Hoist failure

[steves1977uk]

Today the unexpected happened, my bathroom hoist ran out of battery power just as I was at the highest position to get out of the bath! Luckily my PA and Mum managed to safely get me back in my chair.

I often wondered why they don't have a XLR port on the underside to allow the hoist to be powered from a powerchair in an emergency? This would be much quicker than the slow manual release. Surely this must be possible? Also the hoists are supposed to do 60-odd lifts before needing a recharge. It's always placed back into the charging position after use.

Steve

[Burgerman]

Is it 24V?

If so a small hobby pack or similar would do the trick. You just need to add a connector. Sounds like a bad battery. You should periodically test its Ah capacity so you would be forewarned. Most of those chargers sit at 13.8V or 27.6V which is way too high for float charging long term. OK for a couple of days. But if its always put back on charge its basically on 24/7?

[steves1977uk]

Yes BM, they're 24v powered by 2x12v 10Ah batteries I believe. Unfortunately they're NRS property so no modifications allowed! The charger is a 27v brick PSU similar to a laptop one.

Also I think these newer models have a higher idle power draw since they do self-checks, like it can tell when it's due for a service. This is the hoist I have in the bathroom and bedroom... https://www.chilterninvadex.co.uk/ceili ... -range.asp Also there was no audible warning that the batteries were low. The bedroom one is much quicker than the bathroom one I've noticed.

Steve

[Burgerman]

Unfortunately they're NRS property so no modifications allowed!

People have been telling not to modify things because its NHS/NRS? property, because its going to void the warranty, because it will nullify the insurance, because its illegal, because it will do some scary thing, because it will blow up (nitrous on engines for e,g,) and I never took a blind bit of notice. Ever.

[steves1977uk]

Well, whaddayaknow... My bathroom hoist lost all it's charge again 2 days ago, had the service guy out to look at it and he basically said water and circuit boards don't mix. Ummm, the previous models had no problems for years, and he also said the batteries were wrong as he doesn't use that type.

He also didn't check to actually see if the hoist was receiving a charge from it's power brick as my Brother noticed the IEC plug was being pulled out because the cable just hangs down and plugs into a normal 13A socket by the installer guy about 8 months ago. Very poor IMO.

Steve

[Burgerman]

I told you. You are surrounded by them...

[Burgerman]

Also I think these newer models have a higher idle power draw since they do self-checks, like it can tell when it's due for a service.

I wonder if the self checks tell it that its destroyed its own battery doing self checks?

[steves1977uk]

Possible! Why do they add these "features" without thinking it would drain the batteries quicker? It's baffling who thinks these things are a good idea.

Steve

[Burgerman]

Because 2 things.

1. they dont USE these things.
2. they are all built and designed by committee. So the programmer invents lots of marvelous features, because he hasnt a clue about batteries or charging. The motor guy only designs motors. The marketing guy loves "features" as it adds percieved value and he hasnt a clue about anything other than sales. The bean counters only care about cost/profit etc.

[steves1977uk]

Oh I agree BM, people who makes things for the disabled never actually ask us how they could make their equipment better/more reliable. They think we can't make better designs than they can, so we get pushed to one side. Re: My hoist, I'd rip out the self-checking circuitry and make it a simple PCB like the previous models used. At least then I would get about 60 lifts before it needs charging.

Steve

[steves1977uk]

Well, me and my PA took it upon ourselves to fix the hoist. We discovered the batteries are only 2.4Ah 12v Yuasa ones! Testing them with a multimeter they read about 12.48v each.

The main reason it wasn't getting power is because the service guy had left the battery plug off the PCB! Plugged that back in and it fired back into life. My PA is pi$$ed off with Chiltern and NRS since they're arguing about who actually warranties it, and they've ordered a new charger for it which isn't the problem. It's like a circus playground. I actually asked my OT how are NRS techs trained? A fair enough question to ask I thought.

