A123 AMP20M1HD-A Battery pack kit

[deVries]

2. Balance traces are rated at 3amps.

So each trace can handle 3 amps?

I do want to balance charge these cells using isolated single cell chargers. These are rated at 2amps each. If traces are rated at 3amps, then there should be no problems with resistance or heat buildup charging at 2amps through each of the 16 balance traces for 16s = 32amps @ 3.65v, correct?

Thanks for all your help & answers. I too think you have a very good design.

You are on your own here. its meant for balancing only, if you charge separate cells through balance connector it is a risk you have to take.

Does this mean I'm not able to balance charge all 16 cells at same time @ 2amps thru these traces? Too much heat/resistance or ?

Just want your opinion...

I understand it is at my risk, but I need an informed opinion. You are the expert designer.

 

[agniusm]

The current rating for the traces were software calculated and i have not done real life test on feeding them 2amps constantly while charging. You will need to try and see if they get worm or not. I have not accounted for someone using 16 chargers , that's a bit crazy in my opinion. Could you explain the reasons? You can buy proper 48V 6Amp charger for 45USD and 16S BMS for same money.
Put it this way, the traces are not the problem but rather SS bolts. Your charge current would have to go through the trace on to inner aluminum block then from it to 3 SS bolts, on to front aluminum block and then to the cell tab. Its not gonna pop strait away, you will need to test it your self.
My opinion is that if you do something that its not meant for that purpose that way, it can go both ways

 

[deVries]

I have not accounted for someone using 16 chargers , that's a bit crazy in my opinion. Could you explain the reasons?

Yes, I'm hoping I'm crazy like a fox. :lol:

Charging 16 cells is about $160. No need to ever balance or worry about overcharging, because each cell is charged by its own isolated charger it will charge each cell to full capacity but not over HVC. Balancing is "automatic". It will full-charge in 8hrs if I've used 16Ah of capacity.

Then I use Celllogs & amp meter to watch for problems & metering usage. I have an LVC switch that will cut off power if any cell falls to x-volts I set. Of course, all this relies on your traces & interconnections working to carry these charge loads.

I could bulk charge to a lower voltage & use these 2amp chargers to finish the balance charging too. So, maybe only need to run the 16 chargers for 1 hr to complete balance charging.

 

[ohzee]

24s board is done. Still need to put on the top and take off all my tape , but it looks pretty awesome.. I am beat
so Ill work on some pictures and any more lessons learned tomorrow after some shut eye.

No sparks either tho I will admit I had some power go thru my hand to chest a couple times.. It kept me up long enough
to finish lol.

Now if evassemble will ship my darn BMS. Going on 3 weeks and I still do not have a tracking number.. pretty close to
cancelling my order and finding a 24s high power BMS thru someone else.

Screw messing with 16 chargers id rather spend a bit more for an easier solution. Still to each his own your logic make
sense.

 

[deVries]

Screw messing with 16 chargers id rather spend a bit more for an easier solution. Still to each his own your logic make sense.

Just need to use a power strip to plug'em in & a special one-way multi-connector plug to connect for charging. No BMS. Much safer charging method. Auto-balance, full capacity, no over charging. Plus, if one fails it's easy to replace cheap.

Put it this way, the traces are not the problem but rather SS bolts. Your charge current would have to go through the trace on to inner aluminum block then from it to 3 SS bolts, on to front aluminum block and then to the cell tab. Its not gonna pop strait away, you will need to test it your self.

How so??? I look at the traces that come in direct contact with the tabs pressed together and are sandwiched between the wide rose-copper contact base, connecting to traces, which match the same area size aluminum blocks that press-fit the tabs together from above. Current & voltage will take the least path of resistance, so bolts or blocks don't carry any load. Yes? Correct? (Using 16 individual isolated chargers.)

The balance voltage & current hits the tabs directly in contact with the rose-copper base. Right?

I suppose the longer traces might need some solder or a thin wire added... but do you think that is really necessary for 2amps going about 8cm for the line-trace?

 

[megacycle]

Now if evassemble will ship my darn BMS. Going on 3 weeks and I still do not have a tracking number.. pretty close to
cancelling my order and finding a 24s high power BMS

When we discussed it a couple of weeks ago i ordered a 20 & 24S they didn't take long to arrive.
Is yours a special order? Have you spoke to Michael on the online help?
I was surprised hvc is spec'd at 3.9V seems high what are your thoughts?

 

[agniusm]

How so??? I look at the traces that come in direct contact with the tabs pressed together and are sandwiched between the wide rose-copper contact base, connecting to traces, which match the same area size aluminum blocks that press-fit the tabs together from above. Current & voltage will take the least path of resistance, so bolts or blocks don't carry any load. Yes? Correct? (Using 16 individual isolated chargers.)

The balance voltage & current hits the tabs directly in contact with the rose-copper base. Right?

Watch the vid and pics here. traces and large pads are at the back and tabs are sandwiched at the other side. Measuring and balancing done through them.

