Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Student Project - Please Help :)

Status
Not open for further replies.

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
meaning of causa perduta

Hi there guys, im new to this forum so hi :).

At the moment i'm a struggling design technology student on a 2 year course and its now time to create my concept idea but i am totally lost as to how to incorporate the electronics into the design.

I am designing and manufacturing a compact car battery jump starter unit that will be no bigger than 220mm x 70mm x 70mm. The design will have to be based around the internal componentry this time as this project is strictly function over aesthetic.

My ideas came from when my car failed to start one morning, and without a donor car to jump start i was stuck. The ones on the market are quite expensive and bulky meaning it takes up vital space in the car. I am currently on the development stage of design and now it comes to the crunch where i have to specify the electronics i will use.

I have come on here hoping that you will be kind enough to submit some ideas for me to work with. The problem i have is that i need about 12v and around 900 amperes sustained for around 5-6 seconds to give the user enough time to attach the unit, switch it on, wait and then turn the ignition.

Obviously using a huge battery to provide this defeats the object so my idea for the process of electrics was something along the lines of:


Small Power Source (4v etc) >> Transformer (Jumps current up to 12v) >> Power capacitor (power storage) >> Release Switch.

The problem is this system would fail to deliver 900 amps + and space needs to be kept to a minimum.

I am really enjoying this project, so far lol. If you have any ideas on how i could achieve this please reply to this post.

If you know what parts would be required and have any info such as price, where to buy them etc that would be great.

This is my last project now so i'm hoping to make it something special and i hope that i can get the power out of the unit needed to make it function.

Thanks :)

Dan
 

Externet

Advanced Member level 1
Joined
Jan 29, 2004
Messages
449
Helped
26
Reputation
54
Reaction score
21
Trophy points
1,298
Location
Mideast US
Activity points
3,895
Hi.
Charging a ~100 Farad /~12V capacitor (which would work well to start the engine) from an external DC source to "fill up" the capacitor several minutes can work.
Such charged 100 Farad capacitor with leads and alligator clips could be charged from such charging DC adapter and carried to the car to aid boost starting... if that fits your size requierements.
Miguel
 

asd913

Newbie level 5
Joined
Jun 24, 2004
Messages
10
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Canada
Activity points
130
Hi Dan,

I think you've chosen a problem that has some terrible hurdles. First, the suggested method would not work.

A transformer can only convert AC current from one line to the other; DC will simply run through like a short. A power cap will not be able to hold enough charge to produce 900A for anywhere near 5 secs unless it's the size of your trunk.

I'm sure there are a number of ways to actually make a more user friendly car starter. But all of them will require as much space as a second battery. If you think about it, the car's lead-acid battery's only purpose is to crank the engine. After that point, the alternator takes over. Lead-acid batteries were chosen by car manufacturers because they can handle such huge amp-hour requirements in such a diminutive size.

Why don't you look into making a battery charger? This would be something you could plug into a wall when the battery dies.


Best regards,

asd
 

batdin

Full Member level 3
Joined
Jun 3, 2004
Messages
182
Helped
5
Reputation
10
Reaction score
2
Trophy points
1,298
Location
Bulgaria
Activity points
1,928
A capacitor that can give 900A for 5s will be much bigger than a spare accumulator .
My friend,this is "causa perduta",change your mind while you can.
 

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
Hi, thanks for the reply's firstly.

I knew this would be a challenge from the start but im still somewhat determined. I have seen car jump starters that are only about the size of a standard car battery and some that are even smaller. The one that i found interesting was a unit that plugged into the 12v feed to such things as the cigarrette lighter, after 5 minutes this had charged the battery sufficiently to start the car. But for the purpose of my exams and me suceeding with the project the exam board doesnt have to know about that one :).

Ok, say if size wasnt as much of an issue, so you know how some of these jump starters function? I could possibly develop the components into a 'false floor' for the car, make it so that it sits 2 inches etc above the existing floor, conceal the componentry underneath and just have 2 compartment for the + and - clamps.

Does this sound possible?

PS thanks for the help :)
 

R00KIE

Full Member level 3
Joined
Jan 19, 2003
Messages
150
Helped
23
Reputation
46
Reaction score
3
Trophy points
1,298
Location
Portugal
Activity points
1,255
To start i think you should investigate the current you really need, 900A sounds too much for me, i think that lead-acid batteries don't like violent charges so i think i should lower that to lets say 20A max.
Remember you said
The one that i found interesting was a unit that plugged into the 12v feed to such things as the cigarrette lighter, after 5 minutes this had charged the battery sufficiently to start the car
5 minutes is enough time for the battery to recharge a bit so it is able to start the car, also if you look at it carefully you'll see that the cigarrette lighter is protected by a fuse so it can't supply a huge current.
my idea, and it's just my idea is:
the battery will not start the car because it is discharged but it only needs a little bit more charge to be able to start the car, considering that the battery is in good shape that is not "dead" and it as enough electrolite (in the case of battery with maintenance) you can have rechargeable batteries like the ones that power emergency lightning and use enough batteries to make 12v or use a boost converter to make 12v and give the battery the charge it needs to start the car, of course the charge should not be too violent for lots of reasons but one of them is safety.

i hope this helps
 

echo47

Advanced Member level 5
Joined
Apr 7, 2002
Messages
3,942
Helped
638
Reputation
1,274
Reaction score
89
Trophy points
1,328
Location
USA
Activity points
33,176
A 12V automobile starter motor usually draws 100A to 150A, not 900A.

