Source for Rechargeable AA batteries for PCB mounting

[HammerForStickingOutNails]

Hello!

For a little project I need two AA-size 1.2V 2000+mAh rechargeable batteries (LiIo, LiPo or NiMh, no NiCd) for print mount on a PCB. All I could find however were batteries with wide solder tabs for creating battery packs, and most of the tabs were in Z configuration (one tab showing in the opposite direction). And as soon as I filter out the crop of cheap no-name Chinese batteries (which I want to avoid for several reasons) then there is nothing suitable left.

What I am looking for are AA-style rechargeable batteries with either pins for PCB mount or narrow solder tabs (the ones with a hole at the end to put a wire through) which show in the same direction and which have a capacity of 2000mAh or better (I'd prefer something in the 3600 to 4000mAh range).

Does anyone know where to get such batteries from? Since I'm in the UK I'd prefer a source in the UK or Europe.

Of course I could fiddle these batteries in by soldering another tab on them, however I would prefer to have batteries which already come with suitable tabs, especially as space is constrained.

[JoannaK]

First.. Trying to limit some options.. 
- NiCd are out since they don't have mAh you are looking at the size.
- As far as I know, all Lithium technologies are around 3.6V per cell.. so it's too high woltage.

So NiMh (or perhaps NiZn?) it is..

Digikey have at least couple types that seem to be usable. (was second I looked, after Farnell)
www.digikey.com/product-detail/en/NH15/N703T-ND/1040726
www.digikey.com/product-detail/en/HHR-210AAC4B/P220T-ND/598006

As a word of warning .. If you'll look batteries from sites like Ebay, alibaba or any of those China-exports,  the specs are most likely badly inflated. As far as I know, there simply are no AA size 4000mAh NiMh available, and making those would reguire all new technology.

I'm sure there are many well known and respected Accu/battery sellers at net (or even local there) but I can't give any names off hand. I'd expect someone else to fill in here.

[Astroplio]

You have absolutely no room for a PCB mounted battery holder?
This will allow you to use the best NiMH battery you can find for your application instead of looking for what's it is available now to you with solder tabs.

George

[IanB]

Well, first a few facts for you:

1. NiMH cells are nominally 1.2 V and in the AA size come in capacities from about 1600 mAh to 2700 mAh, with 2000 mAh being the common conservative figure.

2. LiIO or LiPo cells are nominally 3.6 V (or 3.2 V for LiFe), and in the AA size come with a capacity of about 600-800 mAh (you get about 1/3 of the capacity because you are getting triple the voltage).

3. Lithium ion cells use completely different battery management and recharging technology from NiMH and you have to pick one or the other to design around. You can't just mix them up as if they were interchangeable.

4. No AA size cell has a capacity anywhere close to 3600 mAh. This is technically, totally unfeasible.

5. Tabs are not fixed to the batteries by the manufacturer. The tabs are affixed afterwards by vendors or pack assemblers using a tab welding machine. If you find a vendor who can fix tabs to the cells, you can possibly contact them and ask them to fix the tabs the way you would like. Or you can simply solder wires to the standard tabs that are attached in the normal way.

6. Have you considered using a battery holder? Rechargeable batteries do wear out after a while and may need replacing. Putting them in a holder makes this easier than re-soldering.

[HammerForStickingOutNails]

First.. Trying to limit some options.. 
- NiCd are out since they don't have mAh you are looking at the size.

As stated in my original posting I already ruled out NiCd, not just because of the very low capacity.

- As far as I know, all Lithium technologies are around 3.6V per cell.. so it's too high woltage.

So NiMh (or perhaps NiZn?) it is..

A while ago I have seen some AA LiIo cells on an exhibition but I can't remember who made them, and a search didn't come up with results, so I guess NiMh it is.

Digikey have at least couple types that seem to be usable. (was second I looked, after Farnell)
www.digikey.com/product-detail/en/NH15/N703T-ND/1040726
www.digikey.com/product-detail/en/HHR-210AAC4B/P220T-ND/598006

Thanks for the links! The Panasonic battery seems to have tabs in Z config but the Energizer battery looks like what I need.

As a word of warning .. If you'll look batteries from sites like Ebay, alibaba or any of those China-exports,  the specs are most likely badly inflated.

I'd never buy batteries (or flash memory cards) from ebay just because of the sheer amount of crap and fakes sold there, and especially with rechargeable batteries I keep with the major brands.

