12/24v Battery Schematic

[Steve Acheson]

I was thinking of making my on camera batteries??

[Keith Walters]

I was thinking of making my on camera batteries??

Unfortunately this opens up a serious can of worms.

I presume you want to have some sort of arrangement where two 12V battery packs can be run in parallel of 12V operation or switched to series for 24V operation, and charged with either a 12V or 24V charger.

 

This works well with Lead Acid Gel-Cell batteries because they're perfectly happy to be switched to parallel mode, and in fact I've made up a large number of such packs in the past using a readily available 4-Pole 2-way switches. However, these were strictly "grunt" devices, which allowed long-term operation of the camera, video assist monitor, associated electronics without having to keep changing the batteries.

 

For something you want to mount on a camera, obviously Lead-Acid won't do because of the weight.

Unfortunately, the commonly used Nickel Metal Hydride and Lithium-Ion batteries are nowhere near as tolerant of series/parallel operation and I would not recommend anybody fool around with such an arrangement unless they know exactly what they are doing.

 

One of the many problems is that if the two packs start to get out of balance capacity-wise, the imbalance tends to grow, the exact opposite of what happens with Lead Acid batteries.

 

A safer arrangement would be to have a permanent "store-bought" 24V battery pack and charger, and add a 24V to 12V switchmode stepdown converter. These are widely used to allow standard 12V car accessories to be operated from 24V truck electrical systems and are readily available at a reasonable price.

[Steve Acheson]

I guess I should have said that I wanted to make block batteries... So I would love to use Lead Acid Cells. I would also like to a battery meter inline that you can see.

[Keith Walters]

I guess I should have said that I wanted to make block batteries... So I would love to use Lead Acid Cells. I would also like to a battery meter inline that you can see.

So when you said "making my on camera batteries" you actually meant "making my own camera batteries"?

 

Unfortunately, you listed yourself as "steadicam operator" which tends to imply you'd want lightweight batteries to use "on-camera". ;)

 

I'll see if I can dig out some schematics or draw up some new ones.

 

Lead Acid cells are by far the cheapest and most reliable solution if you don't mind the weight. You can also get a reasonable idea of their state of charge simply from the unloaded terminal voltage, unlike most ther rechargable batery types.