Before I make ANOTHER mistake

South Africa

Re: Before I make ANOTHER mistake

Let me get a grip on all of this because yes:

When you "operate on the edge" of a system's capabilities, you have to accept that you may hit those limits and accept the consequences that others never see.

And yes again:

I tend to "gloss" over these details. They serve to "confuse" new to solar power (can't see the forest for the trees)... Once they understand the math and overall system design cook book, then talking about the details usually make more sense when laid against the overall system (better able to see the complexities and not get lost in the minor details).

Just needed the very basics maths (for now), but more important than that ... the REAL life experiences from others like the two of you. :-)

We usually use 1-3 days of load support (no sun), and 50% maximum discharge.

What are my loads? Ag, that is easy: What can the array produce in summer, autumn, winter and spring? :-) Loads are matched to that = they are consistently high until the system switches back to grid.

To even TRY and get 2-3 days load support (no sun) is a no brainer ... cheaper to build a new coal fired power station than getting the batteries and array to match. :-)

BRB with what I have learned here, to make sure I am not pushing the envelope to far ... yet.

South Africa

Re: Before I make ANOTHER mistake

Thank you for all the feedback so far. It has helped a lot.

Right, it took a while for me to 'understand' and see the wood from the trees.

In a few years, when grid-tie is legal where I live, I want to end up with this system: Outback Flexware 500 system:

For people who want the ability to sell back renewable energy power to the utility through net metering, and also want the ability to use their renewable energy source in the event of a utility power failure, OutBack offers the GTFX and GVFX lines of inverters for grid-interactive applications.

To get there, I start off with a FLEXMax 80 controller with panels to match a 24v system, 1600w inverter which is, if I understand it right, a 1797w array (using my 310w panels) with 5.5 hours good sun per day with best noon production of 1,384watts (fits inverter perfectly) that will give me useful AC power of 5.14kWh per day.

I am after the usefull AC power per day, daytime loads only, which are adjusted per season.

Next steps is Outback inverter, more panels and so forth when grid tie is reality.

To get it working in the mean time, I think I must go with cheap 2nd hand lead acid batteries to connect the controller to the inverter. There is a risk that they can get damaged.

Lights, add a AC charger to charge the lights batteries, as part of the load per day. They are then 'safe' for the 'oversized' array / battery combination and should last many years.

Does this make sense? Am I, for what I want to get to, on the right track?

If I may ask you guys once more, are these calcs now correct?Attachment not found.

stephendv

Re: Before I make ANOTHER mistake

South Africa wrote: »

In a few years, when grid-tie is legal where I live, I want to end up with this system: Outback Flexware 500 system:

The outback grid tie system of batteries driving off-grid inverter which can also feed the grid is not legal to connect to the grid in all countries. Is there any published info on what the south african grid tie legislation will allow?

South Africa wrote: »

Does this make sense? Am I, for what I want to get to, on the right track?
If I may ask you guys once more, are these calcs now correct?

Seems OK, but a red flag is the battery bank size of 102Ah with an array of 1.8kW. That array can produce 75A at 24V, some flooded lead acid batteries come with maximum current charge limits in the 10% - 20% range, i.e. 20A for a 100Ah battery; others are unlimited until you hit 2.4V/cell. You'll have to check whether the batteries you'll be using can handle such a high current charge.

vtmaps

Re: Before I make ANOTHER mistake

Cariboocoot wrote: »

A good MPPT controller can have its output current limited by programming, even though there's more power potential behind it. The down side is that limits the current for everything, including loads, because the controller has no way of knowing where the current is going. You can't set it up to limit current to batteries at 'X' but current to batteries and loads at '2X'. Although perhaps in future the Classic with the Whizbang Jr will be able to do this because it does know how much current is going to the battery. Program a battery current limit in and the controller could automatically reduce output to prevent exceeding that (as measured by the shunt) or raise to maximum if needed providing the battery current was not at its limit. I don't think it can do this yet.

That is correct, the Midnite Classic cannot do that yet, but the engineers there have announced that it will be a capability in a forthcoming firmware update.

The OP mentioned that he aspires to an Outback system. The Outbacks can do that now (but you need their flexnet DC battery monitor, hub, and Mate3). Also, Outback makes a new line of inverters called "grid zero". I don't know much about them, but they are grid interactive... I think they can be configured to supplement your power needs from the grid without ever selling to the grid.

