I'm done with LIPO technology! Dumping it now!

[edcastrovalley]

I know the feeling. I just went through the same thing this Saturday with my Icharger 1010B+. My 12 volt battery clamp looked loose so I tried to connect it more securely when I let a whole bunch of smoke out of my charger. In looking inside I found only one of the output transistors burned up. I'm glad all of them didn't go off or I wouldn't have never found my way out of the garage. I was loud too. It sounded like a combination of a loud air compressor leak and a pan of bacon frying. It smelled real bad too.

I was thinking of trying to repair it myself but then I spotted my mig welder sitting on the shelf all lonely by itself. It's a Lincoln 110 volt machine and I turned it on at it's second to lowest setting and it put out about 22 volts. Then I connected my six 5s 5000mah lipos all in parallel to it, turned on the juice, and I was charging big time at 15 amps! They were all charged in about an hour! What was interesting is apparentally, the welder is not a regulated power supply. When first charging the welder provided 15 amps but, as it got closer to 21 volts (top allowable battery voltage), it pushed out only 8.9 amps. The whole time I sat there and monitored everything with a volt and amp meter to make sure I didn't go over 21 volts. I also acted like a human bms and went around with a second volt meter, checking each cell voltage. Luckly I had recently balanced them and they were all within a couple hundredths of a volt.

 

[liveforphysics]

I know the feeling. I just went through the same thing this Saturday with my Icharger 1010B+. My 12 volt battery clamp looked loose so I tried to connect it more securely when I let a whole bunch of smoke out of my charger. In looking inside I found only one of the output transistors burned up. I'm glad all of them didn't go off or I wouldn't have never found my way out of the garage. I was loud too. It sounded like a combination of a loud air compressor leak and a pan of bacon frying. It smelled real bad too.

I was thinking of trying to repair it myself but then I spotted my mig welder sitting on the shelf all lonely by itself. It's a Lincoln 110 volt machine and I turned it on at it's second to lowest setting and it put out about 22 volts. Then I connected my six 5s 5000mah lipos all in parallel to it, turned on the juice, and I was charging big time at 15 amps! They were all charged in about an hour! What was interesting is apparentally, the welder is not a regulated power supply. When first charging the welder provided 15 amps but, as it got closer to 21 volts (top allowable battery voltage), it pushed out only 8.9 amps. The whole time I sat there and monitored everything with a volt and amp meter to make sure I didn't go over 21 volts. I also acted like a human bms and went around with a second volt meter, checking each cell voltage. Luckly I had recently balanced them and they were all within a couple hundredths of a volt.

This is epic. I respect the sack on you sir.

 

[John in CR]

Yeah, the Mig welder charger is classic. Now all you have to do to finish the table turn is to do some welding using your battery pack. That's something I want to learn and will be my pinnacle of backyard DIY ability.

EVBiker,
For the record I do own about 1kwh of nicad 4.5ah cells. That is my shit-hits-the-fan-end-of-the-world battery stash that sits on the shelf unused and shorted, where they will be fine for decades. Hopefully they're never needed, but should something happen once my lithium batteries all expire, then I'll still have decades of still being able to ebike, and that's what's important. After I discovered the ebike a few years ago, I realized that I will always need to have an ebike.

 

[knoxie]

nothing wrong with NIMH if you can still get decent cells, you need to look at F cells dont even bother with anything else, 13AH cells, my local RS store still sells them in that capacity, you can get them tabbed as well which makes things easier.

Cycle life on NIMH can be amazing! in fact I have 2 x packs of 24V 13AH cells that are 6 years old and still work, they must have 1000 cycles on them, they sag a little under hard acceleration but they are still working at about 80% capacity, all cells still fine no balance problems (something NIMH doesnt suffer with)

That said I run Lipo as you just can not beat its weight and power density, I am a tinkerer and so dont mind those extra steps you need to take with Lipo, we have all had failures with all chemistries though.

For me its so easy to hook together 4 x little lipos packs and my simple voltage monitor and go ride, I always charge to 4.1V and normally dont ever take the pack under 70% DOD, I run 2S2P so any one pack only ever sees 17A pull which isnt even breaking in to a sweat for 25C Turnigys. I must have 300 cycles on them now and they still delivery full whack and are no different from new.

Good luck which ever way you go as much as I want to help Amberwolf out I still think you should reconsider or at least try one last time? as you cant blame the charger incident on the battery chemistry, good luck anyway

 

[amberwolf]

Anyone here want to comment about Nicads? Maybe Nicad's are what you call "ole reliable" instead of NiMH.

NiCd and NiMH are so close to being the same in their advantages and disadvantages that you can lump them together for most discussions.

Both types can be very reliable, if you start with good quality high-C-rate cells, just like any other chemistry. But...unlike most other chemistries, you can't parallel them easily, because during charge they'll potentially blow each other up due to the voltage drop at the end of charge (where an already hot battery will drop in voltage as normal, then get fed a huge inrush of current from the other cells paralleled with it that havne't dropped yet...KABLAM!).

The one serious disadvantage of NiMH vs NiCd is that during discharge, it's a lot easier to damage a NiMH by fully discharging it, possibly causing cell reversal (death for the cell), where NiCd don't really have a problem going to zero.

Cell reversal can happen with many chemistries (possibly all of them under the right conditions), but unless you're regularly running the pack down to nothing, instead of trying to always leave at least 20% in the pack, I wouldn't worry too much about it.