As far as I know, there simply are no AA size 4000mAh NiMh available, and making those would reguire all new technology.

Not necessarily. For a while now we use GP 3600mAh AA rechargeable batteries in various applications, and while not having tested their true capacity the runtime suggests that the rating is indeed quite accurate.  From what I have heard a 4000mAh variant is already in the works.

[HammerForStickingOutNails]

You have absolutely no room for a PCB mounted battery holder?

Unfortunately no, space is really really tight.

This will allow you to use the best NiMH battery you can find for your application instead of looking for what's it is available now to you with solder tabs.

I know. It's sad that so little is available with solder tabs, and most of them are in Z config for assembly of battery packs which is not good for PCB mounting.

[HammerForStickingOutNails]

2. LiIO or LiPo cells are nominally 3.6 V (or 3.2 V for LiFe), and in the AA size come with a capacity of about 600-800 mAh (you get about 1/3 of the capacity because you are getting triple the voltage).

I have seen some LiIo AA rechargeables with 1.2v. But I can't remember who made them, and I guess they are still in development as I couldn't find anything on the 'net about them.

3. Lithium ion cells use completely different battery management and recharging technology from NiMH and you have to pick one or the other to design around. You can't just mix them up as if they were interchangeable.

I'm aware of that. But charging is not an issue as the device will be connected to an external computerized charger which can handle any of them.

4. No AA size cell has a capacity anywhere close to 3600 mAh. This is technically, totally unfeasible.

Apparently not as for some time now we are using 3600mAh AA rechargeable batteries from GP for some mobile applications:

http://www.dhgate.com/10pcs-lot-hot-sale-gp-aa-3600mah-1-2v-rechargeable/p-ff808081314bd6ef013150aaa8db3cec.html (we didn't buy it from them, though)

As I said in a previous post I haven't tested the capacity, but just based on the runtimes we get the rating doesn't seem to be optimistic. A 4000mAh variant is apparently following soon (or may already be out).

5. Tabs are not fixed to the batteries by the manufacturer.

Not correct. Most manufacturers like Varta, Panasonic or GP sell rechargeable batteries with tabs already put on during manufacturing.

The tabs are affixed afterwards by vendors or pack assemblers using a tab welding machine. If you find a vendor who can fix tabs to the cells, you can possibly contact them and ask them to fix the tabs the way you would like.

I tried that, but none of those I contacted have tabs narrow enough to fit the PCB hole.

Or you can simply solder wires to the standard tabs that are attached in the normal way.

Unfortunately there even isn't room for additional wires or a battery holder (which would make life much easier). Space is really a problem.

[mariush]

I don't understand why you can't just put the terminals on the pcb and just put the batteries in. It's not taking more space compared to soldering tabs on the batteries



etc etc Farnell has a whole section with these :  http://ro.farnell.com/battery-contacts

Or you could solder one of these to the board :   and then you could just snap one of these in the connector and have the batteries sit vertically on the board:    (http://uk.farnell.com/keystone/2474/battery-holder-snap-conn-2-aa/dp/1650681)

Are you concerned about vibrations, flexing, batteries slipping out of these that you want them to be soldered? With the later, you could just use a small metal bar and a screw to lock the thing to the board using a third hole near the 2 battery points.

[FenderBender]

+1 for mariush. Using some cheap metal battery clips  will not be much larger than welded solder tabs. You don't have to use a full-out plastic battery holder. Those I understand might not fit, but the little tabs that mariush recommended are probably your best bet. Not sure how you intend to actually mount the batteries, but I suppose you could just hotglue them in or something?  

Then you could use Sanyo Eneloops...great batteries.

[IanB]

I have seen some LiIo AA rechargeables with 1.2v. But I can't remember who made them, and I guess they are still in development as I couldn't find anything on the 'net about them.

I find the possibility of such a cell existing to be very unlikely. The electrode potentials arising from the chemistry forbid it. Energizer Lithium primary cells are about 1.8 V but they use metallic lithium; metallic lithium has long been abandoned in rechargeable secondary cells because it is too unstable and dangerous in use.

Apparently not as for some time now we are using 3600mAh AA rechargeable batteries from GP for some mobile applications:

http://www.dhgate.com/10pcs-lot-hot-sale-gp-aa-3600mah-1-2v-rechargeable/p-ff808081314bd6ef013150aaa8db3cec.html (we didn't buy it from them, though)

As I said in a previous post I haven't tested the capacity, but just based on the runtimes we get the rating doesn't seem to be optimistic. A 4000mAh variant is apparently following soon (or may already be out).