Steve

[Burgerman]

They do a day course. At best. And are generally the type of people that dont have a damned clue. Unfortunately its endemic. The reason it happens is that all those with any real aptitude for electronics, mechanical skills are capable of earning big money working for themselves or in specialised industries like aerospace or race cars, or whatever.

Whats left is all those that were not capable of that or much else and they chose the ultra un sexy mobility industry. Or usually it chose them. Why? The last "engineer" that I had here from the wheelchair services was a delivery driver 3 years earlier for a high street mobility shop. He had no clue, and almost no training. And this is typical. He was all they could get. He ended up as their tech because he could fix things that the sales guys couldnt. An "expert" is someone that knows or claims to know more than you do.

My mate dave syndrome! My computer (real expert) freind ran a computer shop. Specialising in networks etc. He said every time some numpty with a buggered up computer came to his shop, it was always because the customers "computer expert" freind had been messing with it. Inevitabley this expert was a typical tit who knew just enough to cock it up. And was usually "me mate dave wot did it".

YOU as an end user know 10x more than your expert about batteries and charging and have already fixed it. As he should have done. Now this isnt to say that ALL these experts are useless. There are a few. Like Rover who I never met. But seems to know his stuff well. But he is one in thousands seriously. And note that he is on here. Why are all the useless ones not ALSO on here learning and asking questions? Because they literally do not understand it, and worse dont give a crap. They only turn up for the wage. And they keep their jobs because to the secratary or boss they are an "expert" because they know a bit more than they do... Me mate dave...

[slomobile]

I often wondered why they don't have a XLR port on the underside to allow the hoist to be powered from a powerchair in an emergency?

For what its worth, when I was shopping for a small electric tiller to keep the veggie beds from the chair, I chose https://snowjoe.com/products/sun-joe-24v-x2-tlr14-24-volt-ion-cordless-garden-tiller-cultivator-kit-w-2-x-2-0-ah-batteries-and-charger/ beause each of the 2 24v batteries has a barrel jack on it, which allows me to easily run my powerchair or other 24v devices from it in a pinch. Adapters can be made for any power tool pack, but it can be tricky to get the terminals in just the right place. The 2.1mm barrel jack makes it an easy mod.

[Burgerman]

beause each of the 2 24v batteries has a barrel jack on it, which allows me to easily run my powerchair or other 24v devices from it in a pinch.

You have 2 problems. 1 hose packs are tiny 2Ah calls. Actually 18650 cells . They look like duracells. And there is 7 in series with a BMS. The BMS will limit current to something much less than a powerchair needs. And those barrel connectors are only good for a couple of Amps. A powerchair can pull 100 to 200A. And then theres the 29.4V battery voltage that will attempt to charge your dead batteeries in a chair at around 100A if you were to connect them. And the Barrel connector, its wiring will melt. If the BMS doesent cut off power first. If you try it you will ruin the cells too. You cannot take that much current from them. There are some specialist 18650s that can do 30A. But that will destroy a 2.1mm connector.

[slomobile]

beause each of the 2 24v batteries has a barrel jack on it, which allows me to easily run my powerchair or other 24v devices from it in a pinch.

You have 2 problems. 1 hose packs are tiny 2Ah calls. Actually 18650 cells . They look like duracells. And there is 7 in series with a BMS. The BMS will limit current to something much less than a powerchair needs. And those barrel connectors are only good for a couple of Amps. A powerchair can pull 100 to 200A. And then theres the 29.4V battery voltage that will attempt to charge your dead batteeries in a chair at around 100A if you were to connect them. And the Barrel connector, its wiring will melt. If the BMS doesent cut off power first. If you try it you will ruin the cells too. You cannot take that much current from them. There are some specialist 18650s that can do 30A. But that will destroy a 2.1mm connector.

Yep, that is what I meant by "in a pinch". Fuses take time at temperature to blow. Those 2 AH packs in series run a 500W tiller successfully chewing up turf for over 30 minutes at a pop and recharge faster than I do. Unplug the dead boat anchors and its enough to get loaded into a vehicle, or out of a vehicle into the house, or move the seating(leg elevate) enough to pull the lead acid batteries, or potentially move you off a stuck lift. Emergency use.

