Lithium SuperPack batteries – an all in one solution .These new Lithium-Ion, LiFePO4 chemistry batteries are often an ideal replacement for many 12V and 24V marine, automotive, caravan, motorhome, work vans and similar battery applications. It might even be for an overland motorcycle if using the smallest 20Ah version; to recharge a camera, phone or laptop for instance.

Other examples – take a typical small boat or van which may have a 110Ah to 220Ah lead-acid leisure battery for light continuous loads such as lighting, laptops, phones, instruments, powering a diesel heater, a fridge etc. And for shorter term loads maybe add a small inverter to charge power tools, run a small microwave or travel kettle for example. Using one SuperPack battery it matches well with the Phoenix Inverter VE.Direct 250VA – 1200VA range. Maybe you’ll add in around 100 to 200Wp of solar panels too using a small MPPT.

Regardless of the use, whichever SuperPack you choose it’ll be lighter than lead, can be smaller if you wish or give you more Wh in the same space – plus give you around 5 times the cycle life.

The main difference to Victron’s other lithium (often more kWh) offerings are the SuperPacks keep everything in one package, by having an integrated BMS and safety switch built-in. No additional components are needed as the internal switch will disconnect the battery in case of over discharge, over charge or high temperature. Simple, compact and safe.

If you are considering a new battery don’t immediately discount Lithium as being too costly. Whilst it is true that the capital cost of Li-ion is greater than that of quality AGM or Gel batteries – it is also true that the cost of ownership can be less than lead acid types. Much depends on your application, but rest assured – life with Li-ion is far less hassle than lead.

Over the last 8 years on my sailing yacht I’ve run AGM lead leisure batteries and Lithium-Ion propulsion batteries. Initially it was AGM for propulsion before discovering the effectiveness of Lithium. That journey taught me a lot about loads, capacity, cost and battery life – it’s one of the reasons why I think we’ve reached a tipping point and why these new SuperPack batteries may just be the ticket for your next project or battery replacement.

If in the first instance you are unfamiliar with AGM vs Lithium, then here’s a blog that explains that.

When to use a SuperPack?

Every battery size and type has it’s own particular use. For instance you may use the Lithium battery 12,8V & 25,6V Smart and the Lithium battery 24V (LiFePO4 & NMC chemistries) ranges (all of which have an external BMS) in quite different applications to the new SuperPack range. So, where to use the SuperPacks?

When it comes to replacing lead acid type batteries such as AGM and Gel in many applications, the SuperPack range can be considered the next generation after lead – making it far easier to replace lead with lithium. The only caveats being replacement is down to certain parameters being met, namely – Capacity (Ah), Voltages (12.8V & 25.6V), Discharge and Charge currents (C rates). Do in that case be sure that your chosen replacement fits your criteria by checking the datasheet and be aware the SuperPacks can be connected in parallel, but not in series. Hence in that case you would consider the other Victron lithium products named above.

The Lithium SuperPack

Victron Energy’s recently introduced Lithium SuperPack range comes in the following capacities and voltages:

12.8V & 25.6V Lithium SuperPack batteries:

  • 12.8V – 20Ah
  • 12.8V – 60Ah
  • 12.8V – 100Ah
  • 12.8V – 200Ah
  • 25.6V – 50Ah

These SuperPacks will give you 2,500 cycles to 80% depth of discharge at 25°C, much more than lead.

Comparison: SuperPack 60Ah LiFePO4 vs 90Ah AGM

Let’s compare the 60Ah Li-ion to say a typical 90Ah AGM battery discharged to the commonly accepted economic cycle life of 50% discharge for lead. That would give us 600 cycles at that DOD for the AGM compared to 2,500 at the even deeper discharge of 80% for the LiFePO4. Already you can see you may need to replace your lead-acid type battery 2 to 4 times as often as the Lithium. Of course loads, operating conditions and calendar life have to be factored in too. Regardless you get the idea – Lithium does more and lasts longer.

