Even More Batteries!!

cannonball2 · Apr 7, 2014

Got my shipment of batteries today 87 in all will use 84. The cells are new Samsung 2200mah removed from surplus battery packs less than a year old if the seller is telling the truth. The pack will be 51.8v nominal with a hot of the charger voltage of 58 and 13.2ah. Built a small rack to hold the cells firmly in position for soldering in groups of six. Two groups will be joined in series for a single 7.4V 13.2ah cell. There will be 7 of these cells.

Since Im not running a BMS my thoughts are to make the cells modular with connectors. This would allow balancing of the individual cells occasionally, as well as the ability to up voltage at a later date simply by adding modules. This will likely require a special built box with a easily removable lid. I also bought 10 single cell holders that I will parallel to initially balance the cells. Waiting on some special wire to make the cell connectors from. Then the build will begin into the cell modules.

cannonball2 · Apr 8, 2014

Got a chance to check all the cells. They are excellent with all but 6 being over 4.1v. The 6 are culls, that's one reason to buy a few more than is needed. These should make an excellent pack. They cost $1.66/cell, this build will have $140 in cells and probably $15 in materials like wire, solder and tape. A bit more for connectors if I interconnect them. Not bad for a L-Ion 51v 13ah pack.

silverbear · Apr 8, 2014

Excellent! Thanks for starting a new thread on the pack build. Watching closely...
SB

cannonball2 · Apr 9, 2014

A few pics of the beginning build. The "special" wire I got is simply 22ga tinned copper wire, got a roll(500'!) off ebay. 6 strands are twisted together to make the cell connectors. Easily done with my safety wire pliers. The batteries are then assembled into 7.4v bricks as in the pics. The middle pic shows the bridge connections on the bottom. They are then interconnected with 12ga silicone wire and Anderson power poles making 14.8v at present. The 5 other bricks will be built and added in the same way to achieve 51.8v. Any time I want to check/balance the cells its just a simple matter of disconnecting the individual bricks. Best way I feel to run with out a BMS.

cannonball2 · Apr 9, 2014

A bit more progress on the battery. Its a little more than half done. Ran out of cells(rest are on the way) and 12ga wire. There are 4 separate 7.4v batteries completed, there will be 7 all together. It goes together relatively quickly. Takes about 20min to make a 7.4v brick.

cannonball2 · Apr 13, 2014

I bought 10 of these 18650 cell holders for something like $8 shipped. They are great for cell balancing/charging individual cells. The cells in this build are perfectly balanced voltage wise as received. All are right at 4.15v, great cells! These holders are also great to try to revitalize low cells. Most chargers wont recognize a cell below a minimum voltage. Wire several of these together and insert a good cell. Start the charger and pop low cells into the holders to trick the charger. I then run a discharge cycle on each revitalized cell to check capacity. Some are saved some are not. Its worth the small effort to try though.

I am very pleased with the performance of the 51.8v battery. Not only is the bike faster in acceleration, top speed and cruise, the differential between full charge(58v) and low cut off(42v) is greater(16v) versus a 48v(54v) full charge/42v cut or 12v. I have ordered a Golden Motor programmable controller that will handle 36/48/60v. With the modular battery construction its easily possible to add to the battery to get 60v.

cannonball2 · Apr 15, 2014

A set back with the pack build. The vendor for the cells sent Sony 2400mah cells instead of the Samsung 2200s listed in the sale. I certainly don't want to mix cells. He has agreed to send the proper Samsung cells and a pick up for the Sonys. If he does all is well, if not I will post his seller name for all to avoid.

