A123 AMP20M1HD-A Battery pack kit

[totinen]

Hey just made me think, aluminium over copper might help for blocks pulling big amps.

Aluminium over copper??? perhaps vice verse? Aluminium is 60% conductivity of copper and that is with certain alloys like 1xxx series some 6xxx series and they are most soft which is no good for threading.

Yeh meant copper onto tab/s, high conductivity, high thermal sink.

Silver would be better.

 

[megacycle]

Explaining that's like giving birth :x

I didn't realize guys could do that in OZ. Wow!
otherDoc

Should of said like dropping kids off at the pool, but trying to polite

Silver be really good, but ching ching $$, got some artic silver, any good .

 

[agniusm]

So today last day before production. I will order some extra blocks so i have them i case someone was taking a nap. Sorry everyone for high price tag, cant get it done cheaper here. Scarce material availability which involves more manual labor brings the cost up bit by bit. My thoughts are that A123 is going nowhere even in this situation and new EXT cells will find a backdoor to us. i just grabbed a sheet on nanophosphate EXT from A123 if someone hasn't read it already.

I have last question before i send files for manufacturing about PCB's. Perhaps would be neater if i round the edges of PCB's. I thought it would be better if someone decides to heat shrink the pack not to have sharp edges. Let me know ASAP. Thanks

 

[docnjoj]

I have said it before and I will say it again, agniusm, your kits are really the only game out there to allow those of us with somewhat average abilities to make real high quality batteries out of cells. Perhaps consider approaching companies like Hayin (the dragracers cells) and Kokam with dimensions for their flat cells also. You could be in for a big surprise if these companies want an easy to assemble framework for their cells. It could happen. Your stuff really is world class!
otherDoc

 

[deVries]

I have last question before i send files for manufacturing about PCB's. Perhaps would be neater if i round the edges of PCB's. I thought it would be better if someone decides to heat shrink the pack not to have sharp edges. Let me know ASAP. Thanks

I think rounding the edges is a good idea.

Btw, I think you should order some extra 16s and 24s, as I think many will want these in the next 1-3 months.

Does it cost much more to allow balance traces to take 4A-6A vs 3A??? How much? If not, then I think it's much better to design for 4A-6A. 8)

 

[agniusm]

OK, have changed traces to 2mm for 6 amps. Got the bolt holes reduced from 3.5mm to 3.1mm for less play while assembling. Need to figure out how to round the edges on soft.

 

[deVries]

OK, have changed traces to 2mm for 6 amps. Got the bolt holes reduced from 3.5mm to 3.1mm for less play while assembling. Need to figure out how to round the edges on soft.

Good ideas. Thanks for making that trace change too. 8)

I agree with you too about A123 continuing to survive in business. Even if the company goes into receivership it will still come out the other side. Only the present stockholders are at great risk, but the company will go on under different management if necessary.

Also, that PDF you posted does show a great advance in thermal tolerance by A123, so this is great for motorcycle & especially automobile applications.

 

[agniusm]

A bit of update. I have made mistake in my excel kit calculator and therefore prices i have stated were higher than should be. All who have paid deposits or full amount, i will make adjustments and refund and/or adjust the difference, not trying to rob anyone. They are not final but more precise:
4S-67USD
6S-71USD
12S-102USD
16S-122USD
24S-166USD

For 18S and 30S kits price will be available after few of them are requested. Thank you

 

[arkmundi]

Hey agniusm
I'll tell you it seems that you really are in a position to "corner the market" with these kits. If I were a supplier of A123 cells I would be trying to develop a relationship to start making large numbers of these kits, for both the Velo and Motorcycle markets as well as the ebike. Maybe I'm wrong but your kit makes using the way A123 developed these cells easily assembled and without a huge factory with sonic welders, just people assembling packs. Just my 2 ohms worth. Good luck to you! You deserve it for the effort and quality.
otherDoc

OK, I'm just now getting around to reading the entire thread - looking for tips on the balance of building a pack. FYI, I got one of these very well engineered 12S kits from Agniusm and the A123 cells from Victpower (half tab). Put those together yesterday and charged it up this morning. I choose the Smart Charger (6 A) for 38.4V (12 cells ) LiFePO4, from batteryspace.com (see http://www.batteryspace.com/smartcharger6afor384v12cellslifepo4batterypack110vonlystandardfemaletamiyaplug.aspx). Its specific to the chemistry and voltage of the battery pack, and also has internal measurement and status indicator lights. All is well! Took about at hour to fully charge at 6amps.

