Solar and Batteries is 400ah 2 x 200ah deep cylcle agm's enough

**Blknight.aus** · 17th April 2021, 01:14 PM

for what you're planning, your nominal reserve capacity on the batteries should meet the nominal power draw for 3 days with no solar support.

your solar system should then provide not less than 50% of the reserve capacity of the batteries.

get 2 inverters, a small one for small loads and a larger one for larger loads, the small ones have less standby power draw and the larger ones are more efficient when loaded with something near the limit of the smaller one. it also gives you some redundancy.

With you're current setup you're good for about a day and a half.

(all on back of the napkin maths against how I would normally setup a similar system that did not have the ability to be externally charged by a vehicle, genny or other charging means.)

if you've got access to running water its surprisingly easy to pinch 100w or so out of the stream.

**TheEntertainer** · 18th April 2021, 09:24 AM

Then we have the issue of buying 2 x 2--ah 12v batteries.

Is an AGM battery and AGM battery: I don't know...?

2 of the below would give an extra 200ah total 600ah

12V 300AH Deep Cycle AGM Battery Sealed Portable Solar Power - iPower

or 2 of the below for a total of 400ah

Giantz 200Ah Deep Cycle Battery 12V AGM Marine Sealed Power Portable Box Solar Caravan Camping | Buy Electrical Hardware - 9355720058154

**trout1105** · 18th April 2021, 09:34 AM

Originally Posted by TheEntertainer

Then we have the issue of buying 2 x 2--ah 12v batteries.

Is an AGM battery and AGM battery: I don't know...?

2 of the below would give an extra 200ah total 600ah

12V 300AH Deep Cycle AGM Battery Sealed Portable Solar Power - iPower

or 2 of the below for a total of 400ah

Giantz 200Ah Deep Cycle Battery 12V AGM Marine Sealed Power Portable Box Solar Caravan Camping | Buy Electrical Hardware - 9355720058154

It is my understanding that you can only safely use 50% of you AGM batteries capacity otherwise you will destroy them So 400AH = 200AH useable capacity and 600AH = 300AH useable capacity.
If you need 400AH available then you will need 800AH of batteries.

**TheEntertainer** · 18th April 2021, 05:38 PM

thought I did not post the prev one

**windsock** · 19th April 2021, 06:05 PM

Cannot recommend or advise on either of those batteries as I have neither experience with them nor can I find any specifications, data or literature on them. This latter point makes me suspect the quality of them. Usually you get some data on performance, charging requirements, voltage vs state of charge etc... from a manufacturer.

Others on here may have experience with them.

I also think you need to look for an inverter with a much reduced standby load. That inverter load of 30 Watts is the biggest load and is not necessary when you look at the specs of other inverters. As I indicated earlier, I have seen smaller inverters with standby loads of around 5 to 6 Watts. Some even have a mode that flicks in and out of standby every 2 seconds and can draw around 1 to 2 Watts. When it senses a load it powers up. See the small victron inverters for example.

**prelude** · 22nd April 2021, 07:55 PM

Regarding the battery choice. I have no experience with this battery as of yet but I am eying them for purchase myself; the victron lead carbon AGM https://www.victronenergy.com/upload...battery-EN.pdf

The carbon allows the battery to survive partial state of charge a lot more often/longer and it can be more deeply discharged as well. There is test data provided at the bottom of the PDF.

Cheers,
-P

DiscoMick · 5th May 2021, 04:21 PM

Have you considered, if you haven't already, fitting LED lights to cut your consumption? We are progressively replacing our lights with LEDs, which are great.
Microwaves and kettles are big drains. It is possible to buy 12 volt kettles. Maybe you could also convert some lights to 12 volt LEDs.
Some friends had a rural property on stand- alone solar power a while back and, I can't remember the size of their AGM battery bank, but it was larger than yours.
Another friend bought a second-hand yacht wind generator and hooked it up for some extra charge, particularly at night.

Good luck with it.

**TheEntertainer** · 5th May 2021, 04:42 PM

Hi,

The batteries only run the lights and respirator.

We are going to buy some LiFePo4 135ah hours, and they are not that expensive any more, a tad more than AGM's but you can DOD them to 90% (max). It also means we don't net such a large inverter, might drop down to 800watt. I've been using my 400watt but it seems to work hard and it's expensive to run the fan.

cheers

J

**W&KO** · 5th May 2021, 06:00 PM

Originally Posted by TheEntertainer

Hi,

The batteries only run the lights and respirator.

We are going to buy some LiFePo4 135ah hours, and they are not that expensive any more, a tad more than AGM's but you can DOD them to 90% (max). It also means we don't net such a large inverter, might drop down to 800watt. I've been using my 400watt but it seems to work hard and it's expensive to run the fan.

cheers

J

I’m not sure I understand the link between upgrading to Lithium reduces the size of the inverter.

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