New battery tech for battery replacement (2 9volts)?

[UThomas]

So my battery died and I'm reading through some of the old posts. One thing I noticed is that my old school battery was 650 mAh (from an E-mag extreme), and some of the new rechargeables are 1000 mAh - offering a much longer life span. To me, I'd rather trade 10000 shots for half the size.

So has there been any changes to 9 volt tech for example so that people can now realistically put 2 in series and get around 5-10k shots?

I've seen lots of "I'm going to try this" but never any pics or actual results.

[UThomas]

For example - how would 2 of these do:

NiMH 9volt 300 mAh

http://thomasdistributing.com/shop/-maha-9v-300-mah-nimh-rechargeable-battery-p-503.html?SP_id=&osCsid=a2c690ff4875e3225b261ab9fe47ccae

or

NiMH 9volt 275 mAh

http://www.megabatteries.com/item_details2.asp?id=13546&cat_id=1018&uid=1049

[FiXeL]

You will get only 18 volts @ 275/300 mAh. If you want a longer lasting pack, you have to make one out of AAA cells. You can get those in the 1000 mAh range.

[UThomas]

Well, I'm thinking if the stock battery @ 650 mAh gave like 20k shots, then a pair of these new much smaller 9 volts would still give ~5-10k shots @ 300 mAh.

I'm not an EE so maybe I'm missing something... I know there was a lot of other discussion on LION 9volts and stuff but I'm thinking these new stronger NICAD 9volts might do the trick.

I'm also planning on having a pack made with 1000 mAh AAA's and running my warp and revy off it.

[warpfeedmod]

You will get only 18 volts @ 275/300 mAh. If you want a longer lasting pack, you have to make one out of AAA cells. You can get those in the 1000 mAh range.

can you purchase these types of batteries online somewhere cheaper than at a radio shack?

[maglover728]

What would you do with a smaller battery? Find some one to mill a smaller, shorter battery pac? And then what? Set off a new wave of Emag customization? Where would that end? Humanity would be lost. All would parrish. I would jump that band wagon!

[UThomas]

Yea - I'd have a smaller more ergonomic battery pack milled - or just stick them in the stock pack and benefit from the lower weight.

Any electrical engineers on the boards today?

[Coralis]

well if you have some money to spend you could go with Lithium ion ... they are typically lighter hold more charge and usually have a higher voltage requiring less of them to make 18 volts

[UThomas]

From other posts I gather, I thought they had charging issues (memory) and didn't release their charge quick enough. Hmm...

[blake20]

Shootin' at a French-Canadian!!

can you purchase these types of batteries online somewhere cheaper than at a radio shack?

Really cheap in bulk www.all-battery.com has excellent prices compared to radio shack $19 for 4

From Promethion from one of my threads extremly helpful information on the links!!!

First off Not my site just some useful info for making a battery pack.
Solder 101 A decent amount of info for making a pack just use a little intellect
and revise a way to do it for the emag.

http://www.logoheli.com/end2end.htm

http://www.yourzagi.com/battery.htm

[Coralis]

From wikipedia:

Lithium ion monomer

Main article: Lithium ion battery

Lithium ion battery: A relatively modern battery chemistry that offers a very high charge density (i.e. a light battery will store a lot of energy) and which does not suffer from any memory effect whatsoever. Its chemical composition is LiCoO2, LiMn2O4, LiNiO2 or Li-Ph for the cathode and carbon for the anode. Applications include laptop computers, camera phones, some rechargeable MP3 players, and most other portable, rechargeable digital equipment. Tesla, Reva and Kewet are all releasing new lithium ion battery electric car models in 2007. Lithium ion batteries were introduced around 1990. The problems with Lithium batteries include volatility, thermal runaway, high cost, and limited shelf and cycle life.

[athomas]

I don't know enough about lithium batteries to make a comment on them. The NiMh 9v batteries don't have the required C rating to drive the solenoid properly. They do have the life span needed. When new, a pair of 9v rechargables could theoretically give you 5 cases of paint on a full charge. However, A low C rating means they can't deliver the necessary current to reliably pull the solenoid plunger in. This negatively affects the performance of the emag, especially at high rates of fire.

[UThomas]

Is this low C rating a function of it being a 9 volt, a NiMh, or both?

Can this be compensated for at all in X-mod by increasing the dwell?

[athomas]

"Is this low C rating a function of it being a 9 volt, a NiMh, or both?"

I'd say the low C rating is a function of it being a small 9v battery. There are probably other batteries that can deliver a higher current in the same package, but even that is probably reduced compared to the same battery in a series of larger AAA cells.

Essentially the NiMh 9v battery is made up of 7 cells (8.4v) or 8 cells (9.6v). Having that many cells in a small compartment means that each cell is very small. The small reactive area within the cells equate to increased internal resistance which limits the current capability. The solenoid for the emag just happens to be very large and draws a lot of current. Increasing the dwell doesn't change the load. In other guns dwell compensates for slow response due to friction and such. In the emag solenoid, high current draw from a battery that can't supply it, causes voltage drop while under load and also increases the heat within the battery. The heat will bring about a reduced life expectancy of the battery in both the per use charge and the total longevity of the battery.

[UThomas]

Thanks for the detailed response. I think that answers all my questions :)