Spektrum DX3r Battery Mod

[BrianG]

There is a thread over at nitrokillers where someone (Jason IIRC) used lipos instead. The problem is that the DX3r wants 6v, and lipos are too low in 1s (3v min and 4.2v max) and too high at anything above LVC in 2s (6v min and 8.4v max) to get the right voltage. Normal radios that take 8 X AAs function just fine on 3s since the voltage of 3s is ~9v min and 12.6v max.

He used a BEC and a low-voltage cutoff/alarm, but that's getting a bit pricey just for a radio battery solution IMO. Not to mention what would happen if the BEC went bad and outputted the full 2s (or higher) battery voltage. Not sure how sensitive these radios are to overvoltage, but 8.4v (2s @ 4.2v/cell) is quite a bit higher than 6v...40% higher to be exact.

[MetalMan]

Originally Posted by BrianG

He used a BEC and a low-voltage cutoff/alarm, but that's getting a bit pricey just for a radio battery solution IMO. Not to mention what would happen if the BEC went bad and outputted the full 2s (or higher) battery voltage. Not sure how sensitive these radios are to overvoltage, but 8.4v (2s @ 4.2v/cell) is quite a bit higher than 6v...40% higher to be exact.

Here we go again . The cost isn't that much - $10 cheap switching BEC, maybe $5 for the components to make your own dead-bug style audible low voltage alarm (schematics are at RC Groups).
The chance of the BEC failing in the TX is MUCH less than if used to power a RX at a higher input voltage. So, you are much more likely to have a fried RX than TX due to switching BEC failure.