I have to tell you that those cells are re-labelled with fake wrappers and the capacity claim is bogus. GP does not produce such a cell.

A capacity of 3600 mAh or 4000 mAh in an AA size NiMH cell is utterly impossible to achieve and even if those cells are made by GP they are not 3600 mAh cells. Most likely they are 2700 mAh cells.

[mariush]

I have to agree with above poster.

Most likely fake batteries. The highest I've seen were some Ansmann 2850 mAh batteries and they weren't better than 2500 mAh batteries in my cameras (though, this isn't a scientific test by any means)

And this page seems to confirm it, especially this comment

According to Finnish consumer agencys test:
Capacity after 10 cycles: 2378mAh
Capacity after 50 cycles: 2419mAh
Capacity after 130 cycle: 2241mAh
Capacity after 20 days: 38%

[JoannaK]

Kinda interesting to scan trhough the official GB site and look all available rechargeable NiMh types.. Even the best AA size is definitely under 3000mAh ..
http://www.gpbatteries.com/INT/index.php?option=com_k2&view=item&layout=item&id=261&Itemid=68

And yes, those official batteries look quite different in colors/style of the China-trades. Either GB don't know what they do produce/sell or the Chinaboys have been a bit too sloppy.

[peter.mitchell]

I wonder why they don't make square AA batteries... there is a lot of wasted space putting a cylindrical cell in a rectangular holder...

[amyk]

I wonder why they don't make square AA batteries... there is a lot of wasted space putting a cylindrical cell in a rectangular holder...

More fragile. LiPo can get away with it because they're designed to be fit into a hard case and not handled directly by the average consumer.

[SeanB]

Hard to wind a square using paper and metal sheets............. Round is the best to contain pressure.

[peter.mitchell]

Yes, but with that said, if they had a sizeable capacity difference you could charge a fortune for them and people would buy them as they are the only option.

[IanB]

Round is the best to contain pressure.

True 'dat. Lithium chemistry does not generate any pressure during charging, which is why LiPo can have thin plastic envelopes. However NiMH cells can generate quite high internal pressures during charging and need pressure tight seals to keep the gases in until they recombine. You may notice the "flat" end of a NiMH cell can bulge out slightly after charging so that the cell doesn't sit flat on a table top if you try to stand it upright.

[SeanB]

Pressure in a Lithium cell is almost always followed very soon after by a bang and flame. That is why they are constrained for altitude in the flat pouches, while the cylindrical 18650 cells are space rated.

[HammerForStickingOutNails]

Apparently not as for some time now we are using 3600mAh AA rechargeable batteries from GP for some mobile applications:

http://www.dhgate.com/10pcs-lot-hot-sale-gp-aa-3600mah-1-2v-rechargeable/p-ff808081314bd6ef013150aaa8db3cec.html (we didn't buy it from them, though)

As I said in a previous post I haven't tested the capacity, but just based on the runtimes we get the rating doesn't seem to be optimistic. A 4000mAh variant is apparently following soon (or may already be out).

I have to tell you that those cells are re-labelled with fake wrappers and the capacity claim is bogus. GP does not produce such a cell.

A capacity of 3600 mAh or 4000 mAh in an AA size NiMH cell is utterly impossible to achieve and even if those cells are made by GP they are not 3600 mAh cells. Most likely they are 2700 mAh cells.

If they are fakes then they must be pretty good as they constantly give around 85% more runtime than a GP 2000mAh variant, and this for several months now.

[IanB]

If they are fakes then they must be pretty good as they constantly give around 85% more runtime than a GP 2000mAh variant, and this for several months now.

Trust me when I tell you, there isn't an AA NiMH cell on the market that reliably delivers a capacity of much more than 2500 mAh. Even the genuine 2700 mAh cells fade after a few cycles and soon deliver less.

So the question becomes, what are you doing to your 2000 mAh cells to cause them to deliver an effective capacity in use of only 1200 mAh? You might want to review your source of supply of the cells, your charging system, or your power management system in the application. You appear to have something that isn't right somewhere.

(If you don't know how to measure your cells, get hold of a Maha MH-C9000 charger and find out. It will tell you the capacity of your cells to an accuracy of about 1%. You might be surprised at what you find.)