Wish to use 12v dc charger for lipos and Nimh at home on mains supply

[Dave Rose]

hello

I have a field charger that I would now also like to use at home . Can someone who knows about these thing please point me to a "transformer"? Or whatever that I can buy so that I can charge batteries at home. I have a transformer lead which I thought I could make a connection for, but I was told the output amperage was too low?

Thanks

[Denis Watkins]

Shop around, as you can go much higher wattage rating

This 100w is the smallest, but you don't state lipos or charger type

**LINK**

[FlyinBrian]

At the risk of being barred for suggesting you look at a different forum you could look here

I use one of these, it cost about £18 and can power several chargers at once if require.

Try this

[onetenor]

It's not worth messing about with it as you would need to alter too much internally . Diodes resistors capacitors etc. Keep your field charger as is and buy a variable multi point mains powered PSU .

Look on the Component Shop site. In fact give them a call for their advice.

Regards O/T

[Ace]

+1

Some work required and IIRC will put out up to 50 amps at a regulated 12v? - but worth the effort.

Overkill but powers my 1m hot wire cutter through a brushed esc and servo tester.

[ken anderson.]

hello dave-i bought a transformer from Maplins..

ken Anderson..ne..1.... maplins dept.

[Eagle 899]

Server power supply with conversion instructions (credit to MattyB for this link):-

**LINK**

A chap also sells them already converted and advertises regularly in the BMFA Classifieds.

[john stones 1 - Moderator]

I use one of these, very quiet n cheap. Plenty info on converting them.

[Brian Spearing]

As well as the converted server supply I've been using a Junsi P350 for several years - Junsi make chargers too so you know it's suitable. Not cheap but well made.

Experience* suggests it's important to get a smooth voltage input to your charger, otherwise the all-important cutoff point could be missed.

* If using an ATX PC power supply be sure to check that.

 

Edited By Brian Spearing on 08/12/2017 17:14:41

[onetenor]

Or use a battery charger for a supply A good one

[Brian Spearing]

If you use a car charger remember that car batteries don't care about voltage ripple.

[Geoff S]

Posted by FlyinBrian on 08/12/2017 15:55:21:

At the risk of being barred for suggesting you look at a different forum you could look here

I use one of these, it cost about £18 and can power several chargers at once if require.

Try this

That's the one to use, Brian. Cheap and very powerful. I've had one for several years on the recommendation of a poster there (we know who )

Geoff

[flight1]

two ways of doing this convert a psu which I have done very good cheep and reliable with the post for the server psu conversion a good way or buy from that chap that advertises or use a 12v car or leasure battery and charge as needed via a standard car bat charger , both the best solutions giving clean linear voltage

[David Ovenden]

I too can heartily recommend the HP server power supply conversion as suggested by FlyingBrian. They are so good I have 2. One for each end of the workshop!

[Dave Bran]

I have a number of PSUs used from time to time to feed chargers, some ex-computer, some industrial fully adjustable stabilised lab/bench, but the bank of NIMH chargers (10 of!) I use for the school club are powered by these little devices, three of them. very small, very quiet.

**LINK**

I used to suggest these, HOWEVER, I do not think they are available now AND anyway the price was only £12 each retail when I bought!!

A point with regard using car battery chargers as PSU. They are not! There are also so many types with and without regulation/boost/auto trickle that a blanket "use this" is IMO imprudent.

While I rarely field charge these days, I have a number of very large capacity 4S/6S LiPo which subject to charger input do what I need. They also drive my engine starters. A "Sakura" car engine starter is always in the car anyway and despite being tiny I once used it to start a 7.6 litre 6 cylinder petrol! No more stone age heavy lead acids!

[Chris Channon]

A lot easier to just buy a 12v power supply from a model shop / internet.
Regards
Chris C

[Martin Harris - Moderator]

Certainly easier but many of the "hobby" PSUs are built to a price and may not have the reliability or performance of a converted server PSU. If you have the capability to follow the conversion instructions, they are the best value IMHO.

