Battery Advice Wanted!

Bozzydogg02 · Feb 1, 2023

Hi all,

My knowledge on this stuff is very limited, I don’t understand how to do the equations to calculate exactly what I need so I thought if I just overestimate everything I should be fine for a long time.

Wrong.

Where there is now just the one battery powering my LED light and a 5v USB port there were 5 more ‘solarflex’ 110ah which have all died.

The solar panels are 100w each and there is 5 of them in series.

I have a 400w wind turbine to add to it for additional charging.

I would also like to add another USB port, cool box/fridge and a diesel heater to the fuse board.

We used (it is currently disconnected) the inverter for charging laptops (60w charger for 3 hours max) charging our little vacuum cleaner (this takes 4 hours to charge but is charged maybe once or twice a week) and to charge my drill here and there if required. Also run a small 60w projector and desk fan off it in the summer.

What kind and how many batteries suit this exact system?

Please excuse the dust in the photos we’ve not been able to charge our hoover ?

Also if anyone can spot an error with how I’ve connected anything, please point it out I wont take offence I’m not a spark just a diy’er seeking help from the experts.

Thanks!

Mattb4 · Feb 1, 2023

Starting with the solar panels. You can not use straps across the face of them without serious reduction in watt generation unless that is just used during travel and than removed. The next question that comes up is panel ratings Voc especially. With 5 in series, as you state, if they are 23Voc (5 x 23 = 115Voc) your SCC has to be able to handle this. Indeed your last picture shows 112v at the SCC. What is your SCC rated for?

Concerning battery capacity to serve your loading needs. Try to add up every load you can think of and how long each item will operate. Use the Watts =Volts X Amps equation and to get watt-hr put in the time of operation Example: 60w for 10 minutes = 10wh Since batteries are rated in amp hours you need convert to watt hour. From the previous example 10wh from a 12v battery = .83ah Understand that even though a battery might be rated for a certain amp-hr that does not mean you can make use of all of it. Typically to have some longevity from lead acid batteries you limit use to 50% of capacity. You also have to take in account that it takes power to make power which means what you put into the battery will be more than you get out. Indeed every step in a power system has some loss.

Trying to design a solar and battery setup that will meet your needs involves getting a firm grasp of the load side and supply side.

I know this is not just a simple buy X amount of batteries answer. It is one that I hope explains how you can sit down and figure up something that will work for you.

Bobert · Feb 1, 2023

Bozzydogg02 said:
Hi all,

My knowledge on this stuff is very limited, I don’t understand how to do the equations to calculate exactly what I need so I thought if I just overestimate everything I should be fine for a long time.

Wrong.

Where there is now just the one battery powering my LED light and a 5v USB port there were 5 more ‘solarflex’ 110ah which have all died.

The solar panels are 100w each and there is 5 of them in series.

I have a 400w wind turbine to add to it for additional charging.

I would also like to add another USB port, cool box/fridge and a diesel heater to the fuse board.

We used (it is currently disconnected) the inverter for charging laptops (60w charger for 3 hours max) charging our little vacuum cleaner (this takes 4 hours to charge but is charged maybe once or twice a week) and to charge my drill here and there if required. Also run a small 60w projector and desk fan off it in the summer.

What kind and how many batteries suit this exact system?

Please excuse the dust in the photos we’ve not been able to charge our hoover ?

Also if anyone can spot an error with how I’ve connected anything, please point it out I wont take offence I’m not a spark just a diy’er seeking help from the experts.

Thanks!View attachment 132625 View attachment 132626 View attachment 132627 View attachment 132628

Please include the specs for all your equipment. SSC, Solar panels, inverter and wire size. You appear to have multiple problems. Don’t doom yourself to thinking you can’t understand how to calculate what you need to do what you want. You can learn if you want to. This forum is a great place to start. Previous post is correct you will get almost no output from your panels with those straps on the panels. Buying your equipment before you understand exactly how it works is the wrong way to do an install but it is common and actually the best way to learn. ( Ask me how I know

.

