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Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: Stevieboy118 on March 20, 2015, 04:34:23 PM



Title: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 20, 2015, 04:34:23 PM
I've been offered an ABB 3.6kW inverter (waiting to get the exact model number)bnib at mates rates and was wonfering if i can drive it from my battery bank (my friendly car workshop just shut down and i've half inched the duff battery pile and i'm currently working my way through them with a couple of chargers and desulphators).

I'm thinking the problem is that the invertor is setup to generate as much power as possible, it would pull every bit of power it could from the batteries and push it all out to the grid.

Could i get away from that by have an isolator on the incoming mains? If the inverter has nowhere to output the power to (no national grid) will it just consume what needs to run the drains on it (fridge/freezer, boiler pump,etc)? or will it just draw on the batteries and make lots of heat?

I've already got a small inverter that runs our lighting circuit to get around the "no mains power down" safety.

Just thinking what else could go wrong :)

Obviously a big gti is overkill for a battery bank but i've still got the summer to sort these batteries out before i make any decisions  (and if swmbo sees that it works i'll be able to divert f unds and get some proper batteries!)


Title: Re: Running a solar gti from a battery bank, possible?
Post by: skyewright on March 20, 2015, 05:32:42 PM
If the inverter has nowhere to output the power to (no national grid) will...
If it's a GTI then typically it will want to see a grid before it does anything (unless there is an "Anti-Islanding" setting or some such to allow off-grid use).


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 20, 2015, 06:52:10 PM
Hi SB118,
                  There is also the danger that SWMBO might get annoyed with you spending all the time trying to bring dud batts back to life and for the wrong impression about your R/e efforts. If you can buy the GTI at the right money (mates money) ,you can store it away in a nice dry place and get more experience and power with the system that you are already running. You can always flog the GTI for UNmates Money later and use the extra cash towards a decent set of batts.
  If you are sorting through old batts and hit upon the big truck batteries 130ah x 12v,  pull them out to the one side and when you get time, check each cell.
  These batts usually have the two poles on the one end. Don't waste your time on any s/h battery that weighs less than 40kgs but I have brought a few of those 130ah truck batts back to life.
                                   Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 08:05:53 AM
Thanks for the pointers. I'm lucky in that the wife will put up with any amount of silly buggers when it comes to my projects, i'm still in the process of unloading roughly 2500L of used veg from my biodiesel days (not doing as much mileage + bought a car with a secondary water heater which won't run on bio = bye bye bio kit)

The batteries are mostly around the 75-80ah, maybe half a dozen around the 100ah mark. Not impressive capacity and totally the wrong discharge pattern but if i can get the "proof of concept" passed her, i can throw a few quid at it.

The expected use for the system would be to cover the background load overnight and cover the first few kettle runs until the sun shows up and i can start to refill the batteries.

I am looking at supporting this with the sheer volume of batteries rather than their peak capacity (good job there is no loss in the cabling, eh?)

If reality has it's say i'll end up with two smaller inverters, again to cover the overnight load on each circuit (biggest load overnight is the fridge pump so that's the only one that needs any real umph)

On the other hand i've got the wood burner heating the back half of the house (might need a couple of bathroom type ventilation fans to push the warm air between rooms) so i've reduced our demand for gas by a chunk anyway.

edit, in a perfect world this pile of batteries would have shown up when the pair of 2kW chinese inverters were in the for sale section and i would have grabbed them instead!


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Tinbum on March 21, 2015, 08:33:51 AM
I've been offered an ABB 3.6kW inverter (waiting to get the exact model number)bnib at mates rates and was wonfering if i can drive it from my battery bank (my friendly car workshop just shut down and i've half inched the duff battery pile and i'm currently working my way through them with a couple of chargers and desulphators).

As its the duff battery pile and they have probably been sat there a while I'd be tempted to get decent money by weighing them in and buying a couple of good batteries with the money. I find batteries rarely come back to like.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 08:47:00 AM
As its the duff battery pile and they have probably been sat there a while I'd be tempted to get decent money by weighing them in and buying a couple of good batteries with the money. I find batteries rarely come back to like.

I've been lucky so far, 2 back to almost full power.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 21, 2015, 09:00:17 AM
Good morning SB118,
                   You were doing fine until you mentioned the couple of runs with the kettle. Then I kind of staggered and sat down with the shock.
  I have 2 ton of forklifts cells and I would not use an electric kettle. It is totally against my religion. The earth would open up and swallow me.
          Gas under the kettle is your man,  Or even a cuppa in the microwave is still quicker @800watts as opposed to 4mins @3kw on lecky kettle.
         BUT! I can see you getting a genuine first class induction education on old Batteries and the long list of things that they "cannot" do.
    Tinbum said it, Weigh them in and get rich enough to go and buy a 48v forklift pack :crossed
                                                                                             Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: camillitech on March 21, 2015, 09:05:48 AM
In my loooooooooooooooong experience off vehicle batteries and living 'off grid'. Fourteen years in a garage then 25 years 'off grid' I can quite categorically say you 'are flogging a dead horse'. Still, I wish you well in your project Stevie and am sure you will have hours of fun trying  ;D Tinbum's advice would be hard to beat, last lot I weighed in fetched 400.

