Car Battery Charging

[mapes12]

I've been doing some searching to look for a solution for charging my X9D at the field. I take a 12v car battery with me for charging my lipos via a smart charger. My understanding is that the Taranis has an inbuilt charger and another smart charger isn't needed (and can do damage). So, my thinking was to simply hook up a charging lead with crocodile clips to my 12v car battery and plug it into the charging socket on the Taranis. I've got a suitable jack/connector (see pic).

And according to this this post: http://www.frsky-rc.com/support/Details.php?fqa_id=49 the charging range is 6v to 15v so no probs there.

And I understand that polarity shouldn't be an issue as this is taken care of by the Taranis inbuilt charger, in case I accidentally connect the leads to the battery the wrong way round.

Can anyone see any issues with my simple approach or have I missed something?

Mark

[MikeB]

I don't think that post understood your question. The battery is 7.2V (nominal), so no way will it charge from 6V! The radio will work from 6V upwards though.
Yes, the battery will charge from a 12V lead acid battery as long as it is not itself being charged so it exceeds 13V.

Mike.

[mapes12]

Thanks Mike.

Out of interest I've just checked the wall charger that came with my Taranis. It's output is rated at 13.5v, 0.5amps and centre pin +ve polarity. I've put my multi meter across the output jack and it's reading 13.34v. Slightly above the recommended 13v but it works without any issues.

[MikeB]

The Taranis internal charger has a current regulator in it, the wall device is just a voltage supply. The worst that happens if the 'charger' voltage is not high enough is the charge current is lower than expected. If the 'charger' voltage is too high, then some internal components become hot.

When using your car battery, you could try measuring the current it is supplying when in use.

Mike.