facdemol
16-04-2008, 11:18 AM
here's how we make cheap external batteries here in Romania. :D
this is a DIY concept so if you're not that type of person this may not be for you.
Anyway you must get yourself a sealed acid-lead 12v battery (they are built in the same way as a car battery but smaller) from an electronics shop. They are cheap and come in various sizes. If you want more juice, just buy 2 or 3 of those and couple them in parallel.
Next buy a 12v-220v converter like the ones used in cars. Those that are connected via the cigarete lighter. The smallest cheaper model you'll find will do the job right as long as it can provide 30w.
Don't connect the shift to the batteries, don't be tempted to do this, even if apparently the shift needs 12 v and those batteries supply this voltage. Use the converter.
Now, as you may guesed, simply connect the batteries to the converter and the shift's charger to the converter's output. The converter will suply about 220v at it's output. That's good and that's desirable. Even if your country may use standard 110V values at it's sockets, buy a 220v converter instead.
Now you got a bulky, ugly looking external battery. What's the fun with it?
Well here's the good part.
A standard external battery will give you about 2-3 hours of usage because by the time this is over, it's voltage output will drop from it's nominal value to somewhere around 9-10V. The battery will still be able to provide a fairly large amount of current (amps) but however by this time the shift will be powered off because it needs a nominal value of 12 v (+/- 0.80V) to work (it's internal converter needs it, and has a small tollerance about variations in this voltage). So, 2-3-4 hours of usage, then recharge.
The home made external battery has the following advantage.
After some usage (couple of hours - depending on how much big is the battery you use) the output voltage of the cells will drop. This is normal, and this will happen like the case with standard batteries. BUT you have that converter hooked up. If the converter needs 12 V to supply an output of 220V ac, if you apply only 10 V (the voltage on the battery has dropped because of usage) it will supply only 180V ac. (an estimation). This is well under 220 v. BUT the shift will still work. Why? Here's the cool part. The shift power charger has a nominal imput voltage of 100-240 V (it is rated on it's sticker as the imput voltage). THIS MEANS IT WILL SUPPLY THE 12 V OUTPUT FOR THE SHIFT AS LONG AS THE INPUT VOLTAGE IS SOMETHING IN THE AREA 100-240 V ac. So the converter supplies 180V but that's ok, the shift will still work. So you use it for a longer period of time. When the battery is flat out and has somewhere around 7 volts the converter will supply somewhere under 100v or will stop to work because the battery will also have not enought current (amps) to run the converter's main circuitry or to supply the shift's power requiests.
There are some things that must be said about the eficiency of this method. First you use 2 converters one will raise the voltage from the external batteries ( - your car converter) and the other will lower the voltage to the 12v required by the shift ( - your shift charger). These, both have an eficiency factor. Because of the tehnology used you will have a general factor of about 85%. The rest will be lost in the transfer as thermal heat or EM field radiation.
Still you should get 30-50% more juice then a similar capacity comercial product :). And it's more cheaper to buy. :p
You may achieve the same results if you buy a converter...aah...and a car. Car batteries will provide some good dozens of hours for the shift to work.
this is a DIY concept so if you're not that type of person this may not be for you.
Anyway you must get yourself a sealed acid-lead 12v battery (they are built in the same way as a car battery but smaller) from an electronics shop. They are cheap and come in various sizes. If you want more juice, just buy 2 or 3 of those and couple them in parallel.
Next buy a 12v-220v converter like the ones used in cars. Those that are connected via the cigarete lighter. The smallest cheaper model you'll find will do the job right as long as it can provide 30w.
Don't connect the shift to the batteries, don't be tempted to do this, even if apparently the shift needs 12 v and those batteries supply this voltage. Use the converter.
Now, as you may guesed, simply connect the batteries to the converter and the shift's charger to the converter's output. The converter will suply about 220v at it's output. That's good and that's desirable. Even if your country may use standard 110V values at it's sockets, buy a 220v converter instead.
Now you got a bulky, ugly looking external battery. What's the fun with it?
Well here's the good part.
A standard external battery will give you about 2-3 hours of usage because by the time this is over, it's voltage output will drop from it's nominal value to somewhere around 9-10V. The battery will still be able to provide a fairly large amount of current (amps) but however by this time the shift will be powered off because it needs a nominal value of 12 v (+/- 0.80V) to work (it's internal converter needs it, and has a small tollerance about variations in this voltage). So, 2-3-4 hours of usage, then recharge.
The home made external battery has the following advantage.
After some usage (couple of hours - depending on how much big is the battery you use) the output voltage of the cells will drop. This is normal, and this will happen like the case with standard batteries. BUT you have that converter hooked up. If the converter needs 12 V to supply an output of 220V ac, if you apply only 10 V (the voltage on the battery has dropped because of usage) it will supply only 180V ac. (an estimation). This is well under 220 v. BUT the shift will still work. Why? Here's the cool part. The shift power charger has a nominal imput voltage of 100-240 V (it is rated on it's sticker as the imput voltage). THIS MEANS IT WILL SUPPLY THE 12 V OUTPUT FOR THE SHIFT AS LONG AS THE INPUT VOLTAGE IS SOMETHING IN THE AREA 100-240 V ac. So the converter supplies 180V but that's ok, the shift will still work. So you use it for a longer period of time. When the battery is flat out and has somewhere around 7 volts the converter will supply somewhere under 100v or will stop to work because the battery will also have not enought current (amps) to run the converter's main circuitry or to supply the shift's power requiests.
There are some things that must be said about the eficiency of this method. First you use 2 converters one will raise the voltage from the external batteries ( - your car converter) and the other will lower the voltage to the 12v required by the shift ( - your shift charger). These, both have an eficiency factor. Because of the tehnology used you will have a general factor of about 85%. The rest will be lost in the transfer as thermal heat or EM field radiation.
Still you should get 30-50% more juice then a similar capacity comercial product :). And it's more cheaper to buy. :p
You may achieve the same results if you buy a converter...aah...and a car. Car batteries will provide some good dozens of hours for the shift to work.