### Author Topic: Battery for Axon  (Read 1694 times)

0 Members and 1 Guest are viewing this topic.

#### Kylepowers

• Full Member
• Posts: 117
##### Battery for Axon
« on: April 03, 2011, 09:53:37 AM »
I was wondering if you can use 4 regular AA's if i make a header connection for them. Will that work?

#### MikeK

• Full Member
• Posts: 97
##### Re: Battery for Axon
« Reply #1 on: April 03, 2011, 09:57:27 AM »
According to the datasheet the minimum voltage is 5.35V.  4 x 1.5 = 6V, so you should be fine.

#### Kylepowers

• Full Member
• Posts: 117
##### Re: Battery for Axon
« Reply #2 on: April 03, 2011, 12:00:06 PM »
Ok our is there a battery pack I can get?

• Supreme Robot
• Posts: 11,702
##### Re: Battery for Axon
« Reply #3 on: April 04, 2011, 07:01:38 AM »

#### Kylepowers

• Full Member
• Posts: 117
##### Re: Battery for Axon
« Reply #4 on: April 04, 2011, 05:36:10 PM »
How many mA's do 4 AAs have? So I can use webbot for programing.

#### rbtying

• Supreme Robot
• Posts: 452
##### Re: Battery for Axon
« Reply #5 on: April 04, 2011, 06:56:35 PM »
AA's don't have mA's, they have mAh (mA is a milliamp, a measure of current, while mAh is a milliamp-hour, a measure of current over time, aka capacity).

You will want to read the side of your batteries, which should mention the capacity, but a rule of thumb is something like 1500mAh per cell.

If you put the AA's in series (in order to get 6v), your final battery pack will have a nominal voltage of 6v and a capacity of 1500mAh.

• Supreme Robot
• Posts: 11,702
##### Re: Battery for Axon
« Reply #6 on: April 04, 2011, 08:22:56 PM »
Actually, batteries have both mA's and mAh's.

mA - Max amount of current it can supply at any time.
mAh - Max amount of time it can supply X amount of current.

To find out what it has, you will need to read the datasheet

#### Webbot

• Expert Roboticist
• Supreme Robot
• Posts: 2,165
##### Re: Battery for Axon
« Reply #7 on: April 04, 2011, 08:42:00 PM »
I like/use these: http://www.vapextech.co.uk/acatalog/copy_of_High_Power_Model_Control_Batteries.html

They have a Futaba connector so you can plug it into the Axon switch thingy (although you may need to use a nail file to get rid of some plastic lump on the connector - no worries its easy to do).

6V is good for most stuff (or up to 7.2V if your servos can cope with those higher voltages).

For general testing then buy something with as high an maH rating as you can afford. A 3300maH battery can provide 3.3A for one hour. Saves constantly recharging or wasting time testing only to find your battery is flat!  If you are a busy person then buy two (one in use, and one charging). You may also need a charger.
In total not cheap - but its good to just be able to plug in a battery and know that its up to the job. On the bright side - most stuff needs batteries/charges so if your interest fizzles out then I'm sure you'll find a use for the batteries !!!

If your circuit requires loads of current (eg you've got 8+ servos say) then you will need to double check the peak current the battery pack can provide in one hit.

For a final robot then you may want a bigger/smaller battery taking stuff like weight into account.
Webbot Home: http://webbot.org.uk/
WebbotLib online docs: http://webbot.org.uk/WebbotLibDocs
If your in the neighbourhood: http://www.hovinghamspa.co.uk

#### Kylepowers

• Full Member
• Posts: 117
##### Re: Battery for Axon
« Reply #8 on: April 04, 2011, 09:44:20 PM »
Thanks for the suggestion
I like/use these: http://www.vapextech.co.uk/acatalog/copy_of_High_Power_Model_Control_Batteries.html

They have a Futaba connector so you can plug it into the Axon switch thingy (although you may need to use a nail file to get rid of some plastic lump on the connector - no worries its easy to do).

6V is good for most stuff (or up to 7.2V if your servos can cope with those higher voltages).

For general testing then buy something with as high an maH rating as you can afford. A 3300maH battery can provide 3.3A for one hour. Saves constantly recharging or wasting time testing only to find your battery is flat!  If you are a busy person then buy two (one in use, and one charging). You may also need a charger.
In total not cheap - but its good to just be able to plug in a battery and know that its up to the job. On the bright side - most stuff needs batteries/charges so if your interest fizzles out then I'm sure you'll find a use for the batteries !!!

