Need to replace battery in my POB. It is a Sunnway SW1270 12V7.0Ah.
I see these all over the internet, inc E-bay, is there a better battery than this, for longer lasting. Also would you buy a smart charger for this battery. Where have you bought, and which has the best service?
thanks in advance!
This is a Sealed Lead Acid Battery (SLA), and to be blunt, there isn't a lot of difference between brands (Powersonic, Panasonic, Yusa, Portalac etc.). If you search you may be able to find a slightly larger capacity battery in the same 'foot print', but it won't be a lot higher capacity (7.5AH or perhaps 8AH). These batteries are essentially a slight variation on the battery in your automobile.
There is probably some merit in a smart charger, but not a lot. There are three things that kill SLA's. They are pretty intolerant of full discharge. (Generally you can design a lead acid storage battery to either tolerate overcharging very well, or deep discharge very well, but not both, so unless the battery says it is designed for deep cycle use, it is a safe bet that it is designed to tolerate overcharging rather than deep discharge). Since most SLA's are used in battery backup or emergency lighting applications, they tend to be designed to tolerate overcharging.
SLA's are also sometimes referred to as starved electrolyte batteries. They don't have any excess electrolyte, so prolonged overcharging will also eventually kill them by converting electrolyte into gas, which is vented. However it takes a lot of excess charging to convert 1 mole (18 grams) of water into Hydrogen and Oxygen, so the gains in life expectancy from a smart charger are likely to be very modest.
The third thing that kills these batteries is simply old age. 5 years seems to be about the upper limit on useful life.
It would require a redesign of the charger, but in theory you could build a NiMh pack that would provide a lot more capacity in the same size/weight. Li's would be even more attractive, but that requires a completely different charger, and Li's don't like being discharged at high rates relative to capacity. I.E. a 2AH Li may be damaged by being discharged at more than about 10amps. In addition, SLA's are generally not subject to transportation restrictions, Li's are subject to significant transport restrictions.
