Post by BroJames on Jan 4, 2008 10:09:45 GMT 8
The Bremen Haus 7.4v 15C 2000mAh LiPoly
13C Continous, 18C Rated, 23-26C Burst (conservative).
I hope others will do a more detailed review as this is more of a test report than a comprehensive review.
The Bremen Haus Elektrisch 7.4v LiPoly was developed for use with airsoft guns with FPS range of up to 400FPS using stock gears and 450FPS with STU or 300% gears. Although I have tested the samples last year, which can crank setups with upto 450fps (SP120 stock gears ave ROF 18-20 rounds per second average) and 500fps (Systema M130 on STU gears), my tests on the commercial release was concentrated on the 400-450fps setup - recommended upper limits for the BHE 7.4v 2000mAh LiPoly.
My tests this time is simple due to lack of time, space, and my being busy looking for a bigger store space. So, my tests are just to confirm that this production batch performs as well using non-test aegs. Simple tests, as the BHe 7.4v is used to test-fire the new Jing Gong M4A1, M4-CQB-R, HK416, and S-system versus their stock battery.
Earlier, tests using the PDI190 on stock gears shows an ROF of 12-13rnds per second. On SP120, the ROF ranges from 16-21 rounds per second. The cranking ampere is estimated at 18A. This means the minimum battery required is 15C x 1300mAh or 10C x 1800mAh.
Our FPS using SP120 seems to be higher than average but further tests have to be done. But our theory is this, springs with regular pitch (Linear compression) requires higher torque to crank a spring. With Variable-pitch springs (Non-linear compression), the initial crank is soft and easy on the motor. Although the later crank is hard, the motor and gears has already gained some momentum so the later crank is faster than regular linear springs. The release is the reverse from hard to soft, so FPS is increased, as the hard release puts more forward momentum into the piston head (Does the softer push as the piston head comes in contact with the cylinder head means variable pitch springs are more forgiving on the gearbox?)
For people on a budget, there is also an added advantage for using a 2-cell 7.4v LiPolies as lesser cells are less critical on balancing. They 2-cells in a 7.4v LiPoly are less liable to have problems with a good wall charger (1/3C output in mA) and a good balance-type charger loike the IMAX SK0719 will do almost as fine as a true balance charger like the BHE IBC, BHE Black Box Balance charger, IMAX B series, Triton, Novatech, Vislero, etc.
Excerpts from www.invictaairsoft.org.uk/lipoart.html
For people who are confused with how a 7.4v LiPoly can outperform an 8.4v N iCd/NIMH or even an Intellect 9.6v 2000mAh, some excerpts from the from Neoairsoft (link provided above)
This is the BHe 7.4v LiPoly versus the 8.4v crane stock sub C that comes with then Jing Gong CQB-R which it ourperforms.
Links or references
www.airsoftforum.com/board/lofiversion/index.php/t74476.html
13C Continous, 18C Rated, 23-26C Burst (conservative).
I hope others will do a more detailed review as this is more of a test report than a comprehensive review.
The Bremen Haus Elektrisch 7.4v LiPoly was developed for use with airsoft guns with FPS range of up to 400FPS using stock gears and 450FPS with STU or 300% gears. Although I have tested the samples last year, which can crank setups with upto 450fps (SP120 stock gears ave ROF 18-20 rounds per second average) and 500fps (Systema M130 on STU gears), my tests on the commercial release was concentrated on the 400-450fps setup - recommended upper limits for the BHE 7.4v 2000mAh LiPoly.
My tests this time is simple due to lack of time, space, and my being busy looking for a bigger store space. So, my tests are just to confirm that this production batch performs as well using non-test aegs. Simple tests, as the BHe 7.4v is used to test-fire the new Jing Gong M4A1, M4-CQB-R, HK416, and S-system versus their stock battery.
Earlier, tests using the PDI190 on stock gears shows an ROF of 12-13rnds per second. On SP120, the ROF ranges from 16-21 rounds per second. The cranking ampere is estimated at 18A. This means the minimum battery required is 15C x 1300mAh or 10C x 1800mAh.
Our FPS using SP120 seems to be higher than average but further tests have to be done. But our theory is this, springs with regular pitch (Linear compression) requires higher torque to crank a spring. With Variable-pitch springs (Non-linear compression), the initial crank is soft and easy on the motor. Although the later crank is hard, the motor and gears has already gained some momentum so the later crank is faster than regular linear springs. The release is the reverse from hard to soft, so FPS is increased, as the hard release puts more forward momentum into the piston head (Does the softer push as the piston head comes in contact with the cylinder head means variable pitch springs are more forgiving on the gearbox?)
For people on a budget, there is also an added advantage for using a 2-cell 7.4v LiPolies as lesser cells are less critical on balancing. They 2-cells in a 7.4v LiPoly are less liable to have problems with a good wall charger (1/3C output in mA) and a good balance-type charger loike the IMAX SK0719 will do almost as fine as a true balance charger like the BHE IBC, BHE Black Box Balance charger, IMAX B series, Triton, Novatech, Vislero, etc.
Excerpts from www.invictaairsoft.org.uk/lipoart.html
x x x
The general rules of thumb for ROF and battery life are:
Volts = ROF
mAh = Battery Life
However with LiPo batteries these simple rules becomes somewhat more complex. LiPo's have a higher discharge rate which allows more current (amps) to flow at lower voltages. Confused yet? If you want a more technical understanding try reading this article: neoairsoft.home.comcast.net/lithium.html
With a higher discharge rate you can achieve a decent ROF and a battery that will last an entire day's skirmishing.
x x x
Dimensions of 8.4V 1000mAh Nimh: 111mm x 35mm x 17mm
Dimensions of 7.4V 2100mAh Lipo: 98mm x 34mm x 13mm
x x x
The general rules of thumb for ROF and battery life are:
Volts = ROF
mAh = Battery Life
However with LiPo batteries these simple rules becomes somewhat more complex. LiPo's have a higher discharge rate which allows more current (amps) to flow at lower voltages. Confused yet? If you want a more technical understanding try reading this article: neoairsoft.home.comcast.net/lithium.html
With a higher discharge rate you can achieve a decent ROF and a battery that will last an entire day's skirmishing.
x x x
Dimensions of 8.4V 1000mAh Nimh: 111mm x 35mm x 17mm
Dimensions of 7.4V 2100mAh Lipo: 98mm x 34mm x 13mm
x x x
For people who are confused with how a 7.4v LiPoly can outperform an 8.4v N iCd/NIMH or even an Intellect 9.6v 2000mAh, some excerpts from the from Neoairsoft (link provided above)
This is the BHe 7.4v LiPoly versus the 8.4v crane stock sub C that comes with then Jing Gong CQB-R which it ourperforms.
DO NOT BE FOOLED BY THE VOLTAGE! (remember this old saying? "It's not the volts that kill you, it's the amps.") This battery will run the same rof as my 1700 mah large 9.6 volt. Why? Because of the discharge rate. This battery is rated for a sustained 10C-12C discharge rate.
Links or references
www.airsoftforum.com/board/lofiversion/index.php/t74476.html