Another portable charging station project!!

[copterboy]

Wish I could afford one of your units Grant, were the work is done for me, and to a very high standard. Only problem for me was I want so many things, even having a couple of k to play with doesn't seem to go that far!! Especially when words like helicopters and holidays are involved!!


Hence why I opted for the £25 PSU's that need the work, instead of the £50 Dell PSU's that could have saved me some time and hassle.

Thats what I started to think and made me drop the additional fuses from the plan, the chargers and PSU's are protected and intelligent enough on there own to need them. I will review the need for it on the li-fe packs when I come to add them, but I still think it's a good idea there. Just no consumer unit in the charging box I'll build and no fuses from the PSU to 24V junction boxes. I was just adding them to protect from my own stupidity when wiring up the individual units, but learnt I would already be protected from it anyway, so there was no point.

Think I'll also have to have a reality check on the 2 x PL6's for now. Will just start with the one charger, as I think it will be at least 12-24 months before I get to a point where I actually need it and it will have no requirement for it before then. Might aswell use the money for other projects now. Important thing for me here, is to have something I can add to and not have to re-build.

[copterboy]

PSU's and DX8 just arrived

[sutty]

Woo hoo.

[jperkosk]

Yeeeehaaaa (it's a Tex-Mex version of woohoo)

[copterboy]

Just pasting a quick link to Raf's original build, so I know where it is and don't have to keep searching it out!!

https://www.helifreak.com/showthread.php?t=248358

Want to fix my 450 first, but will order some cable's and connector's now. Also think I'll buy the PL6 in this country now. If I order from Revo Intl, and get hit with duty, then I will have paid approximately the same. May aswell help out the local LHS on this one, IF they have the new MPA's. Otherwise, might just have to play import duty roulette

[Grant_beltcp]

If your coming to Weston park Heli fest OptiPower are a major sponsor and may well be selling all stock there.

[copterboy]

Interesting Grant. I'll hang back on ordering them till your event. Would be nice to support the LHS, but would also be good to support the sponsors of your event If you speak to them, just give them warning to get the new MPA's with wires and not deans!! If I make it (and the signs are looking good) I'll get 1 or 2 PL6's with MPA.

For some weird reason, my browser won't let me look at fast-lads or revolution models website today. Tried clicking my favourites, typed the URL and googled it. My screen just goes blank and shows the timer on the tab.

Watch out guys, I think Jack may have developed a virus to stop us from making more purchases

[jperkosk]

Grumpy old bastard has no sense of decency !!!

[rapidgaz]

The dell psu's I got sutty were 15 each delivered and no mods needed at all. Working very nice too.

[copterboy]

£15 each and no mods is a bargain. Could have swore you said £50 Gaz, but obviously I'm getting mixed up again

Got my new TH switch for the DX6i today, so just getting stuck into that and finishing up the 450 re-build tonight.

[copterboy]

Some progress....just done a quick test and got both IBM X366 server PSU's running, wired for 24V and tested with my multimeter. Getting a nice 24.6V under no load, but have read these PSU can handle it and don't drop volts under load to much.

I simply used 2 x bind plugs to get them working as always on, had to re-wire the bind plug so the wires looped ports 1 and 2 instead of the normal port 1 and 3. Easy mod to do, and I had the parts lying around.

To wire serially to acheive 24V and avoid shorting the second unit, I removed the earth wire from the mains plug. Simple job done. Can't believe it was that easy to get up and running.

Still that was only a basic test on the bench. The hours in this project is in the building of the box me thinks, and now I can get on with ordering wires and connectors

[sutty]

That's the bit I don't get Denis. They have earth wires for a reason. The one that doesn't have one now can kill you. Is that not right?

Anyway I'm pleased you have it up and running so easily, but is it safe to do that? Maybe I'm missing something. If I am I'm sure you or the other guys will advise. Is it as simple as the outer case will be designed such that you can't touch the PSU case, but is that actually enough from a safety point of view, if that case went live?

