Solar garden lights use rechargeable batteries to store energy from the solar panel during the day and use it to power the light at night. They usually use rechargeable AAA, AA battery size with NiCd or NiMH batteries cell type rated 1.2V instead of the regular, normal alkaline batteries.
The storage capacity of the solar garden light batteries usually ranges from 300mAh for the smaller ones to 1800 mAh in the larger lights. Unlike NiMH batteries, NiCd batteries have a weakness – the memory effect.
If they are not discharged fully before the next charge, they lose their ability to store energy. Fortunately, this is not an issue in well designed solar garden lights since their battery energy is depleted during the night before the next day’s charge.
How long solar light batteries take to charge?
Solar light batteries are usually designed to charge within 5-6 hours on a clear bright day. On overcast days however, they may not charge fully and may fail to light as long as usual.
How long solar light batteries last?
Solar light batteries go bad and lose their ability to store energy over time of use. For example, instead of the usual 7 hours of light after several hours of sunshine, they work for much less before dimming or going off completely.
They also lose their stored energy over time through self-discharge when left standing depending on the quality of battery.
That said, good quality battery can last from 3-5 years estimated from 1,000 – 1,800 times of charging they are usually rated for. After this the signs of wear start showing with reduced ability to hold charge.
To get your solar light batteries to last,
- Make sure you charge them fully before first use to maximize their usable life. This is important because even though some solar light batteries come precharged, they are only 30% precharged!
- Always discharge NiCd batteries fully before next use or else their usable life is affected. Beware of the memory effect!
- Avoid using the fast charge option for lower capacity batteries or a charge setting that pumps a charge current higher than the recommended charge current for the battery with an external charger. This can reduce the battery life.
When you need to replace your solar light batteries
Solar light batteries are usually replaceable – and can be easily removed from the solar light’s battery holder (check the manufacturer instructions for how to do so).
Always use rechargeable batteries of the same size, voltage and capacity (preferably) as the original ones. If the original batteries are NiCd for example, replace them with NiCd batteries of the same type for your solar lights to work well.
While solar lights can light with regular, normal, alkaline, non rechargeable batteries of the same size as original, these batteries are not meant to and cannot be recharged by the mini solar panel, therefore do not use them.
Most solar light batteries available today are of the size, voltage and battery types below:
- Size: AA or AAA
- Voltage: 1.2V or 3.2V
- Battery type or chemistry: NiCD or NiMH.
- Battery capacity: 600, 800, 1100 or 1500 mAh.
You do not need special rechargeable batteries as replacement provided the they match the size, voltage and type of the original.
You may choose to replace solar batteries with the higher capacity battery types for example, if the original ones were 600 mAh, you can use 1100 mAh types.
While the large capacity batteries take longer to charge, they will light for longer. However, this is not recommended for NiCd battery type).