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Personal Project electrical question

alanwarrick

Hello all,

 

I am new here. I have a personal project here for the sake of brevity ill refer to as NX Harbor.

 

I have some electrical challenges, there are two major components to this projects that will require a fair bit of power at different draws.

 

One component's supply is listed as a 12v4a(48w) supply, i know for a fact it will not use this much power as it is a generic supply and the important number is the 12v

 

the second one is the challenge, i know for a fact that this device at most uses 15v@1.2a typically at peak.

 

The challenge here is that i want to power both of these off of a single battery bank with between 3-4Ah capacity and is no more than an inch thick.

 

I hope this is a no brainer for someone out there somewhere, and to you, thank you in advance.

  • 0

    Hi Alan,

     

    Unfortunately there isn't enough information  (battery capacity cannot be deduced from an Ah value, unless you specify the voltage of the battery bank; a 1.2V 3AH battery can store ten times less energy than a 12V 3AH battery for example).

    If I make some assumptions, then your goal is possibly unrealistic. 3-4AH at a sufficiently high voltage to make something that consumes 48W, or even half that, for any reasonable amount of time (guessing an hour or longer?) is a large enough capacity to not be a typical off-the-shelf rechargeable battery. A custom one-off battery pack isn't feasible without some experience in building and charging multi-cell batteries, and could be dangerous.

    The easiest way to find a battery is to go to a distributor website and type in your desired max width in the parameters selection box. I did that at farnell.com and this is the result: http://uk.farnell.com/w/c/batteries-chargers/batteries-rechargeable?external-width=20mm|25mm&st=12v+battery

    Just one 12V battery there slightly begins to approach the requirement, but has a 2AH rating.

    Since you require 12V and 15V, one approach could be to select a 12V rechargeable battery, since it will directly be able to power one of your components (use a fuse in-line). For the 15V device, you could use a 'boost converter' or 'DC-DC converter', such as this one:

    JCK2012S15 XP POWER, Isolated Board Mount DC/DC Converter, 2:1 Input, 1 Output, 20 W, 15 V, 1.33 A | Farnell element14

    It will convert a 12V supply to a 15V one, at up to 1.3A which will cover 1.2A peaks. Again, to find these, the parameters can be entered on the distributor website.

  • 0

    Hi Alan,

     

      has given you some great ideas. One other thing that would be a good idea is to use an ammeter to get a real world measurement of the current draw of each of the two devices. One other thing to think about is that depending on what type of device we are talking about you may find that the 12 volt device can tolerate 13.5 volts and the 15 volt device can also tolerate 13.5 volts. If they will operate satisfactorily at 13.5 volts you are back to a one voltage solution which might be easier as this is very close to (2) Lithium  or (2) NiMH battery packs in series.

    John