Battery Charger

Sparky Joe

I've been working in a private jet hanger for the past few days. The guys there asked me to temporarily hook up a bat charger for their new tug.
They wanted it temporary because the charger will have a different final home if this job ever ends. It runs 208/240(single phase) and reads 26amps(at 208).
Their one 208 panel is full, but they had a 208/20A receptacle already in the hanger, so I installed the cord cap they already had and said there was a chance(if the batteries weren't deeply drained)it would work. But it tripped.

So there was a 3 phase 30A breaker in the panel for one of the air conditioners, I piggybacked the charger onto this(mind you this is temp) seeing as it's been 10 degrees here. After 20 minutes it tripped.

I clamped the wires and read 46 amps. There is a 50A 2pole breaker for the range in the kitchen which is never used, and told them I could tie to that, but want them to first call the manufacturer of the charger and ask if this is a normal current reading.

My questions;
Has anyone seen a battery charger(72V 40A output) draw a current higher than the nameplate? I know they vary due to depletion of the battery being charged.
Next; what are the feelings of tapping off two legs of a 3 pole breaker, I know it was stupid, but why?
And; If I do put it on the 50A breaker should I keep the 30A recep and cord cap I already installed. Are the hazards really that significant?

Keep in mind all this is to try and help and customer dodge an inflated charge of doing the same job 3 times(though my work compared to five 40million jets is hardly inflated), and also that any comments will be supersceded by what my shop says in the morning, although some knowledgeable info is very appreciated. Afterall who wants to just do what they are told, knowledge is key to making decisions.

-Joe

CE1

Joe,
Check you data again some of the numbers don't add up. What you have, I can not tell.

Sparky Joe

That's why I want them to call the manufacturer before I burn the thing up, I put 'lektro' in my phone so I can call them if they don't.

The charger was a multi tap for single phase 208 and 240, all that checked out and even the amp meter on the charger read 40amps DC, which is what it says it needs.

MSSI

As far as the plugs go....being able to plug a 30A circut into a 50A breaker is probably not a good idea.(in this environment even if very tempoary) The equipment that floats around an aircraft hanger can be quite expensive (think flight control diagnostic equpiment)and is often under the umbrella of the FBO(fixed base of operations)Which is governed by FAA guidelines. I wouldnt want to try to explain my way out of burning down a $25mil Gulfstream. The first thing they teach an aircraft mechanic is not to put your name on your tools..(lol) picture you new 7/8 snapon wrench getting sucked into a turbine engine...You dont want to be the one they come looking for.

An Aircraft Battery charger has voltage regulated circutry I dont think there is a direct corelation between load on the battery side and amp draw on the line side.
I believe the same holds true for a Standard battery charger.. If the tag reads 26 amps it probably shouldnt be drawing 46??? It sound like we might be missing something..

Sparky Joe

Thanks MSSI, good points about the higher regulations of doing work around aircrafts. My Dad worked for Douglas when they were still around and had something called "FOD free" which had something to do with foreign objects. They had inspectors watching these DC-10's being built from start to finish and when the entire plane was complete, the inspectors would say back on 'such and such' day 'so and so' left a 3/8 socket(or whatever) in a specific part of the plane. What then, tear it apart and find it.

MSSI

sometimes the tugs use the same battery setup as the aircraft.Or it could be a 24V diesel setup..... probably to late but is this a walk behind tug(electrohydraulic ?) ..72v is an aircraft voltage....Thats 6 batteries in series.... there should be settings on the charger for 24 and 48 volt as well. make sure the batteries you are trying to charge corespond with the charger setting.

MSSI

oh ...and aircraft battery arrays can be upwards of $30K

CE1

Hey Joe ,did you get it hooked up or not. Some people need to know you know.

Sparky Joe

Well I took the day off yesterday. But first I'll say the charger has two 'taps' one for 208 and the other for 240. I checked voltage at the panel and read 210. The charger everywhere on it says "DO NOT CONNECT TO THE WRONG TAP" So I didn't.

I get there today and asked if they called the manufacturer, they said "no, they just changed the tap to 240 and it works fine". I thought about opening the panel and checking the current again, but also thought, "if it aint broke....".

Just to satisfy curiosity, next time I'm in the panel I'll hook up the charger and check the current. Then I'll post. I just didn't want to be the one to blow the thing up, but of course I'm the one that looks the idiot now

DAVIS081404

Better safe than sorry. If you had hooked it up and the worst did happen you wouldnt live it down

CE1

You did it right, Sometimes caution is better than charging.

Sparky Joe

I get it -charging- hahaha

Just teasing