6 volt charging

[uphill]

anybody out there know how to charge a tt from a 6v battery. The tt charger says it outputs 5.5v but when i tried this from a socket i wired into my old classic it doesn't work

 

[Andy_P]

The standard TT chargers are expecting between 12-24 Volts input and output a nominal 5 Volts.

Wait for other replies, as others may disagree, but I think the TomTom should cope OK with being fed with 6 Volts directly from your battery. But that is at the top of it's acceptable range and might make the safety diode in theTT run a bit hot or go pop.


So you would need to make a cable from the battery to whatever plug your TT model requires (usually a mini USB with power on the outermost pins - you'll need to check the polarity).

To do it properly, you would want to add two diodes in series (each will drop about 0.7 V), or a little zener diode dropper circuit, or use a "low dropout" power regulator chip such as the LM2940, built into the cable, to get you down to a guaranteed 5V.

If you think your battery may ever produce more than 6V then I would not risk it without the above circuit. For example, if you have a charger for that 6V battery, it is likely to produce more than 6V so it should never be used at the same time as trying to power the TomTom unless you have added that power reduction circuit.

Edit: Google "power USB from 6V" for some more circuit ideas.