The OP is concerned about overpaneling a small battery bank... That is a real issue, but only during bulk charge... Typically the solar output starts out low in the morning. If your battery bank is small, by the time the solar output is too large for the battery, the battery will be in absorb stage and there will be no possibility of over current to the battery.

--vtMaps

mike95490

Re: Before I make ANOTHER mistake

There is still the battery vs inverter power ratio, where the battery is used as a reservoir for the generation of AC. I thought the recommendation was 100ah per KW , so a 100ah battery would be limited to 1kw of inverter.

South Africa

Re: Before I make ANOTHER mistake

stephendv wrote: »

The outback grid tie system of batteries driving off-grid inverter which can also feed the grid is not legal to connect to the grid in all countries. Is there any published info on what the south african grid tie legislation will allow?

VERY good point!!! I know SMA is approved. Will check this very quickly.

vtmaps wrote: »

The OP mentioned that he aspires to an Outback system. The Outbacks can do that now (but you need their flexnet DC battery monitor, hub, and Mate3). Also, Outback makes a new line of inverters called "grid zero". I don't know much about them, but they are grid interactive... I think they can be configured to supplement your power needs from the grid without ever selling to the grid.

Thank you vtMaps, will look into this, at least I am on the right track by getting a FM80 charger controller.

stephendv wrote: »

Seems OK, but a red flag is the battery bank size of 102Ah with an array of 1.8kW. That array can produce 75A at 24V, some flooded lead acid batteries come with maximum current charge limits in the 10% - 20% range, i.e. 20A for a 100Ah battery; others are unlimited until you hit 2.4V/cell. You'll have to check whether the batteries you'll be using can handle such a high current charge.

Ok, question: Let's say the batteries are @ 1-2% DOD. It is a sunny day, 12pm, array can produce 75A at 24V. You switch on the panels.
Will the charge controller now hit the batteries at what the array can produce, or will the charge controller recognise the DOD and manage the charging, reducing the input from the array?

I understand that charging batteries from a large array whilst powering a large load will confuse the heck out of everything. Battery damage is guaranteed.

Also understand that (WITH NO LOAD BEING POWERED):

• An oversized array can provide current longer under less ideal solar conditions.
• A charge controller will handle, irrespective of the array size, the charging of batteries, not damaging them.

NOTE 1: My setup is set to first charge the batteries to 100% SOC and only then the load is switched on. So there is no load to confuse anything whilst the charging takes place.

Therefor I am again confused, because this is what I see happening:

• When the load is switched on, the battery monitor's shunt registers zero current from batteries, so batteries are not being 'used'.
• But, when the array's input is less than the load the battery meter's shunt registers a negative current because the batteries are supplementing.
• So at this point the array's input is not at full amps/volts anymore as it is being supplemented by the batteries, and there is not enough spare to charge the batteries either, for they are supplementing.
• And when the SOC reaches 75% (DOD 25%), the load is disconnected to again favour battery charging till SOC is 100%.
• Then when the SOC is again 100%, the load is switched on ... (the cycle starts again).

For this is the plan:

vtmaps wrote: »

The OP is concerned about overpaneling a small battery bank... That is a real issue, but only during bulk charge... Typically the solar output starts out low in the morning. If your battery bank is small, by the time the solar output is too large for the battery, the battery will be in absorb stage and there will be no possibility of over current to the battery.

The system must get to 100% SOC as fast as it can, which is before +-10h00am. Tried it on a 1330w array on 24v 36ah batteries. :-)
Less ideal days the system will take longer to get to 100% SOC, so that is also acceptable.

What am I missing?

jonr

Re: Before I make ANOTHER mistake

vtmaps wrote: »

The OP is concerned about overpaneling a small battery bank... That is a real issue, but only during bulk charge... Typically the solar output starts out low in the morning. If your battery bank is small, by the time the solar output is too large for the battery, the battery will be in absorb stage and there will be no possibility of over current to the battery.

Unless your loads happen to use all of the morning charge. Then you go to lunch and turn off the loads and suddenly you have the full output of the panels applied to the batteries. I suggest designing for better than "typically" doesn't ruin your batteries.

On the other hand, batteries might tolerate occasional charges moderately above recommended rates without much damage.

BB.

