INVERTA AND BATTERY SIZE

Dougwe · Chief one feather

INVERTA AND BATTERY SIZE

in transit · Senior Member

Doug,
if i had to use a 1000w inverter I would only be doing it with the motor running. None of the products you have mentioned warrant 1000w even if you hooked them all up together. We have been using a 300W modified sine wave inverter for about 5 yrs. Obviously we can't use it for anything with a heating element, but despite what is frequently said it has done a good job running our old Toshiba laptop, battery chargers, phone chargers and miscellaneous gear. After 5 yrs I think it has paid off the $79 it cost us.

KFT · Guru

G'day Doug,

Mate, what appliances do you have in mind to run from your Inverter? a 1000W Inverter can draw around 100 amps from your batteries at full load.

A decent 1000W inverter could cost $950 and upwards anything cheaper may only let you down

A 600W unit on full load could draw around 60 amps from the battery which is quite a bit less.

Now staying on topic!!

Have you unplugged the unit from the 12 volts in order to reset it? does that work?

the protection usually operates when battery volts get a bit low.

frank

-- Edited by KFT on Monday 13th of April 2015 03:20:55 PM

Dougwe · Chief one feather

I know 1000w is overkill for sure and reckon 600w is probably all I will ever need but the bigger is only$50 more so thought why not.

Batteries show 13.9v with good sun and Solar Panels pushing in good power. Nothing else was on at time.

Yes Frank, I actually disconnect the Inverter from socket whenever not in use. I also pulled the plug on the printer this morning when the red light came on and waited a while then tried again with no success. Tried a different 12v socket as well.

The inverter is SCA brand. Maybe I need a better quality one perhaps confuse

KFT · Guru

Ok then Dougwe, thanks for showing some initiative. Many don't.

I think maybe the SCA unit could go in the bin

Projecta make some good equipment but I have no actual knowledge of the quality on the inverters.

I do know that Redarc make top quality products and that includes a 1000W pure sine inverter. Shop around though the web price is a bit exxy

see here: www.redarc.com.au/products/category/4wd-pure-sine-inverter/

Have you considered what you want to run with this Kilowatt inverter?

frank

Phil C · Guru

Hey Dougwe,

As a rule of thumb inverter will draw one tenth of the appliance wattage from the battery eg a 150W appliance will draw 15 Amps from the battery. With a 150 amp hour battery that will give you 10 hours till zip.

AGM batteries don't like to be taken below 50% of their capacity so that cut our 10 hours to roughly 5. It really doesn't matter how big the inverter is, as long as it can handle the expected load eg a 300W inverter should handle about 250W allowing for losses.

It's a big deal as the inverter will shut down if the output wattage, current etc are exceeded. Similarly if the battery driving the inverter falls below a preset voltage it will alarm and eventually shut down.

We have a 2500W eBay inverter (pure sine wave) that drives our electric blanket (150W) after a normal TV and lighting night we have the inverter warning us around 7am. So mate, this means the battery bank (3 110AH should do) the inverter output wattage (the higher the better, as it will only draw what it needs according to the 240 appliance you are using).

If you are confused by this, please give me a call. aww

Cheers mate.

-- Edited by Phil C on Monday 13th of April 2015 08:25:53 PM

frangipani · Guru

confuse dougwe, hmmmm have you checked the fuse on the inverter? Maybe its just blown http://www.performanceshop.com.au/powerinverterfaq.html

Baz421 · Guru

Good advice here Doug especially on the size,,,,, lol. Some more advice for you hopefully good eh????

Our 1000W inverter draws 80A with 1000W load and 40A with 500W load (lights not motors) and this will be a severe drain on your batteries.

Many AGM batteries are limited in current charge rate/draw - for instance the NEW AGM batteries I fitted yesterday (4 X 120aH in a bank) have a max charging current of 36A and I surmise, though it is not stated specifically that 36A would be the max discharge current also, BUT I would NEVER approach this figure for discharge of AGM batteries as I am aiming for long life from my batteries.

If you use a 1000W inverter to it's max you may easily exceed your 2 batteries capacity to discharge the current therefore shortening you battery life CONSIDERABLY.

When I use the 1000W inverter (which is very rarely) it's on a sunny day with 480w of solar charging the battery and I usually don't exceed 15-20A drain on batteries.

As an aside battery number 3 in my battery bank failed again. First one lasted 2 years and this one 6 years BUT I just discovered the ****hole electrician who fitted the inverter at manufacture connected it to no 3 battery only. The other 3 batteries lasted 8 years and 2 are still reasonable but replaced the 4 for conformity.

Hope this helps,,, and I only shouted a couple of times, sorry couldn't help myself.

Cheers Baz

EDIT PS: I forgot to say you will need heavy cables whatever you get 600 or 1000W.

-- Edited by Baz421 on Monday 13th of April 2015 10:26:17 PM

Jaahn · Guru

Hi,

My two cents worth smile

Having a bigger than needed inverter has a couple of down sides and and upside !

The down sides are, 1 you need big cables and probably connected direct to the batteries to work well. Otherwise the full capacity will never be available. Certainly cannot use a socket to plug into for that power. furious

2 the standby power use will be proportionally larger so the losses when not being used will be more. Perhaps the losses on your normal small loads may be more for a large unit and so you will use more battery power to do the same small job. confuse

The upside is that a large unit will be less stressed so should have a happier life and longer. wink

Jaahn

Dougwe · Chief one feather

Thanks everyone so far for as usual great info.

OK then, what I am going to do is, connect heavy cable direct to batteries and run through to a convenient place NEAR the batteries with connection plug on the end and secured safely. Then when my existing 300w Inverter is needed, connect to the plug. If I need to upgrade to a bigger Inverter in the future the cable is already there.

I have never left the Inverta connected when not being used and will continue to do the same.

Just as a side line.....I have just got shorter heavy cable to join the two batteries in parralal as I was far than happy with the 6mm cable and it's 600mm length. I just can't work out why they put such small cable and so long during the build.

Peter_n_Margaret · Guru

My take.....
Inverters are like batteries, or cars, or apples.
Some are better than others. In fact, some are a LOT better than others.

Before you buy, do your research and check the specifications.
Efficiencies vary a lot as do standby loads. Better ones also have much larger short term surge capacity.
It really is a case of getting what you pay for.

The load on the batteries is determined mainly by the appliances you are running from the inverter rather than the size of the inverter, but certainly, running a large inverter at full load will require a large battery capacity.

Cheers,
Peter

Dougwe · Chief one feather

Job done!

I have connected 1.5mts of 6mm cable direct to batteries with a Anderson Plug fitted for easy connection of Inverter and all works well (I changed to Anderson Plug coming off back of Inverter). I have also fitted a 30amp in-line fuse close to the battery.

Also, new heavy duty battery cable is now joining both batteries in parallel.

Thanks everyone for all the good info.

Fran...Fuse was OK.

rayn_boh · Veteran Member

ohh Dougwe I have also solar panels to charge my auxiliary battery & also inverter looking forward to replies :) I always learn so much here

03_Troopy · Guru

Dougwe wrote:
Job done!

I have connected 1.5mts of 6mm cable direct to batteries with a Anderson Plug fitted for easy connection of Inverter and all works well (I changed to Anderson Plug coming off back of Inverter). I have also fitted a 30amp in-line fuse close to the battery.

Also, new heavy duty battery cable is now joining both batteries in parallel.

Thanks everyone for all the good info.

Fran...Fuse was OK.

Hi Dougwe,

Is that 6mm², or 6mm auto wire, which is only about 4.3mm²