New battery, Building a Pack from Turnigy Hardcase packs

[Tommy L]

Very Nice!

Tommy L sends.... \\m//

[fechter]

Mouser has those fuses in stock.
Mouser part# 576-157.5701.6121 $9.05 ea

[mr.electric]

What about this fuse?
125a
dc 450v
bc 2000A
From Toyota gen II prius. I have a few lying around.
I would remove it from the orange housing.

[fechter]

Nice fuse! Bet they're expensive though. I should check my old Honda pack.

[mr.electric]

I am building a pack from 4s hard case packs too. I will add pics soon. I love the way they are durable. You can stack them and use double tape to make a giant brick. They will not be ruined by bouncing around in a bike bag.

[Ricky_nz]

I am building a pack from 4s hard case packs too. I will add pics soon. I love the way they are durable. You can stack them and use double tape to make a giant brick. They will not be ruined by bouncing around in a bike bag.

Yep, definitely convenient. I will be interested to see how you pack comes out.
The way I packed them together is a bit wasteful of space and I suspect mounting the fuse on the end of a block of 4 packs would be better space wise but that wasn't going to happen with the 100mm heatshrink I had and also where I want to put the packs.

[Ricky_nz]

Here is a photo of the top perspex sheet being glued down.

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I'm considering cutting a window in the heat shrink of the best looking pack so the tops of the hardcase packs and wiring are visible but protected by the perspex.

I've heat shrunk all three packs. I'm not too happy about the middle packs heat shrink around the balance connector but I didn't have any spear heat shrink to redo it. Its sealed so water shouldn't get in. I won't seal the discharge lead end fully to allow the pack to breath and any moisture to evaporate out.

All packs heat shrunk

100_3671_all_packs_small.jpg (28.92 KiB) Viewed 473 times

I still need to trim and glue down the heat shrink flap at the discharge lead end on each pack.
This is pretty much how the packs will sit in the frame of a bike.
Lighter colour heat shrink would have probably been a better choice for in the sun but I never had any issues with black on my old soft packs. My bike is normally parked in the shade.
If I regularly parked in it the sun I would probably paint the pack white.

Overall I'm happy with the way the packs turned out.
There is better ways to combine these hard case packs for the smallest volume but since I am not short of space and my design goal was flexibility for experimenting with different bikes and voltages which required each sub-pack to be stand alone and individually protected.

[Ricky_nz]

I did some testing today and it all looks good. The 8s2p bricks are giving just over 10Ah when I adjust for the incorrect current measurement in my Accucell 8150. Its about 7% out so reads pack capacity low.
The 4s2p pack is about 9.6Ah which I expected because it got the weak cells on purpose.
The cells stay in good balance all the way down.

Another feature of my design was the minimising of un-fused wire lengths. These are kept as short as possible including the balance leads to help prevent any accidental damage causing a short or fire.

Some of the packs I see on the sphere really make me cringe when I see harnesses using the stock connectors of the batteries and relatively long parallel series harnesses and if you add up the amount of un-fused wires in those setups it would be well over a meter, possibly several. . The fuse is often positioned too far away from the cells increasing the risk of spectacular failure, then its all stuffed into a space too small to get abraded etc.
A fuse down the line only limits the current in the everything downstream of it. If there is a short before the fuse I hope you like your batteries cremated .
In each of my packs there is <100mm of unfused High current cable in the +ve side . Sure If I wanted to go overboard I could have fused the + and - but for the common failures the + is sufficient.

[Emoto]

I have one pack that is not part of my pack build that I dropped from kitchen bench height and there is no major damage , just loosened the join between the plastic and electrically its fine . Might not survive every time but thats good enough for me.

Hi ricky im concidering some of these pacs, any chance posting some pic's case opened and end connections.

[Ricky_nz]

Hi ricky im concidering some of these pacs, any chance posting some pic's case opened and end connections.

Unfortunately I don't have any photos of the insides of these hard case packs but they are pretty similar to the other packs in that they have a circuit board on the end linking the cells. Maybe someone else has photos of inside the hard case. From memory the thin edge of the cells is up towards the label side of the hardcase.
When I built my pack I just used the existing wires coming out of the pack. I can provide more details of my wiring if anyone needs that.

[Ricky_nz]

Just thought I would give an update now the pack has been on my bike for >7 months, time really does fly .

Only bulk charged since initial cycling/balancing.
The worst pair of cells had dropped about about 4mV out of balance from the rest so insignificant considering 7 months but it was observed on the pack that got the pack with the highest self discharge which is still very low.
The matching of pairs of packs to get average self discharge levels must have helped.

I have just given everything a balance charge for the new year to ensure everything is in line so that the leaky group doesn't get more out of step. The charger didn't spend much time at all to balance the packs.

There is no sign of puffing on any packs ( I have not opened the cases but nothing obviously under tension). There is no significant loss of capacity noticeable on the bike but I haven't measured the capacity recently.

I'm actually being quite nice to the packs at 18A discharge on a 10Ah pack. I charge to 4.1V

NOTE: I regularly check the balance of the cells before bulk charging.

I will be adding some more packs and reconfiguring as a 12S 20Ah pack soon as the place I work for is moving our office to further away from my place. and I want to have some reserve capacity.

[amberwolf]

do ou ever check balance during charge?

[Ricky_nz]

do ou ever check balance during charge?

When I can be bothered. I drag out my accucell and look at the cell voltages during a charge (not balancing mode because I wanted to see how well they hold balance on their own). I don't use my cellmons continuously because they cause imbalance apart from momentary measurements.

I haven't got any charge curves due to a little accident a couple of years ago that vaporised the USB cable on my accucel 8150. I had a meanwell running the accucel and its output is normally floating but a bit of wire bridged to ground (the +12V output) . This was entertaining when that found the -ve of the meanwell through the PC ground/USB and accucell LOL. A USB cable smoking end to end is rather supprising . The PC survived but the accucells USB port never worked again. probably a burnt track.

During the times I have checked during charge all cells come up at the same rate and I have also checked them regularly at different discharge depths. eg sometimes I check and charge after 5Km ( round trip to/from work) and other times after 10Km (2 trips) which also gives me two data points. I also check at full charge when bulk charging sometimes. I have no doubt that if things start going wrong with the pack one of those data points will be obvious.

[mr.electric]

ImageUploadedByTapatalk1357536193.563387.jpg (102.46 KiB) Viewed 197 times

This is my brick so far. I want to make a black plastic tray to cover the nest on top. I double taped the hard packs together. They are surprisingly well bonded together now. I made it a shape to fit down into the main triangle as low as possible. It lives inside a falcon ev bag.

[Ricky_nz]

IHi
I was just building up an extra pack so I could reconfigure things and I revisited an older spreadsheet I made then I made my first packs.
It is some notes about possible failures and how they can be mitigated.
Its not a full risk analysis. I assume that any failure can result in total pack meltdown.

I actually realised when going through it that on my smaller pack there is one more risk because the balance taps and power output wires from the hard case packs are at one end as opposed to the 4 brick ones where i had them in the middle they are more exposed to external penetration damage.

Its a really good idea to write the possible risks down so you can be sure you don't miss anything

I will add an extra piece of polycarb across the end of the pack to prevent damage to these short un-fused wires. I might even remove the heatshrink from my original 2 brick pack and do the same. Currently its only protected by two layers of heatshrink but I would feel more happy with a couple of mm of polycarb.

battery Risk Ananlysis.xls

Battery risk analysis

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I did it on open office but saved as xls to make it easier for windows users.

Maybe we should take the risks list and expand it to be generic so that other people building packs can use it as a sort of a check list?