Re: Before I make ANOTHER mistake

mike95490 wrote: »

There is still the battery vs inverter power ratio, where the battery is used as a reservoir for the generation of AC. I thought the recommendation was 100ah per KW , so a 100ah battery would be limited to 1kw of inverter.

To clarify--That is 100 AH per 1 kW of inverter at 48 vdc.... Or 200 AH at 24 volts, or 400 AH at 12 volts for per 1 kW of AC inverter.

-Bill

Cariboocoot

Re: Before I make ANOTHER mistake

Or why we have these funny little rules-of-thumb about balanced system designs. Start pushing any of the numbers to an extreme and you open yourself up to problems.

Remember it is okay to have 'enough' battery for the array and inverter and simply not discharge it so deeply. True, it's not such a good battery investment at 10% DOD as at 25% DOD but it is the 'lesser of evils' compared to hitting a small bank with too much current or not having enough ripple filtration on a large inverter.

Pick your poison.

stephendv

Re: Before I make ANOTHER mistake

South Africa wrote: »

Ok, question: Let's say the batteries are @ 1-2% DOD. It is a sunny day, 12pm, array can produce 75A at 24V. You switch on the panels.
Will the charge controller now hit the batteries at what the array can produce, or will the charge controller recognise the DOD and manage the charging, reducing the input from the array?

The charge controller just sees battery voltage, not SoC, although the two are correlated. What will happen in this scenario is that before panels are connected the batteries will be at around 25V (for a 24v battery). Turn on panels, controller goes into bulk charging mode and aims to get the battery up to the absorb voltage of 28.8V. Since the battery is already almost fully charged, it'll dump 75A probably for a few seconds until the batt voltage hits the absorb set point. Then it will rapidly cut back the current to keep battery voltage at absorb voltage.
So under this specific scenario, I don't think the batts are in much danger of over current.

South Africa wrote: »

I understand that charging batteries from a large array whilst powering a large load will confuse the heck out of everything. Battery damage is guaranteed.

Also understand that (WITH NO LOAD BEING POWERED):

• A charge controller will handle, irrespective of the array size, the charging of batteries, not damaging them.

Nope, this is the point. The absolute current limit programming into the charge controller is something that you have to manually set. You can configure the controller for a maximum current limit of say 20A for your 100Ah battery which means you'll never see more than 480W from your array. Or you can configure the controller for an 80A limit and risk damaging the batteries. So with your plan you'll have to manually reconfigure the controller twice a day every time you turn the loads on and off.

I'm not sure how batteries behave when they're charged with too much current. I think that overheating is the main problem, so if you have a charge controller with temperature sensor then you may be ok using too much current for the battery. Especially considering that the vast majority of time, they won't be receiving full array current because they'll be shallowly discharged.

South Africa

Re: Before I make ANOTHER mistake

I have ordered a temperature sensor (it is a must for me and my bright ideas:-)). Have emailed the utilities company to find out if Outback grid tie inverters are / or will be approved.

My biggest fear is/was that if I get it wrong that the batteries will explode. And then the point of the inverter not 'balanced' to the batteries (that is a new one) SO the lesser of all evils are to get a bank to match the array to ensure the inverter is happy at all times.

Using not-new batteries till I can go grid tie, with switchover to utilities @ 10% SOC daily (to get to that solar AC power ASAP) with weekends to at least 25% DOD.

I also like the idea on the other thread of having a set of older sacrificial batteries with a AC charger to one day charge the then expensive battery bank using the inverter, seeing as I will have the spare power and the extra losses due to one more device, can be sorted with another panel if needed. :-)

(Note to self: Better you use older, one step before recycled, batteries whilst learning / fine tuning the system.)

stephendv

Re: Before I make ANOTHER mistake

South Africa wrote: »

(Note to self: Better you use older, one step before recycled, batteries whilst learning / fine tuning the system.)

If they're cheap enough you could just risk it with oversized array to battery and see what happens :cool:

jonr

Re: Before I make ANOTHER mistake

South Africa wrote: »

I also like the idea on the other thread of having a set of older sacrificial batteries with a AC charger to one day charge the then expensive battery bank using the inverter

Two alternating banks, one for load and the other being charged allows complete control of the charge profile, including accurate current sensing and long duration charges. I wonder if it could be automated with a couple of relays and a simple controller.