Bozzydogg02 · Feb 1, 2023

Mattb4 said:
Starting with the solar panels. You can not use straps across the face of them without serious reduction in watt generation unless that is just used during travel and than removed. The next question that comes up is panel ratings Voc especially. With 5 in series, as you state, if they are 23Voc (5 x 23 = 115Voc) your SCC has to be able to handle this. Indeed your last picture shows 112v at the SCC. What is your SCC rated for?

Concerning battery capacity to serve your loading needs. Try to add up every load you can think of and how long each item will operate. Use the Watts =Volts X Amps equation and to get watt-hr put in the time of operation Example: 60w for 10 minutes = 10wh Since batteries are rated in amp hours you need convert to watt hour. From the previous example 10wh from a 12v battery = .83ah Understand that even though a battery might be rated for a certain amp-hr that does not mean you can make use of all of it. Typically to have some longevity from lead acid batteries you limit use to 50% of capacity. You also have to take in account that it takes power to make power which means what you put into the battery will be more than you get out. Indeed every step in a power system has some loss.

Trying to design a solar and battery setup that will meet your needs involves getting a firm grasp of the load side and supply side.

I know this is not just a simple buy X amount of batteries answer. It is one that I hope explains how you can sit down and figure up something that will work for you.

Hi Matt thanks for your reply.

I’ve not seen the term Voc used before but I’m guessing it’s what shows up on the SCC which in full sunlight goes up to 125v so I’d assume my panels are 25Voc. All of the photos were taken today (a fairly clear February afternoon) and they were producing 112v, I use the straps so the wind doesn’t rip my fibreglass roof off as they’re stuck down with sikaflex on plastic feet, I’m re doing the roof this spring though and screwing them down so that won’t be an issue going forward.

The SCC is 50 amp / 150 volt

I don’t understand at what point to use the Watts = Volts x Amps ? And where I would find out what volts and amps my loads are using?

I guess that the ah calculation is wh divided by 12 (v) ?

I do understand that the lead acid batteries can only really be discharged to 50% I just thought that with how little we use and how many of them, we would rarely run them down below 50% without them having a decent charge the following day, this is obviously where I’m not getting it I suppose.

Yes I definitely need to get a grasp of load and supply size.

Thanks again for your help hopefully I’ll be able to figure it out properly

David in nh · Feb 1, 2023

why is there so much dirt ect covering things , i would be more concerned about fire , just want you to be save

Bozzydogg02 · Feb 1, 2023

Bobert said:
Please include the specs for all your equipment. SSC, Solar panels, inverter and wire size. You appear to have multiple problems. Don’t doom yourself to thinking you can’t understand how to calculate what you need to do what you want. You can learn if you want to. This forum is a great place to start. Previous post is correct you will get almost no output from your panels with those straps on the panels. Buying your equipment before you understand exactly how it works is the wrong way to do an install but it is common and actually the best way to learn. ( Ask me how I know.

Hi bobert,

Thanks for your reply!

SCC: 50 amp / 150 volt
Solar panels: 100 watt (I can’t find specs for them online I guess eco-worthy have replaced them with 120W ones) in the range of 21-25Voc
Inverter: 4000 watt pure sine wave DC 12V to AC 220V (it has 4 40 amp fuses in it if that helps?)
Wire sizes: standard ones that came with the solar panels 6mm I believe, 35mm connecting batteries together, 35mm from SCC to batteries, 16mm from batteries to inverter, 16mm from batteries to fuse board 2.5mm from fuse board onwards and I think that covers everything, please let me know if not

Thanks again!
Lewis

Mattb4 · Feb 1, 2023

Bozzydogg02 said:
Hi Matt thanks for your reply.

I’ve not seen the term Voc used before but I’m guessing it’s what shows up on the SCC which in full sunlight goes up to 125v so I’d assume my panels are 25Voc. All of the photos were taken today (a fairly clear February afternoon) and they were producing 112v, I use the straps so the wind doesn’t rip my fibreglass roof off as they’re stuck down with sikaflex on plastic feet, I’m re doing the roof this spring though and screwing them down so that won’t be an issue going forward.

The SCC is 50 amp / 150 volt

I don’t understand at what point to use the Watts = Volts x Amps ? And where I would find out what volts and amps my loads are using?

I guess that the ah calculation is wh divided by 12 (v) ?