You could build a "trickle charger" into that size package (or you could buy one at an auto parts store). A trickle charger outputs only a couple of amps, so it takes a few of hours to charge a dead battery enough to start the car. That assumes the battery is discharged but otherwise healthy.
 

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
thanks again.

i think i was mislead by someone on my car forum as to what amperage is needed. I suppose charging the battery sufficiently over the period of 30-40 minutes would be fine. I'll investigate the booster and 'trickle charger', still not sure how each function but hopefully ill find some info.

Ill keep you guys up to date on how its going.

Cheers
Dan
 

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
Great news, i've researched into trickle chargers and the first site i found was a guy in America who has manufactured his own, and i'm in contact with him now into ordering one. On the site it says about charging lead acid batteries and supplying 150 amperes to the battery which sounds perfect.

For reference the site is:

https://www.qsl.net/ke3fl/htm/TRICKLE.HTM

See what you think :)

Cheers
Dan
 

echo47

Advanced Member level 5
Joined
Apr 7, 2002
Messages
3,942
Helped
638
Reputation
1,274
Reaction score
89
Trophy points
1,328
Location
USA
Activity points
33,176
Don't charge at 150 amps. That's way too much.

You may enjoy PowerSonic's lead-acid battery technical manual. It describes their gel cell batteries, but gel cell charging characteristics are similar to automobile wet cell batteries:
**broken link removed**
 

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
Thanks for the link mate

I've given Rookie's comments serious thought and i think i've decided what to do. I'll either use the emergency battery's or just use like a v.small panasonic 12v battery which i saw, twas only 2.2 inches high and 1.9 inch wide. :)

Then ill have to connect it up to two terminal connectors for the output and then wire up a dc socket to be able to re-charge the unit when it is low.

It saves me a hell of a lot of time with wiring, time is a contributing factor with this project as i have very little. Seeing as im also a total novice at electronics, doing a very important project for the first time i cant really risk it.

Most of the units on the market have crap that i dont really need to be on there, thermostats, compressors etc. So just by making the units lighter and smaller is worthy of a project anyway.

So finally thanks for all your help, i've gone from being totally lost to having some great ideas im drafting out as im writing this.

Wish me luck :)

Dan
 

djalli

Advanced Member level 3
Joined
Nov 10, 2001
Messages
825
Helped
31
Reputation
62
Reaction score
15
Trophy points
1,298
Location
1600 Pennsylvania Avenue, Washington DC 20500
Activity points
8,288
You should start what kind of battery you need to go with which would be a better product. If the panasonic device works with your battery then you add the charger.

Most, as matter of fact all of them, of designs in technology done by corporations are not optimal at all as they are driven by market and their stockholders demands.

With one stone hit two birds.
 

Daemon2004

Newbie level 4
Joined
Jul 24, 2004
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
155
Hi there, wow, look at the start date of this post lol.

Though id let you know how it all went, I managed to get an A on my folder and A for my prototype model and this thread has undoubtably helped me to achieve that. So your probably wondering what the solution was......

Well, after countless hours of researching into Li and lead acid batteries it was evidently clear that they were not small enough to get the overall purpose of the prototype (to reduce the size dramatically). I researched further into transformers and the problem lay with the amps as oppose to the volts like you guys claimed from the start. I really couldnt comprehend how much power a standard calcium car battery puts out.

Then randomly i stumbled across a Japanese designers website, who had development sketches for a 'Mini Max 900' jump starter, in association with a company called GP Batteries. I was slightly annoyed that someone had the same design goals as me and had already fully developed it, but thats life. I found they were using a new technology called TMF batteries (Thin Metal Film), and these batteries were easily pushing out 900 amperes at 12-14volts (6 in a battery pack).

I ordered one of these online, they were incredibly hard to find in the uk. And the unit was so small as the main GRP shell only housed a pcb, 9 aa batteries and the TMF battery pack composing of 6 individual lead acid batteries.

Obviously A level projects dont't require you to invent new technologies lol, so i stripped the unit apart, and used the TMF battery unit which was secured to two copper plated clamps as the basis for my design. I then managed to encorporate this into my new grp shell and created a new circuit board which contained the same safety features but got rid of the need for the backup AA batteries which were wired in, which saved a lot of space. This allowed me to reduce the size of the product by 40% for my final prototype. Then using CAD/CAM i manufactured the external shell, created necessary fixtures for the DC charger input and thought i would spice the design up a bit by running two 4000mcd LED's off the power supply, which wasnt exactly cheap.

The overall effect i think was really well made and fully functional, it was able to jump a near dead battery 4 times before needing charging. The TMF batteries can also self charge from the primary car battery once the car is running. I think its an incredible technology and its now being widely used in other applications, the company leading the way are called BolderTech. They didnt have a fully working website so finding more information on them was damn near impossible.

Once again thanks for setting me on the right lines with power outputs etc, i valued every suggestion. Its a shame i wont be using my design skills again as im going onto Computer Science at Durham Uni. This really has been the hardest project ive done yet, ill get up pictures as soon as i get the model back from the exam board.

For those interested, here's some info on the SecureStart - jump starters:

https://www.gpbatteries.com.hk/html/products/jump_starters.html

Cheers :)

Dan
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top