If your circuit requires loads of current (eg you've got 8+ servos say) then you will need to double check the peak current the battery pack can provide in one hit.

For a final robot then you may want a bigger/smaller battery taking stuff like weight into account.

But i dont live in the UK. If i could find something in the US that would be better. Shipping cost get high when it comes in from over seas.

#### Soeren

• Supreme Robot
• Posts: 4,672
##### Re: Battery for Axon
« Reply #9 on: April 04, 2011, 10:31:11 PM »
Hi,

A 3300maH battery can provide 3.3A for one hour.
No, it can supply 660mA for 5 hours giving the capacity of 3.3Ah. Raising the current lowers the capacity and v.v. At (1)C it will be at least 5% lower (and capacity ratings depends on the cells being broken in correctly and being both charged and discharged under optimum conditions and what not).

Further, the nominal capacity is the average capacity for the entire production batch and while I haven't got any precise documentation on what tolerances they allow, I have read some data indicating a +/-10% tolerance on capacity, which makes buying (or DIY'ing) batteries build from "paired" cells a prudent choice for high current apps.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Engineering is based on numbers - not adjectives

#### Webbot

• Expert Roboticist
• Supreme Robot
• Posts: 2,165
##### Re: Battery for Axon
« Reply #10 on: April 06, 2011, 01:08:04 PM »
Hi,

A 3300maH battery can provide 3.3A for one hour.
No, it can supply 660mA for 5 hours giving the capacity of 3.3Ah. Raising the current lowers the capacity and v.v. At (1)C it will be at least 5% lower (and capacity ratings depends on the cells being broken in correctly and being both charged and discharged under optimum conditions and what not).

Further, the nominal capacity is the average capacity for the entire production batch and while I haven't got any precise documentation on what tolerances they allow, I have read some data indicating a +/-10% tolerance on capacity, which makes buying (or DIY'ing) batteries build from "paired" cells a prudent choice for high current apps.

I think you are being overly pedantic!! All I was getting at is to divide the 'maH' of your battery by the 'ma' required by your board to find the number of hours the battery will last. Of course if you overly stress the battery then it falls apart ie 3300mah cannot supply 1000 Amps consistently even for a very short time. I was only trying to give the generally understood meaning of the unit of measure not a science lecture - ie voltage is one thing but the capacity is another.

Check the OP - if he is talking about AA batteries then he cannot be trying to drive a life sized tank in Arctic conditions !!

« Last Edit: April 06, 2011, 01:11:10 PM by Webbot »
Webbot Home: http://webbot.org.uk/
WebbotLib online docs: http://webbot.org.uk/WebbotLibDocs
If your in the neighbourhood: http://www.hovinghamspa.co.uk

#### Kylepowers

• Full Member
• Posts: 117
##### Re: Battery for Axon
« Reply #11 on: April 06, 2011, 08:37:07 PM »
How many amps do 4 AA's produce. I want to use this motor controller. http://www.robotshop.com/solarbotics-l298-motor-driver-kit-2.html for my motors. I can use two seperate battery packs if needed.

• Supreme Robot
• Posts: 11,702
##### Re: Battery for Axon
« Reply #12 on: April 06, 2011, 09:05:18 PM »
How many amps do 4 AA's produce.
Check the datasheet

#### Soeren

• Supreme Robot
• Posts: 4,672
##### Re: Battery for Axon
« Reply #13 on: April 07, 2011, 10:16:07 PM »
Hi,

I think you are being overly pedantic!!
If that's your term for precision in engineering, then yes.

All I was getting at is to divide the 'maH' of your battery by the 'ma' required by your board to find the number of hours the battery will last.
Sure, but you find it too pedantic to include the full facts?
(Which is that it isn't that simple).

Of course if you overly stress the battery then it falls apart ie 3300mah cannot supply 1000 Amps consistently even for a very short time.
A 3300mAh cannot supply 3300 mA for 1 hour. That's the point and nobody (but you) mentioned 1kA, which is of course impossible due to the Ri of the cell(s) and terminations.

A lot of people think they have gotten a bad battery when they cannot get eg. 3.3A for 1 hour from a 3.3Ah battery, so I think it's quite important to underscore how the nominal capacity is reached and that there's quite some tolerance on the rating.

I was only trying to give the generally understood meaning of the unit of measure not a science lecture - ie voltage is one thing but the capacity is another.
I was only trying to give the real engineering facts, not a generalized miscomprehension.

Check the OP - if he is talking about AA batteries then he cannot be trying to drive a life sized tank in Arctic conditions !!
You sure didn't get my point.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Engineering is based on numbers - not adjectives