I do understand that the lead acid batteries can only really be discharged to 50% I just thought that with how little we use and how many of them, we would rarely run them down below 50% without them having a decent charge the following day, this is obviously where I’m not getting it I suppose.

Yes I definitely need to get a grasp of load and supply size.

Thanks again for your help hopefully I’ll be able to figure it out properly

Solar panels have ratings for Voltage open cell (Voc) which is the voltage they produce when there is no load on them in full sunlight per rating. When you connect panels in series the voltage for every panel adds while the current (Imp) for all the panel stays the same as one panel. If you hooked panels in parallel the voltage would stay the same of one panel's Voc and the Imp would add up for all the panels wired in parallel.

Deep discharge batteries are rated based on a length of time they can discharge a measured amperage. The typical time is 20 hours. This means a 12vDC 100ah battery can give you 5 amps per hour for 20 hours before the batteries voltage drops too low to sustain. Thus 5a X 20hours = 100ah 100ah at the nominal battery voltage of 12v =1200wh worth of capacity. 50% discharge for a lead acid would be 600wh. Put a larger load than 5 amps (5a X 12v= 60w) on the battery and the length of time to deplete the battery drops quicker. Example: 200w load for 1/2 hour =100wh 100wh from 600wh leaves the battery with 500wh. If you ran the 200w load for 3 hours the battery would be at 50% capacity and need a recharge.

So you see how it works back and forth. Watts are power and stays constant. So if you are calculating a load and know the wattage rating it will be the same at battery voltage as it is at household AC voltage, however to balance the equation for W=VA if you change the voltage for a given wattage the amperage must change. Example: You have a 100w light bulb on a 220v AC circuit you wish to power it off an inverter being supplied by a 12vDC battery. 100w/220v=.455a but to the battery that is supplying the inverter at 12 volts nominal that 100w/12v=8.33a

If you know a loads amperage and its voltage you know the watts. W=VA

Bobert · Feb 1, 2023

Watts divided by volts equals amps. Let’s say your Solar panel array produces its max output at 100 volts that’s 500 watts divided by 100 equals 5 amps. This means that the wire from your solar panels to the ssc can be quite small and still be quite safe from a heat/fire prospective however the voltage is a shock hazard and these wires should be treated the same way you would the ac output of your inverter. The output of the ssc would be closer to 50 amps at 500 watts divided by 12 volts roughly 42 amp. Since the solar array could be configured to a 600 watt array the wire should be sized for 50 amps. I am unfamiliar with the metric wire sizes but google says that 16mm is adequate for this application. 4000 watts at 12 volts is 330 amps. My assumption is that the continuous output of your inverter is less than half that but even at that the wire size you would need for it to function properly would be closer to 100mm. From the battery to the inverter your wire is way to small.

Bobert · Feb 1, 2023

Let me suggest that you get the 12v side of your system working properly before setting up the inverter. Are the batteries you are useing deep cycle batteries? If they are not they will go bad quickly. Even deep cycle batteries will only last months if they are not frequently fully charged ( that’s a major challenge on a solar system that is continuously in use) with your solar panels partially covered and wired in series you will be getting almost nothing out of them. You need to determine if your battery is still good. If you can’t consistently bring the battery to full charge once a week and not discharge it below %50 you may want to consider getting a lifepo4 battery. It will be cheaper in the long run. In the meantime if you can borrow a known good battery or confirm that what you have is good you can verify that your panels and ssc are working properly.

Bozzydogg02 · Feb 2, 2023

Bobert said:
Let me suggest that you get the 12v side of your system working properly before setting up the inverter. Are the batteries you are useing deep cycle batteries? If they are not they will go bad quickly. Even deep cycle batteries will only last months if they are not frequently fully charged ( that’s a major challenge on a solar system that is continuously in use) with your solar panels partially covered and wired in series you will be getting almost nothing out of them. You need to determine if your battery is still good. If you can’t consistently bring the battery to full charge once a week and not discharge it below %50 you may want to consider getting a lifepo4 battery. It will be cheaper in the long run. In the meantime if you can borrow a known good battery or confirm that what you have is good you can verify that your panels and ssc are working properly.

What is wrong with the 12v side?

