Battery Equivalents and Replacements

How Long Does It Take To Charge The Motorcycle Battery

Motorcycle batteries are generally kept charged by the motorcycle onboard charging system, but from time to time, they get discharged due to the how weather which increases self-discharge rate, parasite loads like alarms, and similar systems, long periods of inactivity (winter, for example) and similar.

Properly recharging semi or even fully discharged motorcycle battery can prolong the battery's operating lifetime and avoid future issues due to the battery's inability to crank the engine when required.

Published: August 10, 2021.

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Motorcycle Battery Types

Most popular motorcycle batteries are starting/cranking lead-acid wet/flooded and AGM batteries, with the Gel-Cell batteries also being used as well.

Lithium motorcycle drop-in replacement batteries are not as common and are mostly used in high-end and professional applications.

Lead-acid motorcycle batteries are mostly 12V batteries with capacity ranging from 5-6 to 20+ Ah.

Although these batteries are much smaller than larger deep-cycle batteries, since they are designed and optimized for one purpose, to crank gas and diesel engines, these batteries are able to provide very strong currents.

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How long does it take to charge such battery depends on the battery age, Depth of Discharge (DoD%), battery capacity, and similar.

On average, starting batteries may be safely charged with currents that are in the 0.1C - 0.15C range, although some models allow charging with charging currents up to 0.25C - 0.33C.

For example, 20-25 Ah batteries may be safely charged with 2-3A battery chargers.

When charging lead-acid batteries, it is highly recommended to go for a smart AGM battery charger that features battery modes for wet/flooded, AGM, and Gel-Cell batteries, since all these battery types have very similar, but different charging end voltages.

Also, temperature compensation is a must-have feature in order to prevent the charger from under- and over-charging the batteries.

Smart battery chargers analyze the lead-acid batteries first and charge the battery according to its condition - if required, desulphation and deep-discharge recovery modes are used as well.

And when the battery is fully recharged, smart AGM battery chargers switch to the maintenance mode, keeping the battery fully charged over a longer period of time.

The following comparison chart lists charging times of the fully discharged (100% DoD - not recommended condition, but it may happen) motorcycle batteries using different AGM battery chargers:

Battery Capacity Battery Charger
0.5A 0.75A 1A 2A 3A 4A 5A
6Ah 12-13h 8-10h 6-7h - - - -
8Ah - 11-12h 8-9h (4-4.5h) - - -
10Ah - - 10-11h (5-5.5h) - - -
12Ah - - 12-13h 6-7h (4-4.5h) - -
15Ah - - -  8-9h (5-5.5h) - -
18Ah - - - 9-10h 6-7h (4.5-5h) -
20Ah - - - 10-11h 6.5-7.5h (5-5.5h) -
25Ah - - - 12-13h 8.5-9-5h 6.5-7h (5-5.5h)
30Ah - - - - 10-11h 7.5-8.5h 6-7h

Note: these are just average values that depend on things like battery condition, battery DoD%, battery age, temperature, etc. Also, values with "-" means that the battery is not recommended at all, while values like "(5-5.5h)" means that the battery may be recharged, but perhaps the battery charger is a little bit too strong. Anyway, if You can find and check the battery documentation and find the maximum allowed charging current then You can more accurately determine the maximum charging current of the battery charger.

As one can see in the chart, if You are looking for a good motorcycle lead-acid battery charger, a 2.0 Amps smart AGM battery charger is probably your best bet.

Lithium motorcycle batteries should be recharged only using lithium battery chargers or smart AGM battery chargers that feature dedicated lithium battery charging modes.

Depending on the battery design, lithium starting motorcycle batteries may be recharged with currents that are in the 0.2C - 1.0C range.

Again, this depends on the battery model, so please, check the documentation of your battery for the proper charging current.

Note: Lithium batteries are charged using the so-called CC/CV (Constant Current/Constant Voltage) algorithm which differs from the lead-acid battery charging algorithm.

The following comparison chart lists charging times of the fully discharged lithium motorcycle batteries using different lithium battery chargers:

Battery Capacity Battery Charger
1A 2A 3A 5A 10A 15A
6Ah 6-7h 3-3.5h 2-2.5h - - -
8Ah  8-9h  4-4.5h 2.5-3h (1.5-2h) - -
10Ah  10-11h  5-5.5h 3.5-4h  2-2.5h  -  -
12Ah -  6-6.5h  4-4.5h  2.4-3h  -  -
15Ah -  7.5-8h  5-5.5h  3-3.5h  -  -
18Ah -  9-9.5h  6-6.5h  3.5-4h  (1.5-2h)  -
20Ah -  10-11h  6.5-7h  4-4.5h  2-2.5h  -
25Ah - -  8.5-9h  5-5.5h  2.5-3h  (1.5-2h)
30Ah - -  10-11h  6-6.5h  3-3.5h  2-2.5h

Note: again, these are just average charging times that depend on many things. Also, values with "-" or "(1.5-2h)" mean that the battery may be recharged with such current, but perhaps the battery charger is a little bit too strong.

Anyway, it is highly recommended when charging the lithium batteries to find the battery documentation and check the maximum allowed charging current - lithium batteries are usually protected via an internal Battery Management System (BMS) that doesn't allow too strong charging current.

As one can see in the chart if You are looking for a good motorcycle dedicated lithium battery charger, a 3.0 Amps smart lithium battery charger is probably your best bet, but first, check your battery and its maximum charging current value!

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Long Story Short: If You ride your motorcycle regularly and everything is alright with its electric system, it is very hard for the battery to get so discharged that it is unable to crank the engine.

In that case, check the battery type, capacity and get a suitable charger and recharge the battery - in most cases, the battery is still good to go for many miles.

But, if the smart battery charger signals "bad battery", perhaps it is time to go for a good Powersports Battery and to replace your current battery.

Note: although these batteries are small, they are able to provide rather strong currents - so, safety first!