If you have ever met someone who is very particular, or who likes things a certain way, let's call them "fussy", then you have met a battery. The very heart of every off grid system is the batteries. They are the one thing that dictates how much power you will have, how long the system will run and how often you will need to start a generator. So it's important that we take a moment to really understand how fussy they are. Just like fussy people who like things a certain way, if we meet their requirements, they will reward us with a long life and ample power for their size. However, if we get it wrong, they are not happy and will have poor life and performance. So in this month's column...let's explore the fussy qualities of batteries.
Firstly, they are a stickler for voltages. I don't know how many times I have arrived at peoples' off grid systems to find that all the chargers (solar regulators and battery chargers) are at the wrong settings. And it's amazing the difference even a few volts difference can make to a system. A fine example is modern lithium batteries that need to achieve a specific voltage before they do what is called a cell balance (not all lithium does a cell balance), where all the cells are slowly "topped up" so they reset to their maximum capacity. Then somewhere on the internet, someone says you should charge the cells one volt lower than recommended to get longer life (you gotta love the internet...right). So now the cells NEVER balance, the batteries don't hold as much charge and they fail early. Seriously, that one volt short of the target voltage can significantly affect the performance and life of the batteries. Fussy hey ?
Secondly, they don't like heat. Now I don't care if you have lead, lithium or the new sodium batteries. None of them like it when things start getting hot. I have met a few battery nerds in my time that even build a dedicated battery hut with an air conditioner to keep them as close to 25 degrees Celsius during the day. It pays to seriously consider where you locate your batteries and how hot they get to ensure you get maximum life.
Thirdly, batteries are very particular about their cables. Unfortunately, most people don't understand this and just scratch around for any old bit of cable they can find. Honestly, the things I have seen! Now people will scoff at this because let's face it, if you get it wrong...the system will still work. But batteries need all their cables the same length and the correct size. Batteries with long cables on one side and short on the other, will always fail early. So always make sure your linking cables AND the cables to and from the batteries are always the same length. Even if you have to loop one, make sure they are equal length.
Finally, they are most fussy about the voltage that you discharge them down to. Lead batteries are particularly fussy about this as they can be seriously damaged by over discharging. Lithium on the other hand can be discharged further than lead and has a BMS (battery management system) to prevent over-discharge, but even they have their limits and the further you discharge lithium the shorter the cycle life.
If you have an off grid system and you're not sure about what the right voltages are for your system, feel free to give me a call or drop by Childers Batteries and we can have a no-fuss Chit Chat about your system.
