eli5: Why do regular batteries last for so long whereas rechargeable ones have to be recharged so frequently?
In: Technology
Rechargable batteries are more “leaky”, they leak more energy by simply existing.
An generic rechargeable battery can lose around 50% charge within a week, while a non-rechargeable can loose 50% in a years time.
This leakiness is a property of the battery technology itself
Besides technical reasons, rechargeable batteries are used where the energy demand is high, where you would have to buy single batteries often. Like laptops and phones. Recharging them often justifies the higher price.
Single use batteries often go in low energy appliances like clocks and remotes, so appear to last much longer.
Imagine you’ve tied a heavy weight to a pulley up in the air. When you first did it, you had a tractor pull the weight to the top so you get the maximum thump when it hits the ground. After you’ve used it once, you aren’t able to use the tractor again, so your buddies will help you pull it as high as possible. But, since you’re all human, you can’t quite reach the same height as the tractor did, so you all agree to give up somewhere near the top. When you let go, there’s still a thump, but it’s not as satisfying.
The tractor pulled rock is a non-rechargable battery. The weight that you and your buddies pulled is the rechargeable one – not as efficient, but you don’t need to borrow uncle Mickey’s tractor to head down to the store and buy new batteries.
The reason for rechargeable batteries not being as great is the concentration gradient – the electron slush inside the battery is designed that you can put all the electrons back into the right place, but as you get to higher charges, you end up working against the new gradient and it’s just not worth it to get it to the 99-100% charge level, so your battery might top out anywhere between 60-80%. (Pure estimate, please don’t quote me)
I’m sure there’s a university-level answer with a breakdown that mentions vanadium, but I tried for a ELI5 and then maybe a high school level in the third paragraph.
There isn’t huge different between capacities, since they are somewhere around 2500mAh for modern batteries, it’s just that some devices can’t use all of that due to lower cell voltage.
At around 1.2V standard alkalines are pretty much dead while NiMhs still have about 40% of capacity. So with around 2500mAh cells, you are only getting about 1500mAh. That means that if device was designed to shut off at around 1.2V, you might get 30 min of use for device that might last 1 hour with standard batteries.
Rechargeables also have higher self discharge, which means they shouldn’t be used in low power devices like clocks or TV remotes since they would drain itself in few months (there are low self discharge versions, but they still have higher self discharge than alkalines and they cost a bit more).We also tend to use alkalines in devices that aren’t power hungry so they last long while most power hungry devices use rechargeables.
Some hold less energy but also the chemicals in rechargables produce a lower voltage (1.2v instead of 1.5v) lots of devices will detect rechargables as less than full battery even when fully charged since the voltage is lower. On top of that the voltage might drop below operational threshold sooner since they start lower.
To add to that regargables degrade over time so eventually they hold less charge and wear out with greater frequency.
Apart from cell voltage others have mentioned, what regular battery use example that you think is long?
I can’t find any example of single use battery where it’s actually used to power complex and high-demanding object like laptops and phones.
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Most likely your “long” life is a bias because clocks and remotes really dont use as much power as a computer chip in phones
In addition to the other answers, it depends which ones you buy. Rechargeable batteries lose energy over time even if they’re doing nothing but some lose it faster than others. “Low self-discharge” batteries like Eneloop will need recharging less frequently because they manage to hold onto more of their energy.
Two reasons, first your battery isn’t being used to turn the wheels only minor things like making sparks, lights, etc. Second your engine acts as a generator for your battery so whenever your car is on its charging the battery
Edit: lol I don’t know why I thought op was talking about car batteries it’s been a long day
Rechargeable batteries are generally supplying power to much more demanding devices. This essentially translates to a larger, more steady flow of electricity. These batteries get much hotter than your portable Double AA batteries and the like. This type of battery is much more susceptible to corrosion and burning.
Over time..the rechargeable batteries lose their ability to maintain a charge. The fact that they are rechargeable and are constantly exposed to electricity means they burn out much more quickly..and their battery life begins to decline.
For the same reasons there’re Maserati, John Deere, and the whole range between. Every task has a best tool/material/technique to fit the needs.
Wow. It’s very rare for a site speel chequer to not flag ‘ there’re .’ But it did flag speel. The first one but not the second. Maybe it’s a stile chequer. Oh well. Stile passed.
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