The benefits of Lithium don’t stop there though. Whilst LiFePO4 chemistry is considered the safest of them all, it’s worth considering other factors too to decide whether the reduced weight and volume of say NMC is of more importance for your application than LiFePO4 for example. Victron Energy do both types. These star graphs do a good job of explaining the differences: https://batteryuniversity.com/learn/article/types_of_lithium_ion

60Ah SuperPack

90Ah AGM

Weight
9.5kg 27kg
Size (mm)
229 x 138 x 213 350 x 167 x 183
Useable energy @ 25°C
614Wh 540Wh
Cycle life
2,500 cycles 600 cycles
Cost
x 2.5 (approx)  x 1

Notes for the table above:

  • Useable energy and cycle life are based on 80% depth of discharge for Li-ion and 50% for AGM, these being considered the most economic use of those battery types.
  • Higher loads with lead will further reduce available Wh (Peukert’s Law) when compared to Li-ion.
  • Capacity is also reduced for both types by temperatures below their 25°C temperature rating (see their respective datasheets)

Make what you will of the above and whilst you are pondering the pros and cons don’t forget to take these additional factors into account for the comparison above.

  • Shipping: If you are replacing your lead from 2 to 4 times as often as Li-on and the fact that the lead weighs around 3 to 4 times as much (depends on Li-ion chemistry used) – then do consider the extra shipping costs.
  • Voltage stability: The voltage profile is far flatter for Li-ion compared to lead.
  • Voltage sag: Subject to the load, voltage sag with lead is significant compared to Li-ion.
  • Li-ion has much faster charge times and if charging from a generator it saves on generator runtime.

Other factors to consider

Is the above enough to convince you of why Lithium might be a better alternative than AGM or indeed Gel? Personally I’m sold on Lithium, but if you are not here’s a few things further to consider:

  1. A lead-acid battery will fail prematurely due to sulfation if it operates in deficit mode for long periods of time (i.e. if the battery is rarely, or never at all, fully charged). It will also fail early if left partially charged or worse, fully discharged.
  2. By comparison a Lithium-Ion battery does not need to be fully charged. This is a major advantage of Li-ion compared to lead-acid which needs to be fully charged often to prevent sulfation.

  1. Efficiency. In several applications (especially off-grid solar), energy efficiency can be of crucial importance. The round-trip energy efficiency (discharge from 100% to 0% and back to 100% charged) of the average lead-acid battery is 80%.
  2. The round-trip energy efficiency of a Li-ion battery is 92%.

  1. The charge process of lead-acid batteries becomes particularly inefficient when the 80% state of charge has been reached, resulting in efficiencies of 50% or even less in solar systems where several days of reserve energy are required (battery operating in 70% to 100% charged state).
  2. In contrast, a Li-ion battery will still achieve 90% efficiency even under shallow discharge conditions.

Make the switch?

Are you ready to make the switch from Lead to LiFe? If you’ve considered all the above I suspect you might be. And if you need more useable Ah why not run the sums on say a 100Ah Lithium SuperPack vs 220Ah AGM using the process I have above. Or indeed a 200Ah Li-ion SuperPack vs your choice of lead.Lithium SuperPack batteries – an all in one solution

Don’t forget too that Lithium has little or no Peukert effect when compared to Lead types. This is especially important when considering loads with lead-acid higher than 0.05C (Battery Ah divided by 20 or Ah multiplied by 0.05). In other words for a 100Ah AGM with a Peukert of say 1.15 or more and discharging at 0.25C (25 Amps in this case – which is 5 times the 20 hour rate) there will be significant reduction in capacity – as there will be at colder temperatures too. Li-ion has a Peukert of around 1.05 when compared to lead of around 1.15 to 1.25.

So – if you were discharging that 100Ah lead at 5 Amps (the 20 hour discharge rate at a temperature of 25 degrees centigrade) then the full capacity of 100Ah is still availaable and it’s not shrunk due to Peukert. But now if it were 0.25C, it’ll be around 80% of that original 100Ah capacity – or less, subject to load type and duration.Lithium SuperPack batteries – an all in one solution

The bottom line is you no longer have the Ah you purchased, whereas with Lithium there is little to no effect, helped by a lower Peukert and good voltage stability. That is especially important with constant inverter loads – a place where lithium shines. If you want to learn more about Peukert and run a spreadsheet to see such effects, then I have found this link most helpful.

Finally and one I’m always grateful of is vastly reduced charge times, no more waiting for hours of lead absorption charging to get from 80% to 100% SOC. Conversely Li-ion flies up to around 98% SOC in bulk with those last few percent in absorption to fully balance the cells – and unlike lead you don’t always have to fully charge to 100% as often. Note that your 12V charging system needs to accommodate 14.2V – 14.4V ‘absorption’ and ‘13.5V’ float. If charging from an alternator also note the maximum continuous charge currents for the 12.8V range, by checking the datasheet.

