2nd Lipo fail - help me buy (not build) a better pack?

[lostrack]

Hi all,

I have a 12S3P Turnigy LiPo setup. After leaving it for a month, both times I've come back and 3 cells (in 3 separate packs) have been pulled down to zero. That's £300 of batteries that are now dead.

This is having left them completely unplugged, the only thing connecting them is a methods balancing connector board.

I think there may be a short in the board, which gradually drags them down, as they were 100% balanced and fine before leaving them.

Anyway, I'm interested in buying a pre-made pack.

Two output cables, and two Hyperion balance cables. That's it.

Does anyone offer this service?

thanks

Tom

 

[dogman dan]

Sounds like that is simple enough to do yourself.

Simple enough to unplug the balance board too, for a longer idle time. Pretty much the same thing you have to do with any bms, or top it up if you are home.

 

[lostrack]

Sounds like that is simple enough to do yourself.

Simple enough to unplug the balance board too, for a longer idle time. Pretty much the same thing you have to do with any bms, or top it up if you are home.

I've spent so many months on this now, I just don't have the time to put into it again.

I've completely rebuilt the pack several times before and I've got the "I need to do it all myself" thing out of my system.

I'm specifically looking for someone else who is more skilled/eager/available to do it for me.

(unplugging the balance board is a massive hassle, everything is bolted in and taped down so I never have to go in the battery compartment)

 

[wesnewell]

You don't have 90 seconds or less to build a 12s3p lipo pack? Dump the BMS. You don't need or want it. You balance the pack every time you charge with the Hyperion (1420i I assume).
Take 6 6s lipo packs and stack them 2 wide 3 deep and tape them together. Split the power cables and plug plug the two inside wires of each 2 packs together to make 3 12s packs one on top of the other. That will leave 3 black wires on one side and 3 red wires on the other. Either make a 3 to 1 harness for each side or buy a 6 to 1 charge cable and use it as a harness which would allow you to got to 12s6p in the future. If you want to parallel at cell level, buy 2 6-1 parallel balance cables and connect the 3 on one side together with one and yep, the 3 on the other side together with the other. Now if you leave the banana plugs on the charge cable, you can just plug that straight into your charger. If you want to balance charge, plug the balance cables into the balance ports also. I could have put this pack together in less time than it took to write this once I had all the parts. Personally, I'd replace the banana plugs with something like 4mm bullets and housing (or XT60's or whatever) so it couldn't short together or it couldn't be reversed when plugging it into your power cable that goes to the controller.

 

[dogman dan]

Best suggestion I can come up with, is go to emissions free, and ask cellman if he can build an A123 pack that would suit your needs as well as the lipo. Maybe he can make you someting you'd like.

But regardless of whether you rebuild your lipo, or go something else, you will have to pay attention, and keep it charged up. Include a way to check the voltage of your cell groups easily into the new pack.

My whole approach to RC lipo is completely different. Battery boxes are very accessible, swapping out a failing pack is easy, and I NEVER ignore lipo unless it's been put into the storage bunkers where it can sit for months unattended. So my whole setup is built around the idea that they never sit on the bike connected to anything. I have a lot more bikes than batteries, so I have to be able to easily move the batteries around.

Works for me, but I've still ruined some packs. A few as a result of the way I plug and unplug it constantly, but mostly packs got killed by mistakes that resulted in overdischarge. I had too many bikes, and not enough CA's and screwed up a few times.

 

[kfong]

This is about as simple as you can get with balance port.
http://endless-sphere.com/forums/viewtopic.php?f=31&t=39291

 

[knoxie]

this is exactly why i never leave mine with anything connected as there is always the possibility of this happening electronics can fail, in the past all my woes and issues were with BMS and monitoring, now I only monitor on long rides where I might hit LVC but day to day I dont, I run a volt meter on the bars, and a watt meter in line, the way I see it is if any cell is going to go south its going to go anyway. I always balance charge on RC charger all 4 packs on 4 separate channels so I can spot any weak cells.

Give Steve a ring, jozzer here in the UK he is in Brighton, he will make you a pack up and he stocks the cells and replacements, www.jozztek.com

 

[Sunder]

My strike rate with Turnigy hasn't been that good either. 2 out of my first 4 had cells that dropped at a rate of about 0.1v per week when left not attached to anything. I bought two more, neither which had the problem, so it could have been a bad batch.

