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Sherlock Ohms

Batteries' Chargers Require a Little Muscle

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warren@fourward.com
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No solution for this one.
warren@fourward.com   5/24/2012 6:06:33 AM
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Unfortunately, I see no solution for this problem.  You can't train everyone to "push hard on the plug when you plug it into the wall."  There is no guarantee that they will always to that. Maybe over time the sockets will loosen up a little and it won't be such a problem.  Maybe a little or not so little sign warning them.  But technically, this is a problem with no or limited solutions.  You're dealing with "people," the weakest link in the chain.

paul-c
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Re: No solution for this one.
paul-c   5/24/2012 11:38:12 AM
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Warren:   I think you've already hit upon the solution, but haven't realized it.  It's true that these "hospital grade" receptacles have extremely strong springs.  The cure may simply be to use a "hospital grade" plug (which usually have quite thick prongs) to break-in each and every new receptacle.  This, plus a bit of contact lubricant on the plug's prongs to lube the socket, should make it easier for the user.

  I think part of the problem is that these receptacles were installed quite high up, makings it harder for the user to apply sufficient insertion force.  By the way, were the staff members short?

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/24/2012 2:22:10 PM
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Good point, Paul-c. Since this was happening multiple times, you can hardly blame the users. There was something intrinsically flawed in the design if plug after plug failed to insert correctly.

  


KMoffett
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Battery charging.
KMoffett   5/24/2012 4:07:04 PM
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Yes, this was a problem with no pat solution...and no one you could point a finger at.  In my opinion the design of the high placement of some of the outlets was the biggest factor.


And, yes there are a lot of the short nurses, aids, pump techs, RTs, ....


Only "Hospital Grade" plugs are used in these environments. I'm not sure that "loosening up" the contacts by plugging and unplugging a plug would work in a reasonable amount of time...although they do get less tight after a few years. Messing around with lubricants is not a solution in an environment where vast amounts of medical equipment cord sets are cleaned within an inch of their lives after every use...and no guarantee that any single device will go back to a location were it's a problem. The fact is that in most hospital beds, though the headwalls have high outlets, they are never used...they're there "just in case". Our NICU was a special case. I had seen as many as 18 devices on one tiny baby.

On many devices there may be no "battery charging" indication during use, it's just on. There are "battery operation" indicators though. The problem was that they would initially work OK, but we suspected that cord movement caused the disconnects. Going into battery operation is usually just one beep. With loads of devices at one bed, this could be missed.

Staff training in those areas, especially the supervisors, pretty much ended the problem.

Ken

Rob Spiegel
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Re: Battery charging.
Rob Spiegel   5/25/2012 10:30:48 AM
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It sounds like staff training was the only reasonable solution, Ken. Why is this situation unique? Apparently this was not a problem in the older building.

KMoffett
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Re: Battery charging.
KMoffett   5/25/2012 10:51:42 AM
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Rob,

The old building/NICU had old worn, inadequate number of low to the floor outlets. All that was changed in the new hospital.

Kren

Rob Spiegel
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Re: Battery charging.
Rob Spiegel   5/25/2012 11:20:24 AM
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That makes sense, Ken. So the new plugs were an improvement even though they required more of a push to seat correctly.

gsmith120
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Re: Battery charging.
gsmith120   5/27/2012 5:36:11 PM
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I have come across these types of "improvement parts" and similar problems.  From time to time the developers will provide a notice to the end-user as a warning so such events don't happen.  Sometimes the smallest change or improvement can cause big problems.

 

Leigh
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Re: Battery charging.
Leigh   5/27/2012 7:58:50 PM
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The USA 2 prong plug must be about the worst designed mains plug on Earth.

An easier solution would be to change to almost any other countries plug, or even a twist lock neutrix style outlet.

