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superchiku
04-19-2008, 12:51 AM
Providing power to my robot is really getting on my nerves , I have been searching far and wide for the battery i need but so far all i have found are batteries which are way below my requirement...

My robot has the following power draw

2 dc motors rated at 12v 550 ma
1 servo rated at 1A
the controller board

so i need a battery pack which should have the following ratings

12v, 1700 mah battery pack min

so any of you having any idea where i can find this battery pack and its equivalent charger then please do post in this forum ...

****please do not post abt international shipments as it will be way above my budget, please give a more indian base solution :wink:

ppppking04
04-19-2008, 09:44 AM
You dont necessarily need a battery pack with 1700mAh+
There is a difference between the Ah rating of a battery and the maximum discharge current (usually rated something in terms of C i.e. 5C, 10C) of a battery.

The mAh rating of a battery decides the run-time of the battery whereas the discharge current capacity is the crucial factor which decides how much maximum current will the battery be able to supply without dropping much voltage (or getting loaded). This depends on a lot of factors including the chemistry of your cells and the internal resistance.

In your case, you say your total current consumption is 2200mAh. Now, a battery with a lesser mAh but a higher discharge current, say 700mAh and 5C (700 x 5 = 3500mAh) will serve your purpose while another battery, say 1700mAh and 1C will not.
In general, lead acid batteries provide a much higher discharge current than others. Ni-Mh, though mostly preferred, do not usually have a higher discharge current. So you might see them getting loaded easily. Li-ion/Li-poly are in general difficult to handle, but most of them are rated for a higher discharge current capacity.

Another important point, the mAh are hugely misunderstood. We generally assume a battery rating of say 1700mAh means a continuous discharge of 1700mAh for one hour. THIS IS NOT SO! The complete battery rating is 1700mAh over 20 hours. This basically means, that the battery will be able to provide 1700/20 = 85mAh continuously for 20 hours. If you try to discharge them at 1700mAh, you ll find that they ll get discharged in a much lesser time.

Sorry I couldn't help you regarding the actual batteries to buy. But I hope I have given you enough pointers to make a better choice.

shashak
04-19-2008, 12:53 PM
@ ppppking04

We generally assume a battery rating of say 1700mAh means a continuous discharge of 1700mAh for one hour. THIS IS NOT SO! The complete battery rating is 1700mAh over 20 hours.


can you explain why it is 20 hour. is it empirical, or dependent on batteries.

@superchiku
you can use Ni-Mh cells use for digi cams and club to make it a battery

or try with these http://triindia.co.in/shop/product_info.php?cPath=33&products_id=60

superchiku
04-19-2008, 04:18 PM
lead acid batteries will be quite bulky for my application so i cant go with them

do u have any other alternatives.. please specify

suppose i use nicd batteries at 700 mah that are available in the market, will they be able to provide sufficient power??

allbits
04-19-2008, 06:34 PM
Nicd - put them in parallel. but then you need 12 V - which means you will need 10 of them, and 20 of them if you put it in parallel.

or, use Li ion.. its available with robokits. etc, , but then you might need to get a charger. (You can charge at home, but yo should be able to monitor the current., and you should know what you are doing...
)but the good thing, is, you need only 3 of them to get your 12V - good in terms of weight, & performance.

I have been using them, and will be using them, till i get my Lipo s. :D

superchiku
04-19-2008, 09:26 PM
the problem remains with the charger , i need the charger do u have any products where i can get both the battery and the charger

superchiku
04-20-2008, 08:17 PM
so anybody know where to get the equivalent battery charger for the new 12.6 v 2000 mah li-ion battery available in robokits.org ???

without the charger there is no use buying the battery...

jitun
04-21-2008, 05:55 PM
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1037,C1078,C1 089,P1495

use this charger from linear technology. It can charge any number of cells up to 30v.

Unlike TI's BQ2057 it's even available in 8 PIN DIP. So you can easily use it in ur PCBt.

superchiku
04-21-2008, 11:23 PM
cool.. but still there are problems

superchiku
04-21-2008, 11:32 PM
the problem is that its quite difficult to get a 25v wall adapter nad the inductor coils from coltronics also when it says 30 v it meant fot NimH or NIcd not for lithium ion coz you can see in the graph that the charging voltage graph for a 2 cell 8.4 volt lithium-ion battery is given , so thats the problem...

jitun
04-22-2008, 01:37 AM
1. No they can charge Li-Ion batteries. Though its not give in the graph the strategy for charging followed by this IC is favorable to charge a Li-Ion battery.

