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


Erratic power supply AKA Dumsor has always been hot topic these past few  years .Pronounced “doom-sore” (or more appropriately dum sɔ, “off and on”) is a popular Ghanaian term used to describe persistent, irregular and unpredictable electric power outages. Everybody from businesses to households has been affected one way or the other. In addition to this most Ghana residents have had to spend 200-300% more than what they used to spend on electricity five years ago.

2016 is an election year in Ghana and I hear lot of promises from political parties and politicians alike. These promises include, good roads, education, health, jobs and of course Energy .

Thousands of Ghanaians attended the much anticipated ‘Dumsor must stop vigil’ in Accra on Saturday.

The protestors clad in red and black outfits marched from the Total Filling station opposite the University of Ghana to the Tetteh Quarshie Interchange here in the Greater Accra Region.

The vigil was led by Yvonne Nelson and other celebrities such as Efya, DKB, Sydney,Van Vicker and a host of others. Watch the the video here 

Can we be brutally honest with each other as Ghana residents?

  • Our energy demands have risen over the years and we require more capacity
  • Energy prices have risen all over the world and reliance on only hydro isn’t sufficient for Ghana anymore
  • There is no political party that can reduce electricity tariffs to rates that were being paid 5-10 years ago. Even if anybody tried, it wouldn’t be sustainable
  • Electricity prices will continue to rise in the coming years and the time to change our mindset is now
  • Ghana needs a serious national policy plan /implementation on energy matters
  • All the are above play a key role in Dumsor

 

I have to admit times are pretty hard in Ghana these days. A lot of people are unable to pay their utility bills. Some have actually resorted to either connecting utilities illegally or using less. Many people in Ghana have been caught, some of them being foreign businesses and all .I also know a few people who switch off their refrigerators or deep freezers at night.

Another interesting fact is that for those who are buying new electrical appliances, price becomes the most important or deciding factor so much  such that efficiency is thrown out of the window.

While interacting with people we get these statements quite frequently: So you tell people to use less electricity and conserve it?” or “Your website has ideas on how to buy appliances, how does that relate to saving electricity?” The easiest way to save energy (or electricity) is to use less of it, but we have to be realistic in our approach. Our lifestyles are changing, and with increased pace of development, our need for appliances is increasing and so is our need for energy.  Thus the ideal mix to save energy will involve both conservation and efficiency. Now let us look at what is the difference between the two.

Dumsor:The politrix of Energy Efficiency VS Conservation

kicking dumsor out of Ghana

What is Energy Conservation?

Whenever you use less of something that means that you are trying to conserve it. So if you use a 1100cc vehicle instead of a V8 vehicle, it means that you are trying to conserve fuel (among many other reasons why you would prefer to use 1100CC over a V8 motor vehicle). If you switch off lights when they are not needed, then you are conserving energy. When you increase the temperature at which you operate your air conditioner from say, 24 degrees to 25 degrees, you are conserving energy. You also conserve energy when you switch off your DSTV decoder boxes and TVs when they are not in use.

Energy Conservation is all about using energy only when it is required and using it as much as needed for the job and not wasting any amount of it. It requires a conscious effort from the user of energy to make sure that there is no wastage on a regular basis. It requires a lot of behavioral change and needs effort. It may not need any investment always.

So what is Energy Efficiency?

Energy efficiency in contrast means using lesser energy to do the same job. When you buy a car that gives more mileage, you use less fuel to travel the same distance. When you buy a 5 star rated air conditioner instead of a 3 or 2 star rated air conditioner, it means that for the same usage and in same conditions, you use less electricity (for the same temperature at which you operate them). If you use a 5 star rated air conditioner at higher temperature, you double the effect and combine energy efficiency with energy conservation.

Energy efficiency has more impact on your personal finances. An efficient appliance may cost more than an inefficient appliance. Although the additional capital cost may get recovered in form of electricity savings. Energy efficiency may not require physical effort but requires change in people’s buying patterns. It requires knowledge of various products and their efficiencies. If people start buying more of efficient products, manufacturers will start producing more of them.

Conclusion

Both energy efficiency and energy conservation have the same goal.That is  to save energy and the same impact: saves money. Both can individually save energy but when coupled together can save double the amount of energy and money. It depends on your choices as to which one you like to do. A good mix of the two can ensure high savings with low investments and efforts. Finally ,going solar is a brilliant way to achieve all this in a single  move by trying  out our mini off-grid solar packages All these efforts will go a long way in curbing  Dumsor


 

Bill Gates once again shunned solar power from his vision for energy access in Africa in his talk at the University of Pretoria in South Africa on Sunday, where he argued that whilst “cheap, clean energy” is what Africa needs, solar does not fit the bill.

During the delivery of his Nelson Mandela Annual Lecture, the Microsoft founder and philanthropist identified that Africa, like the rest of the world, is in need of a “breakthrough energy miracle that provides cheap, clean energy for everyone.”

Africa is more dependent on such a phenomenon than other continents, because seven in ten Africans still lack power at present, while more than 500 million Africans still will not have electricity by 2040.

This is not the first time Gates has taken a less than welcoming stance to solar power. In February, during an interview with a news outlet, he echoed a similar thought. “When I say ‘an energy miracle’,” he said, “I mean that there will be some form of energy whose 24-hour cost really is competitive with hydrocarbons given, say, 20 years of learning curve.

