7 Eleven 9 Volt Battery

[Eri Pfaff]

Ifyou want to use a 3 cell LiPo, get a switching regulator and attach to the 5 volt line of your arduino.

These regulators can be found cheap on ebay for instance: 2014 New Waterproof DC Converter 12V Step Down to 5V 3A 15W Power Supply Module eBay

Hi guys,

Thanks for the reply. Chagrin said that the arduino already has about the same voltage regulator onboard, then can I just plug in a 7.4v 3cell lipo directly to the board? Newest RC Drones, RC Spy Camera Drone, RC Quadcopters, RC Helicopters RC Drone RC MultiRotor RC Quadcopter RC UAV Drones Camera Online SuperStore Sales Lowest Prices

thank you for the link. I was actually looking at that too. I usually power my device with a 5v wall outlet adapter, but I'm going to be using the device on-the-go and I was just wondering if the 7.4v will fry my board or not. I'm new to this.

Either can be used to power an arduino board via it's external DC power supply connector or Vin pin, but the 2 cell battery will be more efficient because of the use of a linear voltage regulator on the arduino board.

You should consider adding a fuse to the LiPo supply since those batteries can supply huge currents

if there is a short - the fuse prevents the wiring from melting / catching fire. Add an inline fuse to the

+ve supply close to the battery.

My truck, 2007 Silverado, 215k miles, flashed a dash message of SERVICE CHARGING SYSTEM this morning while driving kids to school. These trucks are a bit known for weird electrical stuff but I haven't personally had a problem with mine. Yet. The light went off after dropping off the kids, V at 14 on the gauge. Drove to Home Depot. When I started the truck again the service message was back and V were 11-12V. Got safely home and the battery reads 12V whether the truck is on or off and it reads 11.08 at the alternator when the truck is running. Classic case of bad alternator? Or is there something else to chase?

There's always some tiny chance that the controls side of things is not running the alternator properly but usually the alternator itself is bad. If you're actually seeing a lower voltage at the charging post of the alternator then you are at the battery terminals, that probably means that one of the diodes in the alternator has failed and is actually sucking current OUT of the battery. If it's dropping over 1 volt on that charge wire between the battery and the alternator it's probably getting warm too. That would definitely be a bad alternator.

First thing to do is to clean all battery cable connections, at both ends of each cable. Take them off and clean the insides and underneath each connection. Even if that's not the root issue, it can't hurt. Then if you have a handheld voltmeter, measure voltage at the battery terminals. With the engine off it should read 12.5V or so, with the engine running it should be 13.5 to 14V or so. If you don't get the higher voltage when the engine is running the charging system isn't working - whether it's just the voltage regulator or it's the alternator.

buddy of mine posted same failure this morning on his 2007 Suburban, at 208k miles. tinfoil hatters will call it a software issue. the rest of us will say "holy E36 M3, that alternator's been spinning for over 200k miles. it owes you nothing."

Someone here recently pointed me to research voltage drop testing. I'll pass that recommendation along to you. It can really help with troubleshooting in situ if you don't want to just pull the ale and have it tested off the truck.

Easy test to see if it's a case of worn out alternator brushes: with the truck running and the alternator not charging, take something metal and hit the alternator case firmly. If the alternator suddenly starts working, it's the brushes getting to end of life and losing contact with the slip rings.

Polished all of the terminals and grounds and got the voltage to read an even 11.54 both at the battery and the alternator. Cables seem good anyway. Alternator is off and I'm headed to the parts store.

Yeah, I'd say the alternator brushes are worn, so the springs are probably right at the end of their travel. When the parts store tested it, they were probably making contact so it put out good power. At some point in use, they bounce slightly and lose contact because the springs can't push them back against the slip rings properly. Hitting the alternator knocks the brushes around and is sometimes enough for them to start making contact again.

I suppose another possibility could be a duff battery - if it has a dead cell it could be pulling the voltage down. On the other hand, if it had a dead cell it probably wouldn't be able to start the truck...

