PSU - Info

[expresso]

A voltage adjustment allows you to set a different voktage in the event you haveany boost/buck transition issues. Or allows you to charge a lead battery directly, 12 or 24V at high amps, etc. Or test motors, run things on the bench, etc.

I dont do all those things you do which need special PSU Bench kind - i dont even have a bench

but besides the bench PSU - the Efuel model with Adjustable Volt - would that be a good option instead of the others with out one ?

i not sure i even get this boost buck thing going on - i connected my PSU to the charger and charge the chair - so far - cant say i had any issues this way - not sure what i am looking for -maybe its happening and i dont know it - all i know is it charges and ends fine

but i may want to replace the 12V with a 24V - and keep the 12V as a spare in the event its needed - so either i get the same eBay model - another 24V 60A - at half the cost of a new one - but taking a chance - 60 or 90 warranty i think

or New one adjustable as you say it can be useful ? double the cost but one unit - and 1 year warranty - ?

[Burgerman]

Watever you wish!

[expresso]

Watever you wish!

the voltage adjustment would give me some flex - if i need to change the Volts ? if for some reason it doesnt charge as well ? how would i know if this Buck boost thing is happening to me when i charge ?

whats the indication ? - if going to a new unit - then i guess the voltage adjustment option is fine - all in the same price range -

thanks

[Gnomatic]

The buck / bost thing as I understand it(BM correct me if I'm wrong), happens when your PSU voltage is very close to the voltage of the pack you are charging. So the PL8 gets a bit confused and stops the charge.

So you charging your 24v pack with the PL8 powered by your 12v PSU, is not going to run into the issue. If powering the PL8 with a 30V PSU, its unlikely to happen. However, charging a 24v pack with the PL8 powered by 24v PSU, its *possible* the PL8 gets a bit confused and cuts off the charge. Doesn't mean it will or its likely. Your PL8 hasn't had and issues with your 24v Strick PSU so no need to worry about it.

[Burgerman]

It doesent get confused, it does this:

Inside all these hobby chargers are TWO inverters. A BUCK inverter, takes power supply volts and reduces it only.
A BOOST inverter takes power supply voltage and increases it only. So you can charge say a 24V battery from a 12V supply.


So, you press start, and the charger sees the battery voltage is (for simplicity) 12V.
Then sees the power supply voltage is a little bit higher at 13V.
So to charge the battery it must use the BUCK inverter, which drops voltage downwards. All good so far! As soon as it starts to charge, the battery voltage rises up due to resistance in wires etc, and so the charge voltage rises up ABOVE the 13V power supply point. The BUCK inverter cant do that.
So now it tries to swap over to the BOOST inverter quickly. As its doing this, the battery voltage drops a touch, and now the charger needs a BUCK inverter again to increase voltage... Rinse and repeat... Error... It may also do this during charge or near termination. Theres also a voltage point where neither boost nor buck inverter can work.

This can happen for 3 reasons.
Actual battery voltage rises as you are charging.
Actual POWER supply voltage falls under load. Its better if it rises a touch.
Cable resistance on either battery, or power supply is high resistance allowing a bigger voltage change.

Increasing or decreasing power supply voltage will prevent this. Better power supplies with less sag under load prevent it. Thicker cables or shorter prevent this.

[Gnomatic]

Ahh thanks for the explanation.

[expresso]

Ok - i havnt had this happen to me yet - using either PSU - i use both 24V and 12V - -

comes down to a matter of choice then - between cost and function for me - another 24V - half the cost - and hope it works as good as the first one - or New one with volt adjuster and dont worry about it either way -

besides the eFuel model - or the revo. model - same price bracket - what other PSU are worthy to consider - if i wanted to get a New one - ?

[snaker]

Thats not actually true. I use a 20A power supply on 20A every night. And my 40A supply at its 41A maxed out on my bench regularly for 6 or 7 years or so. Unlessthe server supply is less powerful than it is claimed?

Yes. E.g when buying a new server we have to estimate the max power that the server consumes first. Then, we multiple it by 1.25 to have the required watts of PSU. The selected PSU mush have its claimed power greater than that calculated watts. Some server PSUs claim they are "Platinum" and can work fine at 95% of its nominal power but I see they all scream if consuming more than 80%.