I bought some 80amp fuses used mainly by the high amp audio crowd to solder inline to the + output. From reading, these appear to have enough gap to prevent arcing. Hope I never find out! Would hopefully prevent a battery meltdown/fire with a dead short upstream from the battery. http://www.ebay.com/itm/271254878262?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

snellemin · Apr 24, 2014

I use the same fuses in my bikes. Good stuff.

cannonball2 · Apr 25, 2014

Well finally its done! The vendor sold thru the original Samsung cells so I was forced to mix brands, though the cells are the same mah. He was kind enough to pick very good cells voltage wise. This was an easy build. The soldering stand made for easy work and it held up well even if it was made from paint sticks and cardboard! Will leave the top of the battery exposed for now, will find or make a lidded box. The rest is armored with 3 layers of filament tape and the bottom is armored with vinyl gutter guard from the Depot. Tough stuff! The + lead is fused with an 80amp fuse at the front of the pack with a peekaboo window-see pic. The Voltage on the voltmeter is as I received the cells basically a full charge. Not sure if that's good or bad.
I assembled one extra cell in case I want to make the move to 60v. Its a simple matter of taping it on plugging it in and re-soldering the output lead to the + side. The cells are easily isolated from each other by disconnecting and can be balanced the same way.
Will give it a run tomorrow.

cannonball2 · Apr 26, 2014

Got a chance to test the pack today. What a difference new(or nearly so) cells make! Only had time to make a run to my other house (9+ miles) to check on a few things. Left on 57+v returned with 55+ still in the bank. Rode at speeds from 18-26mph with no assistance. This is a 13.2ah pack compared to the other homebuilt packs 10.2 but the fresher cells make a noticeable difference.

Comparing the performance of this pack with my new factory built pack 48v 15ah pack shows a world of difference, due to the increased voltage. I urge any one with a 48v system to consider a 52v battery over a 48 when it comes time to buy or replace. Thinking real hard about an increase to 60v!

cannonball2 · Apr 26, 2014

Been riding the pack on errands this pm. Really is exceeding my expectations. Dressed it up in some blue duct tape and added a cover stolen from the wifes left over containers. A piece of foam keeps the connectors and wiring off the cells and bare cell connectors. The pack kinda has the mad scientist look to it. It generally puzzles most folks until its explained to them. I guess this pretty well puts this pack build to bed, very happy with the results!

silverbear · Apr 26, 2014

Congratulations on a job well done!
SB

paul · Apr 27, 2014

nice job cannonball! don't you just love when a plan works out. making modifications to our motorized bicycles big and small is part of the pure enjoyment of them.

cannonball2 · Apr 27, 2014

Thanks yall!

Yeah Paul, modifying stuff is in my DNA for sure. Am really enjoying the Ebike thing. So easy to work with. Hopefully this thread will encourage more battery builds.

KCvale · Apr 27, 2014

Nice work cannonball!

cannonball2 · Apr 28, 2014

Thanks KC!!

cannonball2 · Apr 29, 2014

If anyone is interested in the modular pack build and has an R/C charger, these 2s balance leads will allow true cell bank balancing. Just add them as the 7.4 bricks are built I can balance 4 bricks at time with this set up. So far as received the bricks are in and are staying in near perfect balance. Sure that will change as the charge cycles increase. I bought mine locally, for about the same price. http://www.ebay.com/itm/10x-JST-XH-...Control_Parts_Accessories&hash=item43c8d9cd8d

cannonball2 · May 6, 2014

The modular battery is also a convertible battery. As configured it can put out any voltage from 7.4 to 60v in 7.4v steps. That means it can be used on 24-36-48-60v systems with just a movement of the pack ground to the last cell in the desired voltage range. Its actually not a true 60v battery though it will come off the charger at 63+v(its a true 15s, 55.5v nominal). I will run it with all cells connected after I drain the pack a bit. as it is now its pretty close to snapping the 63v cap in the controller. After recharging it will only reach 59v as thats the output of my 48v charger. Have yet to add the balance leads as it will require de-taping the battery. Will do when the cells get out of balance. Currently they are staying in nearly perfect balance. If the pack had a floating + it could be connected as a twin double range 24v pack.

KCvale · May 6, 2014

Nice packs cannonball.
What are you using for a controller and throttle on your test bike?

All the throttles I have worked with are voltage specific.
The Kelly controllers I use from SBP are another story, they have a serial port and a windows program to set a whole range of control variables.

Anyway just curious as to how you go about testing all your battery ranges on bikes.

snellemin · May 6, 2014

Your battery pack came out nice man!

Even More Batteries!!

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