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If you can handle 7.4 volts, I would recommend looking into Lithium Polymer, LiPo, batteries. They range is size and wieght depending on the amperage you need but they are generally much lighter than a Nihm battery of the same rating would be. Also, they are generally able to handle larger current draws. I am currently using one to power my $50 robot MCU while I have another 4.8v pack powering the servos. once I figure out what best way to regulate this power for servos and such I will be using one for my servos too.Mark
I am using Futaba modified servos by myself. I run them at 7.2V from a 6 AA pack of NiMH. They work fine, no overheating. 7.4V will also work. I want to get the whole robot running from a single battery of LiPo (2 cells in series), but I need to be able to recharge them together, not separate. I hate to have to take out batteries to put them to charge and then back. I just want to plug the robot to the charger, and when that will be possible, have it autocharge.
Quote from: Ro-Bot-X on August 20, 2008, 12:53:57 PMI am using Futaba modified servos by myself. I run them at 7.2V from a 6 AA pack of NiMH. They work fine, no overheating. 7.4V will also work. I want to get the whole robot running from a single battery of LiPo (2 cells in series), but I need to be able to recharge them together, not separate. I hate to have to take out batteries to put them to charge and then back. I just want to plug the robot to the charger, and when that will be possible, have it autocharge.There are tons of LiPo battery chargers out there. In fact, for my helicopter batteries, all LiPos, I use an Astro Flight charger and a cell balancer. The charger hooks up to the balancer and the balancer hooks up to the balancing wire on the LiPos. The balancer controls the amps going to each cell of the battery making sure that all cells are charged to the same voltage. All in all it takes about an hour, sometimes less, to charge a LiPo battery with a decent charger. No tearing apart battery packs or taking them out of a robot, assuming you have access to the balancing wire or make some custom interface.That's what I'm aiming for, one battery to power everything. From the datasheet file, the axon can't handle 7.2v so I guess Lithium batteries won't work for me.
Absolute minimum required voltage is 5.35V, while the recommended battery voltage is 6V to 7.2V. Maximum voltage at 20V, however most servos cannot handle above 7.2V before being damaged.
Axon is using a Low Dropout voltage regulator so it works with low voltages, like the datasheet says. To use it with higher voltages you better change the voltage regulator to a regular 7805, because this one will disipate less heat (greater voltage drop on it and different arhitecture inside), but you will still need a heat sink.
QuoteAxon is using a Low Dropout voltage regulator so it works with low voltages, like the datasheet says. To use it with higher voltages you better change the voltage regulator to a regular 7805, because this one will disipate less heat (greater voltage drop on it and different arhitecture inside), but you will still need a heat sink.That depends on how much current you take from the regulated power bus (not servo power buses).