18650 pack build using plastic battery holders

Batteries, Chargers, and Battery Management Systems.
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www.recumbents.com   10 kW

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 17 2015 12:09pm

Over the weekend I finished the wiring for main power, charging, cell group testing and balancing. I added a switch and a fuse but could only find a 40A fuse for the holder I bought. I'll have to do some testing to see if that is adequate. I already know the system can pull up to 90A, but just for very short periods. The battery holder array, ESC, etc. are now attached the to the bottom of the plastic case.

I just need to add an LED to indicate power, load up the cells and then, test ride time!

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Re: 18650 pack build using plastic battery holders

Post by steveo » Nov 17 2015 12:42pm

looks really cool

for low current levels should work great

i like that you could take the cells out to easily replace them lol...

wish i could do that with my lipo packs lol

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 17 2015 12:49pm

www.recumbents.com wrote:Over the weekend I finished the wiring for main power, charging, cell group testing and balancing. I added a switch and a fuse but could only find a 40A fuse for the holder I bought. I'll have to do some testing to see if that is adequate. I already know the system can pull up to 90A, but just for very short periods. The battery holder array, ESC, etc. are now attached the to the bottom of the plastic case.

I just need to add an LED to indicate power, load up the cells and then, test ride time!
Better use 2 fuses in parallel or find other fuse holder, you do not want a failed fuse were you less expect it, in middle of nowhere. Once I had a fuse value just on the edge of its designed capability failing after half a year of use, in the worst place and moment. :)

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 17 2015 1:00pm

Yes you are right, I will order the larger fuse holder.

Oh, also I found that if I use some acid-zinc flux, my silver solder flows fine. I will need to be sure to get the solder with a flux core next time...

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 18 2015 4:13pm

On my previous LiPo pack I had used a loopback cable with large Anderson connectors as my on/off switch. This worked great. I thought this time I would use a large DPDT switch as a power switch for my battery pack. I added a battery in the last row of my pack which completed the circuit to the controller as apparently the switch was on. I smelled a whiff of that electronic ozone smell and immediately removed the battery. Hmm, the switch was stuck. Apparently it welded itself together. Looks like I will not not using that switch. Along with the larger fuse holder I have ordered one of those big twist switches to switch a car battery as I had good luck with that on another e-bike build. Fun.

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 19 2015 1:48pm

www.recumbents.com wrote:On my previous LiPo pack I had used a loopback cable with large Anderson connectors as my on/off switch. This worked great. I thought this time I would use a large DPDT switch as a power switch for my battery pack. I added a battery in the last row of my pack which completed the circuit to the controller as apparently the switch was on. I smelled a whiff of that electronic ozone smell and immediately removed the battery. Hmm, the switch was stuck. Apparently it welded itself together. Looks like I will not not using that switch. Along with the larger fuse holder I have ordered one of those big twist switches to switch a car battery as I had good luck with that on another e-bike build. Fun.
I just use regular 120V household breaker, they worked well until now and even interrupt DC over current sometimes :D (mostly the spark interrupts after lowering throttle. You hear kick, then khhhh, then after throttle down everything dies). But you can get DC breakers in same format.

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 19 2015 1:55pm

Solar stores will have DC circuit breakers. RV Parts stores as well. Those stores are everywhere now. I found a few at around $10 to about $15 then of course all the way up. I cant remember precisely what range I was looking at.

http://solarwholesaler.ca/product-categ ... -breakers/

or these fuses with hooks on them, $2 each. These are what I will use. I was thinking for my 65A controller, I will use a 100A for a battery fuse. Anything that shorts will instantly go way higher then 200A.
http://kellycontroller.com/fuses-c-34.html

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 19 2015 2:30pm

Sorry, forgot to specify, I use those AC breakers as switch not as fuse actually. They are dirt cheap and everywhere.

