No
Rechargeable batteries are worth the cost. Let's do the math. A pack of 12 Duracell AA batteries cost around $10-$12. Meanwhile a 4 pack of Duracell AA rechargeable's and a charger is around $15 dollars. A rechargeable battery can usually be recharged 30-50 times. This means for three dollars more you basically get 120-200 batteries. Basic math shows that 120 batteries for $15 (rechargeable) than to pay $120 (non-rechargeable).
You can buy AAA rechargeable batteries and their appropriate chargers online at places like Wal-Mart and Amazon. You can also buy them from All Batteries. The batteries average $12 to $13.
No, a pack of AA rechargeable batteries are not expensive. A pack of four generally runs between 7 and 12 dollars and are manufactured by Energizer or Duracell.
No!
You cannot use a 12 volt charger to charge 2.6 volt batteries. The 2.6 volt batteries will become hot, very quickly, and explode.
Depends on the battery size. If your boat is a 12 volt system and you wire two 12 volt batteries in series you then have 24 volts. If the batteries are 6 volt batteries you will be fine. If you have a 12 volt system on your boat and want to use two batteries then wire two 12 volt batteries in parallel. You will still have 12 volts but will have double the amperage available and this will extend the running time of the batteries.
use two 12 volt batteries in series.
The two types of rechargeable batteries are similar in performance and many characteristics are the same. Importantly, they both deliver a voltage of 1.2V so the devices they drive will respond in the same way. The two technologies differ in the way that they should be charged. This is only a concern for fast chargers. Nimh batteries can be fully charged in about one hour but it is is important that the charger monitors the battery and shuts off the charge at the right time to avoid damage to the battery. NiCd batteries have a different charging characteristic so charging either battery in a fast charger designed for the other type is likely to lead to damage or reduced performance. Solar lights use solar panels to charge batteries over a 12 hour period or more. The charging current is low enough to avoid the risks of damage to a Nimh battery so it is very likely that they can be used. There should be no risk of damage but the only way to see if the batteries work in a light fitting is to try it and see if it works. If it doesn't, it's time to switch back to NiCd batteries.
You could but this is not a very practicable way to run an air pump. There will have to be a large amount of batteries in series and parallel connections to add up to the amp hour capacity to run the air pump. Just use an old 12 volt car battery for your project.
Use a series parallel configuration. Two batteries in series to get the 12 volts. Three parallel banks of two batteries to get an increase of amp hours.
No, 12 volt batteries are 12 volts.
The best place to purchase bulk 12 volt batteries would probably be auction websites. You can go to Ebay website or Amazon website and find them in bulk size.