Yeah, maybe it melts a cheap barrel connector rated for 5A. If it lasts for the right 30 seconds, its been well worth it. I know that is a failure point and I keep n eyey on it, ready to jetson in case of lithium fire. The point is, what portable 24v source do you have available around you when you need it? 8A from the chair charger if you also have mains handy, the chair batteries if they aren't the problem you need to solve, a couple car batteries if you can scrape them together, 1A or so from a wall wart(which can also charge chair batteries slowly in a pinch), or these tool packs which are around anyway.

I don't know how common this feature is, but my Quantum Q6edge came with a battery clamp adapter cable which plugs into the chair's round 2 pin connector or an included manual switch box to drive any single actuator with 12v and override drive inhibit while on the charger. I suspect this is because there is no way to change dead batteries with leg elevate down, short of lifting off the entire seating assembly. Of course, I found this switchbox AFTER I lifted off the seat.

[Burgerman]

Those 2 AH packs in series run a 500W tiller successfully chewing up turf for over 30 minutes at a pop and recharge faster than I do.

2A X 24V = 48watts. The batteries are 48Watt Hours. The most they can run for 30 mins is the 2C rate. Thats 96watts max.

Your 500W tiller, for 30 mins so thats 250Watt hours needed from your 48watt hour battery... You are trying to take a gallon out of a pint pot. So if they could produce the current (250 watts/24V = OVER 10A) and some 18630 cells can, then the tiny 2.1mm connector and its wirig would melt. And the actual run time would be a little under 6 minutes.

So your tiller must pull nowhere near that 500 watts. And the expectations you have for moving a powerchair are wholy unrealistic. As soon as you try and turn, or move anything from 25 to 100 amps (or more) will attempt to be pulled from the batteries. And they cant give that. And if they could a tiny 2.1 connector and the tiny wiring would smoke and turn into your fuse. It might move an actuator. In an emergency. Not a chair. I suggest you dont try this. You might be very disapointed! And need new batteries and wiring.

On my own chairs I have an anderson connectors. It can allow me to power the chair from any 24V source that can give enough Amps at 24V. My 50A power supply, a spare chair, or a small Lithium Ion hobby 6 or 7S pack. These are designed for high C rates. My tiny 4Ah quadcopter battery is 130C capable. That can give 130x its 4Ah. Theres a few ways, but a tiny 2Ah 18650 cell wont work. Esp if it has a BMS system as almost all do. It will just chop off all power the moment you try to move to protect the cells.

Take a look at the size of a chairs battery cables. And those are too small. They get hot enough to melt at high currents. And we are taking about up to 240A max here. An empty chair? You might get it down a ramp. Or move on a flat surface unloaded. Or up any kind of a slope. And dont attempt a turn in place!

[slomobile]

Oh, so sorry the thing I am doing right now is impossible because you can't figure it out because you made bad assumptions.

[slomobile]

Oh, so sorry the thing I am doing right now is impossible because you can't figure it out because you made bad assumptions.

Ok, that was too strong and I can not edit or delete it. I also made bad assumptions. I was running the chair via the "tool" contacts, the spring loaded blades with a wire shoved in there. I had previously verified that open circuit voltage(35v) was present at the barrel jack too and ran some lights from it, assuming they were just paralleled. I assumed it would work in a pinch, but probably be destructive so I didn't run the chair on the barrel jack previously.

Well I just tried running the chair on the barrel jack and it does not work. No smoke or sparks or heat. Just nothing except open circuit voltage. There must be some kind of current limiting device on the barrel jack. To be clear, it does operate the power chair with wires shoved into the battery contacts. It is only the barrel jack that doesn't work for high current, it is still perfectly functional as a charge port and low current output. And since I'm eating crow, the barrel jack center pin was not 2.1mm either, its a bit longer and wider, but I couldn't get calipers far enough in to be sure how much.