Cheers

Sutty

[copterboy]

So far as my understanding goes Sutty, the positive from PSU 2 goes to the charger/multimeter in the pic. The negative from the charger/multimeter goes back to the neg of the first unit, which is still earthed, so it's still protected. Please anyone correct me if I'm wrong

I also need to ensure that PSU 1 and 2 don't touch each other, because PSU 1 is wired to the negative of PSU 2, which is earthed to the case. So if the case of PSU 2 touches the case of PSU 1, it creates a short. My picture is probably not the best example then, as I placed the PSU's about 20mm apart. Still they were not powered up when I moved them together, and that was after testing each one individually. Also, for all tests, I powered up by the switch at the plug socket, so I never came into contact with live wires, or risked moving the PSU's causing them to come into contact with each other.

If you look carefully through Raf's thread, there is a link to an RCGroups forum which gives details about all the server PSU's that have been figured out for wiring in series for this particular application, and each post about each server tells you what mods need doing. No doubt, I'll go back to it again soon, and I'll post a link up for you when I do. After finding the 450 needed more parts, I spent a good few hours trawling through it last night and updating my wiring diagram again. It's looking alot simpler now and will post up again, before going into full production.

[dauste]

I tend to agree with Sutty on the potential danger here. Having the wires connected will only protect you if you have an issue on that line. It won't help if you have an internal short to earth on unit 2. As you probably know, it is possible to buy electrical equipment with no connected earthing. These are IEC class II units or double insulated. The only way I can see to provide a degree of safety for what you have is to ensure that the chassis of unit 2 is completely isolated with non conductive materials in such a way that it is impossible to touch when in use. Oh, and make sure it never gets wet! Lol

Just don't want to see any accidents happening here.

[copterboy]

Isolating the PSU's (both from me and each other) are already in my plans. But I thank you both for your concerns about my safety and making me go back and double check that it was covered in the design. Although I have not added the isolation for the bench test, it has been included into the plans. I had read about the issue's on page 6-7 of Raf's original build thread, and read more about it on the RCGroups thread.

I will ensure both units are securely fixed to the flight case that will eventually contain them, also isolating both units from the flight case, and protecting myself by keeping the units covered, with only input/output ports visible. But air vents will be added to aid air-flow and heat build up.

I have come across a little query with the power lead/wiring of the 24VDC power supply to the charging box (as I am building a separate PSU and charging case). I know I need to ensure these will be 16A/250V rated.

Normal EURO/3PIN plugs are 10A/250V rated which is not enough for both individual chargers at full power. Therefore, the input's and outputs of the PSU need to be something like IEC 3PIN 16A/250V (from RS components).

This means input/output on the PSU will be IEC 3PIN 16A/250V for the 24VDC PS, and the input to the charger box will be IEC 3PIN 16A/250V.

My question/query is what cable/wire is safe to use between the two boxes, as it will carry the full load of the system (24V/80A). Wondering if 32A/240VAC flexi wire is suitable, or would it be better to use some black/red AWG10 on this line. The supply at this point is DC?

[copterboy]

Just got a reply from Revo Intl to my enquiry about the PL6 combo deals with new MPA BW's (blank wires presumably) Computer said no.

So, I'll leave ordering the chargers for now. If I can get some at Weston with the new MPA BW's, great, but if I can't, I'll probably go back to Revo and order direct then. Hopefully the extra weeks might see them release some new combo deals

[jperkosk]

Originally Posted by copterboy

So far as my understanding goes Sutty, the positive from PSU 2 goes to the charger/multimeter in the pic. The negative from the charger/multimeter goes back to the neg of the first unit, which is still earthed, so it's still protected. Please anyone correct me if I'm wrong

OK let's sort it out. Yes, the PL6 will be earthed under your scheme. What's not going to be protected is the chassis of the second PSU. Remedies:

