Li-po (Lithium Polymer) Batteries

[jeep4grog]

Is this a good time to bring this back? I have Dave's Subdriver coming and have been looking at these batteries from All-Battery.com.


Li-Ion - 11.1V 6600 mAh Rechargeable Battery Pack with PCB Protection Bare Leads
Capacity 6600mAh
Voltage 10.8V (Peak at 12.6V, avg. at 11.1V)
Dimensions- 69mm height x 54mm width x 54mm thickness (2.75"X2.25"X2.25")
Weight 10 oz
Max. charge current 2 A
Max. discharge current 6.5A
Cut off voltage over-charge protection: 13V
over-Discharge protection: 7.2V

from All-Battery.com for about $82.00. Thats high, but still a lot of juice...

The closest 12V Nimh pack I can find is:
12.0 V 4500 mAh NiMh battery pack
Made with 10 x Sub C 4500mAh TENERGY high capacity Nimh Batteries
Quick charge, long life cycle (up to 500 times) and rapid charge up

Technical Specifications
- Voltage: 12V
- Battery: Nimh
- Connector Type: 14 AWG bare leads
- Dimensions: 115x44.4x46.76mm
- Weight: 1.3 Lbs

and sells for $73.00. Twice the weight, and a 50% bigger package.

Not a lot of cost difference between the two. I think the Nimh pack has a higher discharge rate, but is that needed for the subdriver?

Any comments?

[He Who Shall Not Be Named]

Is this a good time to bring this back? I have Dave's Subdriver coming and have been looking at these batteries from All-Battery.com.


Li-Ion - 11.1V 6600 mAh Rechargeable Battery Pack with PCB Protection Bare Leads
Capacity 6600mAh
Voltage 10.8V (Peak at 12.6V, avg. at 11.1V)
Dimensions- 69mm height x 54mm width x 54mm thickness (2.75"X2.25"X2.25")
Weight 10 oz
Max. charge current 2 A
Max. discharge current 6.5A
Cut off voltage over-charge protection: 13V
over-Discharge protection: 7.2V

from All-Battery.com for about $82.00. Thats high, but still a lot of juice...

The closesst 12V Nimh pack I can find is:
12.0 V 4500 mAh NiMh battery pack
Made with 10 x Sub C 4500mAh TENERGY high capacity Nimh Batteries
Quick charge, long life cycle (up to 500 times) and rapid charge up

Technical Specifications
- Voltage: 12V
- Battery: Nimh
- Connector Type: 14 AWG bare leads
- Dimensions: 115x44.4x46.76mm
- Weight: 1.3 Lbs

and sells for $73.00. Twice the weight, and a 50% bigger package.

Not a lot of cost difference between the two. I think the Nimh pack has a higher discharge rate, but is that needed for the subdriver?

Any comments?

No.

Typical r/c submarine current load seldom exceeds the C1 rate (current draw is at or below battery capacity). We don't tax these batteries anywhere near what the r/c plane and race care guys do.

Go for the Lithium-ion or Lithium-polymer which have a very high acceptable discharge rate but several times the power density of the other commercially available re-chargeable batteries.

And for Christ's sake! ... dance with the guy who brought you to the prom: buy the batteries from Caswell!!!!!!!!!!!

You come dancing into here, the Caswell site, spouting off about other sources of supply. Damn! Bad manners, guy. We're trying to make a buck here!

David,

[toppack]

These are the packs I use in the Gato SD, no Lipo bombs allowed in my models:

http://cgi.ebay.com/Two-9-6V-3800mAh-Hump-NiMH-Battery-Pack-4-RC-Car-Tamiya_W0QQitemZ330300017322QQihZ014QQcategoryZ34061QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

About 20 bucks each. They discharge a little faster than some but last plenty long enough. :)

I only dance with Safe women! :D LOL :D

[He Who Shall Not Be Named]

These are the packs I use in the Gato SD, no Lipo bombs allowed in my models:

http://cgi.ebay.com/Two-9-6V-3800mAh-Hump-NiMH-Battery-Pack-4-RC-Car-Tamiya_W0QQitemZ330300017322QQihZ014QQcategoryZ34061QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

About 20 bucks each. They discharge a little faster than some but last plenty long enough. :)

I only dance with Safe women! :D LOL :D

(grrrrrrr ....)