[Burgerman]

The limiting device is the BMS and it cuts power because it cannot possibly provide anywhere near the amps your chair draws. Its soldered to the cells to protect them from exactly what you are trying to do because it would destroy them in very short order.

Also, a 24V lithium ion system is 7S fully charged at 29.4V that will work if big enough to provide circa 100A or so at 7S with a powerchair.

35v that you measured is either wrong or its 8S which is too high for powerchair use. Dynamic systems give an error at 32.0V. PG drives gives an error at 35V. And this happens easily as you decelerate and the regeneration current tries to go back to the battery which pushes up the voltage as a spike. In your case the BMS may cut off power due to overvoltage. Due to small battery, already high voltage and high impdance. Which can damage the mosfets in the controller. Dont keep trying this as you may live to regret it.

[steves1977uk]

It's happened again! Bathroom hoist died when I was at the highest point over the bath. The best bit about it though the service guy was here 3 days ago and replaced the batteries in the bedroom hoist, although that seldomly gets used and is always at it's charging point. Which begs the question, are Chiltern cheapening out on poor batteries and chargers? I'm thinking both.

Steve

[steves1977uk]

You're gonna love this quote BM!...

Basically been having the same issues with my bathroom hoist, where it's not charging the batteries correctly. The service guy came out last Friday and said one battery was weaker than the other, so I'm thinking silently to myself, "So that means the good battery is being overcharged hence killing it faster! and the weaker one is being undercharged." So he replaced both of them, but issue still remains because he never tested each battery before fitting them. For all we know they could've been in storage for months without being charged fully.

This morning he phoned again and got my Mum to do a quick test, hoist still going slow... But here's the best bit!!!!... He said...

If you keep using the hoist, it will hopefully build up a charge.

My Mum came off the phone looking and said, "How does that work???? Surely if you use it it's going to deplete the batteries." I said, "Correct! They have absolutely no clue how to charge batteries."

Steve

[Burgerman]

Tell me about it.

[martin007]

They do a day course. At best. And are generally the type of people that dont have a damned clue. Unfortunately its endemic. The reason it happens is that all those with any real aptitude for electronics, mechanical skills are capable of earning big money working for themselves or in specialised industries like aerospace or race cars, or whatever.

Whats left is all those that were not capable of that or much else and they chose the ultra un sexy mobility industry. Or usually it chose them. Why? The last "engineer" that I had here from the wheelchair services was a delivery driver 3 years earlier for a high street mobility shop. He had no clue, and almost no training. And this is typical. He was all they could get. He ended up as their tech because he could fix things that the sales guys couldnt. An "expert" is someone that knows or claims to know more than you do.

My mate dave syndrome! My computer (real expert) freind ran a computer shop. Specialising in networks etc. He said every time some numpty with a buggered up computer came to his shop, it was always because the customers "computer expert" freind had been messing with it. Inevitabley this expert was a typical tit who knew just enough to cock it up. And was usually "me mate dave wot did it".

YOU as an end user know 10x more than your expert about batteries and charging and have already fixed it. As he should have done. Now this isnt to say that ALL these experts are useless. There are a few. Like Rover who I never met. But seems to know his stuff well. But he is one in thousands seriously. And note that he is on here. Why are all the useless ones not ALSO on here learning and asking questions? Because they literally do not understand it, and worse dont give a crap. They only turn up for the wage. And they keep their jobs because to the secratary or boss they are an "expert" because they know a bit more than they do... Me mate dave...

I agree with you about the idiots.
There are them everywhere and each time they are a greater percentage.
If you add to that the lack of vocation, you get the perfect cocktail.

[LROBBINS]

Now all we need is AI to tell us what to do by gathering "information" from a database of "informed" comments from these "experts". Of course, AI has no way to tell true from false, but it can make most anything sound good.

[martin007]

The problem is when that artificial idiot fries a tie and irons an egg...