• Instead of removing the earthing pin form the second PSU I'll try to open it up and remove all internal negative-to-case connections, then I could even connect both cases by screwing them together.
• Grant's found this approach difficult as there can be many of these internal connections. So he just rips the guts from both PSUs, discards the metal cases and mounts everything inside of new plastic case effectively converting the whole setup into double-insulated PSU.
• All that said remember that earthing is important but not a Holy Grail of electricity by any means. My whole house that was built 20-something years ago when the electrical codes didn't exist in my town has no earthing at all, something very difficult to add afterwards. We tend to loose an occasional TV set or a microwave to a severe thunderstorm, though . If you mount the whole setup in a plastic rather than aluminum case, make sure the PSUs can't touch each other electrically, and cover them with a non-conductive top plate so you can't touch ether PSU's chassis accidentally then you'll be perfectly fine. Make both PSUs inaccessible to avoid the dilemma "was this one the one safe to touch -bzzzzzz- ooops, no it was the other one!"

[copterboy]

Cheers for the re-assurance Jerry. Ripping units apart is something I really want to avoid doing, as I don't have the confidence skills to do it, so isolation is the safest option I'm left with.

I just ordered my 450 spares and managed to get the last banana plug connector @ FL's for the 12V output. Also 2 x EC5 male for connecting the PL6's, and some AWG10 and AWG12 wires. 10 packs of EC5's were out of stock, so I've asked to be notified when they are back in stock and I will start converting to EC5/3 from that point.

Just need to sort out the query on the PSU/charger power cable, and then I cen get on with sourcing the mains cable's/IEC and EURO connector's on the 240VAC and 24VDC side of things.

Jerry, do you know if it would be safe to use 16A/240VAC flexi wire on a 24VDC/80A supply? Or, as the 24v current is DC, should I use AWG10/6.0mm2?

[sutty]

Originally Posted by copterboy

Isolating the PSU's (both from me and each other) are already in my plans.

Well that's explains it then. So far this hasn't been mentioned as being included in your design, so I didn't know if you were doing this. Maybe it was obvious, but since I may well follow you, I wanted to be clear, and for you/me to be safe, lol. That's why I said "unless it is designed such that you cannot touch the PSU case". You did mention isolating one case from the other, so that you could use them in series, but you hadn't mentioned anywhere about how you will isolate then from human touch.

I know both Jerry and Grant had explained this, and their different approaches to the same issue, and I was fairly sure it was sensible as well, but I didn't see any specific mention of it in the plan so I was a little bit worried, when I read that you had just removed the earth connection. Right now that PSU has no protection for you against the case going live, and even though you are just testing, and it is unlikely to go wrong, and even less likely during this short build phase, you should still be aware that at this moment it is 'potentially' dangerous.

I know it sounds like I am a worry puss, but you know how when accidents happen and they say, but it was only for 2 minutes, and what are the odds of that, and fancy that going wrong as well. It always takes a bunch of coincidences otherwise nothing would ever happen to anyone.

Originally Posted by jperkosk

If you mount the whole setup in a plastic rather than aluminum case, make sure the PSUs can't touch each other electrically, and cover them with a non-conductive top plate so you can't touch ether PSU's chassis accidentally then you'll be perfectly fine. Make both PSUs inaccessible to avoid the dilemma "was this one the one safe to touch -bzzzzzz- ooops, no it was the other one!"

If I'm honest, I like the sound of leaving nothing to chance, like Jerry says above, and protecting both from touch sounds like a good idea to me. Jerry only says buzz cos it's probably 110V. We go rigid, and need kicking from the equipment.

In truth I've had several mains shocks, but always got away with it because my own earth was so poor. I guess it comes back to a combination of circumstances and bad luck. I used to work on TVs with live chassis all the time, and could barely feel them 'humming' as you touched them first with the back of your hand. Couldn't really avoid touching them so you do. You just had to keep your other hand in your pocket and make sure you weren't kneeling in a puddle of water at the same time, lol.


Cheers

Sutty

[copterboy]

You were absolutely 100% right to call me on it Sutty. Although I had read the plans, and put the safety considerations into the final layout in my mind, I think I probably didn't realise the full potential danger of the bench test, even in the unlikely event of the 2nd PSU casing going live.

I suppose it was just insinct from what I read, that I knew to isolate myself from the units by not touching them when powered up, but it's good to be 100% clear on things like this, and not leave anything to chance. So I thank you all again