Forbes Batteries & Electronics is your Local one stop shop in Toowoomba & Darling Downs for all your LithiumSolar Battery requirements. Lithium, the lightest of all metals, has the greatest electrochemical
potential. This means that lithium provides the highest energy density
per weight--far lighter and more efficient than the popular lead acid
battery. Lead acid batteries can weigh up to 150 kilos, making them far
more difficult to transport. Lead acid battery weight also makes
usability much less convenient for residential solar customers. We have a range of
Lithium batteries to suit your solar energy storage needs. We keep stock of top brands like BYD B-Box, LG Chem and much more.
Forbes Batteries & Electronics is your Local one stop shop in Toowoomba & Darling Downs for all your BYD B-Box Lithium Battery requirements. The BYD B-Box Energy Storage System utilizes the BYD Fe battery and
provides a modular design to give flexibility of 1/2/3/4 pcs of battery
modules in one battery rack. The B-Box is able to meet the requirements of different
storage systems by increasing the capacity through parallel connection
of battery rack.
Flexible capacity configuration Support system parallel connection Support RS485 or CAN communication ∑ Modular design Easy to Install Emergency stop function
1 - How many Batteries/Day of Backup Storage do I need?
This is the most important decision regarding your battery purchase.
The below table will give you an approximation as to how your system will perform depending on the size of batteries/days of Backup Storage you choose.
The table is broken down into 4 options from extra small to large.
Please Enter your Daily Consumption (KWh):
Days of Backup Power
1 TO 2 Days / Day
2 TO 3 Days
3 TO 4 Days
Average Daily Depth of Discharge
*Generator Start up at 70% D.O.D for Lead Acid & 90% for Lithium
Whenever there are overcast days
Whenever there is consecutive overcast days
Whenever there is several overcast days in a row
Whenever there is extended overcast weather
Approx Battery Size
1.5 X Daily Consumption
2 X Daily Consumption
3 X Daily Consumption
5 X Daily Consumption
Approx Battery Size
2 - Lead Acid or Lithium Batteries?
The below table will give you a comparison of important features & metrics between Lithium and Lead Acid Solar Batteries
Lithium Solar Batteries
Lead Acid Solar Batteries
Smaller & Lighter than lead acid
Relativly large and heavy
10 - 20 year life span
10 - 15 year life span
Can be discharged to 90% regularly
Recommended to only discharge max 30% - 50% Daily
95% Charge efficiency
(95% of the power your solar controller produces will make it to the battery)
85% Charge efficiency
(85% of the power your solar controller produces will make it to the battery)
Very Low Absorbtion Time (Will accept full charging current up to approx 95%)
Absorbtion Required (Will accept full charging current up to approx 80%)
Will not operate in Sub Zero or 40+ Dec C Temperatures
Will operate in Sub Zero and 40+ Dec C Temperatures
Warmer Temperatures between 25 - 40 Deg C will not effect the over all life of the batteries
Warmer Temperatures between 25 - 40 Deg C will reduce the over all life of the batteries
Required sofisticated communications with Charging Equipment
Also requires lots of programming to get the charging equipment to work properly
Very basic and simple technology
Simply connect the positive & negative battery terminals
3 - Other Factors to Consider & Common Problems
What happens on days that you use more power than normal?
Smaller Battery banks will run flat reasonably quickly and the generator may be required to kick in during the night.
Larger battery banks will have more storage and are much less likely to go flat during the night.
This means they can hold out comfortably until the sun comes up again the next day.
What time of the day are the batteries likely to run flat?
If the battery bank is small, and has not been fully recharged the previous day, they are likely to run out of charge during the night.
This may require the auto start generator to start up in the early hours of the morning and could be quite noisy.
If you have a larger battery bank, our Victron equipment can be programed to delay the auto start of the generator until later that day when the noise may not be a problem.
This delay will not affect the performance of the system because the larger batteries will have enough back up capacity to handle the delay of the auto start generator.
Will the Batteries lose capacity over time?
Yes! All batteries will lose capacity over time including lithium.
The BYD lithium batteries have a 10 year warrantee which guarantees up to 80% capacity for the first 3 years, then 70% capacity for the next 3 years then 60% capacity for the remaining 4 years.
The Sungel Solar Batteries have up to a 10 year warranty which guarantees up to 80% capacity over the entire life of the warranty.
If you have a smaller battery bank to begin with, the batteries may lose some of their capacity and may result in the batteries simply being too small for the job.
This may mean the generator is required every day (most likely early in the morning) because the batteries canít even make it through 1 night.
What happens if the auto start generator does not start?
If you rely on an auto start generator to kick in when your batteries are low, there may be times it does not start due to issues such as no fuel/oil or other general maintenance problems.
If you only have a small battery bank, the time between the generator failing to start and the system shutting down will be much less than a larger battery bank.
For example: You might use more power than normal one night and the generator tries to kick in at 3am because the batteries are low,
the generator fails to start and the batteries continue to get dragged down. By 5am the batteries are dead and you lose power to the house.
IT MAY GET EVEN WORSE: If the generator is still out of operation for some reason, you would need to wait for the batteries to be recharged by the sun.
If it is an overcast day the batteries may not get recharged quickly enough and you are without power for a substantial period of time).
Can you add more batteries down the track?
Lithium: The BYD lithium batteries are a modular 48v 2.5kWh unit that can be expanded up to 80kWh (32 batteries) at any time.
This makes them a great option forstarting small to keep the cost of the system down and adding more at any stage if you are not happy with the performance of the system.
Alternatively if you were to start using more power several years down the track and the batteries were not large enough anymore, you could simply add more.
PLEASE NOTE! FORBES BATTERIES DOES NOT GUARANTEE THAT THESE BATTERIES WILL BE AVAILABLE IN THE FUTURE.
IF THE PRODUCT WAS NO LONGER AVAILABLE, THERE IS A STRONG CHANCE YOU WOULD NOT BE ABLE TO ADD ADDITIONAL BATTERIES TO YOUR SYSTEM.
Lead Acid: Generally speaking, you cannot mix new lead acid batteries with old lead acid batteries.
In saying that, if you were to add new batteries with in the first 1 to 2 years of your original batteries, the side effects would be very minimal.
The other factor to consider is you most likely cannot just add 1 or 2 more batteries.
If you have a 48v system and you are using 12V Batteries, you would need to buy at least another 4 batteries of the same size to keep your battery voltage at 48v.
If you have a 48v system and are using 2v solar cells, you would need to buy at least another 24 batteries of the same size.
One good thing about lead acid is if one of your batteries fails out of warranty and they are no longer available to buy, you will be able to buy a similar equivalent (in voltage & capacity) to replace it with.
This will not be possible with lithium batteries as they require a communication cable for the batteries to talk to the solar charging equipment.
This charging equipment will only have the ability to communicate with one type of battery at a time, hence you cannot connect 2 different types of lithium batteries to your solar charging equipment simultaneously.
4 - Summary
There is no doubt that lithium batteries are very attractive and in many ways outperform lead acid batteries.
However, we strongly recommend choosing an adequate size battery bank before choosing lithium or lead acid.
Larger lead acid battery banks that may cost simular to much smaller lithium battery banks will still out perform lithium in many ways.
Please feel free to come and discuss these options with us.
NOTE! Most of the potential problems listed above can be largely avoided by installing a battery bank that is large enough (capable of 3+ days of backup storage).
Most problems with off grid systems occur because of Solar Array and/or Battery Storage not large enough.