Downsides

Not wanting to sound too evangelical, we also need to consider the few downsides of Li-ion.

  • Higher upfront cost and to some extent higher capital risk.
  • Charging is restricted to the +5°C to +45° range, subject to an internal means of blocking the charge source when the temperature is below +5°C. Note this is currently automatically possible with Victron MPPTs when used in conjunction with the Smart Battery Sense for instance. Other products are being worked on to achieve this too and documentation to that effect will be updated in due course.
  • The SuperPack (unlike other Victron Lithiums) is not designed for series connections.
  • The peak and maximum continuous discharge current of the SuperPack range is not as much as some of our Lithium batteries as its related to the BMS and the disconnect being internal to the battery – so do check the datasheet to make sure the current peak and discharge ratings suit your needs – or choose from the Lithium battery 12.8V & 25.6V Smart or the Lithium battery 24V range or build a parallel SuperPack bank.Lithium SuperPack batteries – an all in one solution

Conclusion

Whatever your decision when purchasing new batteries, maybe it is time to give the Lithium SuperPack batteries a chance. There’s LiFe after Lead you know – but as I’ve shown that all depends on what you want to achieve. Is it less weight, less volume, maybe it’s capacity or voltage or any of the multitude of factors that go into choosing a battery system.Lithium SuperPack batteries – an all in one solution

Whatever you choose Victron have plenty of choice – with a large range of battery types and sizes: https://www.victronenergy.com/batteries

John Rushworth


Lead acid battery charging in cold weather

This blog covers lead acid battery charging at low temperatures. A later blog will deal with lithium batteries.

Charging lead acid batteries in cold (and indeed hot) weather needs special consideration, primarily due to the fact a higher charge voltage is required at low temperatures and a lower voltage at high temperatures.

Charging therefore needs to be ‘temperature compensated’ to improve battery care and this is required when the temperature of the battery is expected to be less than 10°C / 50°F or more than 30°C / 85°F. The centre point for temperature compensation is 25°C / 77°F.

Cold weather also reduces a battery’s capacity. This is another factor that needs to be taken into consideration, along with the load and charge rate compared to the battery capacity (Ah). Both of these factors affect the correct and consequent sizing of a battery for your particular application.

Battery capacity in Ah is usually quoted as a 20 hour capacity rating at 25°C. The discharge rate or load can be written as 0.05C where for example C is the load factor of the 20 hour rated battery capacity at 25°C.

Worked examples: If a 100Ah 20hr rated battery then a 0.05 load would be 100 x 0.05 = 5 Amps or 100/20 which is also a 5 Amp discharge rate over that 20 hour period. A 10A load on a 100Ah 20 hour rated battery would therefore be a 0.1C discharge rate, a 0.2C discharge rate on a 200Ah would be 40A and so on. C ratings also relate to charge rates as well as discharge rates.

When buying a battery you may see its Ah quoted at 20 (the standard rate), 10 and 5 hour rates so you can see how load ‘shrinks’ the Ah. Some even quote at 25 hour rates, which often fools people into thinking they are getting a bigger battery than standard.

To recap – capacity reduces at low temperatures, as it does for higher discharge C rates above the 0.05C 20 hour rate. This reduction in capacity due to higher discharge rates is due to Peukert’s Law.

Graph showing the effect on battery capacity due to temperature and load:

Lead acid battery differences

Lead acid batteries come in a variety of types:
  • Wet lead with the ability to top up each of the six cells with de-mineralised water.
  • The so called ‘sealed’ wet lead leisure or rather maintenance free battery. These cannot be topped up and often have a green go or red no go cell inspection indicator.
  • AGM (Absorbent Glass Mat) valve-regulated lead-acid (VRLA), where the electrolyte is absorbed in a glass mat.
  • Similar to the AGM, but the electrolyte is held in a Gel.

All of the above are however lead based (as opposed to lithium) technology. Besides lithium batteries Victron Energy sell VRLA AGM and Gel monoblocs (6 x 2V cells in series) due to their superiority over wet lead monobloc types. Victron’s range consists of:

  • Gel (Better cycle life than AGM).
  • AGM (Better than Gel for higher loads and well suited for use with inverters).
  • AGM Telecom. Designed primarily for Telecom applications, but also excellent ‘footprint space savers’ for marine and vehicle applications.
  • AGM Super Cycle (Best if frequent discharge to 60-80% DOD is expected).
  • Lead Carbon Battery (Improved partial state-of-charge performance, more cycles, and higher efficiency).