Ann R. Thryft
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Re: No solution for this one.
Ann R. Thryft   5/25/2012 12:32:14 PM
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I agree with Warren that users are the weakest link in the chain. But that said, as an intelligent, creative and reasonably well-educated user when it comes to things mechanical and electrical, I still find myself stumped occasionally at how to interact with a machine. What used to be common knowledge isn't anymore. There's so much specialized technology in objects we use everyday that without direct experience or specialized knowledge--or well-labeled indicator lights--this type of situation is getting more common.

warren@fourward.com
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Re: No solution for this one.
warren@fourward.com   5/24/2012 3:39:17 PM
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I actually was thinking that, but then I wouldn't have given you a chance to say it.  :-)

 

Maybe the alarm on the devices used should sound until the power is secured.  And loud!

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/24/2012 3:46:47 PM
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Good point, Warren. But perhaps the manufacturer was OK with the idea of the user modulating speed by partial engagement. How else is the user going to slow down the power to the wheels?

warren@fourward.com
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Re: No solution for this one.
warren@fourward.com   5/24/2012 8:27:35 PM
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We were talking hospital plugs, weren't we?  I think you reverted to the lawn mower question.

 

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/25/2012 10:45:17 AM
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Warren, you're right good catch. That's what happens when I read something out of context. That's funny.

ChasChas
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Re: No solution for this one.
ChasChas   5/25/2012 11:03:55 AM
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There is a solution that always works.

Long ago I brought an item into a repair shop. The older fellow took one look at it and gave we the best advice of my life.

"Bring it back where you got it from."

What would us engineers do without feedback from the field? And as consumers - we would keep getting the same junk if the engineers don't get feedback.

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/25/2012 12:56:29 PM
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Sometimes simply, old fashed advice is the best, ChasChas. Thanks. Perhaps that would have been the best solution off all.

Charles Murray
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Re: No solution for this one.
Charles Murray   5/25/2012 5:51:57 PM
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I agree, ChasChas.If the engineers received the proper feedback from the field, my guess is that it would have been designed differently the second time around.

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/29/2012 12:26:08 PM
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Yes, a feedback loop would have done wonders to correct the design. Given the wider acceptance of collaborative tools, it looks like feedback loops -- that could have helped here -- are beginning to sprout. It will be interesting to see if news from the field begins to alter design.

jmiller
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Re: No solution for this one.
jmiller   5/29/2012 8:20:29 PM
You would think they would have a little light on there just like on the battery powered drills that says "charging".  Seems like a simple problem to be solved.

Rob Spiegel
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Re: No solution for this one.
Rob Spiegel   5/30/2012 12:23:00 PM
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Yes, Jmiller, a charging light would likely cost very little. For a specialized system in a medical facility, the small cost would offer clear benefits.

Charles Murray
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Re: No solution for this one.
Charles Murray   5/24/2012 7:48:07 PM
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I agree, Warren. It's tough to train people who don't apply a little muscle to suddenly start doing it.

TJ McDermott
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Re: No solution for this one.
TJ McDermott   5/25/2012 1:18:54 AM
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Warren, a twist-lock plug and receptacle would fix this problem.  The important outlets in a hospital SHOULD be different from a conventional outlet, so mundane things like a fan or radio cannot be plugged into them.

Twist-locks would keep the receptacles dedicated to hospital equipment, be easy to use, prevent accidental unplugging.

It's a Hat-trick solution.

warren@fourward.com
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Re: No solution for this one.
warren@fourward.com   5/25/2012 6:42:10 AM
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I like the twist lock suggestion.  Nice trick, Mr. Hat.

This may not be the only application where a critical circuit could come unplugged.  The twist-lock would solve those problems, as well.  And think of the electricians that could be put to work!

 

KMoffett
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Iron
Re: No solution for this one.
KMoffett   5/25/2012 8:09:51 AM
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TJ,

Twist-loc connectors might solve that particular problem, but would cause greater ones.

First, 120VAC medical equipment with attached cord sets (in the US) come with "standard" hospital-grade 3-prong plugs. And, all standard outlets accommodate these. The cost of switching all outlets where a device might be used and all device plugs to compensate for this one problem would be prohibitive.

