Battery Charger Categories
Have Questions?
Frequently Asked Questions
Speed and application. All three use ISM (Infinite Sequential Monitoring) for automatic 4-stage charging and indefinite float maintenance. The Battery Tender® Plus (1.25 Amp) is ideal for ongoing maintenance of any stored vehicle. The PowerTender® (3 to 15 Amp) charges and maintains faster and adds Multi-Chemistry support for Lithium (LiFePO4) batteries. The WaveCharge is a permanent onboard marine charger that charges and maintains multiple battery banks simultaneously.
Yes — with any PowerTender® Multi-Chemistry model. Select Lithium on the chemistry selector and ISM delivers the correct LiFePO4 charging profile, which requires a higher absorption voltage and different maintenance protocol than lead-acid. Battery Tender® has been engineering dedicated Lithium charging profiles for over 20 years. The Battery Tender® Plus charges lead-acid only — do not use a lead-acid-only charger on a Lithium battery.
ISM stands for Infinite Sequential Monitoring — Battery Tender's proprietary 4-stage charging algorithm. Unlike a basic trickle charger that delivers constant current regardless of battery state, ISM runs: Initialization (health check before current flows), Bulk Charge (full output restores capacity), Absorption (current tapers as battery approaches full charge to prevent overcharge damage), and Float Maintenance (micro-current holds peak voltage indefinitely). ISM is why Battery Tender® chargers and maintainers can be left connected for months without overcharging.
Match charger output to your battery size. For motorcycles and powersports batteries (3 to 30Ah): Battery Tender® Junior 750mA or 1 Amp. For most passenger cars (14 to 80Ah): Battery Tender® Plus 1.25 Amp. For faster recovery or larger batteries up to 250Ah: PowerTender® 3 to 15 Amp. For golf carts and 24V, 36V, or 48V systems: PowerPlus line. For marine multi-bank systems: WaveCharge Standard or Pro.
Sulfation — the permanent hardening of lead sulfate crystals on battery plates — forms when a battery sits discharged. Once significant sulfation develops, no charger can restore the lost capacity. Battery Tender® chargers and maintainers prevent it by maintaining continuous float voltage above the sulfation threshold from the moment they are connected. Battery life consistently extends from 2 to 3 years to 5 years or more with proper maintenance charging.


































































































