half an hour after all three green lights lit solid, which is supposedly when the cells get balanced, but they never really did. Finally, I took the four worst balanced packs and took them apart. For each pack I jury-rigged hooking up a TP-210V RC balancer and matching TP-1010C charger, and used the auto balance charge mode. It took a couple of hours for each pack, but afterwards I ended up with all four fully charged and balanced. I put the packs back together, and did about four more cycles, using the four DeWalt chargers. At the end of the fourth ride I checked each pack, and again all 8 were out of balance. At this point I gave up, ripped all 8 packs apart and made two of these:

Now I use them on this bke:

Maybe I just have four bad DeWalt chargers, but I sure had a bad experience with them.

-- Gary

 

[jjackstone]

Ok, way to start the week. Rained on me this morning(slight, but none was in the forecast). Picked up a nice sliver of metal on the way home. Didn't go flat til I pulled the metal out(at home).

GG: Like your packs. I had an occasional problem with one cell getting out of range also. I just opened the pack and put a C or D cell or two across the faulty cell and got it into happy charger range and everything was fine. It's happened a few times and what I discovered is the problem almost always takes place when the pack is really being pushed. Funny thing is, not necessarily the same cell flakes each time.
Are you using one of Bob's ckts or maybe Victor from Metric Mind? Design your own? Plan to do something similar in the future. I really liked Victor's clamping ckt.

I may have mispoken about my motor size. While I was changing the flat this evening I noticed the tag on my hub actually says Crystalyte 5 505. Anyone know what that is? When I bought it I was told it had a 750W rating which had me wondering how you guys were running close to 3K through it. Also, while I normally ride pretty easily, I have had this bike up to 53kph on a flat ride. That's around 1100-1200W.

Fechter: I'll post pictures of the mold and casting material. They were purchased locally(Sacramento) at Tap Plastics. They have an online store if you don't have one nearby. The material cures to what feels like a hard plastic. Possibly somewhat brittle although the only time I have broken a cast was when I dumped the bike. The weakest point is where the screws are countersunk into the mold holding it to the frame. Even with flat washers mounted the material pulled through and snapped. This was my first experience with mold and cast. It seemed straight forward and has worked out well. I have had some bad casts though. Old material.

JJ

 

[BiGH]

I may have mispoken about my motor size. While I was changing the flat this evening I noticed the tag on my hub actually says Crystalyte 5 505. Anyone know what that is? When I bought it I was told it had a 750W rating which had me wondering how you guys were running close to 3K through it. Also, while I normally ride pretty easily, I have had this bike up to 53kph on a flat ride. That's around 1100-1200W.

JJ

Hi JJ,
While the raiting is only 750w it is capable of taking a LOT more. I'm running a 4 series motor (rated for about 500w i think), but running at 2.5KW

 

[ngocthach1130]

when i got the dewalt charger the manual said to leave the battery in for 8+ hours when i wanted to use the balancing function. Do you think that is why some of yours cell are off? Maybe it's bad that i'm leaving it for that long?

 

[Jay64]

EMF can you post some pics of your mounting set?

John J, do your batteries lock in to place with those polyurethane mounts? Since you obviously already have some molds made, would you be interested in making more and selling them??? :wink:

I'm trying to take this in baby steps, so I am starting small. I don't want to be taking apart the batteries and reconfiguring them while I am trying to figure out all the other stuff with the motor, mounting, throttle, controllers, etc. I don't want to have to make a custom charging sytem at this time. That is why I want to use the batteries untouched for the moment, and figure out a way to mount them to the bike.

I just ordered myself two DeWalt battery packs and a charger. I am going to be putting a Kolls motor into my pocket bike to get me started on a project. I really like the idea of having a mount that I can clip the batteries into for right now.

 

[EMF]

EMF can you post some pics of your mounting set?

Yep. Aside from the fuse holders, there are no fasteners, just held together with Gorilla glue. I used the straps with velcro to hold the batteries in place rather than the clip on the battery pack, to keep the stress of hitting bumps on the straps, as the batteries were jostled. That way there is no strain on the wood pieces.

The wood strips are just stacked and glued to fit the slots in the DeWalts. I had to glue a 1/64 plywood shim on one piece of the plywood strips to make a perfect fit. The batteries are tight;y held in place just like a regular tool holder, even without the straps.

