A solar street light battery should give years of service. A great many of them in Malaysia do not, and the light is usually blamed when the battery is at fault. These are the four causes we see most often when a failed pack arrives for replacement.
1. Heat
Batteries in solar lighting are often housed in a sealed compartment on the pole, or inside the luminaire itself — in full sun, all day. Internal temperatures well above ambient are normal in that position. Every lithium chemistry ages faster hot, and the effect is not gentle.
Where the housing allows it, moving the battery to the shaded side of the pole, or into a ventilated enclosure at the base, does more for its life than any specification change.
2. Undersized for the real weather
Systems are frequently sized on the assumption of a full charge every day. Malaysia has stretches of overcast and monsoon days where the panel simply cannot deliver that. If the battery has no reserve for those days, it is repeatedly taken down to a deep state of discharge — the fastest way to shorten the life of any lithium pack.
Sizing with reserve for consecutive low-generation days costs more at installation and much less over the life of the system.
3. The wrong chemistry for the duty
Solar lighting is a daily deep-cycle application in a hot location. That is close to the worst case for NMC lithium-ion and close to the best case for LiFePO4. Packs supplied with NMC cells because they were cheaper or smaller will generally not last, however good the cells themselves are.
4. Controller and battery disagreeing
The charge controller has to match the chemistry. A controller configured for lead-acid, driving a lithium pack, will charge to the wrong voltage and may never balance the cells properly. This is common in retrofits where the battery was upgraded and the controller was not.
Replacing a failed pack
In most cases the panel, controller and luminaire are still serviceable and only the battery needs replacing. We build replacement packs to fit the original housing and connector, and we will tell you if we think the controller also needs attention — replacing the battery alone into a mismatched controller only repeats the failure.
Send a photo of the old battery, its label and the compartment it sits in. That is usually enough for us to quote.
Send us the voltage, capacity, discharge current and the space you have — or a photo of the battery you are replacing. We will come back with a specification and a price.