Good luck, Paul



Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 09:07:32 AM
Good morning SB118,
                   You were doing fine until you mentioned the couple of runs with the kettle. Then I kind of staggered and sat down with the shock.
  I have 2 ton of forklifts cells and I would not use an electric kettle. It is totally against my religion. The earth would open up and swallow me.
          Gas under the kettle is your man,  Or even a cuppa in the microwave is still quicker @800watts as opposed to 4mins @3kw on lecky kettle.
         BUT! I can see you getting a genuine first class induction education on old Batteries and the long list of things that they "cannot" do.
    Tinbum said it, Weigh them in and get rich enough to go and buy a 48v forklift pack :crossed
                                                                                             Biff

Our kettle is rated at 650w. Microwave is rated 800w, but pulls 1500w to do it. (according to our plug in meter)

Even picked up a couple of metal teapots so i can make a few drinks on the burner (slowly!)


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Tinbum on March 21, 2015, 09:14:26 AM
I must admit though I am always sceptical about garages. I've had occasions when a lights been left on in one of our works vans and its been flat in the morning. Take it to a garage and they will say you need a new battery- but you don't. It depends on how long they have been flat and how deeply discharged.

I've found one quality make of battery never seems to come back to life once deeply discharged but treated well they last years. Our 9 year old Golf is still on its original battery!!


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 21, 2015, 12:10:55 PM

Microwave is rated 800w, but pulls 1500w to do it.

Heat output versus electrical input, unfortunately both measured in watts.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: pj on March 21, 2015, 12:26:18 PM

Microwave is rated 800w, but pulls 1500w to do it.

Heat output versus electrical input, unfortunately both measured in watts.

Surely you mean 'fortunately'? It shows that 700W is essentially wasted by the microwave.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: knighty on March 21, 2015, 01:04:54 PM
is it not just 1500watts peak while it starts up ?

I can't see a microwave wasting 700watts.... to waste that much, the heat coming out of the vent would practically burn you ?


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 21, 2015, 01:20:38 PM
Some of it is inrush, more of it is conversion loss. So not entirely 700W wasted. Transformer microwaves are ~ 50% efficient. Inverter types are a little higher maybe 60%-70%.
Unfortunately because it causes confusion.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 21, 2015, 02:47:36 PM
Well 3 minutes in the microwave makes pretty good porridge,
90 seconds for a scrambled egg that don,t make a mess
20 minutes approx. for plum jam.
  The microwave even beats the gas for efficiency and economy in certain cases.
   I cannot argue scientifically about the merits of either. We run the washing machine and the microwave together quite often and there is no way that our microwave could be pulling 1500watts along side our washing machine and our 2kw Chinese inverter not even starting to breath heavy. Perhaps the start up is a heavy load but 1500watts,?
                                                                     Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 21, 2015, 03:05:45 PM
Most inverters are double rated peak load Mr Biff.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 03:12:17 PM
Just nuked my coffee and i had a constant reading of 1380w after a few seconds.

Had to turn the tumble drier off to do it obviously, it's not THAT sunny...


Title: Re: Running a solar gti from a battery bank, possible?
Post by: camillitech on March 21, 2015, 03:24:14 PM
Seem to remember my 800w Daewoo drawing 1100w when I checked it last year.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 21, 2015, 03:38:33 PM
Still.
    When you think about it, Nothing quite beats the microwave for bacon butties
  Just for the bacon butties alone, I would keep a microwave,  :genuflect
                                                  Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 21, 2015, 03:40:52 PM
We run the washing machine and the microwave together quite often and there is no way that our microwave could be pulling 1500watts along side our washing machine and our 2kw Chinese inverter not even starting to breath heavy.

Come to think of it the washing machine is likely running well below rated given that it has to allow for the drum motor inrush and heating element, neither are on constantly for the full cycle. Appliance diversification or someat sparkies callit. That's why you quite often see a 63A RCD in a distribution board and 120A of MCB's downstream.



Title: Re: Running a solar gti from a battery bank, possible?
Post by: camillitech on March 21, 2015, 04:53:20 PM
Still.
    When you think about it, Nothing quite beats the microwave for bacon butties
  Just for the bacon butties alone, I would keep a microwave,  :genuflect
                                                  Biff

If you'd asked me three months ago I'd  have told you I'd hardly use it. Now we've been without it I'm really missing it. Can't say I've ever tried it for bacon butties though.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: billi on March 21, 2015, 05:01:52 PM
Perhaps , someone mentioned it before ,  but you need some  amount of batteries to reach the 200 Volt   input of your ABB 3.6kW inverter

Billi


Title: Re: Running a solar gti from a battery bank, possible?
Post by: offthegridandy on March 21, 2015, 05:25:37 PM
So which use more power to make 3 mugs of coffee or tea; an 800W microwave or a 800W kettle?