This is kind of the whole point of my post, the batteries went bad after about 14 months, they were sold as deep cycle (see pictures) the technical specs are:
Voltage: 12 v
Capacity C5: 70 ah
Capacity C20: 90 ah
Capacity C100: 110 ah

5 of these batteries were the ‘solarflex’ ones and one ‘probat’ both have the same specs just different brands I guess.

But as I thought I mentioned all of these batteries are now gone, failed testing when sent back under warranty. Hence looking for the best kind to fit into my system.

I currently have 1 temporary battery (just an old spare that a friend had had sitting outside, exact same probat one as I had). It was discharged when I received it, I removed all the wire that was connecting my 6 batteries together and just dropped this one in connected to the SCC and the 12v fuse board both with 50 amp breakers between and an isolation switch between the SCC and the solar panels where the wire changes from the ones that come standard with the panels (6mm I believe) up to 35mm. After being left or very lightly used for 48 hours this battery is now showing 14.6 v and works fine all night to power lights and USB port and has done for a couple of weeks, I took the pump fuse out as it’s not really being used at the minute.

The solar panels are very partially covered if you look closely the straps on the 3 panels are only covering the edges where they are joined together, the max volts I’ve had out of them is 125, on a fairly clear day I still get 118 v with the straps.

I have already determined that my batteries are no good, this is why I’m looking for advice on what ones would fit my system and uses best.

I am fairly confident that the panels and SCC are working well. I also thought I mentioned that I would be removing the straps moving forward so this won’t be an issue.

Concerning your previous post, I have used the wires that came with the inverter (16mm from memory, could be 35mm) with a 200 amp breaker between it and the batteries.

The 12v side consists of:

Usb: max power: 16 W
: input : DC12V/24V
: usb output: 3.1 amp / 5 volts

Lights: voltage: 10-30VDC
: 4 W
Two of these connected to a 12v SPDT double switch CBE

Water pump: 12 volt
: 4.0 amp rating

So using the equations mentioned above I get:

Usb: 16 W x 24 hours = 384 Wh
: 384 Wh / 12 V = 32 Ah

Lights: 8 W x 12 h = 96 Wh
: 96 Wh / 12 V = 8 Ah

Pump: W = VA
: W = 12 x 4
: W = 48
: 48 W x 1 h = 48 Wh
: 48Wh / 12 V = 4 Ah

Total of: 32 Ah + 8 Ah + 4 Ah = 44 Ah per day at an absolute maximum.

would a smaller inverter help?

Mattb4 · Feb 2, 2023

Bozzydogg02 said:
...

I am fairly confident that the panels and SCC are working well. I also thought I mentioned that I would be removing the straps moving forward so this won’t be an issue.

...

I am fairly confident that they were not. You mention voltage but you do not mention how much wattage or amperage they were generating. Voltage in of itself is no indication that you are getting power to charge your batteries.

Good to see that you are working out your loading. That will help you going forward.

BTW. On the batteries C rating. When you see a C followed by a number this means that the rating of amp-hr is derived for that many hours. C5=70ah tells you that the battery can deliver 70ah/5h=14a therefore 14a X 12v =168 watts load.

Bozzydogg02 · Feb 2, 2023

But if they have charged a discharged battery why would they not be working?

Mattb4 · Feb 2, 2023

Bozzydogg02 said:
But if they have charged a discharged battery why would they not be working?

I think we are having a communication error. Your panels and SCC can be putting out some current to charge a battery. Just not put out all that it could put out if the setup was better. It is like trying to fill a bucket from a dripping faucet versus filling it with the faucet full open.

So you use water from your bucket of water at a higher rate than the trickle of water can restore it. Eventually your bucket is empty and no longer can be used until enough time goes by for the trickle to refill it. Batteries are suffering the same fate as the bucket but with batteries, when you consistently empty them, they will go bad.

Bozzydogg02 · Feb 2, 2023

Right I see now we’re on the same page. So to speed the flow of my tap up I should link them in parallel?

The only reason I did them in series is because I watched a guy on YouTube who said to do it this way to minimise fire risk (it’s also been cleaned out now too)

A friend told me to link them in parallel like how he did with his much larger system of 18 of the probat batteries same as mine and 9 much larger panels, he fried his batteries and they started spraying out H2S, however he was running an awful lot more than we do and his panels are much larger so I guess I can’t base my judgment on that?