However, it's the only cheap batteries I've bought that have even come close to their advertised capacity. I've bought 10Ah NiMh batteries that ended up being 1.7Ah. I've bought 5.7Ah LiPo batteries that were actually 3.2Ah, and puffed after 3 charges. My Turnigies were rated at 5Ah, and all 6 - even the faulty ones, rated between 5.2 and 5.3Ah.

I've now rigged them up so it can either be bulk charged as 12S2P, or balanced as 2 x 6S2P. It's dead simple either way.

I think your problem is not necessarily poor quality cells, but leaving them with a draining device on them. Some batteries might be safer to leave like that, but I don't know that any would last very long if treated like that. I'd still be going back to turnigy and getting the right harnesses and chargers set up once and for all. Seems easier than just throwing money at the problem.

 

[lostrack]

Thanks for the replies everyone.

Minimal interaction with the batteries is my preferred method of use.
Simply because it's a two man job to get the battery box on and off.

They were methods LVC boards which are famed for their low current consumption, so unless there is something wrong with them, you should be able to leave them plugged in for something like 15 years without needing to charge.

Of course, when 1 cell goes, it will bring the 3 cells down with it as they are paralleled 3P.

I did a cautionary check of the batteries two weeks after leaving them, and they looked fine. A month after that, they died, so I wonder if it could have been an environmental issue like temperature drops, exacerbating the imbalance?

Cells are all from Jozztek who leaves them for 1 month float charged, to weed out bad cells.

New build should try to minimise excess cables.

 

[wesnewell]

I can not understand why anyone would want a bms on rc lipo. Just something else to screw up. Added size and just a pita. My 24s2p pack weighs 14lbs including the makeshift holder that I can install/remove from the triangle in seconds. If it takes 2 people to install/remove your 12s3p pack, you've got a serious design problem.

 

[lostrack]

I can not understand why anyone would want a bms on rc lipo. Just something else to screw up. Added size and just a pita. My 24s2p pack weighs 14lbs including the makeshift holder that I can install/remove from the triangle in seconds. If it takes 2 people to install/remove your 12s3p pack, you've got a serious design problem.

Why would you want to remove your batteries all the time?

It's like designing a removable fuel tank. Just put the fuel in, use it, fill it up, use it... that's it.

You then benefit from having a more sturdy protection because it's designed to stay put.... or something!

(obviously fuel is more reliable than batteries, so not taking that into account was the design flaw!)

 

[Punx0r]

Security, but mostly to allow the batteries to be charged somewhere safe where you can supervise them

 

[mr.electric]

Lostrack,
I agree that HK lipo can be a total pain in the ass. It can be very time consuming to build and understand a lipo set up. I consider it the price you pay for having state of the art batteries. I have killed a few packs lately and it is getting tiring keeping up on the newest hardware in hopes that an easier solution will be available. I think a cell man a123 pack or ping pack has most of what I want but not everything. Ideally I would want a
- plug and play full bms pack
- a warranty that was honored by a local company so I don't have to try to get warranty from China
- the power to weight ratio of hobby king cells not heavier LiFePo4
- option for pack to be a triangle size
- a pack that has been certified to be shipped so I do not have to call it stereo equipment if I need to ship it back to get warranty
- a reasonable c rating, 10 c would be fine for my needs
With all these factors I think a 10 ah 48v pack would be worth about $600
of course I am a cheap DIY type of guy so I use $200 worth of Lipo and just complain about what a pain in the ass it is to use.

 

[wesnewell]

Why would you want to remove your batteries all the time?

To charge them. To not leave them in 110F heat. To not leave them in 0F cold. So they don't get stolen with the bike. There's more, but that's enough for me.

It's like designing a removable fuel tank. Just put the fuel in, use it, fill it up, use it... that's it.

And if there was a filling station on every corner where you could fill it up in 5 minutes, that would be great. There isn't.

You then benefit from having a more sturdy protection because it's designed to stay put.... or something!

With the insertion of a single lock block that takes a few seconds mine is secure. Enough so you can turn the bike upside down and still be secure.

 

[cal3thousand]

Why would you want to remove your batteries all the time?

To charge them. To not leave them in 110F heat. To not leave them in 0F cold. So they don't get stolen with the bike. There's more, but that's enough for me.

It's like designing a removable fuel tank. Just put the fuel in, use it, fill it up, use it... that's it.

And if there was a filling station on every corner where you could fill it up in 5 minutes, that would be great. There isn't.

You then benefit from having a more sturdy protection because it's designed to stay put.... or something!

With the insertion of a single lock block that takes a few seconds mine is secure. Enough so you can turn the bike upside down and still be secure.

Nailed it.