What is the maximum (SAFE) voltage for Minipulse Plus?

[dotniet]

I want to extend the amount of time I will be able to use the detector on field so I have two questions:

1. What is the maximum number of hours (approximately) I should expect from a 12V/2Ah battery pack?
2. Can I safely increase the number of batteries to 13.2V or even 14.4V, so I can get more hours?

[kt315]

1. 2 Amper*hour is the value you have at board. if your MPP's current is 100mA so 2/0,1 you get 20 hours of work.
2. you can get more hours if you will get MORE "Amper*hour" value. NOT THE voltage you mean - !
from 2A*h you have to go on 5A*h batt for the example. this give you 5/2 = 2,5 times more the hours than you had before.

[Qiaozhi]

I want to extend the amount of time I will be able to use the detector on field so I have two questions:

1. What is the maximum number of hours (approximately) I should expect from a 12V/2Ah battery pack?
2. Can I safely increase the number of batteries to 13.2V or even 14.4V, so I can get more hours?

The quiescent current consumption of the MPP is 87mA. If we assume this to be 100mA (to allow for beeping when a target is detected) then we have 2000/10 = 20 hours operation. Which is the same as predicted by kt315.

[dotniet]

@KT315

Correct me is I am wrong but I think a device 'consumes' power and not amperes (current).
So, by adding an extra battery I increase the total power of my battery pack (10+1= about 10%). Which I (personally) think will result in more hours of operation.

Or... in other words... you mean that I double the number of batteries (it is a theoretic exercise so let's say the MPP will not smoke and burn), the total hours of operation will not change AT ALL?!? I think it will double.

______________________

PS: i love your avatar picture!

[Qiaozhi]

dotniet ..... KT315 is correct.
The capacity of a battery is quoted in ampere-hours (Ah). For example, a 1Ah battery will allow 1 amp to flow for 1 hour.
In the case of PI detector, increasing the battery voltage (but not the ampere-hours) may actually cause the TX circuit to consume more current, and will in fact shorten detecting time. Also, be aware that the maximum input voltage for the LT1054 is 15V.

[sinclairuser]

you need to increase amps not volts, if you add another battery for instance positive terminal goes to positive, negative to negative.

example if you have a 9v pp3 at 400mah, and you add a second, you can either have 18v at 400mah, or 9v 800mah, depending how it is connected.

if both positive terminals go to the same wire(both negative to the other wire) it will be 9v 800mah.

if however battery 1's positive terminal is connected to battery 2's negative terminal , and power wires are connected to the remaining positive terminal(battery2), and negative terminal(battery1) you will have 18v 400mah.
you can add more battery power, but you have to connect it correctly.


these pics should give you the idea.

[6666]

Correct me is I am wrong but I think a device 'consumes' power and not amperes (current).

dotniet

Power consumed by a device is calculated by multiplying the supply Voltage by the Current drawn by the circuit, with the answer given in Watts.

If what you are talking about is increasing the amp hour capacity of your battery, you add them in parallel.
For example a one amp hour battery in parallel with another one amp hour battery will give you 2 amp hours of capacity.

[dotniet]

Ok. Thanks.

[dotniet]

In the case of PI detector, increasing the battery voltage (but not the ampere-hours) may actually cause the TX circuit to consume more current

Most of the current flows through the coil. And the pulse that controls the coil's transistor gets shorter as the voltage increases.
Doesn't this mean that the average consumption is the same no matter what the battery voltage is?

Note: This is a theoretic discussion now because yo said that a 2Ah pack will last 20 hours which is more than enough!!!

[Qiaozhi]

Most of the current flows through the coil. And the pulse that controls the coil's transistor gets shorter as the voltage increases.
Doesn't this mean that the average consumption is the same no matter what the battery voltage is?

The TX circuit of the MPP is designed to adjust the pulse width so that the energy in the coil is relatively consistent and does not depend on the battery voltage. However, I have not plotted the coil current against battery voltage, so the linearity of this relationship is unknown. Other TX circuits, such as those found in the Surf-PI, Baracuda and Hammerhead, will put more energy into the coil when the battery voltage is high, and less energy as the voltage reduces.

[dotniet]

The TX circuit of the MPP is designed to adjust the pulse width so that the energy in the coil is relatively consistent and does not depend on the battery voltage.

Hi Qiaozhi.
I will try to measure the current at different voltages to find out the answer.