 

[docnjoj]

Do you have any idea what went wrong before? It would be nice to know if you figured-out what the problem was/is, so we don't make the same mistake & have to get a random guess solution.

oh yeah! I know what I did wrong! I let one of the blocks slip and it blitzed a few traces! I suggest that they be covered either with tape or more permenently with epoxy or conformal coating. Certainly check continuity before you start assembling, just in case. I thought I only zapped one but I must have hit at least 3! Don't do what I did!
otherDoc

 

[agniusm]

Do you have any idea what went wrong before? It would be nice to know if you figured-out what the problem was/is, so we don't make the same mistake & have to get a random guess solution.

oh yeah! I know what I did wrong! I let one of the blocks slip and it blitzed a few traces! I suggest that they be covered either with tape or more permenently with epoxy or conformal coating. Certainly check continuity before you start assembling, just in case. I thought I only zapped one but I must have hit at least 3! Don't do what I did!
otherDoc

Simple quick solution: use some nail lacquer on the traces. It will dry quick and give some protection.

 

[arkmundi]

Hello. i am trying to finish designing this kit, sourcing some material suppliers at the moment to lower the price. Kit will be available in 6S, 12S, 18S, 24S and 30S configuration. People who need say 20S, will have to cut 4 cell bottom part them selves. 2 min job.
So in short you will have everything you need to assemble your pack. The only thing you'll need to do is to drill 3 holes in each cell tab and trim it to size, i will be including some sort of template.
There will be all bolts, blocks, spacers, connectors + pins, heat shrink wrap included.
Thanx
P.S. Just wander if there would be some interest in this?

agniusm: sometimes folks wander in too late to join in. Are you planning on a repeat offer? If so, any idea when? If not, are you willing to share the details of your suppliers so as to replicate? Thanks.

 

[docnjoj]

Do you have any idea what went wrong before? It would be nice to know if you figured-out what the problem was/is, so we don't make the same mistake & have to get a random guess solution.

oh yeah! I know what I did wrong! I let one of the blocks slip and it blitzed a few traces! I suggest that they be covered either with tape or more permenently with epoxy or conformal coating. Certainly check continuity before you start assembling, just in case. I thought I only zapped one but I must have hit at least 3! Don't do what I did!
otherDoc

Simple quick solution: use some nail lacquer on the traces. It will dry quick and give some protection.

Thanks agniusm! I hope I can find some aroound the house. My wife doesn't use the stuff.
otherDoc

 

[agniusm]

Hello. i am trying to finish designing this kit, sourcing some material suppliers at the moment to lower the price. Kit will be available in 6S, 12S, 18S, 24S and 30S configuration. People who need say 20S, will have to cut 4 cell bottom part them selves. 2 min job.
So in short you will have everything you need to assemble your pack. The only thing you'll need to do is to drill 3 holes in each cell tab and trim it to size, i will be including some sort of template.
There will be all bolts, blocks, spacers, connectors + pins, heat shrink wrap included.
Thanx
P.S. Just wander if there would be some interest in this?

agniusm: sometimes folks wander in too late to join in. Are you planning on a repeat offer? If so, any idea when? If not, are you willing to share the details of your suppliers so as to replicate? Thanks.

Hi, thanks for enquiry. It depends on interest. I need to gather up 10 kits to do another run. Doctorbass needs 2, someone else asked PM'ing me so 7 more needed to go ahead. I have some left thou. Sharing design wasn't my intension, sorry.

 

[docnjoj]

Hello. i am trying to finish designing this kit, sourcing some material suppliers at the moment to lower the price. Kit will be available in 6S, 12S, 18S, 24S and 30S configuration. People who need say 20S, will have to cut 4 cell bottom part them selves. 2 min job.
So in short you will have everything you need to assemble your pack. The only thing you'll need to do is to drill 3 holes in each cell tab and trim it to size, i will be including some sort of template.
There will be all bolts, blocks, spacers, connectors + pins, heat shrink wrap included.
Thanx
P.S. Just wander if there would be some interest in this?

agniusm: sometimes folks wander in too late to join in. Are you planning on a repeat offer? If so, any idea when? If not, are you willing to share the details of your suppliers so as to replicate? Thanks.

Hi, thanks for enquiry. It depends on interest. I need to gather up 10 kits to do another run. Doctorbass needs 2, someone else asked PM'ing me so 7 more needed to go ahead. I have some left thou. Sharing design wasn't my intension, sorry.

I still think that you have the best commercial design for building A123 20 ah packs. I hope you do commercialize it, perhaps to one of the larger battery sellers in Europe or the US and have trained folks assembling the kits. I think for scooters and E-motos there is a bigger market than E-bikes, but perhaps one of the larger E-bike manufacturers would be interested, like Giant or Panasonic?
otherDoc

 

[999zip999]

The biggest problem with these cells is there large format. And price, Plus they might be to good of a cell. A golf cart repair man said they wouldn't come in for service, and replace there lead batteries ect. Cost of a replacement battery on a Gaint ect.

 

[docnjoj]

The biggest problem with these cells is there large format. And price, Plus they might be to good of a cell. A golf cart repair man said they wouldn't come in for service, and replace there lead batteries ect. Cost of a replacement battery on a Gaint ect.