[ex-Gooserider]

I just built a somewhat 'scary' power supply box... A couple years back I picked up a Meanwell "shoebox" supply - 63A out @ 24V, input 110/220V, 50/60Hz, 25A - which is more than a US wall outlet can supply, so don't run at full load... I think it was around US$30 at the MIT Flea, so not something that could be easily repeated...

It had exposed terminals for power in and out, so I mounted it in a cheap and cheerful plastic toolbox with a hole cut in one end for the cooling fan, and a bunch of small holes drilled in the other to let the hot air out, but still keep the fingers away from the shocking bits...

Figure that if I set the PL8 to a low current limit, I won't blow wall fuses and the supply will never get over-stressed...

ex-Gooserider

[Burgerman]

Correct. Set the input current to never exceed what you think it can do and you are safe to do anything you want.

[Burgerman]

Correct. Set the input current to never exceed what you think it can do and you are safe to do anything you want.

[expresso]

https://www.ebay.com/itm/14-inch-14AWG- ... 0677.m4598

would this work fine for the PSU i am using has two power cords - if i added a Y cable like above - 14 awg should be fine ? What would be the Min. size cable i should use - ?

https://www.ebay.com/itm/ClearMax-3-Pro ... 0009.m1982

16 AWG

[ex-Gooserider]

It depends on how many amps the supply draws on the INPUT side, and possibly how long the cord is... There are charts, often found in manuals for power tools that give a list. However for typical short distances, say under 10' from the supply to the wall outlet, cord length isn't a worry.

Following is for US, 110V 60Hz electric, I'll let those 220V folks work it out for themselves...

As a reference, standard wiring inside the wall on a 15A circuit is AWG14, and on a 20A circuit is AWG 12. Almost everything you encounter will be sized to work on a 15A circuit.

So an AWG 14 cord will definitely work on a 15A circuit, AWG 16 will probably be OK, but is a bit iffy at a full 15A. However AWG 16 is good for about 10A (note that this is what most power-strips use)

AWG 18 is mostly light duty, but OK for up to about 6 or 7A, it is what you will see on most desktop computers and monitors...

You will not see an AC power cord that is lighter than AWG 18 as the codes don't allow it, not because of the current draw, but because they want the mechanical strength of that wire size as a minimum to prevent physical damage.

ex-Gooserider

[expresso]

thanks - i emailed the seller of the PSU - his cables are 18 AWG - but there are two of them - for a Y cable he suggests recommends a 14AWG - so if i get one - it will be 14 AWG - Y cable -

[Burgerman]

https://www.powerstream.com/Wire_Size.htm

Look at the top on the chart, and use the MAX AMPS FOR CHASSIS WIRING column.

Thats designed for automotive/hobby type use where getting warm doesent matter, and its a max rating.

[expresso]

https://www.powerstream.com/Wire_Size.htm

Look at the top on the chart, and use the MAX AMPS FOR CHASSIS WIRING column.

Thats designed for automotive/hobby type use where getting warm doesent matter, and its a max rating.

i stick with 14 awg Y cable if i go down that road -

thanks

[hotwheels_75]

I use a SKYRC eFuel 1200w, 50A PSU, 15-30V

https://www.flyingtech.co.uk/accessorie ... cd-display

What gauge wires did you use for the output to the charger? And how did you connect them to the psu? Did you have to put some kind of pin or connector on the wires?


There’s not a lot of info on this psu that I can find & the manual is only 2 pages with very basic info.

[sad_vampire]

One of these

Revolectrix croc clip to EC5

https://www.ebay.com/itm/Revolectrix-Ce ... 1638211880

butchered off the croc clips & replaced them with ring terminals

10AWG original Revolectrix

The 50A output terminals on the eFuel are threaded posts with a hole to put a cable through & trap, so you have a few options from trapping a tinned cable, using ring terminals (crimped & soldered), or you could just use the croc clips on that lead & go for the wobby connect to upset the PL8.