Cariboocoot

Re: Before I make ANOTHER mistake

Batteries aren't smart. They can go to low enough resistance to draw more current than is good for them if it is available. Therefor an over-sized array on a battery bank can cause trouble if it isn't current limited.

Why on Earth do people keep trying to make things more complicated than they need to be? Add more stuff and what you get is more stuff to go wrong.

jonr

Re: Before I make ANOTHER mistake

Cariboocoot wrote: »

Why on Earth do people keep trying to make things more complicated than they need to be?

Because they don't like it when the charging system ruins their batteries? That's what PSOC or systems designed for high daytime power output will do in some cases if you don't add some complexity to address it. If you don't have such a case, then yes, consider yourself lucky.

Cariboocoot

Re: Before I make ANOTHER mistake

jonr wrote: »

Because they don't like it when the charging system ruins their batteries? That's what PSOC or systems designed for high daytime power output will do in some cases if you don't add some complexity to address it. If you don't have such a case, then yes, consider yourself lucky.

I don't consider myself lucky. I am intelligent, educated, and experienced. That is why my systems work. Complexity is not required to achieve a well-balanced system.

South Africa

Re: Before I make ANOTHER mistake

stephendv wrote: »

If they're cheap enough you could just risk it with oversized array to battery and see what happens :cool:

Ditto.

I looked into the costs of a real battery bank ... my WORD!!! Not a chance as a city dweller. To pay that much for something you have to replace every X years and you have access to the grid ... does not compute.

All started a year or two back when I was told that a 24v Cotek 1000w inverter needed min 2 x 36ah batteries. So that was what I did. Bought 2 new 36ah batteries which gave me about 10-15 minutes down to 10% SOC with the load at the time, as the batteries supplemented the array during cloud cover, late afternoon. And being small they re-charged quite quick in the mornings.

Worked so well that on sunny summer days the system started before 9am and stayed on solar till about 6ish pm and on less sunny days, switching over a few times during the day to charge the batteries, the array was not at full power due to clouds. Array at the time was 1330w.

Today those batteries are still being used in other applications.

Then I started replacing 102ah UPS batteries as a favour to a IT friend. The batteries taken out of the UPS may last few minutes at UPS full load so I figured, why not use them to connect it all. It is free and once done, recycle them.

And that is when the drama started. The batteries did not die and now it takes too long to charge in the mornings due to the bigger bank. :-)

But going to 1800w array, expensive 1600w inverter, expensive FM80, the game is upped for I already burnt out a Phocos 100/30 MPPT controller a while back with a 930w array. I think it could not handle the heat working at full power the entire day.

Plowman

Re: Before I make ANOTHER mistake

Cariboocoot wrote: »

Batteries aren't smart. They can go to low enough resistance to draw more current than is good for them if it is available. Therefor an over-sized array on a battery bank can cause trouble if it isn't current limited.

How would you quantify an oversized array? 20%+ charge rate? Or is there some other metric?

vtmaps

Re: Before I make ANOTHER mistake

Plowman wrote: »

How would you quantify an oversized array? 20%+ charge rate? Or is there some other metric?

Depends on the battery. for example, AGM batteries can take much higher charge rates than flooded batteries.

--vtMaps

Cariboocoot

Re: Before I make ANOTHER mistake

vtmaps wrote: »

Depends on the battery. for example, AGM batteries can take much higher charge rates than flooded batteries.

--vtMaps

Yes; exactly that.
Most flooded cells can take 20% for a short time. Extended time or repeated high current = shorter battery life.

South Africa

Re: Before I make ANOTHER mistake

jonr wrote: »

Two alternating banks, one for load and the other being charged allows complete control of the charge profile, including accurate current sensing and long duration charges. I wonder if it could be automated with a couple of relays and a simple controller.

Anything is possible. I had a electrical engineer build me a switch with AC relays that are triggered using a battery monitors relay to switch proper high quality AC 220v relays between inverter AC and grid AC. For months I was told it cannot be done until after 8 months a retiree whom ran a successful UPS business told me what to do. Boils down to UPS logic which none of the solar people I spoke to even thought possible. Been working flawlessly now for over 2 years, as are the computers, TV and a whole lot of other stuff. And when the relays degrade, unplug the worn out one, push a new one in. And, thanks to him, he suggested a timer to break the current cheaply to ensure the different sine waves do not degrade the capacitors in computer equipments PSU's. That cost me a 2nd hand online UPS to not only solve the break, but also to protect the equipment against mistakes.