Do you think with my panels and SCC I could safely do parallel and if so then do you think my system is optimised?

Also I’ve been thinking of doing away with the inverter and installing a couple of 12v cigarette lighter holes for charging laptops and running a cool box/ fridge in the summer, would this help?

Mattb4 · Feb 2, 2023

Bozzydogg02 said:
Right I see now we’re on the same page. So to speed the flow of my tap up I should link them in parallel?

Sadly we are not. To increase what you are getting you need to remove anything that can shade your panels from the sun. Ideally you should angle them towards the sun. Solar panels rarely deliver their rated wattage. If you watch the amount being delivered during the day on panels you will see an increase as the sun rises and a decrease as the sun sets. Any shade from objects, clouds and even a lower sun in the horizon based on Season cuts wattage production drastically. Let's say you have a 100w panel flat mounted in good sunlight and no shade on any part of it. It might reach 60w output during midday. The days output due to this looks like a curve if you plot it out going from nothing at sunrise peaking at highest sun position and back to nothing at sunset. The amount created for the day may be 300wh. This is equal to 3 hours at 100w.

From the 300wh you charge your battery. Using a 100ah battery that is 50% discharged (600wh remember?) you have charged it backup to the 65- 70% point (it takes power to make power). You can see that this 100w panel is not keeping up in a day to fully charge your battery.

There are advantages to be in series and advantages to be in parallel. Many of us run a combination of the two based on SCC specs and our particular location needs. When you do run a combination such as two panels in series connected in parallel to another two panels connected in series it is labeled 2S2P

ETA: Charging batteries from any source requires you to know the specs for the batteries. If you charge at too high of amperage or if your charger continues to charge after battery is full you can destroy the battery which is what you mention that a friend did with his. Your solar panels amperage and voltage is converted by your SCC to battery voltage and amperage. Know all the specifications for every component in your setup. They all have limits including the wires and fuses. Everything is only as strong as the weakest link.

mikefitz · Feb 2, 2023

A number comments.
The batteries.
Do not believe the advertising hype, these 'leisure deep cycle' batteries sold In the UK are starter batteries, not real deep cycle types. A real 100Ah deep cycle will cost in the region £200 to £300

https://www.alpha-batteries.co.uk/105-ah-trojan-ultra-deep-cycle-premium-leisure-battery/

The low cost 'leisure batteries ' may work in a motorhome or caravan for low power lighting used for a few weeks holiday, but will not handle daily charge and recharge and high current loads. It's probable also they were not correctly fully charged which accelerated their demise.

Solar panels.
Solar panels are basically current generating devices. Any slight shading, such as the straps you have fitted, or from the trees that surround your location, will reduce the current output considerably, but the voltage may still remain high.
Horizontal panels in UK winter conditions will deliver very little current and thus power.

Charging lead acid batteries.

It takes a long time to fully charge a LA battery, 5 to 12 hours. In UK winter with solar, its probable the batteries were never completely charged to full. The effect of this is an increasing loss of capacity.
A typical charge voltage is 14.5 volts. Under charge the battery voltage will gradually rise to this level. Once this 'target' voltage is reached the battery will be around 80% charged. It will need to have the 14.6 volts applied for a least 2 more hours, typically 3 or 4. This absorbtion period is crucial to maintain the battery in good health
What often happens is that under charge leads to capacity loss, the batteries are still reaching the 'target' charge volts but do not have the amp hours they started life with.
Having a number of low cost batteries in parallel has a number of risks. The interconnections between batteries should follow best practice . Issues in this area can lead to unequal share of load and charge power. This in turn will 'age' one battery more than the others until the point where it compromises the whole pack.
Even with ideal interconnections, batteries that have different characteristics , age or quality, can suffer the same fate.

Inverters.

All inverters take a standby current, even with no AC load. The lower the quality and the higher the power rating, the greater the standby current. You seem to have an low cost 4000 watt inverter. My guess this power is not needed and a lower power unit would be adequate. A further comment is that 16mm2 cable is unsuitable for a 4000 watt inverter.

Recommendations.

I have a good idea of your power requirements and suggest the following equipment. I will add circuit diagram later. I will give links to UK suppliers, you may find better deals or alternatives shopping around.