O'Reilley's have been hit or miss for me. Let's just say I'm glad they come with a lifetime warranty. Napa has a better reputation. If you don't mind potentially having to do it again in a year, try the O'Reilley's ones with a LT warranty.

SO there are only 3 wires that go to the alternator: The charge wire, the field control wire, and the voltage sense wire. You already know by deduction that the charge wire is fine because if there was no connection between the battery and the charge post you wouldnt see the 11.54 there. The other two small wires on the connector could be issues, though. I would start by just checking that the terminals actually make a good connection to the alternator when you plug it in, and after that i would probably check continuity from the alternator end to the PCM end. There's also still a chance that its just worn brushes so i guess the first thing i would do is smack the back end of the alternator while the truck is running and see if the voltage moves.

The recommended input voltage of the Arduino Uno when powered through the DC jack or VIN pin is 7 - 12,V, but that the full range is 6 - 20V so it is probably fine for you to just directly connect one of those LiPo batteries to the board even though the voltage of the fully charged 11V battery will be a little above 12V.

Let's put it this way... There is a reason why electronics (including things like servos) have a min and max voltage rating... Over volt them and bad things can happen... My advice is buy a battery that matches your servos or use a voltage reg to bring down the 11.1v to 7.4v

Search for the BUCK regulators or DC to DC stepdown voltage regulator on ebay. Be carefull to put one regulator to one servo. They are cheap. If you put too many servos to that regulator above it's max amp allowance, it will get hot and come apart because it is mostly surface mount technology.

According to the website, the regulators have solder points that headers can be soldered to or terminals blocks can be soldered in and then wires can be inserted into the blocks and screws hold the wires by tightening them. Both are included with the regulator.

The issues are expense and your input voltage. One for each servo can turn into a huge amount of money. All of the inline voltage regulators will only step 6v or 7.4v down to 5 to 5.2 volts that I have run across.

Everything you asked for in a converter is in the first link Doombot pointed you to. With that unit you will not have to solder or even use a volt meter to know how much voltage your outputting. It's small also 2.5" x 1.5".

It that unit is too big then the Pololu converters are great units. Cant go wrong with Pololu. However you'll have to learn how to solder to attach the header pin. You'll also need to get the proper Molex connectors or jumpers to attach to the header pins. Some people like to solder the power wires directly to the board to avoid using connectors but I think that's a bad idea. How are you going to disconnect if you need to change something.

A word of advice and I don't mean to seem condescending. If your planning on building robots you really need to learn how to solder and use a multi meter. The robots you will be able to buy through the store here at EZ Robots will be mostly plug and play. However if you plan on building your own from scratch or other platform you may need some more advanced skills. Learning simple soldering and a basic understanding of electricity and electronics will open many doors for you and take you on some real cool journeys in robotics. Youtube has thousands of vids on most anything you will need to know about these two topics. At the Instructables website there are millions of tutorials also.

Here's that link:Instructables

Yes, very easy. Just be careful when you tighten down the set screws. Hold the connector with your fingers when you tighten it down and don't over do it. It's easy to twist the connector and crack the solder joint underneath. If that happens you will have no or intermittent power. The only way to fix that is to reflow the solder joint.

EDIT: one more thing. Make sure you don't attach anything that will draw more then 3 amps max to this unit. If you do you will burn it out. You may need more then one if your servos (all added together) draw more then this can provide. Think of it like sucking all the air out of a plastic bottle. If you do this and make a vacuum the bottle will crunch.

As far as the extra wire: that's the signal wire that go directly from the outside pin of one digital port of the EZB to the servo signal wire. You run the power wires (+ and -) from your power source (the EZB it's self or and external power supply like a battery) through this unit and to the servo.

Two different things. Simplistically, The amps are the power (electrons) that runs the motor and the voltage is the pressure that pushes the electrons through the circuit. Imagine shaking up a bottle of soda and uncorking it. The Amps would be the soda and the pressure pushing it out of the bottle would be the voltage. There's really a little more to it then that but you should get the idea for this description. It's really not a compacted theory and one worth learning about.

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