Second, medical devices running in battery-mode frequently accompany transported patients.  That would mean that any area or vehicle where the patient might be held for any significant length of time would also have to accomodate these plugs for recharging to maintain operation. That would include ambulances, clinics, waiting rooms, hallways....even homes.

That problem, in that hospital was resolved economically through staff awareness.

As an aside, a large percentage of medical devices are now using wall-plug power supplies...for two reasons. The medical devices could be made smaller. And, maybe more practically, the UL approval is now entirely on the power supply manufacturer, not on the medical devise manufacturer. The "wall-warts" compounded our outlet problem. I'm sure you've experienced the situation of a wall-plug supply, plugged into one outlet of a duplex, blocking the second outlet. Each such device occupies two outlets.

Ken

streetrodder
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Re: No solution for this one.
streetrodder   5/25/2012 10:43:21 AM
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To build on Ken's argument regarding twist-lock plugs:

Operating rooms used to require twist-lock plugs.  They don't any more.  It doesn't work. 

Reasons:  In the OR, it's not unusual for someone/something to snag a power cord.  with a regular plug, the device comes unplugged - not good, but better than what happened with twist lock plugs.  Those are - the clinician trips, dropping whatever they have, possibly hitting others, etc. etc.  The cord tears out of the plug, rendering the device useless, and depending on the case, causing a major hazard. 

In a NICU, or any critical clinical area, the solution of twist lock plugs/outlets or other specialized combo simply doesn't work.

Think of a hospital as an oversized piece of equipment - except it's always being redisigned on the fly, inputs and outputs randomly change, and a large part of the components (the people) are generally running just above the chaos threshold.

Regards,

Paul Sherman, CCE

jmiller
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Re: No solution for this one.
jmiller   5/29/2012 8:28:09 PM
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Isn't there a saying about the impossibility to make something idiot proof because there will always be a bigger idiot.  At the same time we as engineers need to be trying to do all we can to make everything work as much as possible. 

Quite often in a case like this it's people working hard and doing the best they can that struggle with something that should be easy to do.  But under the wrong set of circumstances it doesn't perform the way it is expected.

 

GlennA
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Typo ?
GlennA   5/24/2012 8:44:46 AM
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I think the line was supposed to be "if the plugs were NOT inserted far enough".

The article mentions 'battery charging mode' which I think would be an indicator lamp.  I know this will sound ridiculous, but a 'plug inserted fully to get AC power' lamp would confirm the plug is seated.  Or a more obvious 'running on battery' indicator or alarm might bring attention to the plug being loose.

Jennifer Campbell
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Re: Typo ?
Jennifer Campbell   5/24/2012 10:15:15 AM
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@GlennA - yes, that most certainly is a typo. Thank you for pointing it out.

KMoffett
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Iron
Alarming alarms
KMoffett   5/24/2012 4:18:53 PM
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"Maybe the alarm on the devices used should sound until the power is secured.  And loud!"

Warren, can you imagine a power failure, and having a hundred-plus devices going into battery-mode and continuously, loudly alarming. The manufacturers make choices based on real world user input...hopefully.

 

Ken


warren@fourward.com
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Re: Alarming alarms
warren@fourward.com   5/24/2012 8:28:54 PM
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With 50 alarms going off at the same time, and the heart attacks created, it would be good for business. 

warren@fourward.com
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Re: Alarming alarms
warren@fourward.com   5/24/2012 8:28:55 PM
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With 50 alarms going off at the same time, and the heart attacks created, it would be good for business. 

