This question is best answered by asking, how much do you use?

By building a load profile that outlines all the power you intend to consume during a day and estimating the duration of each device and its power draw you can build a power profile. A power bill is similar but not to the same level of detail as it only shows a total for the month which you divide by the number of days in that month. That gives you a kWh value. That number is sometimes referred to as the number of units. It's what you are charged for on your power bill. i.e. 500 units for the month at 20 cents per unit (1 kWh) would be $100. 500 units divided by 31 days equals 16.12 units per day. So that's 16kWh, and in New Zealand, the peak sun hours over winter are only 2 hours. So you'd need an 8kW solar array which will produce on a clear day 8kW per hour and with the 2 hours of usable sun energy in a day you'd generate 16kWh of power.

This would generate enough power to offset your consumption, but it's not all at the right time. You use power at night from the grid so you'll be charged for importing power to your house. But during the day while you aren't at home or your power usage is low you'll be exporting to the grid which may result in you receiving a small credit to your account.

You can see how the real way to benefit from solar is to utilise the sun's energy during the day and limit your need for it at night. This is where batteries can help as they store the day's energy for you to use at night.

What is a Total Loss Ignition System? Its using a petrol engine without an alternator.

Effectively you are running your vehicle's electronics from your battery which includes any spark to the ignition system, gauges, lights, fans, pumps, transponder or data logger, GPS, radio, comms etc etc.

Again we'd highlight the purpose of this battery is the most critical thing to consider. Do you want to have enough cranking power to start the vehicle or do you need to drive for a few hours without a recharge? (the latter being something to consider if your alternator dies while in competition or along way from home. Its referenced on the specs of a battery as being the reserve capacity (RC). It's measured at 25 amps and simulates SLA which was considered the essential requirement to operate a vehicle some 20 years ago. (Starting, Lights, Accessories). So the 25 amps could be discharged for X number of minutes (i.e. 90RC) until there is no usable voltage remaining in the battery.

With high flow fuel pumps and water cooling systems on high power engines a fully charged 12 volt battery might only be 11.5 volts under discharge load. This is to low a voltage for the ignition system to operate effectively and it makes current draw that much higher that it is far from ideal. An alternative would be to run a higher voltage battery like our XS Power 16 volt battery. Underload the voltage would still be 14 volts which is similar to the voltage output of a high powered alternator without the overhead of the alternator drive belt loading the engine or the extra weight being carried.

This is ideal for systems like drag cars or midget vehicles used in speedway which are push started. The 16 volt batteries also make for excellent jump start batteries on 1400 plus horsepower engines used in Hydroplanes, river racers and jet sprint boats.

The importance of using the correct charger for lithium batteries becomes apparent when comparing standard 12V lead acid batteries used for deep cycle applications with their lithium counterparts. Although the nominal voltages may seem similar, with lead acid ranging from 12.5V to 12.9V and lithium exceeding 13V, it is essential to understand the differences in charging behavior and requirements.

Lead acid chargers typically allow a longer duration for bulk charging, around 20 hours, while lithium batteries require a much shorter time, usually 4 to 5 hours. This discrepancy arises because the charger's capacity should be within 20-25% of the lithium battery's fully rated capacity. Rushing the charging process for lithium batteries can cause overheating, potential faults, and failures in the Battery Management System (BMS).

The subsequent charging stage, known as the Absorption stage, differs significantly between lead acid and lithium batteries. Lead acid batteries exhibit increased internal resistance as they approach their maximum capacity, absorbing every last bit of energy. This process, accounting for 40% of the total charged capacity, brings the battery to around 80% state of charge (SOC). However, lithium batteries do not require this absorption phase. Instead, the charger algorithm typically transitions straight to a float voltage as the lithium battery is already at 80-90% SOC. The purpose of the float voltage is to slowly balance the remaining capacity without overloading or overheating the BMS. During this absorption charge, the balancing system may activate, and the BMS may initiate a shutdown to allow the unit to cool down and the cell voltages to return to nominal levels. These additional stressors on the BMS can compromise its functionality and longevity.