2. You can get the 33uH inductor from "coilcraft". Ask for free samples from them. I have successfully used them in past in white LED driving circuits.

3. For power supply if you cant find a 25v wall supply get a printer power supply. It can provide you upto 32VDC

superchiku
04-22-2008, 07:46 PM
do you think the ic can handle 12.6 v li-ion

jitun
04-23-2008, 01:01 AM
Yes it can charge 12.6 v Li-ion

superchiku
04-23-2008, 11:13 AM
good i have ordered samples for LT1512 and coilcraft, hope they arrive soon

jitun
04-23-2008, 01:20 PM
Coilcraft may call you and inquire further details. Actually they called me. But they have a good service.

asimov_18
04-23-2008, 08:20 PM
Hi frnds......

I think its not really a good practise ti ask companies for free samples...as many a times because of this companies black list many countries and its hard to get samples when actually needed......

This solution to chrging li-poly battery exixts its very cheap indeed....


one can buy an external li-on charger we get these days mobil battery charges at mobil repair shops. These might not charge battery at very high charging current but seem preety good for the price I piked up mine for 60 Rs att alminton rd.......these are chinese good and when I opend it up I realizes it had a switching mode power supply...a small cob ic for charging the lithium ion battery...two small to-92 transistor (one for smps and one for chagring the battery...I gess the second transistor would be a switching transistor)....there were a 4 led and a couple of zenner and 4148 diodes...along with that.....se the pic of his charger .

http://rohittkhanna.googlepages.com/lithiumbatterycharger

pratikmahale
04-23-2008, 10:48 PM
Why ask for free sample ?

Go thorough this link for li-on charger circuit using low cost LM 317 IC

http://shdesigns.org/lionchg.html

Regards,

pratik

superchiku
04-23-2008, 11:49 PM
hi asimov and pratik,

well the problem is that the charger asimov told about isnt available everywhere and also i dont think it can charge 12.6 v 2000 mah li-ion battery ...

pratik its a nice link you have given since i have never used it do u think it will be reliable and also will it be able to charge the above battery tyoe i told you about without exploding it ??

pratikmahale
04-24-2008, 12:31 AM
Hi,

If u don’t wants to take a risk and build your own li-on battery charger then
You can buy charger from Nex Robotics
But they have only 8.4 v battery charger

http://nex-robotics.com/viewCategoryList.php?cid=8

Just ask robokits for 12.6 v 2000mah li-on battery charger as they sell the battery they mite have charger for it also .


Regards,
pratik

superchiku
04-24-2008, 12:54 AM
ill try to do that i really dont trust a custom made charger its just too risky it would be a huge wastage if there is an odd connection in the circuit so i needed some links from where i can buy the charger for li-ion

Nimh would also do like 12v 2000 mah nimh with charger but i guess u cant find them online in india

hesslei
12-03-2008, 02:58 PM
When a battery is recharged at an excessive rate, an explosive gas mixture of hydrogen and oxygen may be produced faster than it can escape from within the walls of the battery, leading to pressure build-up and the possibility of the battery case bursting. In extreme cases, the battery acid may spray violently from the casing of the battery and cause injury.

---------------------------
hesslei.........

SEO (http://www.drivenwide.com)

asimov_18
01-11-2009, 12:09 PM
Hi all,
First and foremost Lithium Ion batteries are sensitive and dont take abuse....the result can be catastrophic. By cheap chargers I mean the hacked LM317 circuits. Its simple to build a LI-On charger but use some precision voltage references like TL431 and come current sensing precision resistors and comparators for designing a constant current charger(1C at max) with termination at precise 4.2V followed by constant voltage charging till current drops to 0.2C(take some security margin in this).

asimov

tpsbpl
10-30-2010, 07:25 PM
How to select suitable Battery for my robot ? -Here are few tips

First calculate the total current on full load (in running condition of your robot)
say for example it draws 500mA, then a 700mAH Battery will ideally give backup for 1hrs 15 Min or roughly in practical 1 Hrs, then after it will not stop working immediately but the rated voltage fill fall moderately -fast

It is very important that the measured current of boat in full load (Running condetion and all associated mechanism in operation)

Generally any standard geared motor takes 80-100 mA at 12V but in load conditions it may take upto 200-600 mA ,

Generally battery (lead-acid) comes into 6V 1.3AH (1300mAH)(wight is aprox 160gms),6V 4.5AH (wight is aprox 900gms),12V 1.3AH (wight is aprox 290gms),12V 7.5AH (wight is aprox 2.25KG), 12V-120AH ...... Even More

