Winding transformer

[ban-all-sheds]

Maybe partially - but with an input voltage range of 5V - 36V, they presumably also have other sources in mind.

24V has long been a common voltage in commercial vehicles.

I'd not be surprised to learn that some newer and/or larger vehicles use 36V.

Or that there's a target market for Turnigy where 36V batteries are common.


Also, am I the only one who looks at the product name and the styling:

and thinks "chances are that's a pile of tat"?

 

[Nozzle]

So it's a charger for RC cells - nothing exotic. Quit your dangerous dicking about with microwave transformers and get a PC power supply. I used to use a Schumacher CCD20 with a PC Power Supply and it's ideal. link the green sense wire to any black on the ATX connector and it comes to life.

These chargers are designed to clip onto a car battery, if you start shoving full wave rectified DC into it, you might find it's none too happy.

Nozzle

If you know of a tried and tested 24V 30A PC power supply please send a link, I would prefer to buy one, than make one.

C.

The input range is so wide, there is no need that have it at 24volts. Also, you cannot sink 1000W (product claim), 720W (24V x 30A) or anything like that into some RC car cells and expect them not to melt. Admittedly, my experience is used NiCds that is now old technology, and although the charging current (pulsed, not sustained) could be adjusted up to 10 amps, anything more than 4 Amps would cook the cells. Even top-of-the-range matched and conditioned sets. Just think how much a 1000W is. Two and a half halogen lamps worth, if you've ever sat next to a 400W halogen lamp you'll know how hot that gets.



Nozzle

 

[JohnW2]

The input range is so wide, there is no need that have it at 24volts. Also, you cannot sink 1000W, 720W or anything like that into some RC car cells and expect them not to melt. Admittedly, my experience is used NiCds that is now old technology, and although the charging current (pulsed, not sustained) could be adjusted up to 10 amps, anything more than 4 Amps would cook the cells. Even top-of-the-range matched and conditioned sets. Just think how much a 1000W is. Two and a half halogen lamps worth, if you've ever sat next to a 400W halogen lamp you'll know how hot that gets.

Indeed so- as I wrote:

I obviously don't yet know, but I still rather wonder whether the OP may be seriously over-estimating how much current he will need.

Kind Regards, John

 

[Nozzle]

JohnW2. That post added nothing, are you on a mission to increase your post count?

"I agree with stupic"

This very post is at the limit of being pointless.

Nozzle

 

[JohnW2]

JohnW2. That post added nothing, are you on a mission to increase your post count?

I don't think I have any need to

I suppose that I was more-or-less implying the same about your post as you are saying about mine. I had already pointed out/implied that the OP almost certainly would not need anything like 30A at 24V to charge his RC cells - and you then wrote essentially the same thing, more verbosely, with analogies about 400W halogen lamps!

"I agree with stupic"

Who is stupic?

Kind Regards, John

 

[ericmark]

I was going to say toy cars but really the helicopters cars and other items which use large batteries have gone over what one would call a toy.

Some of the drones used to take photos are quite large devices and clubs tend to run events where rapid charging is really required.

1000W for 5 minutes is not that much when compared with liquid fuel pouring in the two stoke mixture used with compression ignition engines is so much quicker than a recharge.

Looking at electric cars it would seem a lot of work is going into rapid recharge.

The problem is to get 24 volt DC at a reasonable cost one needs to use high frequency and so reduce the size of the transformer so one is looking at a ready built unit rather than a collection of parts in order to use the switch mode technology and high frequency transformers.

The PC power supply does seem the most likely unit.

 

[conny]

I've read the first two pages of this thread and am amazed some of you are still alive!

Transformer winding, like armature and stator winding, is a specialised technique. You can't just rip out the old winding and bung in a few turns of thicker wire and hope you have it right. Higher currents will mean higher levels of insulation, higher levels of protection from overload. Magnetic interference with other appliances, (or even people with pace-makers etc), has to be considered. People who repair electric motor and transformer windings have to serve at least 5 years apprenticeships and have a thorough knowledge of electricity. But this doesn't mean they can design and build a transformer from scratch.

If you want a specific transformer then go out and buy one from a reputable supplier before you kill yourself or someone else.

 

[ban-all-sheds]

Higher currents will mean higher levels of insulation

 

[conny]

BAS, are you saying you don't need higher insulation properties if you have larger current?

Then why do we double up on slot insulation on a large motor instead of using single thickness?

I've spent over 40 years in the motor/transformer repair industry and know that larger motors carry larger currents and therefore need better insulation.

 

[ban-all-sheds]

BAS, are you saying you don't need higher insulation properties if you have larger current?

Yes.

Then why do we double up on slot insulation on a large motor instead of using single thickness?

IHNI.

I've spent over 40 years in the motor/transformer repair industry and know that larger motors carry larger currents and therefore need better insulation.

Insulation requirements are entirely related to voltage.

Ar you sure that these larger motors aren't operating at higher voltages?

 

[conny]

As an example;

22Kw 4 pole motor 400v uses one layer of slot insulation.

75 Kw 4 pole motor 400v we use double layer slot insulation.

HT motors, such as 3.3KV, have at least double slot insulation and the slot length section of the coil is wrapped in resin tape, compressed to the right thickness and then heat cured.

 

[bernardgreen]

Motors have voltages higher than the supply voltage due to inductive effects between windings. The largest voltage spikes occur when the motor is switched off and the magnetic field collapses. With the supply open circuit the collapsing field creates these voltage spikes. Higher currents mean more "stored" inductive engergy and hence higher spikes.

 

[ban-all-sheds]

22Kw 4 pole motor 400v uses one layer of slot insulation.

75 Kw 4 pole motor 400v we use double layer slot insulation.

Well, there must be another reason then.

An xV cable needs the same amount of insulation if it's carrying 1MA or 1μA

 

[DetlefSchmitz]

Well, there must be another reason then.

Almost certainly the reason Bernard gave.

 

[ban-all-sheds]

Almost certainly the reason Bernard gave whilst bas was typing his reply.