Solar, Battery, Inverter...etc...

[Beach Advanced Member Find all posts View Profile Close Beach]

I really could not think of a good title for this one.

I have been charged with a project at work and could use some input from those experienced with powering sensitive electronics in remote locations.

I have a device, we can call it an expensive computer, drawing 230watts max AC. We are using a 600w pure sine wave inverter hooked up to a car battery (with the car running). The requirement is to be able to helicopter this kit into remote locations and operate for anything from a few hours to a few days. A lead acid battery is obviously out of the question. Through a lot of searching I have found Fusion lithium batteries to be very promising as they are dry and very light for a given size. (amp hour).

http://www.superstart.com.au/Product...8/Default.aspx

My question to those that have some experience with solar - what sort of systems are available off the shelf to put some herbs back into the battery whilst we are in the boonies? Remembering this will be choppered in and out.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

need a bit more information mate! Does it need to be built into an all in one rig? Put some herbs back into the battery? How much would this computer drain the battery? How long does it need to be self supporting for? Indefinite?

You've kind of asked how long is a piece of string...
Essentially, what you will need without being specific is

Panel/s
Solar Charger (strongly recommend multiple stage charger for maximum life from the battery)
Battery
Inverter

I can guarantee there is no off shelf unit. You will need to do your homework.

My own personal recommendation is the C-Tek D250S
http://www.ctek.com/au/en/chargers/D250S%20DUAL
Its multi-stage charging, allows for the battery to be charged using a solar input or 12volt source.

I understand a convetional lead acid battery is out of the question, but what about SLA-AGM? These are safe to transport in harsh enviroments. You might want to check with the CAA about transportation of a Li-Po battery. It is a potential explosion risk unlike the AGM.

Just the first thoughts that are popping into my head at this late hour.

[cfryback Find all posts View Profile Close cfryback]

I've got a few mates that do remote towers for WaveLan routers, so based off of their builds I'll offer the following:

1) Does the "computer" actually have to run on AC - seems like a massive waste of power to go DC -> AC -> DC (on board the device). Just a suggestion to look at getting it on pure DC for a start.

2) Solar Cells - I'd be looking at least 2 x 230 Watt Cells

3) Batteries were mentioned SLA-AGM, but I would get 4 (if possible) and mount series-parallel for your 12v

*above mentioned based on mate's experience and builds, not my actual experience/builds! *

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Any constraints on dimensions or lift capacity of the choppers?

[Guest Close Guest]

Based on the provided in, I will make the following assumptions:

• The PC and inverter will draw 230W (i.e. it's unlikely that the PC will be drawing max power all the time and there are inefficiencies going through the inverter) so 230W is worst case scenario
• The PC will be on 24/7
• An AGM battery will have 80% usable capacity to what it's rated at
• Out in the boonies could have very sunny or very rainy days
• There is usually 4-5hr of solar generation at the full rated power of the solar panel

So the calculations are:

• As the PC/inverter uses 230W combined, this is ~20A current draw
• Over a 24hr period, thats 480Ah. Which means on a rainy day, you would need to run off batteries only and so the batteries would need to be 600Ah. Unfortunately, this would mean that if the next day is also rainy, you won't be able to power on your PC.
• In order to get the batteries fully charged up everyday to provide day and night time usage, you would need 6x 230W panels.

In order to get more reasonable real life calcns you would need:

• Avg power used by the PC
• Avg time the PC is used

[MadJak Lurker Find all posts View Profile Close MadJak]

If weight is an issue and price isnt then you can get Lithium-ion deep cycle batteries for around $1000 per 100ah. They are half the weight of other. batteries. Combine a couple of these with a fuel cell, something like the methanol ones that can generate a couple of hundred ah a day. They are also nice and light but cost a fair whack.

if this thing is mission critical you cant use solar as its not 100% reliable. Also solar panels arent actually very light and are bulky. Not the easiest of things to pack into a chopper.

You may also have some issues packing lots of battery and liquid fuels into a chopper.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Li Po are considered a hazardous substance.

[Beach Advanced Member Find all posts View Profile Close Beach]

So to add some more info-

This is a flyaway system. There are times its transported by commercial flight, but we have a hire car and a small generator waiting for us at the other end.