NimH battery comes 1.2V -700mAH,1000mAH,1300mAH,2300mAH,2500mAH (wight is aprox 50gms),
you will need 10 such battery connected in series so that it becomes 12V ,

Important
*If you use 700mAH battery in series (say 10 Nos) total will be 12V-700mAH
*dont mix different mAH battery
* Never use Nokia or other mobile battery , it may give you bad experiance
* China made ordinary batteries are not reliable (it may sows you full voltage in no load - but as soon you connect it to your bot or any other load it may show 10-20% of rated voltage -12V become 1.2-2.4 V
......
further study
http://onlinetps.com/forum/index.php?topic=29.0

Ulhas
10-30-2010, 08:19 PM
Very simple Lithium Ion, Lithium Poly Charge Circuit

http://shdesigns.org/lionchg.html

tpsbpl
10-30-2010, 09:29 PM
Very simple Lithium Ion, Lithium Poly Charge Circuit

http://shdesigns.org/lionchg.html

Good one, nice & simple design

rahulcreations
11-08-2010, 01:11 PM
Why to spend so much money on batteries for micromouse or any other robots, when china mobile batteries works extremely well and are cheaply available? I Have used four such batteries to make a power supply of 16V when fully charged. Few batteries also have very large current capacity, around 6 Amp/hr and I have such batteries. Just go for it, cheaper and yet effective solution.

allbits
11-08-2010, 06:12 PM
6AH mobile battery??
:eek:

rahulcreations
11-08-2010, 06:31 PM
yup i still have it....it was quite surprising to me for the frst time but ultimately seeing is believing.

docel
11-08-2010, 07:14 PM
Dont fool around with Li-ion / Li-Poly batteries.
They are quite dangerous and explode with authorized hi-tech ( expensive) chargers itself.
Cheap / self made chargers should not be used at all.

Remember this - you may cause damage and physical harm to innocent people because of your stupidity.

You have no right to do that.

Ulhas
11-08-2010, 07:48 PM
Why to spend so much money on batteries for micromouse or any other robots, when china mobile batteries works extremely well and are cheaply available? I Have used four such batteries to make a power supply of 16V when fully charged. Few batteries also have very large current capacity, around 6 Amp/hr and I have such batteries. Just go for it, cheaper and yet effective solution.

To get 16 V from mobile battery you must connect 4 seperate batteries each 4 VDC in series, In such combination Ah rating of this battery pack still remains unchanged of that of single battery itself or else your single battery must be rated for 4VDC ,6 Ah. 800mAh battery is normally availlable in many nokia handset, i can guess in your case it may be 1500mAh. Comparatively size wise if what you are saying is right then size of your battery pack will be of cosiderably bigger for micromouse

Is it So?

Any way what is the cost of your battery?

rahulcreations
11-08-2010, 10:39 PM
To get 16 V from mobile battery you must connect 4 seperate batteries each 4 VDC in series, In such combination Ah rating of this battery pack still remains unchanged of that of single battery itself or else your single battery must be rated for 4VDC ,6 Ah. 800mAh battery is normally availlable in many nokia handset, i can guess in your case it may be 1500mAh. Comparatively size wise if what you are saying is right then size of your battery pack will be of cosiderably bigger for micromouse

Is it So?

Any way what is the cost of your battery?
I am very well aware of series and parallel connections of batteries. 6Ah is the rating of a single battery. So total series current will remain definitely the same. As far as size is concerned, it is just somewhat larger than that of nokia 800mAh battery. Not larger for micromouse. You can easily find batteries of around 2.5mAh in China mobiles or few new brand mobiles having like micromax, spice, etc. You may have a look at my micromouse, unfortunately I don't have any separate picture of those batteries.
http://images.orkut.com/orkut/photos/OgAAAOjW2UEIoh5vCw2rHr_z0M0FeSTGdMu0kMwHDQAiuTSny7 vSwvLS3P-otRk7zqJB4Uib5AiIlfzyy5-xbeUcwswAm1T1UJjEXZYjnmDFRnHF3oxkLwh5POii.jpg

I got that battery at Rs. 70, a year back, but yes after bargaining :).

vikas
11-08-2010, 11:34 PM
6 Ah , 16V and little larger than nokia batteries ... hmm . Do you have any pics ?

The specs you are posting are really good if they do exists. IF you cant find pics point us to any pics on the web ... Maybe ill buy a few to test.

rahulcreations
11-08-2010, 11:46 PM
6 Ah , 16V and little larger than nokia batteries ... hmm . Do you have any pics ?