Inverter. Here for safety I recommend only the best. You have a low power requirement for AC power so 500 watts should be more than enough,

Victron Phoenix Pure Sine Wave Inverter - 12V 500VA (VE.Direct-enabled)

Victron Energy 12V 500VA professional, high efficiency, pure sine wave inverter with VE.Direct interface. For caravans, motorhomes, campervans, boats.

www.12voltplanet.co.uk

Batteries .
It seems you are limited, inthe main, to solar for charging.
Ideal would be lithiun, no worries about under charge, fast charge from solar , long life. At the price the fogstar batteries are lower cost than quality lead, 230 or 280 Ah

Lithium Leisure Battery - Fogstar Drift 12v 230Ah

230ah 12v Fogstar Drift Lithium Leisure Battery | Grade A LiFePO4 cells, JBD BMS, Bluetooth, Heating | Lowest Prices in the UK. 10 Year Warranty.

www.fogstar.co.uk

The low circuit breakers you have unreliable and may be unsafe. Suggest fuses and isolation switches if needed.
Details with diagram.

A battery monitor will allow you to manage battery power and evaluate power input and power use.

https://www.amazon.co.uk/Victron-Energy-SmartShunt-Battery-Bluetooth/dp/B0856PHNLX?th=1

Just seen your last post.

Keep the panels in series. It's OK with your solar controller and 500 watts of panels is a maximum into the batteries of
40 amps. This is is good for any lithium battery and 200 Ah or more of lead battery. It will not over charge.

Dumping the inverter and using 12v chargers for charging laptop may save energy. Only use manufactures 12v chargers for laptops, the low cost stuff may damage your computer. Using a quality low power inverter, even as low as 250 watts, with manufactures mains chargers is an option.

Mike

Hedges · Feb 2, 2023

Deep-cycle AGM batteries can give 300 to 700 cycles to 70% DoD. More if shallower, but same total Ah of cycle life. That's 1 ~ 2 years of nightly deep cycling.
FLA can give more.

Having a suitable low-voltage disconnect for loads is important, to prevent over-discharge.

Frequent full charging, to a particular voltage and followed by some hours of absorption, is also necessary. So simply low-voltage disconnect is not sufficient load control; with insufficient PV the battery will bump along at a low SoC and die from sulfation.

One solution would be sufficient PV to fully recharge despite loads connected.
Another could be to latch loads off at low-voltage disconnect and not reconnect until fully recharged. But I'm not away of off-the-shelf products to accomplish that.
Small loads always connected, and large loads enabled only at higher voltage, might be a compromise.

PV is quite cheap, and batteries expensive. I think about 20x the cost of PV (per kWh, over useful life.) So considerable over-paneling is my approach. But must limit charge current to optimum, which may be around 0.2C (5 hour rate.)

As has been mentioned, LiFePO4 may be attractive. It has 5x the cycle life and can charge at 0.5C, also is not harmed by low SoC. For modest loads like this system, the one significant issue is not charging below freezing.

(Oh, for lead-acid, charge controller needs battery temperature sensor. But is fine charging cold. However, maximum DoD must be limited depending on cold temperature; freeze protection varies with specific gravity of electrolyte.)

Bozzydogg02 · Feb 3, 2023

mikefitz said:
A number comments.
The batteries.
Do not believe the advertising hype, these 'leisure deep cycle' batteries sold In the UK are starter batteries, not real deep cycle types. A real 100Ah deep cycle will cost in the region £200 to £300

https://www.alpha-batteries.co.uk/105-ah-trojan-ultra-deep-cycle-premium-leisure-battery/
The low cost 'leisure batteries ' may work in a motorhome or caravan for low power lighting used for a few weeks holiday, but will not handle daily charge and recharge and high current loads. It's probable also they were not correctly fully charged which accelerated their demise.

Solar panels.
Solar panels are basically current generating devices. Any slight shading, such as the straps you have fitted, or from the trees that surround your location, will reduce the current output considerably, but the voltage may still remain high.
Horizontal panels in UK winter conditions will deliver very little current and thus power.

Charging lead acid batteries.