It is important to note that other charging issues, such as thermal runaway, can occur when using the incorrect charger. These issues further strain the cells and contribute to the premature degradation of the battery. Lithium battery lifecycles are typically measured in years rather than cycles. While the claim that "it works fine" may initially seem valid within the first year, a lithium battery is often sold with the expectation of a 10-year lifespan and 6000 cycles. Evaluating its usable power and performance at the five-year mark will reveal whether the battery is still functioning as originally advertised.

In summary, using the correct charger for lithium batteries is crucial due to the significant differences in charging behavior, absorption stages, and BMS requirements. Neglecting these considerations can lead to safety risks, compromised performance, and a shortened battery lifespan.

Here's a quick rundown on parts used in a variety of solar installations and what they are used for:

Solar Battery - to store energy for later use

Solar Panels - Framed cells with a series of silicone wafers which generate DC voltage used to charge batteries

Solar Array - A collection of solar panels connected together to provide DC voltage

Frame rails - Support structure used to build a platform to place solar panels on. They can be mounted on walls, roofs, ground, tilted frame rails.

Solar Controller - (also called Charge Controller) connects the solar panels to the battery bank. The cheaper version use PWM (Pulse Width Modulated), the better versions use MPPT (Maximum Power Point Tracking) to harness the variable energy from the sun during a day and convert it into the correct charge voltage which is put into the batteries.

String Inverter - is really a solar controller that you'd use connected to the national grid across a larger array at a residential voltage up to 600VAC. In commercial installations, the string inverter can be up to 1000VAC. These higher voltages allow the solar panels to be connected in series to add voltage while the current remains the same as that of just 1 panel. These units only convert DC energy from solar to AC and connect to your main switch board. If the mains power stops for any reason these inverters also stop working for safety reasons.

Grid-Tie or Grid-Tied or Grid Connected - means a system connected your onsite power generation to the national grid.

Off-Grid - means your system is stand-alone with no national grid network attached. Typically used in remote locations.

Hybrid Inverter - allows a string inverter which only generates AC power from DC solar, to also be able to use the DC power from solar to charge a battery bank.

DC Coupled System - Uses the DC power from solar panels to be put straight into batteries with only the MPPT controller ensuring the voltages are correct to charge the batteries and minimilising conversion inefficencies. It then uses the stored DC energy in batteries to pass through an AC inverter to power the AC load. It can also export this power to the national grid once its in AC if you configured your system to do so.

AC Coupled System - Inverts the DC power from solar panels into AC and supplies the main switchboard and any loads attached. When there is excess power from solar available it can either export the AC power to the national grid. It could also convert the AC power back into DC power and charge a battery bank. When the stored power is needed it converts the DC back to AC to supply the main switch board.

Zero Export - this is when the national grid carrier doesn't want you to export any of your excess power back to the grid. Many regions in NZ now have a 5kw Max. export limit managed by Transpower and many power retailers only pay back a certain number of units of energy back to the grid per day.

Fuse - Fuses need to be held in place so use some form of fuse holder, they have different current ratings and each rating is typically a different colour. So if your blue fuse blows then you need another blue fuse to replace it. There are many different style of fuses from Class T, NH, Auto Blades, Maxi Fuses, Midi Fuses, Mega Fuses, ANL or FBT tag Fuses. The right type of fuse should be used for each instance.

Circuit Breakers - These are like a fuse, used to protect your circuits from over current. A fuse breaks and needs replacing but a circuit breaker can be reset and used again. There are 3 types of circuit breakers, automatic (which disconnect when blown but reconnect once they have cooled down). Manual Reset meaning it blows (opens the circuit) if tripped, then requires manual switching on to reactivate the circuit. Lastly PTT (Push to Trip) You can manually open the circuit and then re-close the circuit just like using a switch but with current protection builtin. Variations include double pole which means a breaker for the negative cable and a pole for the positive cable so total electrical isolation is achieved. There are also polarised and non-polarised, the later meaning they do not have an inward direction or outward direction in which the energy should flow from battery to loads.

Charger - A device that provides voltage above the open circuit voltage of a battery. This could be a solar controller, mains powered charger or DC power charger (DC to DC charger). Modern-day chargers would have charge profiles and can be set to best match the charge voltages required by the batteries manufacturer.

