Adding extra batteries

Bill thankyou for your reply , i have 300 watts of solar on the roof.

The fridge runs the 2 x 110 amp batteries down to 11.9 to 12.1v overnight (it is 230litres ).

The solar tops the batteries back up if there is good sun but will not if the sun is poor.

This is why i thought to increase battery and also solar capacity.

your #1 problem is insufficient solar capacity ..... the first thing you need to spend on is sufficient solar capacity to fully charge the batteries every day, even if the sun is not strong.

No matter how much battery capacity you have ...... it won't help you if you have insufficient charging capacity.

cheers

Listen to this guy. He knows what he's talking about

In addition to HBK which I agree with, If two batteries that size are not lasting all night and the voltage is so low in the morning, it would seem the batteries can't store what is being delivered to them, ie not able to hold sufficient charge and are below their rated capacity OR they aren't being FULLY charged each day even though the voltage is "all good" by lunch according to the voltmeter.

Pop thankyou for your reply , you are correct and i will consider a generator .

I was at congo national park recently near moruya , their rules are that generators may be used between 10 am to 12 pm and 2 pm to 4pm just out of interest , so i did use a small honda generator on one day.

Yep re the gennie comment above - given that you have that big power hungry fridge, and a copious yet semi-reliable solar supply (could be overcast), a gennie is certainly indicated. A few points that seem valid from my experience (but I'm not a qualified technician): 1. Letting batteries get down around the 12V level and under is bad for their health (and your wallet). 2. Adding a portable solar panel to your setup is worth considering...you can often catch sun early and late in the day that the fixed solar panels aren't exposed to. Adding another deep cycle would help (as mentioned, as long as it can get charged), but also as mentioned, make sure you can accommodate the extra weight in that locker. 3. A small, inverter generator for topping up the batteries is worthwhile (being mains quality power, it can be used for running other 'delicate' appliances too...and might help at home when the power goes out...as it does here in SA.. :-)...a 1k gennie might weigh 12-13kg.
For the record...I have 3 x 100Ah deep cycles in the van, a 150L Vitrifrigo 2 door, 2 x 100w panels on the roof, a 100w folding portable solar kit and a 2k inverter gennie...(so when camped out, monitoring of incoming power and the state of battery charge never ends) ! True that there are many camps/places where you can't run a gennie....but if you need power and can run the gennie, you might well save those expensive batteries.

2 x 120 ah additional batteries is around 70 litres of grog too. A bit less if stubbies.

Can put additional batteries in the back of the cruiser so accomodate the necessary beveradge in the van fridge ....or ....just add one extra battery or use a gennie...lo..lol..
Btw the van has a capacity of 620 kg of load items..should be ok..

Regardless of whether you add extra solar, a genny or use 240v mains as a charging method, I would have your existing batteries load tested as Bantam has said before connecting extra new batteries and risk shortening their life span.

Cheers
Pop

Bantam thankyou for your reply , its a good idea will get it done this week.

Macca, there are cheaper ways than that to put Lithium in. If you go to somebody like EV Works and buy the 3.2 volt cells, the cost is about $7.20 per amp hour, plus connectors, battery monitoring, relay, and appropriate chargers. So, 120 Ahr will be $864, plus the other bits. They recommend charging the Winston cells at 14.2 volts so you need an appropriate charger. A Sterling BcDc charger will set you back around $600-700, so it will be a lot cheaper than the figures you have used. I have a 400 Ahr pack I charge at 100 amps from my alternator/cranking battery and the system is only 56 kgs compared to over 200 kgs if I had the same capacity in AGM batteries, and a much smaller footprint. There are some crazy prices being charged for lithium at present, due to the way the systems are being packaged for those not wanting to build their own system.

I keep hearing this AGM comparison .... and AGM....AGM....AGM.

Serioulsy ....... there are very few situations that actually require AGM or where AGM has any specific advantage.

A lot of sellers will offer nothing but AGM .... simply because they do not have the ability to economically freight wet cell batteries .... AGM can be shipped in general freight.... wet cell batteries can not.

You can save yourself a lot of cost by rejecting the assumption that AGM is best ...... in many of the commercial high intesity applications AGM is not the prefered option and has no advantage.

Most golf buggies and small electric vehicles use conventional screw top wet cell batteries and in the market "Trojan" dominates.

Many remote area and off grid installations use either screw top batteries or sealed maintenence free batteries. ..... because they will stand the hammering better than AGM.

Yes a lot of modern telecommunicaton installations particularly small ones are using AGM .... mostly because of workplace saftey and freight issues more than anything else.

You may wish to avoid the issues of maintenance and go for a sealed maintenance free battery, that will have most of the advantages of AGM but at 1/2 to 2/3 the cost ..... AND they will generally be more temperature tollerant than AGM and tolerate higher charge rates.

While you are at it look at AGM manufacturer spec sheets and the recommended operating temperature range is quite narrow.

If you have AGM because it does not require ventilation ...... think again ..... ALL responsible AGM battery sellers and ALL manufacturers clearly state thet AGM batteries require ventilation.

There are a lot of AGM batteries out there living very short lives, because of failure to control charge rate and being used outside their recommended temperature range ..... this could have been avoided using a similar spec sealed maintenence free wet cell battery battery rather than a starved electrolite battery (what we used to call them before marketing made up the AGM label)

Because the AGM battery is starved of electrolite they can not cool them selves as efficiently..... thus the charge rate and temperature range is often limited.

Yes there are high charge and discharge rated AGM batteries out there with good temperature tolerance ...... but they are far more expensive than those commonly sold.

Please consider other options ....... there are good options other than AGM and at considerably less cost.

cheers

Bantam thankyou for your considered reply,as a matter of interest the best deal i could find was 140 amp deep cycle batteries for $309 , these were "giant brand " with a 5 year warrenty.

I was focussed on AGM batteries as this is what the van manufacturer and many others suggested.

I thought they would accept charge more quickly than flooded wet cells , this appeared an advantage in a van that telies on solar charging as there is only approx 5 to 6 hrs of good sun per day.

But your argument makes sense to me , i will check out flooded batteries as you suggest,thankyou.