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 19 2015 4:15pm

Yeah, I think overall as a general rule, whatever the AC rating is, you can use a percentage. I forget if its up or down %, or if it actually needs a DC rating. I think DC is 1/2 AC. Heres a link to a product,
BUSS DUAL ELEMENT SLOW-BLOW 250VAC/125VDC FUSE FRN R 20
Keywording tho, might be "Dual Element"
Another
P&B 3 AMP PUSH TO RESET CIRCUIT BREAKER W58XB1A4A3 MAXIMUM VOLTAGE RATING : 50VDC / 250VAC
Most just say something like this,
BUSS 13/32"X1-1/2" FAST-BLOW MELAMINE TUBE 600V FUSE KTK 2 2A/2AMP
- no statement of AC or DC.

Of course I have no idea.

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 19 2015 5:12pm

markz wrote:Yeah, I think overall as a general rule, whatever the AC rating is, you can use a percentage. I forget if its up or down %, or if it actually needs a DC rating. I think DC is 1/2 AC. Heres a link to a product,
BUSS DUAL ELEMENT SLOW-BLOW 250VAC/125VDC FUSE FRN R 20
Keywording tho, might be "Dual Element"
Another
P&B 3 AMP PUSH TO RESET CIRCUIT BREAKER W58XB1A4A3 MAXIMUM VOLTAGE RATING : 50VDC / 250VAC
Most just say something like this,
BUSS 13/32"X1-1/2" FAST-BLOW MELAMINE TUBE 600V FUSE KTK 2 2A/2AMP
- no statement of AC or DC.

Of course I have no idea.
The ark extinguishing capability/mechanism is what makes fuse and breaker V rating, in some designs V rating can be equal for DC and AC, others should not be used for DC at all. I am afraid there is no rule of thumb. :roll:

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 19 2015 5:57pm

Of course I have no idea.
That was my thumb, btw. :oops:

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 21 2015 1:40pm

Ha, yes, using electronics equipment switches for e-bikes is not generally a great thing to do. It did work fine for my LifePo4 pack with Crystalyte controller and BMC hub motor, but that system peaked at about 2000 watts (40 amps). I was hoping a similar switch may work for this bike because I had one in the 'ole parts bin, but apparently not. This system peaks at about 90 amps, and I think that the caps on the Castle Creations ESC probably have a higher inrush current.

Amazon came through with the new switch and fuse holder. The pack wiring is completed and the batteries are loaded. I have run tests to ensure all the balance leads are wired correctly including attaching a cell logger to verify cell group voltages. I switched the power on and off a few times and the big battery switch appears to work fine.

Image

Before installing the battery case cover I will do the first balance charge and test the pack with the e-bike.

Warren

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 21 2015 5:05pm

You give me some great ideas for something similar. I have several that I am contemplating.

Looking good, looking good. So 4P is easy to figure out, is it 12S or 16S, my guess is 12S (3x4p)?
You will place a cover over top to hold down the cells in their place right, then the strip under the battery is to pop them out.

That is a good design, I like it. Its a little bulky, but its great work. Off the shelf parts, a little soldering and boom your done.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 21 2015 6:10pm

Thanks! I'm happy I was able to figure out something that didn't involve soldering directly to the cells, or having to build a spot welder. I feel good about this being a safe and powerful battery pack but only testing will show how it holds up.

Yes, it's 12S, 4P. It's bulky for an upright bike, but it's only 1.25 inches thick with the box which is the perfect size to fit behind the seat of a recumbent bike. For an upright bike you could do 6 battery holders in series, and attach them back to back with another 6 to make 12S. That way the pack would be 15 inches long by 3 inches high, by 2 inches wide. That should fit nicely under the top tube of most upright bikes.

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 21 2015 6:50pm

The only thing that comes to mind, is to use dielectric grease on the contacts.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 22 2015 6:50pm

Dielectric grease was considered, but after seeing how tight the batteries fit I don't think there will be any corrosion issues.

I ran the first balance charge and then tested the battery pack on the bike. Ok, I tested the battery pack on the bike in the garage. No tires actually touched pavement because currently the pavement is covered in ice.

After debating several methods of fastening the battery case together, including pop rivets, screws, zip ties and glue, I decided on... Duct tape. Not just any old duct tape though, I am using Gorilla tape. It's like duct tape on steroids.

The battery pack is done, now I just need a reasonable day to take a spin on it for a stress test to see if anything melts down.

