scoobydoo "I like Gadgets a litte bit too much" says:

Tested with Moonrays Solar Path Lights *EDIT 12/7/2011* They currently have an 8-pack of these batteries for a few dollars cheaper – *original review*When I purchased my I decided from the beginning to switch out batteries in half of the lamps with the other battery types because I had read the other review for this battery pack.Honestly, I found these work better through the night over a longer period of time. Sometimes I wake up very early in the morning for work, and have noticed that the lamps with these batteries have lasted longer and brighter into the morning. It has been a couple months since i got the lamps and will definitely purchase these batteries again.I decided to do a little research on Wikipedia to find the reason.These Moonrays batteries are Nicd, on the page it says “The primary trade-off with NiCd batteries is their higher cost”But the advantage it says is”the NiCd battery has a lower self-discharge rate (for example, 10% per month for a NiCd, versus 30% per month for a traditional NiMH under identical conditions”that means that over time, these batteries will hold their charge longer than others.The other type of rechargeable batteries are the NiMH batteries, and their page also says”NiMH cells historically had a somewhat higher self-discharge rate (equivalent to internal leakage) than NiCd cells. This is not a problem in the short term, but makes them unsuitable for many light-duty uses where the battery would normally be expected to last many months or years.”Wow I’m a nerd. But it makes me happy

NLee the Engineer says:

Don’t bother with this outdated product There is simply no reason why anyone should buy those NiCd (Nickel Cadmium) rechargeable cells for solar rechargeable light applications. For about the same price, you can easily find NiMH (Nickel Metal Hydride) cells which offer the following advantages:- Higher capacity: NiMH AA cells are typically 2000-2700mAh, compared of just 600mAh for those NiCd cells.- No memory effect: NiMH cells are less likely to suffer from reduced capacity when they are partially charged and discharged.- Environmentally Friendly: NiMH cells do not contain Cadmium, a highly toxic heavy metal. Expired NiCd cells must be disposed in special battery recycle bins, but most people don’t bother to do that. So those cells end up buried in landfill or, worse yet, incinerated. (*)The only advantage NiCd cell has over NiMH is lower internal resistance, which allows it to provide very high peak current in short bursts. That’s why NiCd cells are still used in cordless power tools and RC race cars. But in the case of solar rechargeable lights, the battery current is delievered slowly over 8-12 hours. So NiMH cells, with much higher capacity, are far superior as replacement batteries.(*)UPDATE:As of Sep 2008, imports of NiCd rechargeable batteries were banned for all EU countries (thanks to a 2006 Battery Directive). Prices of NiCd cells plummeted as a result. It is sad to see that the U.S. is now being used as the largest dumping ground (literally) for those outdated products.[Update#2 on Nov 29, 2010]Some people claim that NiMH cell cannot be used in Solar charger because it needs higher voltage to recharge. This is COMPLETELY FALSE based on my own measured data, shown in the Customer Images section. Note that both NiCd and NiMH cells have nearly identical voltage profiles (adjusted for time scale) during slow-charging.[Update#3 on May 17, 2012]It should be noted that the same company is now selling . So there goes the claim that “you can only use NiCd for solar lights”!