Additionally Victron also sell specialist lead acid type batteries.

  • OPzV 2V individual battery cells. Long life, high capacity gel.
  • OPzS 2V individual battery cells. Long life high capacity flooded tubular plate batteries for specialist solar applications.

Temperature compensation and charging

Now we know about the kind of batteries, capacities and loads we are dealing with, we need to put some numbers together for temperature compensation and charging.

The recommended temperature compensation for Victron VRLA batteries is – 4 mV / Cell (-24 mV /°C for a 12V battery).

Besides accounting for cold weather charging the charge current should preferably not exceed 0.2C (20A for a 100Ah battery) as the temperature of the battery would tend to increase by more than 10°C if the charge current exceeded 0.2C. Therefore temperature compensation is also required if the charge current exceeds 0.2C.

How to achieve temperature and voltage compensated charging

There are a range of Victron products to achieve this.

With our range of inverter/chargers and since VE.Bus firmware version 415 was released some time back this has ensured that:

– Temp compensation continues down to -20C

– This is for all voltage set-points, except for float, storage and the start of bulk charging

– As soon as the temperature goes below -30C, the compensation mechanism is disabled (normal charge voltages are applied) and a warning is shown.

For systems that don’t use an inverter/charger – we can use Smart Battery Sense to ensure that charging sources provide optimal voltage and temperature compensated charging to your batteries, by wirelessly transmitting accurate battery voltage and temperature values to your Solar Charge Controller or Smart battery charger.

This information is then used to set the ideal charging parameters, resulting in more complete, faster charging – improving battery health and therefore extending battery life.

The Victron Toolkit app allows you to calculate cable sizes and voltage drop. Here’s an example where cable length is the round trip of the positive and negative battery charging cables. This is so you get an idea of what Smart Battery Sense automatically takes into account to ensure the correct charge voltage goes into the battery, by ensuring the charge voltage is compensated for and corrected due to any cable losses.

Victron’s range of SmartSolar MPPT Charge Controllers all work with the Smart Battery Sense. In fact I’ve just fitted one to my motorhome, along with the required Smart Battery Sense, due to the fact the leisure battery temperature location when compared to the location of the controller can have a difference of up to ten degrees. Definitely a case for ensuring accurate temperature compensation.

Other products can be connected too by using what we call ‘VE.Smart Networking support’. See the VE.Smart Networking page.

Conclusion

With the above solutions I know I’ll be happier now that my batteries are getting exactly the right charge due to optimal temperature and voltage compensation.

Why not make sure you are doing the same…

John Rushworth


Punjo is not Puna : Not All Solar Panels Are Equal

Nii koi’s wife was pregnant with their third child, and as usual her food cravings seemed to change by the hour. This morning she wanted Pona yams with smoked fish light soup. Being a great husband Nii Koi dashes  to the nearby  grocery down the road  and ends up being sold Punjo yams ,a lower priced ,larger variety of yam. Most Ghanaians prefer the higher sugar content and finer texture in Pona yams even though they can be quite pricey especially when yams are not in season. Thinking he had found a great deal Nii Koi proceeded to complete his assignment.

His wife was very furious, I will not eat this yam

“All yam be yam he exclaimed” and she hissed back, Punjo is not Pona

To cut a long story short his wife refused to eat the Punjo yams and insisted that he get Pona yams to satisfy her cravings

Jinko Solar panels are durable and efficient

Selling Solar in a harsh economic climate like Ghana can be quite challenging ,it’s not unusual for prospective customers to ask questions such as  “why your solar panels cost Ghc X when so and so in the market is selling it for so much less at Ghc. Y.”

The simple answer is – Not All Solar Panels Are Equal.

Punjo is not Puna : Not All Solar Panels Are Equal

So when you compare prices for solar panels (and we do encourage you to shop around), you do need to pay attention to 2 key aspects of the panel’s quality – GRADE and MANUFACTURER TIER.