“You invent it, then you look at how much its costs go down over the next 20 years, that it really beats hydrocarbons.

“You might say, well, aren’t people saying that about wind and solar today? Not really. Only in the super-narrow sense that the capital costs per output, when the wind is blowing, is slightly lower.”

In fact, Gates has been advocating anti-solar sentiment for a while. In 2014, he blogged about energy poverty, arguing for outdated fossil fuel solutions to tackle the electricity deficit in underdeveloped economies, characterising energy poverty as a climate issue.

Solar is ‘not enough’

In the speech on Sunday, the software entrepreneur recommended increased investment in renewables, namely hydropower and geothermal. He went on to argue that recently launched solar power initiatives have not been enough:

“There has been a lot of experimentation with small-scale renewable energy, including micro solar,” he said. “This approach can provide individuals with some electricity for basic purposes, but it’s not going to be the solution for the continent as a whole.”

PV Tech contacted the South African Photovoltaic Industry Association (SAPVIA), who vehemently disagreed with Gates’ sentiments.

“To downplay the role that solar photovoltaics (PV) can play as part of a unique African energy mix in the strive to alleviate Africa’s energy constraints would be irresponsible,” a spokesperson said, whilst citing data that should deem solar a ‘no brainer’ solution for Africa: “Africa has 7 of the 10 sunniest countries on earth and, according to IHS Technology, a US-based economic and energy market research company, Africa’s total solar power–generating capacity is projected to reach 3,380MW by 2017.”

bill-gates-quote

Solar deployment in Africa

In fact, solar power is undergoing rapid deployment and implementation as many countries across the continent are battling energy crises and look to alternatives to expensive fossil fuels such as diesel and coal. A series of feed-in tariffs and solar tenders have offered a foray into a solution that not only is clean and inexpensive, but is easily accessible.

In South Africa in particular, the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP) has successfully awarded 965MW of new solar capacity, which SAPVIA points out “is being delivered on time and on budget”.

“The rapidly escalating uptake of the technology in the rest of Africa can be clearly seen,” argued SAPVIA. “Expedited solar PV roll-out is being seen as supportive policies and regulations, such as the Get FIT Programme are developed and implemented. These policies and programmes, combined with the drop in the cost of PV technology (currently fully off-grid solar-PV technologiesdeployed at site can be deployed for as little as US$ 0.15/kWh and they do not require additional expensive transmission networks to move the electricity around), [we] see solar PV will make a significant impact on Africa and its energy challenges.

“One can expect – as has happened in South Africa – as the necessary supportive policies and regulations are scaled up, the rest of Africa will experience an increased uptake of solar PVtechnology. New renewable energy markets in Africa are already showing greater appeal to international and local investors – further spurring the uptake of solar PV in African markets.”


Salima Visram is the 23-year-old entrepreneur behind the Soular, a backpack company equipped with solar panels, which allow children who don’t have access to electricity in rural parts of Africa to study at night without having to use an expensive and carcinogenic kerosene lamp. Soular will be launching a new one-for-one model today, through the sale of trendy backpacks on HSN in collaboration with Disney, alongside their new movie, Queen of Katwe, which is set in rural Uganda, where the kerosene lamp is central to the plot of the story.

“I was inspired to launch Soular after seeing how some children in Kenya, where I grew up, were not able to study every day and get into secondary school, which perpetuated the vicious cycle of poverty,” Visram said.

these school children seem very excited about their solular backpacks

these school children seem very excited about their solular backpacks

Oscar winner Lupita Nyong’o, who stars in Disney’s Queen of Katwe, is a supporter of Soular Backpack. Nyong’o and Disney went with the Soular team to Katwe in Uganda to distribute backpacks there in July.  Soular will also be showcased at the premiere of the movie in Hollywood later this September.

“On every Soular Backpack, there’s a quote from Lupita that reads, ‘The Power Is In Your Step,’” Visram said. watch the video here

Visram launched Soular by starting a crowdfunding campaign, which exceeded its goal by 25% raising $50,000. Soular has since distributed hundreds of backpacks across Kenya, Uganda and Tanzania.

“So far, we’ve distributed backpacks to 500 children but we’ve realized that with one backpack in the family, on average 3 children are able to study with it,” Visram said.

Soular’s new one-for-one backpack

Soular’s new one-for-one backpack

Visram has big plans for Soular.

“The next phase of Soular would be to scale the one-for-one model across North America in a big way and make sure that everyone who needs a backpack is aware that they could buy a backpack that gifts light to a child in need,” Visram said. “We’re excited to position ourselves as a leading backpack company that stands to create social impact.”

Soul’s new one-for-one backpack is for sale on HSN for $49.95 in two colors, navy and white

Visram stays committed to making Soular a company that finds sustainable solutions to poverty.

Salima Visram, founder of Soular, with the new backpack for sale on HSN

Salima Visram, founder of Soular, with the new backpack for sale on HSN

“My vision for Soular is to make a holistic system of interventions and services that give people the tool to alleviate themselves from poverty,” Visram said. “We want to partner with a bank, so that the money saved on kerosene every month goes into a secondary education fund for the child. We want to set up micro-franchises in rural villages to sell lamps and batteries, in order to generate employment. We’ve just moved production to Kenya, which is creating more employment and impact within the region. Realizing how electricity is at the center of education, health and economic development is also something that inspired me to start it.”

 


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.