264 miles so far with NP. I have been up to 32 MPH. The fuses I got off ebay. If they work right with my voltage/current they should blow @ 10 amps. I almost wish one would, as they have a light up LED in the middle to indicate they blow.

 

[magudaman]

wow that is a very nice setup. Very clean and I like the nice use of the spade plugs on the pack. Nice wood fab. The only concern with a set up like that is going over current and blowing the internal fuse on the BMS but you have it pretty well fused.

 

[jjackstone]

when i got the dewalt charger the manual said to leave the battery in for 8+ hours when i wanted to use the balancing function. Do you think that is why some of yours cell are off? Maybe it's bad that i'm leaving it for that long?

I leave my batteries charging for as long as possible which is usually no more than four hours each during the day. Ride to work. Charge battery A til noon. Charge battery B til four. Ride home. Charge battery A 2 to 3 hrs. Charge battery B overnight. Rotate A and B every couple weeks. I have a couple spare sets that I keep for pleasure riding.
I think the cells become unbalanced for a few reasons.
1. As previously mentioned these chargers aren't the best in the world, but then again the batteries were not designed to take the beating we give them.
2. We give the batteries a beating.
3. I believe that there are a certain amount of bad or weak cells that just can't keep up with the rest of the pack. I've had seriously unbalanced(unlike my own level of mild unbalance) cells in at least three different packs. I was always able to regenerate them which amazes me because one was actually reading below 1V.
4. I understand what DeWalt did with their little spring setup for monitoring but I believe that in some cases that may not be reliable.
5. I haven't seen a tab weld bad yet, but perhaps only three of the four tacks are good sometimes on the weld. Could cause a little extra heat buildup, hence a bit of extra resistance. That is total conjecture and would need to be verified with a meter.

JJ

 

[EMF]

wow that is a very nice setup. Very clean and I like the nice use of the spade plugs on the pack. Nice wood fab. The only concern with a set up like that is going over current and blowing the internal fuse on the BMS but you have it pretty well fused.

Oh, thank you! Luckily, I had some stuff from my basement remodeling job. Oddly, these tools, a power miter saw and bench saw, are also made by Dewalt. LOL!

I have read your posts over and over again, earlier this year at the Vis for voltage forum, especially that real good thread with you and bio_diverist and I think even mn_aerorider and you guys are the ones that made me think DeWalt was the way to go! I must say, these cells do not dissapoint. Now, if I only had the smarts of some of the other guys around here, I could make a cool charger.

I don't think it is possible to blow the internal fuse, as I have these packs wired in 2 in series and then the sets of 2 in parallel. I have a 10 amp fuse wired to the positive lead of each single pack. Since the current is evenly distributed over 6 packs and I have my CA set to 40, the most amps I can pull from a single Dewalt is ~7 amps.

 

[Jay64]

EMS, nice!!! 8) Now that looks like something I could do. Thanks for the very detailed pics. I will start work on something like that when my packs come in. Hopefully Sat. or Mon.

 

[vanilla ice]

Since the current is evenly distributed over 6 packs and I have my CA set to 40, the most amps I can pull from a single Dewalt is ~7 amps.

If you're running 2s3p, shouldn't that be around 40/3 or 14 amps each?

 

[EMF]

Yes, you are right! Ooops. Looks like I'm on the ragged edge of blowing a Dewalt internal fuse! I guess I need to cram 2 more batteries into my pack somehow. I've got 'em.

Edit:

 

[Doctorbass]

I have many BMS left... in case theyr would blow again... :wink:

also there is a way to repair the 15A fuse.. i've posted it few month ago

That only take 5min to repair :wink:

Doc

 

[EMF]

I have many BMS left... in case theyr would blow again... :wink:

also there is a way to repair the 15A fuse.. i've posted it few month ago

That only take 5min to repair :wink:

Doc

Thanks Doc! I saw a thread too somewhere. So far, my max amps on the CA is 38...so maybe I will be OK. *crosses fingers* Plus winter has set in here and I can just re-configure a new box to hold 2 more batteries. I have two spare fuse holders in the present setup. I need more range anyway.

 

[EMF]

EMS, nice!!! 8) Now that looks like something I could do. Thanks for the very detailed pics. I will start work on something like that when my packs come in. Hopefully Sat. or Mon.