GRADE refers to the quality of solar cell used in the solar panel, and are categorized as A, B, C, or D. Grade A cells are the highest quality, in that they are tested against highest quality criteria to ensure there are no micro-cracks in the solar cell, and all the cells are of the same type. The quality diminishes for grade B, which may have micro cracks and not all cells are of the same type (they sometimes mix and match). Grades C and D are much worse quality with larger cracks and chips, and the cell mismatch is even worse.A typical solar cell will be exposed to sunlight throughout its lifetime. Sunlight contains harmful ultraviolet (UV) light that deteriorates all materials, including solar cells. The tiny flaws in the material become worse after prolonged exposure to sunlight, and its power output reduces over time.As a grade A cell has the least flaws to start with, its deterioration will be the slowest.

MANUFACTURER TIER refers to how automated a manufacturer is in its manufacturing process, its manufacturing volume, how long it has been in the industry, and how much it invests in R&D. There are 3 tiers to classify this:

certified engineers installing Jinko Panels in the heart of Ghana capital city,Accra

Tier 1 manufacturers are the top 2% of solar manufacturers, normally producing over 1 GW of solar panels in a year. They are vertically integrated meaning they make their own cells and wafers. They invest heavily in R&D, and have advanced robotic processes for manufacturing. They have been manufacturing panels for longer than 5 years. Tier 2 manufacturers are small to medium scale manufacturers, with little or no investment in R&D. They only use partial robotics in their manufacturing process, and rely more on manual work from human production lines. They have been producing panels for 2 to 5 years. Tier 3 manufacturers are actually just Assemblers – i.e. they assemble other manufacturer’s cells into a panel. This is 90% of the new solar PV companies, with no investment in R&D, and they use human production lines for manual soldering of solar cells instead of advanced robotics. They have been assembling panels for 1-2 years. You get best (and consistent) results from Grade A panels manufactured by a Tier 1 manufacturer. They may cost a little more on a per-watt basis, but when you consider the energy output and the longevity of their panels, you actually get more energy out of Tier 1 / Grade A panels than anyone else. And ultimately, you have to ask yourself what matters to you more — the total number of watts of a solar panel, or the actual kWh (units) of energy produced by the panel?

That’s why we at Nocheski Solar use Grade A solar panels from Tier 1 manufacturers like Jinko Solar, which ensures the best overall value in terms overall electricity output and long-term high quality.Hope this helps you when you compare solar panel prices.Let us know your feedback.All that being said, its  prudent to watch out for unscrupulous industry players  who may be selling counterfeited solar products but that is another whole discussion for another day.

Punjo is not Puna : Not All Solar Panels Are Equal

 

 

 


100 MW Ghana Solar Farm Gets Funding

Home Energy Africa, which specializes in the development and sales of renewable energy products for businesses, governments, and residential homes in Africa, has obtained a $705,000 grant from the US Trade and Development Agency (USTDA) for the development of a solar PV power generation project in Ghana.

Projected to begin construction in 2017, ESI Africa reports that this solar project will generate 100 MW of power, providing electricity to approximately 80,000 average homes in the country.

The agreement between the two countries was signed by Robert P. Jackson, the US Ambassador to Ghana, and Charles Sena Kwadzo Ayenu, CEO of Home Energy Africa.

“Lack of power is a challenge we see across sub-Saharan Africa. Two out of three people in this region lack access to electricity. That hinders business, and it hinders prosperity. We’ve made increasing access to power one of the top priorities for our bilateral relationship. Today’s grant is just one more way we’re bringing together government and the private sector to make Ghana’s future brighter,” said Jackson.

Boosting the Supply of Electricity

“One of Ghana’s paramount constraints to sustainable economic growth is the country’s inadequate electric power supply. This grant will support us in bringing our solar power PV project to financial close in order to fill the gap in power supply, meet Ghana’s goals for clean and sustainable energy, help create over 200 jobs to local communities and provide electricity to at least 80,000 average homes in Ghana,” said Mr. Ayenu.

Ayenu stated Ghana presently has 2,450 MW of installed capacity, adding: “The government of Ghana aspires to double that capacity to 5,000 MW this year, including 10% from renewable sources.”

The USTDA grant targets providing technical assistance to Home Energy Africa by using GreenMax Capital Advisors, an American firm, in finalizing the legal and financial details necessary to implement the project. Project assistance includes preparation for power purchase agreement negotiations with the Electricity Company of Ghana, services contracts, and financial arrangements.

Ayenu said the signing of the grant was the last barrier that the company has had to cross for work to begin on the project. He added that the firm has also acquired a 30% equity funding agreement for the $150 million project.

Originally published on Planetsave.