Topic: Cheap 9v Li-Ion batteries?

[Chuck]

Are any of you using these?

http://www.batteryspace.com/Li-Ion-9V-500mAh-4.5Wh-Rechargeable-Battery.aspx

I wonder about them, because they are only $3.60 each. They are 500mAh 7.2v (nominal) rechargeable batteries. The charger is $10.

http://www.batteryspace.com/smartcharger03afor9vli-ionpolymerrechargeablebatterypackwithplasticend--celisted.aspx

Typical NiMh batteries of the same size and voltage are ~175mAh and in the $10 each range. That makes the Li-Ion's pretty cheap. 

[kirk97132]

Are any of you using these?

http://www.batteryspace.com/Li-Ion-9V-500mAh-4.5Wh-Rechargeable-Battery.aspx

I wonder about them, because they are only $3.60 each. They are 500mAh 7.2v (nominal) rechargeable batteries. The charger is $10.

http://www.batteryspace.com/smartcharger03afor9vli-ionpolymerrechargeablebatterypackwithplasticend--celisted.aspx

Typical NiMh batteries of the same size and voltage are ~175mAh and in the $10 each range. That makes the Li-Ion's pretty cheap. 

SO in essence they the same as a lot of rechargables and do not put out 9V.  Equipment they are being used on would need to be able to work in the 7volt world and not expect to see 9volts.  Might make soem equipment shut down if it sensed it as low voltage and/or might not perform right using 7volts instead of 9

[bryonsos]

Are any of you using these?

http://www.batteryspace.com/Li-Ion-9V-500mAh-4.5Wh-Rechargeable-Battery.aspx

I wonder about them, because they are only $3.60 each. They are 500mAh 7.2v (nominal) rechargeable batteries. The charger is $10.

http://www.batteryspace.com/smartcharger03afor9vli-ionpolymerrechargeablebatterypackwithplasticend--celisted.aspx

Typical NiMh batteries of the same size and voltage are ~175mAh and in the $10 each range. That makes the Li-Ion's pretty cheap. 

SO in essence they the same as a lot of rechargables and do not put out 9V.  Equipment they are being used on would need to be able to work in the 7volt world and not expect to see 9volts.  Might make soem equipment shut down if it sensed it as low voltage and/or might not perform right using 7volts instead of 9

Plus, they admit they are a bit larger. I can see them getting stuck/harder to remove from a lot of gear.

[Cheesecadet]

Just out of curiosity...how do these companies getting away with naming something 9 volt if it only puts out 7.2 volts???  Is it just because they have the same shape or something?

[Todd R]

Just out of curiosity...how do these companies getting away with naming something 9 volt if it only puts out 7.2 volts???  Is it just because they have the same shape or something?

A 9v alkaline battery is actually made with 6x 1.5v cells.  If you look at a typical 1.5v battery, they drop quickly from 1.5v and spend most of their life at 1.1v to 1.2v.  Hence, a 9v battery spends most of its life at ~6.8v - 7.2v.  Do a search on 9v alkaline battery discharge curve, and you can see what I mean. Li-ion batteries have a much flatter discharge curve, so a 3.7v li-ion battery spends a lot of its life at 3.4v to 3.7v, so in use, a two-cell li-ion battery is not much different than a 9v battery.

Equipment designed to use a 9v alkaline battery and actually needed 9v (or more than say 8v), would not operate for very long using a 9v battery.  I'd guess most designs are assuming more like 6.5-7v as a cutoff from a 9v battery.

[Chuck]

I found a nice efficient 6-8v to 48v DC circuit I want to put into my littlekit. I found I don't like charging up (5) 9v NiMh batteries when I want to use it. So, I haven't been using it as much as I should.

These look like a good way to generate the 6-8v DC I need for that circuit. If I run two of these batteries in parallel and use a smart charger I get 1000mAh for $7.20! Two of these beauties will fit into the littlekit box too. I can't see a downside to them yet. I just wonder why they are so inexpensive?

[F.O.Bean]

I would stick w alkaline/NIMH 9v's

[Chuck]

Batteryspace has a hazmat handling fee for lithiums that will drive up the cost of a small battery purchase though.

Does that apply to the battery packs too?
Do they apply that during check-out? Because I put a couple into the cart and there is no mention of a hazmat fee.

[kirk97132]

Just out of curiosity...how do these companies getting away with naming something 9 volt if it only puts out 7.2 volts???  Is it just because they have the same shape or something?

A 9v alkaline battery is actually made with 6x 1.5v cells.  If you look at a typical 1.5v battery, they drop quickly from 1.5v and spend most of their life at 1.1v to 1.2v.  Hence, a 9v battery spends most of its life at ~6.8v - 7.2v.  Do a search on 9v alkaline battery discharge curve, and you can see what I mean. Li-ion batteries have a much flatter discharge curve, so a 3.7v li-ion battery spends a lot of its life at 3.4v to 3.7v, so in use, a two-cell li-ion battery is not much different than a 9v battery.

Equipment designed to use a 9v alkaline battery and actually needed 9v (or more than say 8v), would not operate for very long using a 9v battery.  I'd guess most designs are assuming more like 6.5-7v as a cutoff from a 9v battery.

Todd, I am going to disagree with you hard about this.  Any 1.5volt battery that is below 1.3 volts will not run most equipment.  And a new battery voltage test at 1.58-1.60 volts. We use AA batteries(also a 1.5volt battery) in our wireless mics at work and once the battery hits 1.3volts the mics shut off.  So I beleiev it is a wrong assumption to believe that a battery spends it's life in the 1.1-1.2volt range. 

[kirk97132]

I agree Jon, I pull them and re-purpose them in my flashlights, kids toys remotes etc.  I refuse to toss them until I have drained them to dead.  I guess my point was I don't beleive that they drop off imdeiately to 1.1 - 1.2 volts where they spend mot of their life.  Rather they have a gradual discharge curve that is way above those kinds of numbers.

[Chuck]

I e-mailed batteryspace about these batteries. They are not going to work for my purpose, but I still can't believe how cheap they are. Thomas Distributing is selling similar Li-Ion 9v batteries in the $17 - $20 each range. http://www.thomasdistributing.com/9V-Lithium-Polymer-Batteries_c_958.html

[Jamos]

We use the iPower 9v 520mAh LiPoly batteries at work in wireless mic packs all the time -- and they work really, really well.
They operate at 8.4v (like most NiMh rechargeables also do), but last about 2x as long as the NiMh equivalents. 

Some devices that are calibrated for alkalines will read "low battery" when inserting a fresh iPower because of the 8.4v, but they still run a long time.

I'm not sure a 7.2v battery would function well in a lot of 9v applications, but I could be wrong.

[Red Boink]

I use the ipower lipoly 9v in eight lectrosonics wireless mics and they work great.  Haven't had a failure in years  of service.  Well worth the extra price.  Nothing truly well made comes cheap.  I'm still using nimi np1s in my cooper mixer, and fostex fr2, but next buying cycle,may switch to lion for those too. 

Best,

John