Well at 25 bucks per cell they just dont seem that costly. How many would you need for a golfcart? They usually run 48 volts and say 100 AH. So that is 16*5*25 bucks is about 2000 new for batteries for a golf cart. What do lead replacements cost and how often do they need to be done. I'm a crappy golfer so I don't play anymore
otherDoc

 

[999zip999]

You got your hands on A123 cells from China, look at those 3p7s packs where did these cells come from ? A dealer would have to get new cells from ? Mavizen at 70usd maybe volume discount. Remenber you have a backdoor girl in China. !8.50usd. Where did these cells come from ? Are these B-grade ? I need more bike time to tell as using 20ah in one day that's 2hr's. At 30amps from my controller I thought it was a 40amp, but that would melt a bmc600hs. @ 84v.

 

[ohzee]

Here it is. Had to email the picture for some reason the USB driver does not like my mac so will try to get some more up when I get home.

Anyway cutting the tabs down as I mentioned before made a big difference in play. I also used blue painters tape on each side of the tabs
and then also covered up my work on top as finished so Id have no sparks.

I am very happy. Still need to place the top on and get my BMS.

The BMS I ordered from evassemble was custom. It's 24s 100a 150a max. I was told it would take a week which was fine , but then a week
later I was told the warehouse failed or something , but they still cant get me a tracking number.

If nothing by this weekend I am going to cancel and reverse the paypal payment and order from someone else.

 

[docnjoj]

That is one good looking battery, ohzee. I need to get on the stick and assemble my second 6S so I can use it. I also gotta make a case for both of them.Way too much work with limited time but there is no other way to get it ready. My second one should have an easier time since we supposedly get better with practice.

 

[deVries]

How so??? I look at the traces that come in direct contact with the tabs pressed together and are sandwiched between the wide rose-copper contact base, connecting to traces, which match the same area size aluminum blocks that press-fit the tabs together from above. Current & voltage will take the least path of resistance, so bolts or blocks don't carry any load. Yes? Correct? (Using 16 individual isolated chargers.)

The balance voltage & current hits the tabs directly in contact with the rose-copper base. Right?

Watch the vid and pics here. traces and large pads are at the back and tabs are sandwiched at the other side. Measuring and balancing done through them.

Now I understand. Ooops.

I guess you did the design this way so the traces would not be exposed to damage or shorts on the rooftop "exposed" top side? Or, is there another design reason you did this?

I also used blue painters tape on each side of the tabs...

What is the rational for using the blue painter's tape? Don't you want a tape that will bond as strong as possible to the tabs? You want the tape to remain bonded to the tab permanently, right?

Ohzee or Docnjoj, did you use Vaseline or other anti-corrosion compound? What about some type of locktite too? I think Agniusm recommended using some "locking glue" to prevent loosening of bolts?

 

[docnjoj]

Yeah I use that No-Ox stuff but wiped most of it off before putting the parts together. I think it may be overkill. The painters tape is only a temporary barrier between cells but I will leave it on. I'm gonna use silicone parchament paper between the cells when I put it in it's case. In the next build I may paint some liquid plastic between the cells . Too much to think about all at once but it does work!
otherDoc

 

[docnjoj]

As far as threadloc I used an electric driver and then hand tightened all the screws. I really dont think they are going to get free.
otherDoc

 

[deVries]

Too much to think about all at once but it does work!
otherDoc

I would suggest using thread lock on bolts, light to medium strength, tiny drop for peace of mind.

As far as threadloc I used an electric driver and then hand tightened all the screws. I really dont think they are going to get free.

I guess you should at least double check these every 6 months or so just to be certain everything remains tight and secure.

I would be seriously concerned about vibration loosening those bolts & blocks... I think you should consider using some thread lock glue too.

 

[docnjoj]

Perhaps on the second battery but I ride a fairly plush full suspension trike and on smooth roads. I accept the suggestions and before I re-install the cover I 'ii seeif I can lock thread at least one screw on each block. Even though they are dissimilar metals I think it very unlikely that those little 3mm bolts are going anywhere!
otherDoc

 

[ohzee]

Yea I am not worried myself. I think deVries is a perfectionist or a very hot chic. Neither are a bad things I just don't worry as much.

What's life without a bit of spark ;p

The blue tape works fine it's mostly there just for assembly. With my cut tabs even with some flex they can't touch.

When your fishing those little bars between the cells especially if you drop one that blue tape keeps the sparks away.

 

[deVries]

My concern is the pouches will expand/contract & "breathe" over time. The double tabs are not perfectly flat or press-fit "to perfection", so it's possible over time there could be some contraction compression of the sandwiched tabs reducing the forces against the aluminum block and fiberglass.... This might allow the bolts to vibrate loose or loosen with contraction/expansion of those tabs underneath.

I am a bit paranoid about shorts & fires with batteries. I think it's better to be safe than sorry considering the "cascade effect" that can happen once a short makes contact that can continue to spread at extremely high temperatures destroying your battery, bike, and setting fire to nearby objects including your house too within seconds or minutes.

I would at least inspect & check the bolts every 6 months to see if any are loose.