Cables - These are used to connect all the components on the DC circuit, normally multi-string copper cable which might also be required to be tin-coated. This cable is measured by its cross-section in mm squared. The number of strands is important for flexibility and ultimately affects its maximum current capacity. The insulation is also important, many require double insulated where there might be a coloured (blue or red) plastic around the copper, then each colour, if the cable is 2 core (a red and blue together), is then moulded inside an outer insulation like black for instance as seen in twin-core solar cable. They can also be built to be circular when cut cross-section, cheaper and more popular is a figure 8 shape when you look onto the end of the cut cable. This outer layer might also include a high content of silicone so the cable slides easily during installation. It can also be manufactured to include a UV protective material so it doesn't break down in sunlight. This outer is referred to as PV1. AC power cables are normally solid core cables in 1.5mm or 2 or 2.5mm2 and are either 2 or 3 core TPS in white or purple outer colour. With the Life, Earth & Neutral wires inside (Red/Brown, Black/Blue, Green/yellow)

We get asked questions like this all the time and I guess most would say yes that will be fine, some might say it depends on your load requirements, few would say no. The answer lies within the maths and calculations of your power consumption which is subtracted from your power generation. To work this out you take the power of each device and how long it's used for to get a daily demand. Now there are also peak loads and hours of minimal usage but for now, let's just work with a total figure for the day then divide that by 24 hours. 

We recently investigated a system where the customer had spent over $6500 on multiple replacement batteries & upgrades to the charging and solar system on top of the base installation the motorhome came with to resolve their shortfall. Only a few years ago a 150W panel and a 220Ah or 260Ah battery were all your motorhome came with which would be considered only a mid-sized occasional off-grid solution now. Many still don't have anything more, especially those vehicles out of Europe built for the rental market unless upgraded locally.

Their new setup included 540W (3 x 180W) Solar panels and 2 x 270Ah AGM batteries, DC charging from the alternator but it turns out they don't actually travel that much. The panels are connected in parallel into a 20A solar controller and they have 50A of AC Battery Chargers they run off a generator if the batteries get low. As it turns out that means they run the generator every second day to ensure they keep the batteries above 12.5 volts so they will get 5 years cycle from them.

With a moderate 5A discharge per hour, 24 hours a day the performance figures of their new system look like this:

We didn't want to alter the chart in any way to correct the errors we can see but we will explain something to clarify. The last column is headed LOLP meaning Likelihood Of Lost Power. in the months of May through to July there is Zero % of the system working and Battery State of Charge will be 100% discharged. But you will notice in Jan - Mar then Oct - Dec there is less than 1% chance of the system failing. April it's 50/50 and in August an 80% chance based on the last few years sun hours in the Coromandel when the panels are mounted flat on the roof of your motorhome. The reason the chart is displaying errors is nobody with this level of information would actually design-build, or implement a system that is shown to fail. The system would require over 1kW of solar to be able to maintain a 5A continuous load (120Ah but 133.3Ah when losses are included daily). You can see days carry over for the batteries is only 3 days without sun and that in summer months in the southern hemisphere you'd have plenty of excess power.

That might lead some people to figure out that 540W of solar far exceeds the 20A controller included. But over the summer months, the battery will fully recharge from the max 50A discharge from overnight in the first 3 hours of sun in the morning so will be in float mode only supplying discharge load at midday in the full summer sun. With the large array size, you have the benefit of collecting more of the low-level power for longer over the winter months. It's just not enough to meet demand.

Case Study - VSR or DC to DC charger

Well that will depend on your situation. We recently advised a client on the benefits of DC to DC charging because he highlighted a problem with his existing system in a boat they just purchased. The system had a start battery (N150) a service battery for house loads (to run equipment like fridge, lights etc) and a battery up-front (bow) with the anchor/winch. The system used a DVSR between the start battery and house battery. The start battery circuit also had an isolated single smart output VSR with Low Voltage Disconnect so it didn't flatten the start battery. (essentially features of a VSR but marketed to suit the sales purpose). The customer said if the engine was running it potentially kept all 3 batteries charged.

Lets work this out; If the start battery was an N150 with 184Ah, it might have only needed a 15 minutes charge at 13.6 volts to recharge from one engine start. It is however connected to the anchor battery which was a 100Ah and is over 5 metres away from the start battery which was close to the alternator. We know that there will be voltage drop over that distance, a higher internal resistance of the battery and the added resistance of the cables over 5 metres. There is no way the alternator can differentiate between the two batteries needs. It provides a fixed voltage and the same current to both batteries. Equalisation may occur if the banks are connected for 24 hours but we know they are only connected while the VSR is active and the engine is running.