It takes a long time to fully charge a LA battery, 5 to 12 hours. In UK winter with solar, its probable the batteries were never completely charged to full. The effect of this is an increasing loss of capacity.
A typical charge voltage is 14.5 volts. Under charge the battery voltage will gradually rise to this level. Once this 'target' voltage is reached the battery will be around 80% charged. It will need to have the 14.6 volts applied for a least 2 more hours, typically 3 or 4. This absorbtion period is crucial to maintain the battery in good health
What often happens is that under charge leads to capacity loss, the batteries are still reaching the 'target' charge volts but do not have the amp hours they started life with.
Having a number of low cost batteries in parallel has a number of risks. The interconnections between batteries should follow best practice . Issues in this area can lead to unequal share of load and charge power. This in turn will 'age' one battery more than the others until the point where it compromises the whole pack.
Even with ideal interconnections, batteries that have different characteristics , age or quality, can suffer the same fate.

Inverters.

All inverters take a standby current, even with no AC load. The lower the quality and the higher the power rating, the greater the standby current. You seem to have an low cost 4000 watt inverter. My guess this power is not needed and a lower power unit would be adequate. A further comment is that 16mm2 cable is unsuitable for a 4000 watt inverter.

Recommendations.

I have a good idea of your power requirements and suggest the following equipment. I will add circuit diagram later. I will give links to UK suppliers, you may find better deals or alternatives shopping around.

Inverter. Here for safety I recommend only the best. You have a low power requirement for AC power so 500 watts should be more than enough,

Victron Phoenix Pure Sine Wave Inverter - 12V 500VA (VE.Direct-enabled)

Victron Energy 12V 500VA professional, high efficiency, pure sine wave inverter with VE.Direct interface. For caravans, motorhomes, campervans, boats.

www.12voltplanet.co.uk

Batteries .
It seems you are limited, inthe main, to solar for charging.
Ideal would be lithiun, no worries about under charge, fast charge from solar , long life. At the price the fogstar batteries are lower cost than quality lead, 230 or 280 Ah

Lithium Leisure Battery - Fogstar Drift 12v 230Ah

230ah 12v Fogstar Drift Lithium Leisure Battery | Grade A LiFePO4 cells, JBD BMS, Bluetooth, Heating | Lowest Prices in the UK. 10 Year Warranty.

www.fogstar.co.uk

The low circuit breakers you have unreliable and may be unsafe. Suggest fuses and isolation switches if needed.
Details with diagram.

A battery monitor will allow you to manage battery power and evaluate power input and power use.

https://www.amazon.co.uk/Victron-Energy-SmartShunt-Battery-Bluetooth/dp/B0856PHNLX?th=1

Just seen your last post.

Keep the panels in series. It's OK with your solar controller and 500 watts of panels is a maximum into the batteries of
40 amps. This is is good for any lithium battery and 200 Ah or more of lead battery. It will not over charge.

Dumping the inverter and using 12v chargers for charging laptop may save energy. Only use manufactures 12v chargers for laptops, the low cost stuff may damage your computer. Using a quality low power inverter, even as low as 250 watts, with manufactures mains chargers is an option.

Mike

Hi Mike,

Thank you so much for actually reading and responding to what I am asking. And communicating your answer in a language an everyday person can understand.

I’ve taken all of your advice on board and couldn’t agree more.

The only remaining questions I have are:
Will my SCC be ok for lithium batteries or would I need a specific one?
Are lithium batteries safe? (I only ask as a mechanic friend showed me a video of them randomly combusting)

I look forward to seeing your diagram!

Thanks again,
Lewis

mikefitz · Feb 3, 2023

Hi Lewis,
I will try to add the diagrams later this evening, UK time. There are different types of lithium batteries. The type used in 12v batteries intended as replacements for lead acid is not the type that randomly combusts.
Your solar charger is suitable for all battery types
Mike

Mattb4 · Feb 3, 2023

Bozzydogg02 said:
Hi Mike,

Thank you so much for actually reading and responding to what I am asking. And communicating your answer in a language an everyday person can understand.

...

Sorry about that. I try to but sometimes my explanations are like the adults talking in a Charlie Brown TV show. Wah wa wa and wha wa.

mikefitz · Feb 3, 2023

review for off grid system.

