Motorcycle Battery Replacement – Lead Acid or Dry Cell which is Better?

If you have owned a motorcycle for any length of time you know that battery replacement and motorcycle ownership go hand in hand. Fortunately for today’s prospective battery buyer, there’s a wider choice of improved designs and engineering available. While the rugged traditional wet cell is still common, it has largely been replaced by the permanently sealed lead acid (SLA) design. The AGM (absorbed glass mat), improves battery design changing using a gelled electrolyte gell held in a lattice structure.

So, is there a clear winner – which battery is the best choice for Touring Motorcycles?

  • The best value, with the most useful features, is a sealed lead-acid wet cell battery (SLA),
  • A close alternative choice is an AGM dry cell battery, which may be better depending on your specific requirements. 

As it turns out I am once again looking for a new battery, so I thought it would be good to post the results of my research and add in some of my experience as a reformed “battery killer”. The battery in question, that needs replacement has failed while offline on a smart charger. It is just too old and all it does now is put off a lot of heat and doesn’t take a charge (also noticed that 2 cells are bulging).

If you are curious, my old battery is an AGM type, it came with a used bike I picked up. So, I have no idea of its time in service…but the manufacture date stamp says Feb-2005, making it at least 13 years old!  It has lasted 3 years for me, overall pretty impressive it would seem.

In this post, I will cover the basics of dry versus wet. Then I round it off with some buying tips, more great info on recognizing symptoms of failing battery and how to test your battery to make sure you actually need a replacement. Then a few related battery questions that might come up.

Hope this helps you out!

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Dry versus Wet

Dry cells are considered “high performance” designs since they have a greater power to weight ratios (lighter). And they can be mounted/relocated in non-standard positions and orientations, with no liquid electrolyte inside to be concerned with. They generally operate in a wider temperature range. These features are more valuable to the adventure (on-off road) touring rider where weight, orientation, and potential spillage matter a lot more.

Wet cells are less expensive, but do not have the “performance” features listed above. If you just need a drop-in replacement they will do very well. For most touring applications weight is not a huge factor either, neither is orientation or accidental spillage. You can get these in a sealed “maintenance free” version too. So, a standard lead-acid wet cell battery with a sealed design is a good choice for most motorcycle touring applications.

Battery Designs

Lead acid batteries, as the name indicates are made with a series of lead plates in an acid bath (electrolyte). They are naturally called wet cells because of the electrolyte sloshing around inside. If your battery has caps that allow access to each cell then this is a wet, lead-acid design.

The sealed lead-acid (SLA) design is a leap forward – they virtually eliminate pesky maintenance and the risk of accidental acid spills. Note, this same design can also broadly be categorized as a valve-regulated lead-acid (VRLA).

The alternative, dry cell batteries still use the same principles to store electrical energy, but the liquid acid is replaced by a non-liquid substance, like a gel or paste.

There are three basic types of dry cell designs,

  • Gel
  • Absorbed glass mat (AGM)
  • Lithium-ion (and other exotic combinations)

Dry versus Wet – Pros & Cons

Wet Cell – Pros

  • Less expensive
  • More choices and availability
  • Less vulnerable to over and under charging
  • Can use a “standard” motorcycle battery charger
  • Last longer than most dry cells, having more charging cycles
  • Better if you have accessories, or parasitic draw (alarms, GPS)
  • Can be stored indefinitely if no acid has ever been added

Wet Cell – Cons

  • Contain acid, spills & leakage possible (not SLA)
  • Much heavier than a dry cell (30% to 300% more)
  • More vulnerable to very low temperatures damage
  • More maintenance – electrolyte levels, cleaning (not SLA)

Dry Cell – Pros

  • Lighter than wet cell = higher power to weight ratio
    • AGM – 35 to 40% lighter
    • Lithium-ion – 60 to 70% lighter
  • Preferred in high-performance applications
  • Can be mounted in any orientation (usually not inverted)
  • Less maintenance required (still need inspection & cleaning)
  • Do not require initial charging (minor benefit)
  • Discharge at a slower when not used regularly
  • Operate in a wider temperature range (not lithium-ion)
  • Lithium-ion can sit indefinitely in a semi-discharged state, also have a relatively low self-discharge rate

Dry Cell – Cons

  • More expensive
    • Gel – more costly than AGM
    • AGM – somewhat more expensive
    • Lithium-ion, multiples higher cost
  • Less choice for a direct replacement, especially older motorcycles
  • Lithium-ion can be permanently damaged with incorrect charging
  • Lithium-ion can be permanently damaged if allowed to go below an 11V charge (accessories with your bike not running, or parasitic draws)
  • Lithium-ion requires a specialized charger (dual mode chargers available) – this is an extra cost on top of the expensive battery

My 2 Cents

I prefer riding down the road versus getting my “Ph.D. in Batter Sciences”. So, I did not see the need to go deep into all the specific differences and technical aspects of battery design to end up with the best choice. I recommend basing your choice on what performance you want for the price range you are OK with. After all, a battery is a battery in my opinion – as long as you take proper care they will provide acceptable service.

Along the same lines, I tend to go for the medium-to-higher price (quality) range. The super economy choices usually are disappointing. If, however you are getting an older motorcycle ready for sale an econo-battery may due. I would still put in something decent, just to be fair and it for a few bucks it may make the sale easier.