The specs you are posting are really good if they do exists. IF you cant find pics point us to any pics on the web ... Maybe ill buy a few to test.
Well, as I mentioned earlier I dont have any pics of batteries. I have those batteries but may be lying somewhere in my robotics bag, which is closed since last 3 months. And at present I dont have that time to open that old stuff. But in the micromouse picture posted above, the batteries can be seen slightly.
Even if you go and search in any mobile shop you will surely get such batteries. (Note - 16V by making a series combination of four Li-Ion Batteries).

shobhitkukreti
11-09-2010, 10:13 AM
How can you be sure that the chinese batteries, do deliver 6AH. Playing with Li-ion/LIPo isn't safe either if you do not charge them properly

allbits
11-09-2010, 10:53 AM
I can see some misleading here.

For a single cell Li-Ion to deliver 6AH, the size has to be BIGGER. Remember, it is NOT a LIPO. And if that is a mobile phone battery, It will not be 6AH, and it definitely will not be @ 70 Rupees.

If it really is, I am quite sure it would have taken the world by now. @70, I would buy as much as I can buy.

may be, you should find that out and take a pic and post it here, just to prove your point. If that is the case, I will buy them @200/piece.

rahulcreations
11-09-2010, 12:02 PM
How can you be sure that the chinese batteries, do deliver 6AH. Playing with Li-ion/LIPo isn't safe either if you do not charge them properly
6Ah cannot be guaranteed since its finally china made, but it was much efficient to drive my micromouse and few other robots including RC Car which had 4 DC geared motors, each working on 12V. Charging Li-ion/Po batteries with the mobile chargers is quite safe.

rahulcreations
11-09-2010, 12:03 PM
I can see some misleading here.

For a single cell Li-Ion to deliver 6AH, the size has to be BIGGER. Remember, it is NOT a LIPO. And if that is a mobile phone battery, It will not be 6AH, and it definitely will not be @ 70 Rupees.

If it really is, I am quite sure it would have taken the world by now. @70, I would buy as much as I can buy.

may be, you should find that out and take a pic and post it here, just to prove your point. If that is the case, I will buy them @200/piece.
I will try finding it out. I am not here for marketing of those batteries or any business, so it doesn't matter how much u can pay for it.

pratheek
11-09-2010, 05:03 PM
I have had really bad experiences with Chinese mobile batteries. The batteries I had bought had a poor life. Li-ion batteries have a short life of a few years, but the current capacity of the Chinese batteries started decreasing only after a few chargers. I am not generalizing the topic, by saying all China batteries have a poor life, just that the batteries I used had a really short life.

Also, most recent handycam and digicam batteries come with li-ion and li-poly batteries. And they are designed to hold a lot of current and come in large Ah ratings. Most of these batteries charge through external chargers that connect directly to the mains so you will not need the camera to charge the battery. They come from reputed companies and perform well.

But like docel said, it is best not to mess around with these batteries, unless you know exactly what you are doing.

pratheek
11-09-2010, 05:07 PM
For a single cell Li-Ion to deliver 6AH, the size has to be BIGGER. Remember, it is NOT a LIPO. And if that is a mobile phone battery, It will not be 6AH, and it definitely will not be @ 70 Rupees.

I agree with allbits.

If Li-ion batteries could be manufactured so small at such cheap prices, then all our laptops would be a whole lot slimmer (and cheaper).

Darrellenior
04-07-2012, 10:40 AM
the problem is that it is very difficult to get a 25V AC adapter get nad, the coil bobbin coltronics even if he says 30V NiCd or NiMH not Lithium-ion coz FOT you can see from the chart, the graph of the charging voltage of 8 can 4 volts first February-cell lithium-ion is given, then that's the problem ...

electronicsbasecom
08-21-2012, 02:56 AM
From name of this thread I can conclude that you want info about bateries :)
Here one interesting link:
http://www.electronics-base.com/index.php/general-description/all-about-batteries

Classical lead acid bateries are best solution for you.

streetjerk
10-15-2012, 10:32 PM
I bought Rhino 1250mAh Li-po battery along with a charger for less than 1000 bucks including shipping. So all international shipping won't burn a hole in your pocket. Rather battery prices here in india are higher than international. I've seen Arduino Mega clones in hobbyking its available for 18.99$ . Add a shipping of 2.99$. So u can understand how cheap its out there !! www.hobbyking.com

anir
02-05-2014, 09:49 PM
Get the batteries and adaptor you want
http://www.frugal-labs.com/store/en/11-power-supply

DalenWirth
02-06-2014, 11:53 AM
Yeah...that could work in a better way i guess.