FYI, I'm in dialog with A123 corporate and as yet hopeful for a better sourcing arrangement for the cells in the USA. So maybe your suggestion is right on! Regards.

 

[arkmundi]

Yes You can bet I'm going to measure 3 times and cut once here. I am not going to use a BMS but the Hyperion charger set for 12S. I figured with BMS systems costing between 60 and 200 bucks and us using a standard fixed route with usually about 13 amp/hours for 21 miles I should be able not to have problems. I do use a Whatmeter to keep track of overall wh/hours and amp/hours when we ride.
otherDoc

Yes, after doing a lot of reading up on the topic, I also jetisoned the idea of using a BMS, investing instead in a really good, state of the art charger (see previoius post). I believe BMS has a place in large automotive packs, especially when there's a lot of charging/discharging going on, with regenerative braking. But for a small 12S pack for an e-bike, I believe its too much (as in dollars and the wasted time & effort). Just my thoughts on the topic.

I'm grateful for the extra cell-by-cell circuit on the kit, however, as this will allow me to measure each cell independently, over time, and check on when a cell sags too much.

 

[arkmundi]

Good stuf... How was drilling holes on the tabs?

• My only contribution to the process of assembling the kit is an easy to make drill jig
• Just used a shipping box; left the Styrofoam inserts inside as supports
• Don't care that the drill punches through – the box is deep enough to take it
• I used two of the 3-hole bars that came with the kit as drill guides, tapped on top
• Its just 4 pieces of cardboard cut square; 2 pieces on either side of the A123 cell; 1 piece on the bottom; and 1 piece overlapping on top
• the cell slides in and the tabs bump up against the bottom piece
• piece #3 on top catches the bottom edge of the pouch right above where the aluminium foil thins out
• the trick is to use a ruler and pencil to mark it out before taping it together, using the bottom plate that comes with the kit as guide
• the jig worked great, making perfectly placed holes, three to a tab, just where they need to be

 

[arkmundi]

I've held off also since I dont think the tabs themselves on new cells should short... I am holding off charging them until I make 6S batteries. Less voltage means smaller sparks. otherDoc

Just wanted to concur, because I had the same thought. I waited until after building the pack to charge it up, believing that packs would ship with lowest possible safe charge state. I cluxed the hex wrench a few times and was glad the sparks were little, compared to Agnius video. All in all, this path worked well for me.

 

[agniusm]

Very detailed instructions with informative photos. Thanks for sharing and effort.

 

[arkmundi]

Well I have 3 cells in and am developing some technique... those tabs are tougher to bend than they look. Also the socket head screws work well to hold the blocks in place while you then can use those little tiny button heads to crank things down. A scratch awl works good to line up holes with tabs. otherDoc

Yes, take the time to have good tools on hand, think it through and get the first one right, so the others will follow wihout fuss. I used a wooden pencil instead of a screw driver to press the tabs flat against the kit plate. Getting the tabs inserted through the slot, bent down, flattened and drill holes aligned with plate holes was the most time consuming part of the operation. A wooden pencil meant no metal in play for that part of the operation (lead point removed). I used a phillips head screw driver from a computer tool kit (small) to do the hole alignment operation. Though the holes were well drilled, once the tab folding and hole aligning process comences, you'll need to work the holes together. I drilled one cell at a time, so I could adjust my drill rig accordingly (see post above).

 

[arkmundi]

My guess is that inner block fell lose and shorted the trace. One rule assembling - be extra careful, don't rush.... I don't know how else i can help as i have not expected people having such difficulties assembling this.. Any way, any questions ask, before doing, not do then regret not asking!

I had no trouble what-so-ever, taking it easy and careful. No tape or masking, just deft.

 

[docnjoj]

Yes if I need to assemble another one (which could happen soon for my son) I would sharpen some bamboo instead of metal tools. My failing was in letting the tabs touch the traces and when I get more of agniusm's kits, which I will because they are wonderful engineering devices and I now can make them, I will use non-conducting tools and cut the tabs shorter. I did learn to tape the cells with wide elictrical tape but cutting them down really makes sense, as agniusm does! It may be that only short tabs will become availible, but we will see. Punching the holes with a scratch awl and then Amazons punch really worked well. I don't think I will give up my day job but assembling the pack really was enlightening for an old guy like me.
otherDoc

 

[arkmundi]

I am interested in getting one of your kits, but it has been a long time since I checked where for find a good source for the 20Ah A123 pouch cells. Could some of the users post some reputable sources. I was looking at A123rc.com and they have the cells for $32 each, but someone mentioned that they could buy them for $25. Any help would be appreciated.