With most chemistries (other than lead), if you never charge them past 80-90% and never discharge them past 20-30%, they'll last a lot longer (potentially many to many dozens of times longer) than if they're being fully charged and discharged. This is typically what EVs and hybrids like the Prius do to lengthen lifespan of their packs.

But NiCd is one chemistry that can handle full total discharge ok (though I don't know how it affects the lifespan of the cells if done regularly at high rates like an ebike/ev uses).

 

[EVBiker2000]

....I run 2S2P so any one pack only ever sees 17A pull which isnt even breaking in to a sweat for 25C Turnigys....

You know, I'm thinking now that's where I might have went wrong. These are 5ampHr 20C Turnigys, and I forgot how that before I ordered these things that I was going to parallel the packs so that the current is shared by the separate strings. But I got excited and since all I had was wires hooked up for a 3 pack in series, I threw it on the bike without thinking about that.

I have a 72V 50Amp Crystalyte controller, but does that thing really limit the current if it goes above 50 amps for a few seconds? Or is the only safe guard the CA? Right now my CA is set for something like 99 Amps.

btw, just for fun, here's some pictures of my battery box. I like looking at how each person designs their E bikes, so figure you guys would like to see what I did for the battery compartment.

 

[LegendLength]

[...] all I had was wires hooked up for a 3 pack in series, I threw it on the bike without thinking about that.

I've heard hobbyking lipos are overrated for the discharge rate and so I like to think of a 20C pack as a 10C pack to be safe. Not sure how true that is I just remember reading it here somewhere.

But you'd think they'd handle a 20C burst easily which is 100A . So I see no problem with using a 18s1p pack like you did. It might be bad to run it like that all the time but for a day or two surely the batteries can handle it. Were the batteries warm after the ride?

As for giving up on lipo, remember you are also giving up light weight, low price and a high discharge rate.

 

[neptronix]

I've heard hobbyking lipos are overrated for the discharge rate and so I like to think of a 20C pack as a 10C pack to be safe. Not sure how true that is I just remember reading it here somewhere.

I believe they are overrated some. My 20C packs get quite warm after 8C continuous. ( 30-43 amp draw on a 5ah pack ). Takes a while for the voltage to recover also after hitting the throttle hard for a long time.

When i ran them at 3C constant with my old 250w kit though, they would not rise above whatever the outside temperature was though.

 

[AussieJester]

The thing is....I don't want to be constantly tearing apart...soldering/desoldering....searching for the cheapest onesie twosie batteries on EBAY the rest of my life.

Buy a Charging Harness Kit + 2x6s LiPo LVC Kit Combofrom Tppacks.com (or make one similar yourself) and then you wont have to 'tear apart' your pack each time you charge, there is no need to do this whatsoever. Paralel and series connect your packs to the volatage you wish to run and charge them also in this configuration. Parallel balance taps and you can bulk charge and balance similtainiously if you wish. For more info on this setup and charging maybe this thread might be worth you reading.

KiM

p.s your 300 cyles for lipo is way off the mark too you will get into the 1000's if you only use 80% of the pack and re-charge to 4.15v a cell rather than 4.20v

 

[edcastrovalley]

[/quote]
This is epic. I respect the sack on you sir.[/quote]

Why Thank You! I am very careful with the welder. I sit there with two meters monitoring everything and I don't leave until the charing is done. While waiting I listen to some music. Last night they were playing "Burning Down the House" by the Talking Heads. Great song... :wink:

 

[EVBiker2000]

Well, it's all over now. The LIPOs and me have decided to separate. A member of the forum has already bought them from me and they are on their way now. Just how those things go sometimes.

It's very interesting to read each person's opinion about LIPOs. Some guys on the forum say that LIPOs are overrated....or too difficult for people starting out with E bikes. Others say it is the easiest thing to use.

Well, will being switching soon. I'll create a thread. I'm sure it will cause a lot of controversy.

 

[northernmike]

Go for it.

How many AA cells are you considering??

How could you encourage someone to do something as horrible as that? Those rechargeable Energizer NiMH are total pieces of dog crap.

Just being Socratic. :wink:

 

[auraslip]

I believe they are overrated some. My 20C packs get quite warm after 8C continuous. ( 30-43 amp draw on a 5ah pack ). Takes a while for the voltage to recover also after hitting the throttle hard for a long time.

Does anyone else think that a battery run at it's C rating shouldn't heat up at all or have any voltage sag? I really wish instead of "peak" and "continuous" ratings they'd use "C-rate at which nothing bad happens - the cells don't get warm and the voltage doesn't sag" and "C-rate just below the point where cycle life is negatively effected."

Headways are 10c...what a joke... 20c lipo... more like 5c..... hk 20c lifepo4... more like 3c.
I could go on for days...

Anyways... sorry for your loses. Don't give up though... people here will help you build a pain free charge setup.
I wouldn't recommend nickle at all, it's a great chemistry, but each series string requires a separate charger. Which means it's not by any means cheap!

John in CR,
Is there a thread with pictures of your charging setup? I'm interested in joining team konion!

 

[jlustig83]

Why would charging to 4.2v per cell reduce the life of the pack? I never discharge my pack below3.5v but when it comes to charging I can't set my charger to 4.1. The charger I have is a hyperion duo2 12s charger. If I could adjust it to 4.1v I would but I don't think I can so 4.2v is what ill have to live with. Also, I balance charge most the time. Would it be ok to just turn the charger off when the cells reach 4.15 or so?