Much cheaper than anything I found on the web, and it is safer and the equipment is better protected.

Cariboocoot wrote: »

Complexity is not required to achieve a well-balanced system.

Cariboocoot, you are 100% correct but here is the thing: You get grid-tie or off-grid, batteries or no batteries, there is no middle road system that I am aware of that is cost effective, that can start small and grow bigger, that is easy and safe.

Funny thing is I found that the UPS market should get into solar. Why? They understand more about inverters, batteries, current and sensitive equipment, than 99% of the solar people I have spoken too to date here where I live. Solar people work maths, stick to the rules as per manufacturers specs, for there are a lot of variables. UPS people have fine-tuned their equipment to a T, everything is off the shelf plug and play and you cannot break it unless you are really really stupid. Solar is on its way there but it needs more customers to demand more flexibility.

Take for example a 3kva online UPS. It has all the protections in place to protect sensitive equipment, have a wide voltage input range, is earthed if plugged into a socket. So why not take the next logical step: Add a charge controller to match the panels for the inverter's output with a plug and play port to connect the solar panels into, and a little software programming?

That is a LOT cheaper than a 3kva inverter and all that goes with it. Why have I not done it yet? UPS people do not know solar so they are not sure what will happen to the batteries or the inbuilt chargers.

jonr wrote: »

Because they don't like it when the charging system ruins their batteries? That's what PSOC or systems designed for high daytime power output will do in some cases if you don't add some complexity to address it. If you don't have such a case, then yes, consider yourself lucky.

Ditto. Batteries are solar's achilles heal ito failability and costs, are very easily damaged for whatever reason, needs a lot of TLC to make them last and they are going to die on you, with or without the help of teenagers or careless guests.

As more and more users start demanding features, the PSOC will improve to have more flexibility, at a price that is affordable for everyone. But someone needs to ask for that.

And keeping things simple. I like to use simple, tried and trusted devices, like UPS'es to protect my equipment rather than rely on a manual to install a very expensive solar inverter to power it all.

I am not supposed to use a on-line UPS either to absorb the fridge startup current, nor are you allowed to run a pump off a inverter due to their startup current. Get a bigger inverter, is what everyone tells me. So I ask, will it work, or not? Answer I get most of the time: No or Um, we don't know, it is inefficient, we have never done it, we are not sure. Well, the fridge works and it did not cost me a bigger inverter, just a panel or two more. :-)

So my question is: Why not make a plan using off the shelf equipment and the immense brain power on this site and make it work, with the maths, the simple way, that more people can afford solar instead of the thousands they are required to spend today to get less than what they expect, totally reliant on batteries, if they cannot go grid tie, yet want to use the grid where possible.

Now THAT is a challenge, to make it simple.

Cariboocoot

Re: Before I make ANOTHER mistake

There's one or two engineers on the forum who might disagree with your assessment about the UPS people knowing more. They'd be well-founded in some respects on that.

You may want to look at the designs and specs of some of the better quality solar equipment before judging the industry as a whole. People who buy junk, get junk.

niel

Re: Before I make ANOTHER mistake

s africa,
inverters did not start with ups for pc use as it started with outdoors people needing to power some of the ac stuff and some of the early solar and wind people. most pc ups are cheap modsine inverters that started much later in time that can't run constantly at its rated output and they generally do not compare to the work or quality done at solar inverter companies. very few ups i would consider to be quality and they aren't designed for the riggers of solar work.

btw there are hybrid inverters (that is off grid capable + grid capable with sell abilities) even for 230v 50hz that one can expand on. here is an example,
http://www.outbackpower.com/index.php/outback-products/inverters-chargers/item/sealed-gfx1312e?category_id=448

South Africa

Re: Before I make ANOTHER mistake

I did say "... where I live ..." and "... online UPS ..." and that UPS people are not solar people. :-)

niel wrote: »

s africa,
inverters did not start with ups for pc use as it started with outdoors people needing to power some of the ac stuff and some of the early solar and wind people. most pc ups are cheap modsine inverters that started much later in time that can't run constantly at its rated output and they generally do not compare to the work or quality done at solar inverter companies. very few ups i would consider to be quality and they aren't designed for the riggers of solar work.