Victpower. Only has half tabs, but these are OK to use for this kit. FYI, I had to do some additional trimming on the tabs, down to the 8mm recommended. Package came DHL (3-5) days. No problems. Cells are up to original A123 specs. I strongly recommend getting these cells now, as I believe the supply is going to dry up.

 

[megacycle]

I not sure if not having a bms for the A123 they go out of balance too easily unlike lipo.

 

[arkmundi]

Question: I believe it was stated that the balancing leads on the plate are rated for 3 amps - yes I don't want to cook those leads, as has happenned. I'm going to take the manual intervention approach to keeping the cells in balance. That approach is to use a 2 amp single cell charger to balance one cell at a time, when and as required. I'm expecting the cells in my pack, using the 6 amp Smart Charger are goinng to stay reasonably well balanced. But every once in a while I'll use those cell leads on the plate to first test and then charge each cell individually.

I just bought one of these and will test out in thes scenario:
https://p10.secure.hostingprod.com/@www.voltphreaks.com/ssl/catalog/product_info.php?products_id=28
Single cell chargers for LiFePO4 batteries. These are constant current constant voltage (CCCV) chargers for 3.2V LiFe batteries. Max charging current of 2 amps.
CCCV to 3.65V,
AC input: 100-240V/50~60Hz 0.35A MAX

 

[arkmundi]

OK, just did a marathon internet search for an eclosure box. Problem in today's highly connected world is that there are a billion choices for every concievable purpose. My specs were simple: 1> more or less sized to my battery pack, 2> metal, so it siphons off any heat, 3> preferably hinged lid and a latch to lock it. You'd think simple spec, simple search, but well, as they say, size matters. Finally found what I wanted in a cash box from Amazon - "Master Lock 7111D Locking Cash Box". A rather perfect fit.

 

[agniusm]

Question: I believe it was stated that the balancing leads on the plate are rated for 3 amps - yes I don't want to cook those leads, as has happenned. I'm going to take the manual intervention approach to keeping the cells in balance. That approach is to use a 2 amp single cell charger to balance one cell at a time, when and as required. I'm expecting the cells in my pack, using the 6 amp Smart Charger are goinng to stay reasonably well balanced. But every once in a while I'll use those cell leads on the plate to first test and then charge each cell individually.

The traces on the kit will hold 3amps continuous and the connector is rated at 7amps. You can use those balance chargers for 75USD, BC168 or hyenas high end version, just limit charging current to 3amps.

I have played with those A123 cells with high discharging and then charging again and must say even Icharger was having problems keeping them in balance. Personally, i would not go BMSless route myself after seeing these cells drifting a lot. BMS or balance charger is the way to go.

 

[ohzee]

Yea I have 2 BMS on both my a123 battery builds and so far no problems. Hoping to get some real testing on my latest one this week though.
Had a snag with my 5404 cargo bike rebuild.

 

[agniusm]

Yea I have 2 BMS on mine and so far no problems. Hoping to get some real testing on my latest one this week though.
Had a snag with my 5404 cargo bike rebuild.

Do you. have a topic on your cargo bike? I am starting mine from scratch and at the moment i am at 2600mm in lenght compared to bullitt 2400mm.

 

[ohzee]

nah man I don't. I started with a mid urban kit and since it's mostly commercial figured it was not worth it.

I will probably for my phasor though since it's going to be piece by piece.

 

[arkmundi]

I have played with those A123 cells with high discharging and then charging again and must say even Icharger was having problems keeping them in balance. Personally, i would not go BMSless route myself after seeing these cells drifting a lot. BMS or balance charger is the way to go.

Thanks for the recommendation. So what's the range you've seen? What exactly is an unbalanced AMP20 cell? My cells are all testing in the range of 3.3 to 3.4 volts. Is 0.1V out of balance? 0.2V? 0.5V? What's the impact of an unbalanced cell on battery performance? I