Ni-Cad Battery Packs latest...?

[trappermike]

Does anyone here know of a good source for some high quality Ni-Cad battery packs? (36v-8ah-10ah)
Suppliers seem to be harder to find,but I'm still determined to use them,my last supplier doesn't make them anymore.
I see now that there are some "F" size cells being made,would these be useful?
Another company I found makes "Sintered" Ni-Cad cells,the specs seem incredible,but I fear they are only for large industrial applications,anyone know anything about those?
Also one company a also makes NiCoMn packs,I'm wondering what these are,and if they are of any use for e-bike packs?
Any tech help or good suppliers is appreciated!!

 

[webfootguy]

It is possible to buy high quality Ni-Cad cells, especially the Sanyo cells. The 3000mAh C size cells are a good choice for around $5 each. Another possibility which I investigated is to have someone build a custom pack with NiCad cells. I had good luck getting Batteries Plus to quote me a custom pack built to my specification with a choice of cells. Using their in house Chinese cell (3000mAh but higher IR) was around $3.75 / cell, using the 3000mAh Sanyo cell was $6 / cell for a 20 cell pack (includes tab welding and they supply the cells). If you go this route, you can have them build it to any physical configuration.

In my opinion, if you are building a Ebike this worth investigation (only because cheap nicad is cheaper than the cheapest lifepo4 or lipo especially when you consider the charge/balance/low voltage cutoff issues). If you are trying to save the most money, buy the cheapest cells you can find and then pay them to battery tab weld it for you (avoid solder as it is possible but difficult to do right and can have failures under physical stress of a bike). A NiCad pack is very safe and trivial to charge.

I have been seeing a few eBay auctions go by with large number of surplus Ni-Cad cells. Worth watching for.

 

[Jeremy Harris]

The other point worth noting is that, if looked after, NiCd and NiMH can have an extremely long life - if you're prepared to restrict the depth of discharge to around 30% and ensure that you never over-charge the cells then the cycle life will be up in the tens of thousands.

I do have a slight word of warning, though. My first ebike pack was made up from 6off 12V RC NiMH packs. I was doing what I thought was a low C rate (0.05C) safe, low level charge (overnight) to gently balance the pack. Stupidly, I was charging it in my study, which is just down the hall from our bedroom. I was woken at around 4am by a dull thud, followed, a few seconds later by a louder bang. I leapt out of bed, rushed to the study to find a smoking battery pack. I managed to pick it up by the leads, run out of the house and dump it on the path outside the back door, where it exploded with a tremendous firework display. This is what was left when the smoke and flames died down:

NiMH and NiCd can be perfectly safe when looked after, but, as my experience shows, they can be as delicate (or maybe more delicate) than LiPo if not charged very carefully.

Jeremy

 

[texaspyro]

if you are building a Ebike this worth investigation (only because cheap nicad is cheaper than the cheapest lifepo4 or lipo especially when you consider the charge/balance/low voltage cutoff issues).

No, not really. You can get cell_man to build you a pack from A123 cells for like $6 a cell. Each of these cells replaces like 3 cheap NiCad C cells and has MIUCH better performance and cycle life. No matter what type of cells you use, a good charger and some form of cell management is your best friend.

 

[dogman dan]

Still a lot of nicad drill batteries out there. You could buy a pile of those, or better still, make friends with the guy who collects them for recycling. Each bad pack is going to have some still good cells inside.

 

[marty]

High performance NiMH Battery Packs
http://www.rabbittool.com/

 

[texaspyro]

Still a lot of nicad drill batteries out there. You could buy a pile of those, or better still, make friends with the guy who collects them for recycling. Each bad pack is going to have some still good cells inside.

Same for LiFePO... NiCd is just soooo last millennium. And SLA is epic lame.

 

[D-Man]

And SLA is epic lame.

 

[trappermike]

Thanks for the info so far folks! :wink:
I must explain here that I'm not interested in any form of lithium packs,been there-done that. As a mechanic of 35 years I believe that simplicity is one of a products greatest virtues. The Ni-cad pack satifies my requirements of supplying large current demand reliably at an economical price. I really look for the best Ni-Cad pack that I can have assembled. I'm glad to hear that Sanyo cells are a good choice to ask for...
What about the "F" size cells? Would they be beneficial to build a good pack? Here I would appreciate anyone's input regarding "F" cells.
Also what amp-hour packs can be made,I mostly see 8ah packs,I'm looking for 36v packs,8ah to 12 ah,anyone know of any suppliers that make packs of more than 8ah?
See,basically I'm going to connect 2 36v packs in series to create a 72v power source to run my 72v-48amp motor controller...
I'm trying to learn about Ni-Cad here because I have no experience with them.Yes I know they are older technology,not a problem for me.
Currently I'm using a 48v-12ah SLA pack and they have reliably powered my 40 amp powered bike for almost 3 years,but they are just too damn heavy...
I've used the Lithium packs,but I prefer something more simple and reliable,money is not really an issue,so I'm not looking to assemble a pack with used parts etc.,just the best quality and most suitable components.
I have a good friend at a HK manufacturer who made Ni-Cad packss,but they don't make them anymore. He told me that they had tested their Ni-Cad packs at 50 amp draw-ok,even 80 amps for a brief test!

