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Given the state of battery technology, is it viable for either motorcycles or cars to replace the original spec 12V lead-acid battery with a different type of battery?

My question comes about as I bought a OEM-spec lead acid battery two weeks ago and put it in a recently purchased but sitting vehicle, only to find that it has somehow been sapping the battery and now seems unable to be recharged to it's original capacity :-(

Interestingly, lead-acids seem to be sold based on their CCA (cold cranking amps) whereas other types seem to be sold based on total amp-hours.

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  • Could you elaborate on how, during what period of time, and under what conditions the sapping that you refer to occurred.
    – vini_i
    Commented Sep 24, 2015 at 13:06

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I have never seen that CCA is the most important number when buying a new battery. The first number you are looking for is the amp-hours (plus physical size). As the amp-hours already define the volume of the battery, they also roughly determine the CCA. One you have found a couple of batteries fitting into your car, you may look for one with higher CCA, or even one with same dimensions, but a little more capacity.

Back to your question:

There are no alternatives for cars on the marked, because lead-acid batteries are some kind of unique.

  • They can be charged without the need of too much electronics and tolerate overcharging quite well. Finally, apply 14.4V to them, and they will charge until they are full.
  • They can be charged very fast.
  • They can deliver very high currents for a short time needed to crank the engine.
  • They still show a good performance at low temperatures. The CCA is the current the battery can source at -18°C (0°F) for 30s, while maintaining a voltage of 7.2-9V (for 12V batteries).
  • They are cheap!

But one also has to say that their capacity/weight or capacity/volume is low (bad)

Looking for a replacement, LiFePO4 batteries are the best option, but they may easily explode when overcharged. They must be monitored carefully during charging, because when they get too warm, they may explode, too...
This is already the problem why you can't just replace a lead-acid battery with a lithium-based one: Because you need additional electronics to charge it.

Further more, LiFePO4 batteries can deliver very high currents for a short time, but each current peak adds some wear to it.

Finally: The price. I've just found a german shop which indeed sells LiFePO4 batteries as replacement for motorcycle racing sports. They claim a 3.3Ah LiFePO4 could replace a 7Ah lead-acid battery concerning (cold?) cranking amps, but you pay 109€ for it. The lead acid battery is in the order of 40€. However, you also need the full capacity of a battery to supply electrical devices when the motor is not running. The shop sells 7.5Ah for 249€... You may now scale this up to the size of a car starter battery...

Also, they show lots of impressive data about the cranking performance, but nothing about the life time, which is not so important in racing sports.

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  • You are forgetting there are other lead-acid types which aren't OEM, such as AGM and Gel types. In most cases these are not OEM (some cars do use AGM batteries as OEM). I cannot wait until carbon fiber batteries are on the market and viable.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Sep 24, 2015 at 10:25
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    Ah does not determine CCA, Ah time the "C" rating determines CCA. A high Ah battery with a low C will have low CCA. Also LiFePO4 batteries have one of the most stable chemistries in the the lithium family. They don't explode, at most the make lots of smoke. Li-Ion, LiNiMaCo, Lithium polymer are all much more volatile.
    – vini_i
    Commented Sep 24, 2015 at 13:21
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Well, lead-acid batteries can be replaced and in some cases, have been replaced. Toyota Prius has a high-voltage nickel metal hydride battery to start the engine and to provide additional electric power. The superior fuel economy (and the simplest and most reliable kind of automatic transmission) of Toyota Prius may mean that all gasoline powered cars of the future will have similar hybrid technology.

However, Toyota Prius has not eliminated lead-acid batteries entirely. The high-voltage nickel metal hydride battery, if continuously connected, would be a safety hazard. Thus, the systems of the car boot up on a low-voltage battery and the high-voltage battery is connected only after safety checks have been performed.

The low-voltage battery in Toyota Prius is actually a lead-acid battery. However, in this application I believe there is no obstacle to replacing this battery with e.g. a nickel metal hydride or lithium ion battery, as cold cranking amps are no longer a consideration. I suspect the main reason for having a lead-acid battery is its low cost and the fact that regular light bulbs have been designed for the charging voltage of 12V lead acid systems. Even very slight changes in the voltage can mean huge changes in bulb lifetime or brightness. However, LED lights of the future might mean the voltage compatibility is no longer an important thing, meaning that we are one step closer to replacing the lead-acid battery with something else.

The fact that power tools use special kinds of lithium ion batteries today also shows that alternative battery technologies can provide the required power.

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