Battery Equivalents and Replacements

How To Keep Generator Battery Charged

Power generators with remote and electric start feature built-in lead-acid or lithium starting batteries, which are required for cranking the internal combustion engine and for powering remote start electronics while the unit is in standby mode.

For a generator to be as reliable as possible, it is very important that its battery is fully charged and ready to be used at the moment's notice. However, some people wonder how to charge the generator's battery.

Published: December 22, 2022.

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Generator Battery Charger

First of all, power generators come with detailed Owner's Guide/Manuals and explanations on how to maintain the power generator and how to store it over a longer period of time - if You have a power generator, but You never read the Owner's Guide, do yourself a favor and read it.

Onboard Battery and Onboard Battery Charger

Every power generator featuring electric and remote start also features an onboard cranking battery - these batteries are mostly lead-acid batteries, but some newer power generators feature lithium starting batteries.

As soon as the engine has started, the onboard battery charger (part of the generator's electric/electronic system) starts to recharge the battery and keep it fully charged.

So, if You use your power generator regularly, on a daily or at least weekly basis, your battery will practically always be fully recharged.

Power Generator Battery Types

Most power generators feature 12V batteries with a nominal capacity in the 5-20Ah range.

As said before, most power generators feature lead-acid onboard batteries, which are relatively heavy, but they tolerate vibrations very well, can be easily charged, and are rather cheap.

Lead-acid batteries can be flooded/wet, AGM (Absorbent Glass Mat), and Gel-Cell batteries.

When used regularly, lead-acid batteries can last for a long time. But, when the unit is not used for a longer period of time, the battery must be recharged at least every 1-3 months, depending on the temperature and the exact battery model.

When being recharged using external battery chargers, lead-acid batteries should be charged using 0.1C-0.15C charging currents.

Lithium batteries are mostly Lithium Iron Phosphate (LiFePO4) starting batteries, which are not cheap when compared with similar lead-acid batteries, but they tolerate vibrations and mechanical impacts rather well, they are rather lightweight and must be charged using dedicated lithium battery chargers.

Lithium starting batteries feature a relatively low self-discharge rate and should be recharged every 2-6 months, depending on the model, using dedicated lithium battery chargers or charging modes.

When being recharged using external battery chargers, lithium batteries can be recharged using 0.1C-1.0C charging current, with 0.333-0.5C charging currents being often recommended.

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Battery Chargers and Maintainers

When the power generators are stored for a longer period of time, their batteries are disconnected in order to prevent any parasite load from discharging the batteries.

However, all batteries feature a certain self-discharge rate; lead-acid batteries usually have a faster self-discharge rate than lithium batteries.

Thus, when being stored, generator batteries should be recharged fully and then should be connected to the automatic battery maintainers, which will keep the batteries fully charged during the storage.

The good thing is that modern, microprocessor-controlled automatic battery chargers are often designed as battery maintainers, allowing the users to store the power generator, disconnect the battery from the power generator, and connect it to the automatic battery charger/maintainer, which will first recharge the battery completely and then keep the battery fully recharged during storage.

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Note: some power generators even have an additional automatic battery charger/maintainer. If not, 0.75 - 2.0 Amps battery chargers/maintainers are fairly cheap and can be easily found in local hardware stores or can be ordered from online shops.

Long Story Short: In order to keep the generator battery fully charged, crank the power generator regularly and let it recharge the battery. If the power generator is stored, using a dedicated battery charger/maintainer will keep the battery fully charged and ready for the next use.

Again, power generators come with Owner's Guides/Manuals describing maintenance procedures, including how to keep the batteries fully charged even when the generators are not going to be used for a longer time.