Warren

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Re: 18650 pack build using plastic battery holders

Post by Doubled6789 » Nov 29 2015 3:37am

Thinking of using test tube racks. 4X10 spaces. 18mm holes, plus the bottom holes are smaller and could provide short circuit protection. https://www.indigo.com/lab_supplies/tes ... lq3UF9OLKD
Epoxying two together, will have to trim the second down to fit inside the braces. Using 8 total 130 holes for my trike, the other for a battery to run lights and cooling fans for electronics. Panasonic NCR18650B's. A plastic hardcase.
http://www.carrycasesplus.com/blow-mold ... /px-5.html. Seperate chargers inside the case.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 29 2015 5:47pm

Interesting. Those may be a tight fit. 18650 cells are 18.3 mm dia and the test tube holders are 18 mm.

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Re: 18650 pack build using plastic battery holders

Post by pguk » Nov 30 2015 7:32am

Hi Warren, thanks for documenting your efforts here. Looks to be a great solution for building a pack without a spot welder. I do wonder just how much current those cell holders can handle before you see heat and voltage drop? Looking forward to your feedback after running on the bike! (bother the cold!) How do you make your bends on the Lexan box?
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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 30 2015 12:13pm

Doubled6789 wrote:Thinking of using test tube racks. 4X10 spaces. 18mm holes, plus the bottom holes are smaller and could provide short circuit protection. https://www.indigo.com/lab_supplies/tes ... lq3UF9OLKD
Epoxying two together, will have to trim the second down to fit inside the braces. Using 8 total 130 holes for my trike, the other for a battery to run lights and cooling fans for electronics. Panasonic NCR18650B's. A plastic hardcase.
http://www.carrycasesplus.com/blow-mold ... /px-5.html. Seperate chargers inside the case.
It appears to be same rack as this one http://www.amazon.com/KeL-Scientific-KS ... rack&psc=1
Read reviews, it appears to be made of very brittle plastic.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 30 2015 1:23pm

Yeah the polystyrene plastic in those test tube holders is not very resilient and will crack if abused.

Bending polycarbonate (Lexan)
If you have a sheet metal break you can bend polycarbonate plastic just like sheet metal, but I don't have one. I use a heat gun to heat it up enough to easily bend. You have to be careful when heating though because if you get it too hot it will get bubbles.

Here's my Lexan bending rig. My heat gun can't heat the entire bend at once, so I use the vise bench and other clamps to hold it bent while I run the heat gun up and down the bend line. As the part bends, the clamps are tightened.

Image

Eventually the part is clamped flat to the table, with the bend at 90 degrees.
Image

I should have tested the battery pack yesterday, as the snow had melted and the roads were dry. Rain for the next few days. I will get it tested soon and do a couple high current runs to see if anything melts. The spring tab distance between the battery and the solder attachment to the copper bus wire is very short, so I feel pretty good about its current handling capability.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Dec 05 2015 5:32pm

Took the bike out for a cold blast up and down the block today with the new battery pack. The CA said the system peaked out at about 3500 watts (75 amps). No drama.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Dec 05 2015 9:59pm

Here's the battery pack mounted on the bike. The bike bag will go on top of the battery pack so it won't be too noticeable.

Image

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Dec 06 2015 9:44am

www.recumbents.com wrote:Here's the battery pack mounted on the bike. The bike bag will go on top of the battery pack so it won't be too noticeable.
Nice job! I like the part of seeing every one of those little buggers at any moment. :D In hope to use my packs for purpose I originally made them sometime soon.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Dec 06 2015 6:11pm

Parabellum, what are you using your pack for now?

The first long shakedown cruise up and down the bumpy bike trail went well but I need to find a way to attach the battery pack more firmly. No chance of it falling off but its not solidly mounted yet.

This pack doesn't seem to deliver as much current as my LiPo pack. My Lipo pack would deliver 4000 watts all the down to my LVC at 39V. This pack seems to start off at about 3500 watts, and by the time I am down to 40V it's only delivering about 1500 watts at WOT. Oh. Maybe temperature related? It was 40 degrees F when I was riding today.

Image

Closeup of the drivetrain and battery pack
Image

-Warren

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