The ability to helicopter it and be self sufficient for limited times is the challenge.

The helo is a single engine A-Star or Squirrel.

When its deployed it is mission critical, but not continuous 24/7 operation. More likely fifteen minutes at a time. How many times over a day will depend on how much battery capacity I can provide. The solar option has been suggested as a "top up". Personally, I think its a waste of time as solar technology isn't that good yet and there won't be space in the helo. Realistically, we won't be away from civilisation for very long. So I'm working on the assumption of deploying for one day at a time.

The device itself is AC only. I'm still wanting to find out what numpty decided that was a good idea, especially considering remote deployment is one of its primary features.

The power requirements on the spec sheet says - "90–260 VAC 280W (Max)" (I made a typo earlier when I said 230W) Of course it won't be running at max power, but for now I need to get some rough numbers as a guide as to how battery capacity is required to run it for a given amount of time. We have some testing set down with some engineering types to get some accurate numbers on current draw.

The Li-Po batteries so far are the preferred option as they are dry and the lightest that can be found. The helo pilot is ok carrying them, provided they are in a pelican case. At the moment budget isn't a consideration. I'm of the belief that "mission critical" and "cheap" will never go together.

Thank you for the info so far.

BTW - How long is a piece of string? Twice the distance from the middle to the end.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

First thing I would do is get a power meter and check the power consumption. If it is a modern computer it may be a lot less than 280w as that is the capacity of the power supply. You will probably find that you are dealing with less than 100ah for the application that you described .

I have a cheap meter at home that appliances plug into and it is quite accurate

[Guest Close Guest]

If you are returning back to civilisation each day, then a good high current multi stage will charge it overnight.

It sounds like the power requirements can be flexible dependent on practical carrying capacity of the chopper and whether employees are happy to lug heavy batteries around. So perhaps just a large AGM/lithium battery and a good 240VAC charger will do. Keep things real simple that way.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Seriously, verify about transporting it. The pilot may not have a choice.

[Beach Advanced Member Find all posts View Profile Close Beach]

If you are returning back to civilisation each day, then a good high current multi stage will charge it overnight.

It sounds like the power requirements can be flexible dependent on practical carrying capacity of the chopper and whether employees are happy to lug heavy batteries around. So perhaps just a large AGM/lithium battery and a good 240VAC charger will do. Keep things real simple that way.

Yeah thats what I'm leaning towards. As for employees happy to carry it - thats me! So a simple, elegant, easy solution is what I'm looking for.

It would also be great to an indicator showing the state of the battery when in use. Any ideas?

[Beach Advanced Member Find all posts View Profile Close Beach]

Seriously, verify about transporting it. The pilot may not have a choice.

As mentioned I have already spoken to the pilot and he's happy provided the batteries are in a pelican case. He was specific about that bit. Its his ship and licence so we go by what he says.

[Guest Close Guest]

Yeah thats what I'm leaning towards. As for employees happy to carry it - thats me! So a simple, elegant, easy solution is what I'm looking for.

It would also be great to an indicator showing the state of the battery when in use. Any ideas?

As an example, my 130Ah AGM weighs 30kg. Will you be happy lugging that around? You might want to consider multiple smaller batteries in separate Pelican trolley cases and plug them together during deployment. You can take as many as you need depending on usage.

Not sure how 1 smart charger will handle multiple batteries though. I'd imagine it would be ok if all batteries are fully charged and load is distributed evenly during deployment.

You can get voltmeters from eBay to check the state of charge. Otherwise there are energy monitors that give you readings in Wh.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

As mentioned I have already spoken to the pilot and he's happy provided the batteries are in a pelican case. He was specific about that bit. Its his ship and licence so we go by what he says.

Yeah I get that and I'm really not trying to push a point. Just make yourself aware of it first is all I'm saying. As a Pelican case isn't going to contain it. OH&S, if anything happens, insurance won't cover him yadda yadda yadda... Just so long as he is and you are blatantly aware of the legal ramifications and that no-one will have a leg to stand on and that not only will fall back on your company having knowledge of it but the pilot also.

Thats all I have to say on the matter. My employees are happy to work on machines without guards and prefer it that way. Doesn't mean I'm gonna let them.