 

[trappermike]

So Jeremy,if I understand you correctly,are you suggesting not to use a charger on Ni-Cads that has too much amp output?
I know that a top quality charger is on my shopping list,I was thinking of one with about 3amp or 4amp output. Would a charger of 2amp output extend batty life?

On a slightly different note I have found a manufacturer that make chargers from 24v-72v,and a nice feature is the normal/fast charge selector switch. They say they can configure it to be 3a/5a etc,anything you want. Also! they have some great DC-DC convertors,24v-72v,10 amp output,I'm gonna get 2 of these,they look good and I think they aren't expensive,I'm waiting for the price now...

 

[Jeremy Harris]

Because of the legal/IP restrictions on NiCd/NiMH cell production, most development has gone on in the smaller cell sizes. Sub-C are probably the very best in terms of capacity for a given weight/size. They also have the highest discharge rates. The F size cells seem to be a dead end, with no real development having taken place with them, or larger cells, for years. I'm pretty sure they are right at the legal/IP restriction in terms of cell capacity, so unless the bastards in the oil/motor industry ever decide to release their stranglehold and allow bigger cells to be manufactured, you're probably best off using sub-C cells in big arrays.

The challenge is to find a way to charge a large array of NiCd/NiMH cells. You can't just parallel cells together, so you need to build sub-packs and then interconnect them with Schottky diodes or some other effective isolation method. This makes battery management a pain, as you need to then find a way to reliable detect the delta V at full charge (or maybe the cell temperature rise at full charge). There isn't an off-the-shelf solution to this, as far as I know.

Jeremy

 

[webfootguy]

There are a couple of ways to deal with the Ni-Cad charge issue. First, I would educate yourself about the charge behaviors of Ni-Cad cells. Here are some links:

http://batteryuniversity.com/learn/article/charging_nickel_based_batteries
http://www.powerstream.com/NiCd.htm
http://www.mpoweruk.com/chargers.htm

I completely agree that if you are doing parallel cells, any mismatch in capacity can lead to catastrophic failure. This is because the voltage drops at the cell gets greater than 100% full. This means you need to charge strings of cells separately (this is unlike lithium which can pretty much be charged in parallel safely). If your application can get by without paralleling cell, you should have no problems getting a working solution.

After you understand how the cells work, figure out your charging strategy based on charge time, etc. It might be sufficient to adapt an existing commercial charger or tool pack charger to meet your needs.

 

[texaspyro]

And SLA is epic lame.

The pain! Oh, the pain! Make it go away. PLEASE make it go away!!!

 

[texaspyro]

Wow! just noticed that I've grown a set of double-D's

 

[trappermike]

I've recieved a quote of $148 US for samples of 36v-8ah Ni-Cad packs,but haven't been able to get any technical details yet from the sales-person,so I'm unsure of the quality...
What details should I ask for when,"C" rating,cell size(C,D,etc.),or whatever?

 

[webfootguy]

Here is a 48v 8Ah NiCd pack with charger for $299. Slightly used.

http://www.cycle9.com/c9store/clearance-c-19/48v-8ah-nicd-battery-with-charger-p-63

 

[John in CR]

It is possible to buy high quality Ni-Cad cells, especially the Sanyo cells. The 3000mAh C size cells are a good choice for around $5 each. Another possibility which I investigated is to have someone build a custom pack with NiCad cells. I had good luck getting Batteries Plus to quote me a custom pack built to my specification with a choice of cells. Using their in house Chinese cell (3000mAh but higher IR) was around $3.75 / cell, using the 3000mAh Sanyo cell was $6 / cell for a 20 cell pack (includes tab welding and they supply the cells). If you go this route, you can have them build it to any physical configuration.