David,

[toppack]

Take it Easy, David! I'm just 'Yankin' your Chain'. :D LOL :D

[He Who Shall Not Be Named]

Take it Easy, David! I'm just 'Yankin' your Chain'. :D LOL :D

... mission accomplished!

David,

[jeep4grog]

Ok Dave. I can do that. When you send my Subdriver, can you make sure it's sent with 12V motors so when I get it installed I will buy the Lipo's from you guys?



...and I don't dance with guys...:D

[toppack]

I noticed that you have a picture, on Caswell website, of 3 Li-po batteries that appear to be connected in parallel.
Don't Li-pos Discharge into each other, when in parallel, like LA batteries do?
Or is it a very Slow discharge that way, if all have been charged close to equally?
I don't see any of them Exploding, so it must be a fairly slow discharge. :D LOL :D

[He Who Shall Not Be Named]

I noticed that you have a picture, on Caswell website, of 3 Li-po batteries that appear to be connected in parallel.
Don't Li-pos Discharge into each other, when in parallel, like LA batteries do?
Or is it a very Slow discharge that way, if all have been charged close to equally?
I don't see any of them Exploding, so it must be a fairly slow discharge. :D LOL :D

They will 'equalize', sure. The lower voltage battery(s) will be boosted up till all batteries share the same voltage. No biggie.

David,

[toppack]

Okay, Sure can't do that with Lead-Acid and Ni-cad batteries.
They will discharge quickly. I've tried it with both.
Since they are never really equal in charge, they keep See-sawing current back and forth until they are Dead. It seems that Li-pos would do the same thing, but maybe they are different.

[He Who Shall Not Be Named]

Okay, Sure can't do that with Lead-Acid and Ni-cad batteries.
They will discharge quickly. I've tried it with both.
Since they are never really equal in charge, they keep See-sawing current back and forth until they are Dead. It seems that Li-pos would do the same thing, but maybe they are different.

No two cells (a collection of cells, either in one unit or the cells in a collection of units, makes a 'battery' -- hence the term) are of equal capacity. It's the internal resistance between the plates of a cell (the electrolyte) without a load that dictates the internal discharge rate. All voltaic cells self-discharge, the weak sisters in a battery pull the other cells down with them, regardless the chemistry of the cell.

Some types of cells undergo a chemical change that can not be reversed if their potential drops below a certain limit (Lithium and Lead-acid batteries for example); others can be totally discharged without harm (Ni Cad's and Nickle-metal hydride).

All cells internally short out a bit -- some more than others. Ni Cad's evidence the swinging you pointed out more than other type batteries, hence the caution not to connect those cells in parallel -- where voltage is constant, or is supposed to be; where the voltage swings between cells can escalate to the point of destruction. The other type batteries self-damp a bit when their cells are connected in parallel or series-parallel circuits, and won't run-away like Ni Cad's will (if the cells are not evenly matched).

Did any of this **** make sense?

David,

[Kazzer]

Did any of this **** make sense?

David,

No! Total gibberish, if you ask me!


>
>
>
Just kidding!:D

[He Who Shall Not Be Named]

No! Total gibberish, if you ask me!


>
>
>
Just kidding!:D

(tugging on collar, trying to loosen tie)

Man! ... tough audience!

David,

[toppack]

I think he said:
'It's okay to connect them in parallel, if you don't leave them that way for a long time'. ;)

[mickelsen]

The chargers that Caswell sells don't use the balancing connectors at all and, unless I'm mistaken, Merriman has cut off the balancing connectors from the battery packs pictured for the Seaview. From what I've tried to learn about LiPo's, that seems kind of risky for those rather expensive batteries. I've already had one set of Vislero batteries go dead on me and I think it's from charging without balancing. I'm just a newbie so I don't know for sure, but I cut the balancing connectors off like it appeared in the picture, so now it's too late to find out. I won't do that again:mad::(:o!