Cariboocoot wrote: »

There's one or two engineers on the forum who might disagree with your assessment about the UPS people knowing more. They'd be well-founded in some respects on that.

I am referring to UPS people whom protect data centres, entire offices / office blocks / houses, for it is big business here due to us having many years of (sic) excellent grid stability, which is probably going to get worse. Never once did I refer, imply or thought of in-line or off-line UPS'es. They are for people who want the illusion of protection.

A 3kva pure sine wave online UPS running 24/7/365 on its inverter powered by batteries which can be charged from ranges of problematic AC incoming, now THAT is a UPS for small guys like me. I swear if I did not dislike batteries so much, I would have charged it's batteries from a solar array, bank big enough to run 24/7, as they tend to have a 48v bank. :-)

Versus a very new local solar industry whom are just getting their tracks bedded down with grid-tie, which are in most places still very much illegal (and theft!!! Boy, that is another story).

But, we will get there, as we always do.

Cariboocoot wrote: »

You may want to look at the designs and specs of some of the better quality solar equipment before judging the industry as a whole. People who buy junk, get junk.

Only recently I started looking again at what Outback has to offer, due to posts here. For more assistance, Outback referred me immediately to their local national distributor. What a hoot!!! They did not know of all the possibilities for they do not import them all and the best part was that the national sales guy complained he cannot handle 300 webmail request every day from people wanting to know more about what Outback has to offer!

Most local suppliers of brand name international products also warn you that they can get any device but if it breaks, it can sometimes take weeks, even months, to repair / replace if you do not stick to their imported ranges, which are relatively limited.

I even tried the get info locally on MidNite products ... bar a curt email back re. a price, that was it. No answer to questions on availability or repairs if it breaks.

Another joke was a reputable (recommended to me by a international solar manufacturer) local national supplier whom I asked this morning when their grid-tie ranges will be grid approved, as the SMA ranges are. Answer: We do not deal with the utilities company ... yet they sell some of the Outback grid-tie devices. If I was the international supplier, I will get my ranges approved ASAP for that is where we are heading here.

So Cariboocoot, I tried, man I tried, we just do not have what you guys have in the US of A, Canada or Europe ... yet. :-)

BUT!!! Thanks to all the feedback here, I now ask them the right questions to ensure I get what I pay for.

Africa is not for sissies. We may not have easy access to solar yet, but we do have:
Elephants indoors: http://thewildsource.com/tws/blog/post/2009/11/Mfuwe-Lodge-Elephants-and-Predators-Checking-In.aspx
Giraffes coming for tea: http://www.south-african-lodges.com/blog/wp-content/uploads/2013/11/giraffe-manor-kenya.jpg
And hippos coming to town: http://www.ecr.co.za/post/bumping-into-hippos/

Cariboocoot

Re: Before I make ANOTHER mistake

Don't blame the engineers for the failings of the business managers, salesmen, and indeed politicians who run things.

South Africa

Re: Before I make ANOTHER mistake

Cariboocoot wrote: »

Don't blame the engineers for the failings of the business managers, salesmen, and indeed politicians who run things.

I am not. :-)

As I also said in my other post:

So my question is: Why not make a plan using off the shelf equipment and the immense brain power on this site and make it work, with the maths, the simple way, that more people can afford solar instead of the thousands they are required to spend today to get less than what they expect, totally reliant on batteries, if they cannot go grid tie, yet want to use the grid where possible.

Now THAT is a challenge, to make it simple.

... was for the engineers to make things simpler and even easier.



Understanding Engineers:
Normal people believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet.
What is the difference between mechanical engineers and civil engineers? Mechanical engineers build weapons. Civil engineers build targets.

Graduates:
The graduate with a science degree asks, "Why does it work?"
The graduate with an engineering degree asks, "How does it work?"
The graduate with an accounting degree asks, "How much will it cost?"
The graduate with an arts degree asks, "Do you want fries with that?"

I want to know how does it work, how much will it cost, with fries please, not why it works, for it just works, but it needs more features, and it must not blow up. :-)

Cariboocoot

Re: Before I make ANOTHER mistake

Well I spend much (perhaps too much) of my time (and life) making things that don't work, work.
Sometimes it is the engineers at fault.