We get this question quite a bit. Why do we use SLA (Sealed Lead Acid) and not Lithiums or Alkalines?
There are many advantages to the SLA type batteries the biggest by far is there tolerance to many different types of charging methods. Being able to accept a charge from different charging methods is what separates sealed lead acid batteries from just about any other battery. This is also important if you want to use solar chargers to help keep your battery charged up. If you look at the nature of lithium batteries for example they require a very specific charging method and have no tolerance for any other methods. The lithium batteries are typically controlled (regulated) as to their “on” and “off” as well as their “charging”.
Seen the reports of lithium type batteries catching on fire, exploding or just melting down? This is usually due to a failure in either the charge control or the regulated control allowing the battery to get too hot, over charging or discharging or all of the above. Lithium batteries have a very tight tolerance for these functions and if they go outside of those tolerance bad things can and will happen. End results can be from benign to catastrophic. At at the end of the day you really do not gain anything over the SLA battery in power, weight or physical size not to mention that the lithium batteries are more expensive.
Alkaline batteries are really not a viable option when you consider the heat/cold and power requirements, plus the fact that they are one and done in most cases. Our IR “flash” alone would be enough to sink most alkalines in very short order.
We use the SLA battery because they operate in a reliable, simple to use power spectrum and if properly maintained should easily last 3-5 years in the field. The one downside to SLA batteries is they need to be properly maintained. The quickest way to ruin a SLA battery is to leave it in a discharged state for a long period of time. Even new batteries have to be properly maintained in order to keep from losing capacity. This is one reason why it’s important to buy the batteries from someone who sells a lot of batteries (like us!) because shelf life “maintenance” is extremely important. You can buy a brand new battery from someone who has had the battery on their shelf for over a year and not properly maintained it making it completely worthless (even though it is brand new). So be careful buying cheap SLA batteries – you get what you pay for….
And once a SLA battery has lost capacity it will never be the same.
Think of the battery like a fuel tank. It starts off brand new fully charge and can hold “10 gallons”. Then you leave it in the field discharged for a couple of weeks, it will no longer hold “10 gallons” – it will charge up and appear to function normally except now it only holds “8 gallons”. So you can see if you repeat this process several times (leaving it in the field discharged for a couple of weeks) it will eventually lose all it’s capacity – it will act like it is charging but only last a couple of days in the field. This is because it now will only hold “1/2 a gallon”. At the point where a SLA battery loses it capacity it will need to be replaced as it will never regain it’s capacity.
If you keep the batteries charged and don’t leave them in a discharged state for very long you can expect years of solid performance from a single SLA battery. This is one of the main reasons a good solar panel is worth the money simply because they can keep your battery maintained properly for years.