In my opinion, if you are building a Ebike this worth investigation (only because cheap nicad is cheaper than the cheapest lifepo4 or lipo especially when you consider the charge/balance/low voltage cutoff issues). If you are trying to save the most money, buy the cheapest cells you can find and then pay them to battery tab weld it for you (avoid solder as it is possible but difficult to do right and can have failures under physical stress of a bike). A NiCad pack is very safe and trivial to charge.

I have been seeing a few eBay auctions go by with large number of surplus Ni-Cad cells. Worth watching for.

Webfootguy,

You're overlooking voltage. NiCad are actually pretty expensive. Those 3ah cells for $3.75-$6/cell are only 1.2V, so you're looking at well over $1/wh. Brand new matched and tab welded A123 M1's can be had cheaper than nicads for a given amount of energy storage, and the nicads will cost much more to ship because they weigh a lot more.

I've got 180 D size 4500mah nicads. Those are my if the shit hits the fan batteries, because they will be good for decades sitting on a shelf at 0 voltage. Safe and cheaper than the cheapest are definitely not nicad attributes though.

 

[webfootguy]

No, I'm not overlooking the voltage. I did not do a direct comparison between cells of different types. What I am saying, is that some older technologies such as NiCd cells are robust and reliable and can be fairly inexpensive. A NiCd pack does not require as much care as lithium because it does care if it is at zero volts for months or years, it does a self balance if you charge at C/10 rates or lower, and has very reasonable cycle life at full discharges (true for industrial cells, not so much for consumer cells). None of this is true for any lithium technology except the last part. Both will vent/explode on overcharge or reversal. End of charge for NiCd can be detected by delta temp, delta voltage, or capacity. For lithium, you either have to have good capacity counting and equal capacity cells or accurate voltage measurement to detect the cell is full. They don't blow off excess charge as heat.

That being said, for small cells, you can buy new high quality NiCd cells for around one dollar per watt hour (even less in quantity). Lithium varies all over the map depending on whether you believe the vendor is selling you new cells or remarked cells from China. Cell_man has the best deals on the A123 M1 cells but the history of those cells is not yet proven as his source is unknown and could switch to B cells at any time or grey market cells (but the 15Ah and 20Ah prismatic are awesome).

As always, it is buyer beware. I personally find it safer to harvest cells from new tool packs because I know the quality control process they had to go through to get tested and sold as such. The shelf life of such cells is well proven and thus lowers the risk. The downside is you don't get a bunch of cells from the same batch which is the best way to assure such cells are similar in capacity. Testing and batching similar parts only gets you part of the way there because cells from different batches that test the same are more likely to drift apart over time than all cells from the same factory run/batch.

I personally favor lithium cells but I also realize there are circumstances where NiCd is better suited.

 

[trappermike]

I think I'm going to keep looking for a company who will custom build me a few packs with good quality cells like the Sanyo's.
Then get a good quality fan-cooled charger like the "High-Power".
Simple and reliable,not too expensive,and no rivers of tears from failed/puffed cells,faulty BMS,etc. related to the expensive risks of Lithium packs. Just my preference for my application. Right now I'm looking at $300 for a 72v-8ah Ni-Cad battery pack,that doesn't mind a heavy amp draw sometimes.
I'm following up one of your leads with an inquiry to Batteries Plus also...

 

[liveforphysics]

NiCd is a bitch to charge. Its heavy. It has some lame failure modes, and some catastrophic failure modes.
Ideally you need 1 charger per string, and the string needs to be matched cells.

Lithium is so much cheaper and lighter and easier to charge

 

[dogman dan]

Yep. If you lived in the USA, I'd be trying to unload my old nicads on ya trapper. Since I'm stuck with em, I run my mower on em. No cheaper than lipo that's for sure.

 

[trappermike]

Well everyone has their preferences,and entitled to them.
I place most importance on reliability than high technology. Yes the Ni-cads are old technology and heavier,but I know I can install them and they will give trouble free operation for 2-3 years(For the riding I do)until they finally get old and tired. They really are trouble free unless I commit some gross error charging them.

 

[aaronski]

Hey Trapper,

LiMn sounds a lot like ni-cad but better to me. have you considered that? I have 72v 7ah konion cell pack that I pull 70 amps out of all day, and charge with a 72v charger that cost me $40. There's no balancing, no matched strings or diodes or any of that fancy crap.

 

[29a]

Hey Trapper,
I totaly agree nicd very stable if treated right.
Nothing beats nicd for winter rideing at the temps we get here in Canada !

 

[texaspyro]

They really are trouble free unless I commit some gross error charging them.

The exact same thing can be said for LiFePO cells. And they have a much greater cycle life than NiCd. Plus they are a lot more environmentally friendly. And a lot lighter. And less filling.