The house battery which is parallel connected to the house battery using a Dual sensing Voltage Sensitive Relay (DVSR) in this instance was another 100Ah battery. So parallel with a starting 184Ah start battery). They are never going to be the same state of charge so let's just assume the house battery will have a current discharging from it while being used. The alternator will supply a float running voltage of approx 13.X volts. That voltage is required to charge a flat or discharged house battery with its low internal resistance because of its discharge. But its got in parallel with it a twice the capacity almost fully charged start battery with high internal resistance. The differences in capacity and resistances will cause the low supply of current from the alternator. The low current and low voltage will slow charge the house battery meaning it may not ever reach a full charge unless you run the onboard engine for 8 plus hours a day giving both batteries time to equalise and the batteries to finish the absorption and or float phase of charging a battery.

The solution: the installation of a DC 2 DC charger on the house battery where the voltage can be ramped up to meet the demands of the charging profile required to fully recharge a potentially flat house battery. The customer increased the battery capacity to offer a longer time between charging requirements but this wouldn't of been possible if some form of regulation was used as charging at 14.7 volts is 50% more efficient than charging at 13.X volts from an alternators output. It means the house battery with its larger capacity has a regulated voltage that's matched to the battery type (14.4v for flooded or 14.7v for AGM or otherwise) so best maintain and support a healthy state of charge.

The start battery is no-longer paralleled to the house battery because the DC 2 DC units isolates the batteries ensuring the capacity and state of charge isn't messing with the absorption of energy into the start and now that is inline with the bow battery which is only used with the engine running the current requirement is met by the alternator. Later the client may add another DC 2 DC for that battery but it raises the other question.

Do I need a DC 2 DC charger for the extra dollars it will cost if the secondary battery is less money than the difference between a DC charger and a VSR?

Well, that's a question only you can answer, but with DC chargers also managing the chemistry type, or being able to select a custom charge profile that suits your situation it doesn't take long to make the number work whichever way you need to justify on way or another and that's your call.

Batteries are built with a specific purpose in mind. This encompasses the materials used in the manufacture of the battery, the glues/adhesives used. The types of plastics used in the case and many other physical attributes. But there are things that can't be seen or measured easily like, the thickness of plates, Specific Gravity (SG) of the acid which has a huge impact on the battery's ability to give a high CCA when new, but if a high SG also limits the batteries longevity.

The next is true of all batteries and brands but we'll generalise one brands product offerings to give an overview of how their models within the range differ. And we'll be even more specific and limit this article to just AGM batteries within a single brand to give a better overview of the variations.

The first and cheapest entry-level AGM would be a 3-5 year design life battery (which means typically a 1 year warranty) it also means traditionally a battery manufactured with cheap labour and high volumes of turn over. Design life does not mean it will last 3-5 years either, the product will typically last 2-3 years in its desired application. Please note if you use it in the wrong application it might only last 6 months to a year. These batteries are also always referred to as float life batteries as they are meant to be connected to a charger or power supply full time like used in an alarm or UPS system.

Next would be a float life battery with a 10-year design (meaning it might last up to approx 8 years if conditions are suitable). These are occasionally used as an entry point deep cycle battery as they will give approx 250 cycles to 80% which would be similar to use of an occasional user in a cyclic application like a weekend motorhome or boat enthusiast. They might advertise 400-500 cycles at 50% but this can rarely be proven.

Then you'd enter step up to the next design of thicker plated batteries with a lower SG level to give the batteries a better reserve performance over a longer duration. This is really where true deep cycle batteries start. They might have an advertised performance of 800-1200 cycles at 50% depth of discharge. They are also flat plate construction and in a general statement we'd say are the high end of Chinese production. These batteries will however all look the same as the above 5 and 10 year design float life batteries so you really need to know what to look for and test yourself to prove the claims of capacity and longevity.