EEMEDIC
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Lose Plugs...
EEMEDIC   5/25/2012 9:33:28 AM
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We have similar problems with loose charging plugs of battery operated equipment on ambulances...and of course the battery is always dead when you need it most. Maybe its time we created a new "standard" outlet for medical equipment....something easy to use but with better retention...and then create a simple adapter that allows the device to be used in a standard outlet, of course the adapter needs to be somehow mounted to the plug so its never lost...medical equipment typically doesn't have the same price pressures as consumer electronics...when you buy a $30,000 EKG monitor, you don't mind paying a few extra $ for a plug that works!  One simple solution that we have tried that seems to work is switching to plugs with small LED power indicators in them, with a quick look you can tell if there is power being supplied to the power cord.

bob from maine
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Re: Lose Plugs...
bob from maine   5/25/2012 10:31:52 AM
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I'm guessing that a partially inserted plug with exposed metal could be considered a hazard, so what may seem to be the obvious solution is to require the plug to be fully inserted by moving the contacts deeper into the socket. Ditto with old worn-out plugs falling out indicating thicker contacts to prevent poor retention. Then the facilities team puts the plug up in the air so the cord can't touch the floor and will be easily seen. Adding the human element of nurses who have become accustomed the old non OSSHA, easy-plug, early wear-out, non facilities enhanced plugs and the expected outcome is exactly what we're seeing. The people designing the next hospital or laboratory unfortunately are not the ones who use all these newly deisgned products. They all look good in a catalog and once bought and installed, they'll last for years.

CliffG
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Re: Lose Plugs...
CliffG   5/25/2012 2:58:47 PM
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My nurse/neighbor likes the idea of a power light in the plug. Some of my extension cords have neon lights in the clear plug or receptacle to indicate power. I've noticed that they tend to burn out after a few years, but the 3-way tap I just got has an LED power indicator.

The receptacle location so high up it can barely be reached is a contributor, perhaps even the root cause since this issue does not appear to be a problem elsewhere in the hospital.

William K.
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Requires more muscle
William K.   5/26/2012 4:51:39 PM
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This case includes two examples of the "it seemed like a good idea at the time" syndrome. The first being to put the outlets at a non-ergonomic height. Above head height is certainly a very poor choice for anything except plug in permanent lighting fixtures. The second poor choice was selecting receptacles without specifying the insertion force. Different levels are available from some suppliers. 

Of course, having an "AC present" indicator on all of the battery backedup devices would have immediately indicated the problem, and it should always be provided.

The mention of twist-locking connectors is certainly a good comment, and it is applicable in a wide realm of applications. OF course, in some areas the equipment would need to have loss of power alarms to instantly allert the users to the problem.

Tim
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Plugs
Tim   5/27/2012 8:26:52 PM
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Good job on the go and see approach to solving the problem.  In a previous job, we had a similar problem with power supplies on bench weigh scales that would suddenly stop functioning.  The warranty held on the first few units, but after three failures, the scale company said that we had a problem as their units typically do not fail.  Review of the systm showed that some of the plugs were to be used only for industrial fans and these had a hard wired power monitoring / controlling circuit designed to minimize power usage while using the fan.  When a scale was plugged into this plug, the monitor would effectively drain the power supply and cause it to fail.  We changed the plugs for the fans to a round 120 V plug which eliminated the possibility of plugging the scale into that plug.

KMoffett
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Re: Plugs
KMoffett   5/27/2012 9:45:20 PM
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Again, the concept of switching to a nonstandard plug/socket on medical equipment is precluded by the fact that almost all medical devices must be able to be used in almost any environment...for convenience, economic, and safety reasons.

The high placement of outlest iwas the real issue, and in most patient stations these are only used for permenently installed monitors. The new NICU was/is a highly device intensive environment...maybe more than they planned for. Research hospitals are always pushing the edge of technology for patient care...which can mean more equipment.

One change that I see now that could have made a small difference is the orientation of the outlets. In the past the outlets were installed so that the ground pin was on the botom. At that time the concern was to maintain the contact with the ground if the plug was partially pulled by tilting. This was for preventing electrical microshock to patients.  Now the outlets are installed with the ground pin on the top. The power pins are the last to lose contact if the plug is tilted downward.

I like the lights in the plugs. I see them in "cheap" extension cords at Home Depot. It sometimes amazes me how nickle-and-dimey manufacturers can become on $50K-100K devices.