Solar Epever 150/50 solar controller with 5 off 100 watt panels in series.

to get better solar yield you could add more panels, or engineer mechanisms to angle the panels in winter ( if you are travelling around this may not be practical).
You are at the limit with 5 in series ( to allow for cold weather when the panel volts increase) . Add one more100 watt panel ( any panel with similar voltage output) and rewire as two sets of 3 panels in series, with the sets wired in parallel to feed the controller.
With the roof space you have fitting domestic large panels is very cost effective,

Product not found!

www.bimblesolar.com

(Perhaps too late at this stage)
The current location seems to have shading from the trees and the straps will be having an effect even if they cover a small part of the solar cells. Your solar controlled allows monitoring of panel input amps and watts at any instant, this will give you an idea of the situation.
The plastic panel mounts you have are known to detach if only using adhesive fixing ( release agents in the plastic) and stress cracks around any fixings used.

Battery System.
There is a choice between sealed lead acid, or lithium. with lead acid you need a minimum of 200Ah, more ideal would be 300Ah. Battery costs have increased significantly in the UK over the last few years and to have a life over one or two years, a quality battery will have a cost of £200 to £300 per 100AH.

https://www.alpha-batteries.co.uk/12v-victron-100ah-super-cycle-agm-battery-bat412110081/

If you need to install sealed lead acid to get by for perhaps a year or so, then any of the low cost batteries will be suitable. Don't have more capacity than you can charge, I suggest no more that 300Ah of lead acid, and limit the discharge to 100AH.
Lithium batteries.
In the UK there are a limited number of outlets and two relatively small companies have excellent customer support,

all

For continuous power for non-stop adventures, say hello to Roamer – the next generation in SMART 12v and 24V LiFePO4 leisure batteries for campervans, boats and off grid life. Equal parts power, intelligence and reliability - managed with a smartphone app that puts the power in your hands. 10...

roamer.com

Lithium Leisure Battery - Fogstar Drift 12v 105Ah

105ah 12v Fogstar Drift Lithium Leisure Battery | Grade A LiFePO4 cells, JBD BMS, Bluetooth, Heating | Lowest Prices in the UK. 10 Year Warranty.

www.fogstar.co.uk

Since Fogstar batteries are by far the best cost per Ah even competing with the quality lead, this is what I would recommend. Although ideally you want as much capacity as is reasonable, 200 to 300Ah for your modest use, even a 100Ah would be practical with careful management of power use.
Consider the maximum current output of the battery if you are intending to have a high power inverter.

Battery monitor.

This is a kind of battery fuel gauge and will indicate , along with other information like volts, amps and watts, how much power is in the battery .
Ideal, victron smartshunt, low cost, AILI monitor

Diagram.

I am not a fan of circuit breakers, quality items are not readily available in the UK and the breakers sold on Amazon and eBay are unreliable.
Any battery pack need a 'master' fuse as close as possible to the positive on the battery pack. The ANL fuse is ignition protected and a suitable choice for battery protection, readily available on Amazon and eBay.
Although shown are two batteries in parallel it could be a single battery on a number in parallel. Note the connections for positive and negative are at the 'diagonal' across the battery pack.
Cable sizes shown on the high current cables are for 100 Amps maximum , there is no problems using larger cables, and this would be required if , for example a high power inverter is connected to the battery pack.
I am assuming for the moment that no inverter is in the system.
note the use of a negative buss bar for the negative cables.
No master isolation switch is shown , if required install between the master fuse and the distribution fuse block.

Marine Battery Isolator Switch - 2 Positions - 300A Continuous

2 position ON/OFF single pole battery isolator/master switch for boats, cars & other vehicles. Max. current @48V - cont. 300A, peak 1000A (5secs).

www.12voltplanet.co.uk

the fuse distribution holder is ,

Mega & Midi Fuse Power Distribution Box

Compact power distribution & fuse box that distributes power theough a single mega link fuse into 4 midi or strip link fuses.

www.12voltplanet.co.uk

available from other suppliers also, I have no connection with 12 Volt Planet but you will find everything you need from this company.

Do you have any alternative charging available, portable generator, vehicle alternator?

You mentioned wind generator, how is this connected to your system?

Mike

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