Running directly from a battery charger risks damage to the charger through "dirty" outputs and simpler ones being unregulated and I would caution against the practice. You might get away with it if you have a suitable car battery float charging across the output but there are much better options.

[Steve Hargreaves - Moderator]

Xbox power supplies also do a good job after a little bit of modification.... see here

[Mike T]

The HP server PS can still be got for under £20 on ebay. The conversion is really easy - just jumper a few pins and away you go. I did the 'full' conversion with mine with fan speed reduction, voltage trim pot and removing all the extraneous metalwork. Outputs are 4mm binding posts - which were cannibalised from a failed 'model shop' PS...

A more complicated, but more flexible alternative is an ATX PS (desktop computer type PS). Also plenty for under £20 and capable of providing multiple outputs at 5, 12, 17 and 24v. Lots of "how to's" on the 'net.

A couple of pics to sum up:

1. HP Server PS:

2. ATX PS:

Edited By Mike T on 09/12/2017 14:30:34

[Geoff S]

Not quite clear about your diagram, Mike.

On mine, I've linked the 3 pins diagonally from PSON and it's been working fine for several years. You show the fan speed control as linked to those 3 as well but then suggested grounding it. Is that after disconnecting it from the other 3 or are all 4 pins grounded? I've left that fan speed pin open circuit.

The only thing I don't like about mine is the fan noise and it would be an improvement to either eliminate or, at least, reduce it.

Geoff

[Mike T]

Geoff, the PSON and PSKill pins are shorted to ground, this gets the thing running when you plug in your kettle cord. If you also short the un-named pin to ground, that drops the fan speed. The drawing shows the pin already connected to ground, so the caption was perhaps a little misleading! If you connect together as drawn, you'll have a working PS with a slower fan. HTH.

PS - the easiest way to do this is with the wires stripped out of a servo-type connector.  The sleeves are a good fit on the pins, so you only need to cut the wires down to manageable length, solder them all together and heat shrink.

Edited By Mike T on 09/12/2017 17:08:58

[Hamish]

The power On and Standby LEDs appear to do the same thing?

 

Edited By Hamish on 09/12/2017 17:27:55

[MaL]

Be aware there are several different server power supplies that are available for conversion. almost all will be admirably suitable for conversion to charger power supplies but most are converted slightly differently. As this has already been covered I thought it would be useful to link the info here

 

**LINK**

 

The server power supplies do not suffer from the issues that PC power supplies have a tendancy to suffer from with regards to unstable voltages with load.

Edited By MaL on 10/12/2017 11:10:14

[Geoff S]

Posted by Mike T on 09/12/2017 17:05:35:

Geoff, the PSON and PSKill pins are shorted to ground, this gets the thing running when you plug in your kettle cord. If you also short the un-named pin to ground, that drops the fan speed. The drawing shows the pin already connected to ground, so the caption was perhaps a little misleading! If you connect together as drawn, you'll have a working PS with a slower fan. HTH.

PS - the easiest way to do this is with the wires stripped out of a servo-type connector. The sleeves are a good fit on the pins, so you only need to cut the wires down to manageable length, solder them all together and heat shrink.

Edited By Mike T on 09/12/2017 17:08:58

Thanks, Mike, that clears it up. I think that's how I connected the pins originally (ie servo connector sockets) but it was a year or two ago. Do kettles still use standard euro mains leads? I have so many of the latter, my mains sockets/switches/leads drawer won't shut properly because I can't bear to throw them away

Geoff

[Mike T]

I think"euro-style socket" is nearer the correct term, Geoff! Most of my power supplies use them, though the ATX used the two-pin type. This thread whetted my appetite, so I ordered another HP PS to convert...

Good link from MaL - I'm sure that's where I got my conversion info from.

Hamish - sort of. The power LED (green) indicates power to the PS, the standby LED (red) shows that the outputs are 'live'