[steves1977uk]

It happened again!, stuck dangling over the bath at the highest point!

Testing the batteries with the PL8 reveal some interesting results, one battery had 1130mAh capacity during discharge at 1A discharge rate, they actually should be 2300mAh! Still have to test the other one.

But as I explained to Melissa, both hoists exhibit the same problem when pushed the charging point in the bathroom. Yes, the light comes on to indicate it's charging the batteries, but as soon as you move it off the charger, dead! The "tech experts" can't figure out what the problem is when I can tell them the exact issue! But they won't have it and keep on insisting it's the batteries! So they keep on replacing them with 15 year old batteries!

Steve

[Burgerman]

Well I had EXACTLY the same issue with a hoist. I have 3x batteries. Each has a set of 2.9Ah leoch AGM batteries in them.

So if I discharge at the 20 hour rate, and test down to 10.5V they vary from 1.00Ah up to 2.23Ah. How do I know? I wrote it on them. I tested all 6.

I put the best 2 into 1 of the cases. Realize that these are still totally knackered.
I put the next best 2 into the 2nd case.

I dont trust either. They get charged on the stock charger for 16 hours every month. Those are all emergency backups only.

The third and worst set were given to the "equipment centre" with a print out...
They gave me a brand new (12 month old) set! These test as correct capacity though. I didnt open them up yet. Because they do what they say they are on the tin. So presumably the same leoch 2.9Ah ones.

As long as I dont leave them discharged. Top up for 16 hours every 2 days, these should last years.

If your chargers (I have 3!) are like mine they charge at 14.7V for a few mins, and after around an hour they go to a 13.8 to 13.9 float.
So they NEED 16 hours to complete the charge. And then should be removed as this 13.8 (27.7V for the pair) will soon cook them if left on continuously as it says to do on the instructions...

And I have measured carefully and a 15Ah 21700 (TESLA) cell will fit JUST! 21 of them. Thats 7S and 3P on the 5000mAh cells. That should last many months between top ups. But I am wary of fireworks! So may just connect 8x 10Ah (3x bigger, 5x better usable capacity) lifepo4 cells and run a wire from the base to the lift control.

You are wasting your time trying to educate the tech guys. They dont have the interest or time to learn.

[Burgerman]

Incidentally, discharging a 3Ah (2.9Ah) at 1A is only going to give you a 3 hour rate capacity. Say half the rated capacity because peukert.

So you cant test capacity reliably in that way. Because the battery with the best capacity may have a higher resistance due to electrolyte loss and its voltage will drop to the cut off point much faster. The lift itself draws about 3A under load. More at max load. So while that discharge wont measure capacity accurately it will show you what happens under load. Try a 3A discharge and when it falls below say 10 or 11V the lift will cut out. Better still measure volts as you lift.

To test capacity accurately set cut off point to 10.5V and discharge at the C20 rate (145mA for my 2.9Ah ones or 115mA for your 2200mAh ones) which if healthy will read full capacity and take 20 hours.

[steves1977uk]

Thanks for the info BM. My hoists are ceiling track ones, so it's a bit more difficult to do load testing on them. The laptop style PSU these hoists come with are 27v. Looking at the RT1223 battery specs, they require a 13.7v (27.4v) minimum float voltage. I'm guessing they're being under charged, hence killing the batteries faster. Here's the spec sheet for them... https://www.ritar.co.uk/wp-content/uplo ... RT1223.pdf

Steve

[Burgerman]

That float charge means continual. But that will be with minimal discharge. If you keep them on a float like that you wil get around 4 years. But you are also discharging them and recharging too. So at best 3 years. And yours is less volts... So probably sulfated. They really need a 14.6V charge and then float at your chargers low level.
How old are they?

You need to do a load test. Preferably with the lift. Lift a fully grown human 3 or 4 times and watch the battery voltage. I expect it will drop a lot as you lift. That will cause it to stop...

Or it could be the lift.

Either way that will tell you.