 

Ken

Tim
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Re: Plugs
Tim   5/28/2012 6:41:05 AM
The lighted plugs do have their advantages.  The light works as a quick troubleshooting tool that comes in handy especially at the end of a long extension cord.

LloydP
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Re: Plugs
LloydP   6/2/2012 12:13:29 AM
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It has been my experience that outlet orientation (ground "U" pin up or down) is usually an indication that the outlet was installed by a union or non-union electrician. The "code" seems to vary in different cities across the US, though.

warren@fourward.com
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Platinum
Lighted Plugs
warren@fourward.com   5/29/2012 8:35:39 PM
I give an A++ to the guy who suggested lighted plug.  What a great idea and simple solution to the problem.  No light, no juice.  It's the simple things in life...

 

warren@fourward.com
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Re: Lighted Plugs
warren@fourward.com   5/29/2012 8:37:14 PM
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Also, you can never make something idiot proof.  The public schools are making idiots too fast.

Tool_maker
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Re: Lighted Plugs
Tool_maker   7/11/2012 12:42:59 PM
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I seriously doubt that all of the nurses, the installing electricians, the contractor's purchasing agent and the designing archetect were the products of Public Education. That sort of snarkey comment adds little to the discussion and nothing towards solving the problem at hand.

warren@fourward.com
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Re: Lighted Plugs
warren@fourward.com   7/11/2012 12:47:49 PM
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Really?  When many of the beginning college courses revolve around remedial english and math before today's students are capable of beginning real college classes?  I think it IS the problem.  And there is a lot of evidence that it is.  Snarky?  Probably.  The truth?  Surely.

Tool_maker
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Re: Lighted Plugs
Tool_maker   7/11/2012 3:15:24 PM
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  So what evidence do you have that those remedial classes are for public school students only. I teach in a private high school, which my parents could never have afforded to send me to, and I run into some of the same unmotivated brick heads I met when I was student teaching in one of the more well-to-do suburban high schools in this area. I am at an all male school and the students all come to us from private grade schools. Some come literate and well prepared, but others arrive through the back door because their father is Doctor whosawhatsis, or attorney ambulance chaser and they contribute large sums of money. One of our faculty has several degrees from Harvard, but he was fired because he could neither teach nor control his classes.

  Point being, incompetance is no more exclusive to the public school systems than excellence is confined to Ivy League schools. We also have to teach remedial classes because some students think, "u r rite," is acceptable English. I challenge you to enroll in any 101 level class in any university you choose and pick out those students came to that campus via a public school system.

KMoffett
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Re: Lighted Plugs
KMoffett   6/2/2012 7:13:26 AM
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kf2qd,

The architectural design problem was not forseeing the possibility of having the need for more low level outlets than is normally needed in an NICU. This unit had come from an old building where outlet strips (cringe!) were a necessity.  Our hospital pushed the technical limits on keeping these premies alive.

EEMEDIC
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Re: Lighted Plugs
EEMEDIC   6/4/2012 8:08:14 AM
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Thanks! It seems to be working well in our application....the plugs cost a few $ more, but much easier than explaining why a critical piece of portable battery powered equipment was dead when you really needed it! 

kf2qd
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Platinum
Poor Facility Design
kf2qd   6/1/2012 4:26:02 PM
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This is a case of poor architectural design. If he had to reach up over 6Ft to push teh plug, how was that little nurse supposed to ever push the plug in? Hospital Grade plugs have a much higher gripping pressure on teh contacts and are very difficult to plug in as well as to pull out. If a short nurse was trying to plug them in, at near full extension of her reach, at which point she had very little mechanical force to impart to the plug.

 

Receps were mounted too high, poor ergonamic design.

Rob Spiegel
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Re: Poor Facility Design
Rob Spiegel   6/1/2012 4:39:52 PM
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Good point, Kf2qd. The plugs themselves may not have been the problem, but rather it was where they were mounted on the wall. Even so, it would have been wise to have an indicator showing whether the batteries were charging or not.

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Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
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Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
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