If you were to try comparing one brand with another you must first match the above 3 characteristics before reviewing and matching apples with apples the following technical specs: Amp hour, C rate (number of hours discharged to calculate the Amp hour rate), end voltage of discharge rate, temperature of discharge rate, start temp of discharge rate test, weight of the battery. Again, like for like as in AGM with AGM, not AGM with Lithium or AGM with Lead Carbon). Cycle life vs. depth of discharge. Once you have worked your way through that nightmare, brand, warranty or number of pages and exclusions, after sale service, advice given up front vs. retrospective, cost, location, distribution, ability to diagnose or test if there is ever an issue. All these need to be reflected to get a sense of value or worth in a battery.

That typically brings us to the end of the upgrade path by a single brand as the technology doesn't change for a 6 volt or 2 volt cell if its AGM. There are other chemistries available from the same said manufacturer like OPzV which are typically a tubular gel and in many cases far superior to the 12 volt AGM deep cycle batteries with cycle life charts normally starting at 1000+ for 80% Depth of Discharge. Do not even confuse these with traction batteries, they are used very differently from a reserve capacity battery.

As far as OPzV or traction batteries are concerned do not think they are better for you though, it's all about the balance of charge time, current and discharge rate. Mostly there is a cost difference and which point you might consider Lithium. This is where expert advice is required to match your use with the intended purpose of the battery and your available charging systems.

Returning to traditional 12 volt batteries or the slightly higher capacity 6 volt cells we then move to high-end global brands where the reputation of the brand is world-renowned. Like Odyssey, SunXtender, Lifeline, Optima, Trojan, Sonnenschein. These batteries typically use industry-standard systems for measuring performance, life cycle and are well proven and offered by distributors like ourselves because of the brand's reputation and the requirement to service and support with adequate ability.

A typical alternator that most people might have a basic understanding of generates power that is used to recharge a vehicle's battery. Why that's correct in principle the reality is that when the voltages are only 13.3-13.8 volts as typically found after the first 5 minutes of starting a vehicle. This is why an alternator is only used to replace the energy used to start the vehicle in the first place. Many people may make short journeys to and from work and have already found how quickly their battery needs a replacement this is due to it not getting adequate charge.

Also if you revise charging voltages why are they important in our FAQ you see this isn't enough voltage to fast charge (or bulk charge) a vehicles battery. This problem is compounded if a secondary battery is attached.

Now for the Smart Alternator, it goes one step further and is controlled by the engine management system which controls when the turning of the alternator by the motor is applied. This additional load that is placed on the engine also consumes fuel, therefore, increasing emissions and that costs the manufacturer Carbon Credits so they now actively limit the time the alternator is on. Which means more flat batteries which is why we see the rise of EFB or AGM batteries as start batteries to try to counter the problem.

The engine management system knows how much power is drawn by every factory fitted item in the vehicle and therefore if you turn on lights, wipers and are using electric fans to cool the motor the vehicle knows to provide just the right amount of current the vehicle needs to operate with little wasted energy. Unfortunately, that previously wasted energy was actually absorbed by secondary battery banks needing a charge. These days this doesn't occur as much, in fact, with recent tests we have found a factory Iveco van only outputs a maximum of 22A above the engine management system requirements. That's typically the same amount of current required to run a DC powered fridge while driving. So your batteries aren't really getting any charge while driving from the alternator. Many vehicles now have smart alternators like Mercedes, VW, Fiat, Renault, Ford & more.

To try and combat this problem DC chargers draw their power from the start battery and by design try to flatten the start battery while the engine is running by feeding the secondary battery bank the correct voltage up to the max current of the charger. This in-turn causes the start battery to flatten which in-turn forces the alternator to come on and recharge the start battery While this is a very crude overview of the process the result is the alternator running for longer charging the secondary battery bank with the added benefit of being charged at the correct voltages for the secondary batteries which may be more than the output of the alternator. All in all that can lead to batteries being charged 30% quicker than the old alternator systems and est. 80% quicker than the new smart alternator setups.

1. When you select a battery charger you need to first choose a style or form that is appropriate for the task at hand. A desktop charger isn't suitable in an application where the charger needs to be retained or mounted. These form factors may include dust or water ingress considerations or power cables in and out of the unit.
   