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Battery Buying Tips

  • As with everything bought online – find out what is required to return or make a warranty claim. If you are responsible for the postage back to the seller, this might easily wipe out any savings.
  • Buy a brand name, or OEM branded.  You almost allows get what you pay for – a 50$ “Krackamotto” battery may seem like a good deal until it dies 6 months down the road.
  • Do not buy a lead-acid battery with caps that access each cell. This design is now completely obsolete.  By design, the electrolyte level will decrease, causing you the extra work to check and maintain levels. Plus there will be the continuing concerns with possible spills and seepage.
  • Do not be influenced by design features that are not needed, or have minimal benefits for motorcycling. A deep discharge battery it not relevant, neither is the ability to operate in sub-zero temperatures (for most of us!).  A super light lithium-ion battery that can be mounted sideways doesn’t add too much for most of us either.
  • Be aware that Lithium-ion and AGM batteries require a dual mode charger (it will have an AGM charge mode). Using the wrong charger can permanently damage the battery.

 Battery Care Tips

Manufacturer’s studies show a motorcycle battery lasts between 4 to 7 years. However, poor maintenance can very quickly shorten its lifespan significantly. 

  • Never let a discharged battery sit discharged. This can be happening and you are not aware of it. If you take short rides, and the charging system is weak or under designed the battery may not be getting its full charge. Note: lithium-ion batteries do not have this problem.
  • Get a “battery tender”, aka smart trickle charger. These chargers use computer-controlled, that monitor the battery and only send current when needed to top up the charge. Many come with an extension that is permanently installed and allows you to plug in the charger conveniently without direct access to the battery. Very handy for the occasional or medium length inactivity (2 plus weeks).
  • When you top up the electrolyte immediately charge or ride.
  • Clean the top with baking soda and water, rinse completely. This will neutralize any electrolyte spilled or seeping. Excessive electrolyte on the top side can cause the battery to short out and drain its power.
  • Never use an automotive type, high amperage charger.
  • Do not store (park) a battery in a cold to a freezing environment.
  • Inspect and clean regularly – wash with baking soda and water to neutralize any seeped out electrolyte. Keep positive and negative terminals tightened and corrosion free. Inspect for any signs of bulging or cracking (this will mean replacement required but at least you will not be surprised out on the road).
  • Handling tip – to make battery removal and installation easier I use a length of sturdy synthetic ribbon or strap wrapped around the battery and tied off. This forms a sling that lets me pull the battery straight up or lower it very easily.

Symptoms of Pending Battery Failure

As your battery ages, its performance decreases slowly over time. You can spot potential failures by watching for these symptoms.
  • The starter motor cranks slower than usual, even after a full charge or long road trip.
  • The outer case has noticeable bulging or discoloration.
  • Loose positive or negative terminals with respect to the battery itself, this is a physical damage issue, very likely a sign of internal damage.
  • Excessive heat produced when charging.
  • Does not hold a charge as expected.
  • Poor idle, or hesitation on acceleration (note there many other causes).
  • Accessories operate slowly or lights are dim.

How to Test a Battery

  • Use a digital voltmeter for these tests.
  • Disconnect the positive (red) terminal – test, a fully charged, healthy battery reads 12.6V to 14V.
  • Voltage below 12.0V you may have a failed battery, and it’s more likely if it was left sitting like this.
  • With the battery connected and the ignition disabled (pull the ignition fuse, use kill switch or take plug wires off), crank the starter for 15 seconds – take note of the voltage – a healthy battery should not drop below 9.6V.
  • Do not overlook the charging system – it could be the root cause of poor charging issues.

Related Questions

What is the advantage of an AGM versus sealed lead-acid?

AGM batteries are typically somewhat more expensive by 20 – 30%, but provide more cold cranking amps (CCA). They also weigh less, by about 35 – 40%. All things being equal (price, brand/quality), an AGM is a good choice.

When is a Lithium-ion battery worth the extra cost?

In the world of motorcycle touring reliability is probably the biggest benefit of this design. A lithium-ion battery is very rugged, has many more charging cycles and comes with a longer warranty period than a standard lead-acid.

For off-road oriented adventure touring the reduced weight, especially relatively high up on the motorcycle can be a secondary benefit.

Can I jumpstart (boost) from a car battery?

Yes, but take extra steps to avoid damage to the battery and motorcycle electronics. Turn off both vehicles (remove car’s keys – do not run the car during setup or the boost). Connect positive (red) jumper cable first – double check there is no contact to ground (any metal on the motorcycle).  Connect the negative cable. Continue to start the motorcycle, as usual, let the motor get warmed up before disconnecting. Do not trust the battery until you have figured out why it wasn’t able to start your bike.

Summing Up…

For most road-going touring motorcyclists a traditional lead-acid, in a sealed case (SLA) offers the best bang for the buck. If you find a similar AGM design for a good price you get a little less weight and more cranking power.

With proper care, you can greatly increase your battery’s lifespan beyond the average, and save yourself some money, as well as avoid a lot of inconveniences just when you would rather be riding. A large online battery reseller states that only 30% of vehicle batteries make it to the 4-year mark! You can probably guess what killed the other 70%.