Thank you. Yes, it's very easy to make, cheap and light. Once you get started, it goes together real quick as each particular piece is the same. Get the first ones measured up and that's it, crank out the same thing for how many batteries you will use.

 

[Jay64]

EMF, what material did you use to make those battery connection boxes in the grooves.jpg pic? Is that delrin or something?

 

[EMF]

I got it at McMaster-Carr. It's UHMW Polyetheylene. Part number 8702K87. If you put that in their search bar, it comes up as 1/2" thick x 3" wide and you can buy it by the foot for $5.92 per foot. It machines nicely, also it's extremely tough.

When the machinist milled the channels, I gave him a 2 foot strip, a Dewalt battery and had him mill the entire length with the grooves. It made it easier for him to see what he was trying to do and take his measurements. Each guide is the same on the DeWalt battery, but one is a bit taller than the other. To save time for the machinist and money for me, I had him mill both grooves in the plastic, to fit the tallest guide.

Then I measured my DeWalt, where this plastic would go and set my table saw to 1.5 inches and cut the strip into blocks.

 

[efreak]

congrats !!

this is really nice. its like cyclomatic ( you know the one) but fuses instead of the switches i guess. so 8 batteries should keep the amps to below the 15 amp bms board fuse . Ok it has moderate amp draw per cell but do you baby it or can you GIVE ER?!

just wondering i have started accumulating my dewalt so f ar 5 i am aiming for 8 .
untill i saw your set up i was gonna go the bypass route ,my only concern is attempting to discharge through bms. you have it fused and stacked at least 8 deep that is like 10 amps per cel then the fuse probably good 10+ i don't know i might still have to by pass will see i like this set up though or the poly plaster mold holder wild stuff.
thanks for your frontierism!!!

keep up the good work and updates too please and thank you

efreak

 

[dean]

Hi there I have been reading this forum for a couple of months now with interest. thanks for all the great information.

i have an ebike with a x5303 motor, running 4 unmodified dewalt packs for 72V originally with a 20A controller. Its great fun to ride, will run along at between 50 and 60km/hr although at that apeed the range isnt great - maybe 15km.

I had 2 of the 20A controllers die on me, (I'm told they shouldnt be used with the 5303 motor in the first place... oh well lesson learned) and the only thing i could get my hands on is a 35A new model of crystalyte controller. I dont really need to go any faster and I'm concerned that at 35A the batteries will pull around 9A each and this seems like a lot to me.

Tried the controller last night - it only worked briefly and I now have 4 batteries that wont charge on the dewalt charger, one of which is reading 0 volts and smells like burned plastic, I'm hoping I can salvage the rest by balancing individual cells) but am not keen to try again until i understand what went wrong...

I double checked everything and hesitantly put in my remaining batteries with the bike on a test jig. The motor would run fine, the only thing i noticed was if i throttle up to speed, then let it wind down, as i reapply the thropttle not much happens until it kind of kicks back in really hard and i see a voltage jump at the batteries - is this normal?

I see some people on here using the same motor (or 5304/5303) with 35 or 40A controllers and dewalt batteries but dont quite understand the terminology to see how you have your batteries setup. (10s2p???)

I've built the resistor network to enable the BMS on each pack (takes power from the switched negative) so am wondering if the BMS will limit each pack to a certain output and thereby look after them? If so how did i fry a pack?

Or do i need to add more batteries in parallel to keep the draw from each pack down to a lower level...

Any advice you can provide would be much appreciated.

thanks

Dean.[/img]

 

[fechter]

Nice bike!

The larger controller is able to draw more current than the DeWalt BMS allows. When the BMS senses an overcurrent, the FET switch opens. Unfortuantely, the FET will see the full 72v across it when this happens and it is not rated for this much voltage.

I suspect you fried the BMS in the battery pack.

When running high current at 72v, I think you need to bypass that part of the BMS to prevent this problem.

You might be able to score a repalcement BMS from Doc or one of the other members that has removed them from packs.

Plan B is to ditch the DeWalt BMS altogether and use some other form of battery management.

The behavior you're describing in the no load test sounds pretty much normal. It takes a while for the controller output to get up to the speed the wheel is moving, so it would seem like a delay in response.

 

[Jay64]

About those BMS, Does any had blown their BMS here?

I have 12 left BMS.. 8)

:wink: