12 Volt Drill Power supply query

[#1]

@VileReynard  Obviously,... if you read the original post,     you will see why ..... Doh

[#2]

I did read it - but it won't work - probably!

[#3]

---

@shutter wrote:

@7up  & @RobPN  Thanks for your input.... from the "general gist" of it, it seems you are assuming that I am going to be using this "contraption". for some really heavy serious wood working.however that is not the case... if it were, I would not be considering it,  (the work ) nor the construction of this project.

I understand your concerns, regarding the practicality of it, and appreciate the technical content of the input from all, and from that I have gained enormously... I shall probably construct the framework, and the adjustable table underneath, ( to adjust the height of the blade on the cutting deck) . then give it a trial on some small items of wood...probably deal/pine  of about half inch thickness, using the battery charger, as the power supply... From that position, I should be able to see if it is worth considering @7up  suggestion of going down the scrap yard and buying a half decent battery.  Of course, having the battery, will also make the saw table more "portable" and usable where there is no mains power outlet !

The work envisaged is only of a "modelling" type,,  not building a sofa or a four poster bed ! ! ..

---

@shutter 

I can think of several reasons why I wouldn't go ahead with such a project.

Despite what you say, I'd consider ripping 3" timber (i.e. cutting length-ways, otherwise why mention the length?), even if only 18" long (as you mentioned previously) fairly heavy going for the drill you intend to use.

If the use is going to be as occasional as you say, why go to all the bother and expense of buying stuff such as batteries and possibly materials to build the contraption when you could just use that money to go out and buy the size of timber required.

And elf and safety is worth seriously considering!

[#4]

@RobPN 

Again... I am not intending to be continuously cutting 3" timber... length ways or across ways... so the "workload" you envisage does not exist... only on a "possible" one-off job

---

If the use is going to be as occasional as you say, why go to all the bother

Because the drill is doing nothing... !  it never gets used anymore... I do have a powerful mains drill, but I want to keep that for drilling... whereas the "project" as described, will give me something to do... challenge my brain, and my constructional and design skillset... and be a project that, if it works, then I will have achieved something worthwhile... if  it doesn`t work... then ... so what... I`ll revert to the old hand saw and make more work refining the cutting by planing and sanding to the required finish !..

---

expense of buying stuff such as batteries and possibly materials to build the contraption when you could just use that money to go out and buy the size of timber required.

And elf and safety is worth seriously considering!

---

as for the "expense"... as already mentioned, the 12v battery from the scrappy, would not be a great expense..  and be useful as a stand by for other projects in the electronics department, if needed.  ! The "materials" i.e. other bits of wood, are already in the shed, again...waiting for something to be done with them... 

This "project" is a kind of "re-cycling" effort  so, its better than chucking it away...

as for elf and safety... nah... that only kills off these grandios projects... and makes life dull and boring... ! 

[#5]

---

@shutter wrote:

Because the drill is doing nothing... !  it never gets used anymore... . 

This "project" is a kind of "re-cycling" effort  so, its better than chucking it away...

---

eBay it?  

[#6]

Ebay it ? ? ? ?   hardly worth the effort,.... not going to make a fortune, and cost me more in transport and and packing costs and time, than the final price achieved... AND.. I would not have a project to do

[#7]

Will you be using a proper steel saw table to mount the device under?

[#8]

That depends on what I have available .....

[#9]

@shutter 

How about this as Plan B. Instead of getting a battery from a scrappy get a small sealed lead acid battery such as one of these. If necessary you could also back it up with your battery charger but it would also make it more portable then an old big battery.

https://www.ebay.co.uk/sch/i.html?_nkw=12v%203ah%20battery&ul_ref=https%253A%252F%252Frover.ebay.com...

[#10]

@Baldrick1  But those you have shown in the link are only 1.5 ampere hour  type ! ! .. and 7up suggests that the drilling of the metal plate on the boat, probably drew more than 2 amp..

I suppose the only thing to do is give it a go ! ... and see ... haven`t had time to get the charger and the drill in the same place to connect them up ! and see what happens on "free load" ...

Thanks to all for the input...  it`ll be great fun if it works...

[#11]

@shutter 

Bigger capacity batteries are available but this is not really the point I need to make.

1.5Ah is a measure of the capacity, not the maximum output current of a battery. It means that the battery can theoretically supply 1.5A for an hour or 3A for half an hour and so on before going flat. In fact this is not true because at higher discharge currents lead acid battery capacity falls. The Ah figure is normally specified for the 20 hr rate. This is called .05C that is a current of 1 twentieth of the capacity per hour. However discharge rates are generally specified up to 3C meaning supplying 4.5A from a 1.5 Ah battery be it only for less than 29 minutes.

There is a current limit for sealed batteries due to their higher internal impedence. That is why I suggested also using your battery charger at the same time. Providing you connect the two at the battery terminals the battery should absorb any spikes generated by the drill hold up the battery voltage and keep the intelligent battery charger on control.  However depending on the current your drill requires this may not be necessary. 

[#12]

@Baldrick1  OK.. thanks for the explanation... will see how things pan out... but I suspect a half decent car battery from the scrap yard, will be only a couple of quid, and I suspect have a bit more "oomph" than the lower end jobbies you have mentioned...

cheers

[#13]

Watch out for the Health & Safety angle.

Low voltages aren't always a hazard-free zone...

[#14]

As I once found out when I got my metal braceleted watch across a car battery. Also look out for sulphuric acid spillage.

[#15]

@shutter 

A 12v drill at 2a just ain't going to cut it, and certainly not three inches. 

Get the right tool for the job? They are cheap enough from somewhere like Aldi's

PS. Have you thought of dialing 999. Seriously, don't.