   
2. When selecting a battery the capacity required for you to run with a few day's autonomy needs to be matched with a batteries need to be recharged with the appropriate sized current. As a general rule we say use 1/10th batteries AH for its charging rate given you have 12 hours to recharge overnight. If you have less time then you need a larger charger if the battery can accept a higher rate of charge. Or if you are using some of the charging power to run equipment while the charging is simultaneously occurring.
   
   
3. The intended use of the battery is a key factor in the life you will get from it if you use a starting battery in a deep cycle application then be prepared for an early end of life. If you have recently increased your Ah capacity because you required a longer autonomy and used a deep cycle battery but have not increased your charging current to match you can also expect issues. Using any battery charger or regulator which doesn't use the factory recommended recharge voltages of the battery you are charging will lead to an early end of life issues also. These are not covered by the manufacturer's warranty which covers physical defects in production.
   
   
4. Chargers are a logic programmed electrical device that uses timers and measurements of voltage and current to determine the charge cycle. They are therefore pre-programmed with time limits for each stage, or current (amps) and a minimum value before the stage is complete then moving to the next stage of a charging cycle. If you haven't sized your charger correctly to your batteries these rates can be either too long because of undercurrent causing issues with recharge. Or just as annoying if the charger is too big you can reach high voltages quickly but not be able to change modes for a minimum number of hours which can lead to unnecessary overcharging.
   
   
5. Purpose of the system design, simplicity, effectiveness, and efficiency are all core factors in power storage and conversion. Choosing the correct components from the outset might cost a little more upfront but the return well worth the effort in getting it right.

Solar Modules carry approx 0.5v each so a 36 cell produces 18V which is perfect for charging 12v batteries using a solar regulator (either PWM for cost efficiency or MPPT for yield efficiency).

A 60 cell panel was originally designed for use in residential installs where higher voltages are used to string series arrays together. They are typically connected to the grid and use MPPT to convert the varying energy throughout the day into a usable power on the grid. When used in portable applications an MPPT controller can convert the 30-40 volts output by a 60 cell panel into a 12 or 24 volt battery bank.

More recently 72 cell solar panels were used when solar was used to charge 24 volt systems like in off-grid. It was previously typically done by connecting two 36 cell 12v panels in series. Later panel manufacturers series connected 72 cells to produce the same voltage output which is actually closer to 38 volt open circuit than it is the 24 volt often referred to within the mobile industry. These panels are best used in high voltage strings in commercial applications up to 1000VDC because of their size and weight. But when space is tight on a roof and there's only room for a few panels in an off-grid system you can utilise the large frame size and high power output using MPPT controllers to bring the voltage down to 12, 24 or 48 volts. These panels have been up-sized from their humble beginnings of 200W right up to 365-400W today with larger wafer sizes, they are almost 2 metres by 1 metre in size. (Sept 2019).

Cells numbers when connected in series gain higher DC output voltages and those voltages are best matched to the solar controller's maximum DC input. Do not exceed the max input voltages or input max current.

More recently half cells have been produced to help negate shading reduction. A 120 cell is very similar size and power output to a 60 cell but has cells half the size of the 60 (thus twice as many).

In its simplest form "the grid" is the power grid that connects homes all over the country which provides them with mains power.

When you are connected to the mains power grid you are referred to as grid-tied or vice versa tied to the grid. So Off-Grid simply means operating your own power not tied to the nationwide grid.

When you go bush or remove yourself from your device people quite often refer to this as going-off-the-grid. Not quite the same but it might be where some people associate off-grid with being remote or removed. It doesn't mean without technology though as a modern-day off-grid setup can actually be smarter and more intuitive than your current smart meter.

In-fact building your own power source with battery backup, solar and grid independence gives your location the ability to store, sell, distribute, manage, monitor, and action your power in almost unlimited ways. All with the benefit of resilience to outside infrastructure, outages, or scheduled power cuts. The components and hardware used in grid and off grid should be from a quality internationally recognised brand as the hardware should be assessed as a system costs that you can calculate over a 20 year period for a good return on your investment.

There is another variation from grid or off-grid. It's really a hybrid of the two systems taking the best of both and in recent years its becoming more and more common. Grid-tied with battery backup has been around for some 15+ years but marketing by Telsa and the Teslawall has made everyone aware of its existence. LG chem and others have similar "wall" designs which give people options for internal or external system storage designs.