I not used our microwave for 12 years now, (Panasonic 800w combination), purchased in 1988. Only used the oven when we've run out of oil for the cooker, 3 or 4 times in last 12 yrs. The things so broody heavy it's got to be an emergency to persuade me to get it out of the back of the cupboard under the stairs.

Ditto Paul with slightly less loooooong, enjoy the experiment but the methinks the batteries will be carp I'm afraid.

Andy


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 21, 2015, 05:44:03 PM
And of course you al know about my plum jam making experiences,
                      I never bothered my head making jam in my life before but last year, I discovered how to make microwave plum jam.
   I ended up using 500kgs of plums to 400 or even less of sugar and "no lemon".
  I set this to the one side for use with deserts, Etc. It has a brilliant tardy taste which set off the rice puddin or semolina or even custard.
  I was as chuffed as could be, I did the lot with solar power.
                                                                  Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 21, 2015, 06:35:58 PM
So which use more power to make 3 mugs of coffee or tea; an 800W microwave or a 800W kettle?

They both use the same power but the microwave is faster.  ;D

I've not had any success bringing batteries back to life. Even when I've gotten the SG to improve significantly they still discharge tested pants.
Once got a big box of over-ripe cadbury's cream eggs, microwave brought them back to life right good!  :ballspin


Title: Re: Running a solar gti from a battery bank, possible?
Post by: camillitech on March 21, 2015, 06:48:35 PM
500kg of plums and 400kg of sugar, you'd need a helluva a lot of sun and a big microwave to turn that lot in to jam, not to mention a container load of jars  :crossed


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Nickel2 on March 21, 2015, 07:28:14 PM
Or maybe a boiler?
(http://s24.postimg.org/ie78p3wu9/Stokers.jpg) (http://postimg.org/image/ie78p3wu9/)


Title: Re: Running a solar gti from a battery bank, possible?
Post by: oliver90owner on March 21, 2015, 07:56:00 PM
Microwaves do not have a huge fan for no good reason.  It is there to force cool the magnetron.

A kettle used properly is a far better water heater than a microwave.  About 92% efficiency for the kettle (dependent on material), but a microwave would be good to get above 60%.  Fan power, light, control panel and an inefficient conversion of electricity to microwaves all push the efficiency down.

A 2kW kettle does not require 4 minutes to boil water for one mugof tea or coffee - unless the mug is huge.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 08:08:46 PM
So which use more power to make 3 mugs of coffee or tea; an 800W microwave or a 800W kettle?

They both use the same power but the microwave is faster.  ;D

Nah, if it takes an estimated 5 minutes to make the drinks, the kettle will be pulling 800w for 5 mins but the microwave will be pulling 1300w (in my case) for the same 5 minutes to give 800w of heating effect.

Rather have the bacon sandwiches myself  ralph:


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Stevieboy118 on March 21, 2015, 08:10:43 PM
Perhaps , someone mentioned it before ,  but you need some  amount of batteries to reach the 200 Volt   input of your ABB 3.6kW inverter

Billi

This a good point, my weekend number skills had worked out that 10 x 12v = 200v or summit like that. I'll try that sum again in the morning.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: billi on March 21, 2015, 08:37:53 PM
.... i know a few people running a GTI  connected to a battery , but not such a big one ...

Axel Joost  http://www.solarelectrix.de/power_2_grid_uk.html   uses a Gti  to feed the house Grid from a battery ...

Just an example !

Billi


Title: Re: Running a solar gti from a battery bank, possible?
Post by: Scruff on March 22, 2015, 12:01:39 AM
A kettle used properly is a far better water heater than a microwave. 

I stand corrected, true that.
I was going to measure it except I don't have a lecky kettle.  Turns out google already thought of it first.


Title: Re: Running a solar gti from a battery bank, possible?
Post by: biff on March 22, 2015, 12:12:08 AM
By Gum,
          500kgs of plums and 400kgs of sugar is indeed an awful lot of jam,
  It should have been 500gs +400gs, and I could never muster up the jam jars to pot a ton of jam anytime soon.
                                                 Biff


Title: Re: Running a solar gti from a battery bank, possible?
Post by: camillitech on March 22, 2015, 07:04:39 AM
By Gum,
          500kgs of plums and 400kgs of sugar is indeed an awful lot of jam,
  It should have been 500gs +400gs, and I could never muster up the jam jars to pot a ton of jam anytime soon.
                                                 Biff

Hmm http://business.highbeam.com/3548/article-1G1-115575724/police-impound-400-bags-sugar I thought you'd been up to your old tricks again  :crossed