Get two, keep one with the croc clips so you can connect the PL8 to a battery.

[expresso]

dosnt that PSU take banana plugs ? cant you use one of these cables instead already made - EC5 for the PL 8 end and banana plugs for PSU end - ?



https://www.rcsuperstore.com/Banana-Plu ... pingengine


something like this is what i use on my charger and PSU - just made sure you get the 10 AWG cable

i dont have the same PSU - mines just has banana plugs out from the PSU - -

[expresso]

http://www.progressiverc.com/banana-plu ... gJLffD_BwE

this is the one i use - its 10 AWG wire -

just make sure you get the correct EC 5 end for the PL 8 charger end -

[hotwheels_75]

Thanks for the replies and info. I have some options to look at. I was thinking banana plugs would work, I saw one picture online & it looked like that’s what they were using. I just got the PSU but haven’t been able to really look it over yet. I like that croc clip too. I thought the 50A terminals were the type where you unscrew the outside shell a bit, insert some stripped wire & retighten the cap & it clamps the wire tight, but I see what you mean about the hole to trap the wire.
Time to do some more shopping!

[sad_vampire]

dosnt that PSU take banana plugs ? cant you use one of these cables instead already made - EC5 for the PL 8 end and banana plugs for PSU end - ?



https://www.rcsuperstore.com/Banana-Plu ... pingengine


something like this is what i use on my charger and PSU - just made sure you get the 10 AWG cable

i dont have the same PSU - mines just has banana plugs out from the PSU - -

Yes, it will take banana plugs as the 50A output is hollow posts, but 50A through a 4mm banana plug might get a bit warm I think, the decent ones are rated around 30A, the cheaper ones 10A. Certainly use the banana plugs with the 3x 10A outputs.

I'm sticking with my ring terminals for the 50A because it will be drawing current for a long time & I don't want to worry about it getting too warm. The ring terminals can't be pulled out by accident either (although I suppose the EC5 could be).

If I was only ever going to use the PSU with the PL8 I'd cut the EC5 off the PL8 & replace it with ring terminals to trap in the PSU 50A outputs, but I may use my 24V 30A Sterling charger through 2 spare batteries with the croc clips, or use the croc clips to connect to a 12V secondary battery in the boot of my car (connected with hefty cables to the primary battery). I like to keep these options open.

John will be using Anderson connectors, something I only have on the lead circuit for the Otto Bock B500 for use with the Sterling charger at the moment.

So, cut off the EC5 from the PL8 & replace with Anderson, make an Anderson to ring terminal cable for the PSU side, then a Anderson to croc clip for the battery options.

[cdb0ewm]

What is the recommended minimum amps for a power supply to charge a BM3 sized battery pack using a Hyperion 1420 EOSi
Thanks

[Burgerman]

600 or 650 watts.

[cdb0ewm]

Thanks --- so does it matter if its 12v or 24v

[Burgerman]

Yes. 24.

[steves1977uk]

I have the following PSUs...

http://uk.farnell.com/digimess/sm3040/p ... dp/1076813 Mine was an ex-demo from eBay which I paid about £200 for.

https://www.amazon.co.uk/SKYRC-Efuel-12 ... B00ISTUAFA 15v-24v selection, 60A max at 20v otherwise 50A at 24v. Paid about £170 for this PSU from eBay.

http://www.coolice.co.uk/cfs/coolice-psu-s.html I have the 2400w one (24v 100A) which I paid about £110 for directly ordered from the website.

Steve

[expresso]

i like the Coolice one - 100A - too bad the shipping would cost alot i would think - coming from UK to US ? i be curious to ask - how much it would cost total - i like to have another 24V on hand -

[expresso]

Steve - would you have a picture of the Coolice PSU you have - i like to see the connections - on there website it dosnt show them - i am going to email them for a cost with shipping -

can you tell me how you think of it - the built quality of the connections etc, if you can post a few pics - if not too much trouble -

thanks

[steves1977uk]

You could build your own by using two of these wired in series and properly isolated... https://www.ebay.co.uk/itm/HP-1200W-POW ... 2645258933

Steve