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Tuesday 22 September 2020


The Good, Better and Best of Riders and their Relationship with Battery Chemistry

A question often asked is why OptiMate has different battery chargers for lead-acid and lithium starter batteries if the two battery types work fine in the same vehicle, i.e. in a 12V vehicle charging system.
Both 12V lead-acid and 12.8V lithium starter batteries work well within the 13V to 14.5V voltage zone required for a vehicle's ignition system to perform. That's why the stock lead-acid battery in a modern powersport vehicle can be replaced with a suitable LFP/LiFePO4 battery. In other words, for all intents and purposes, and without going into primary differences such as weight or cranking amps, for most riders a battery performs the same function - starting the engine, never mind the chemistry.  

If riders kept their batteries maintained every time they park their vehicle, not much else is needed other than an OptiMate 1 DUO, but we know that does not always happen!
As soon as that battery is dead-flat, you need a different type of charger to bring it back to life. Following deep discharge, lead-acid and lithium batteries require completely different reconditioning methods to successfully recover them from a vulnerable 'dead-flat' state - and "successfully" also means safely where LFP/LiFePO4 batteries are concerned.
The four cells in a dead-flat battery will be in a critical state of health and need to be treated gently. High current or voltage will cause damage or even kill the battery. OptiMate lithium battery chargers automatically deliver controlled low current and low voltage to bring all cells safely back up to the normal voltage zone before ramping up charging.  
A sulphated AGM 12V lead-acid battery on the other hand will not accept charge at normal voltage (up to 14.5V). It needs a higher reconditioning voltage to overcome its reluctance to accept charge, and that's within the charge algorithm of both the OptiMate 3 and OptiMate 4 battery chargers - and it's a pretty smart algorithm too.
If vehicle circuitry is sensed, it will not engage that high voltage SAVE mode. It's therefore best to recover that battery 'off vehicle'.
The basic things to remember are that higher voltage kills lithium batteries, but a sulphated lead-acid battery needs higher than normal voltage to overcome its reluctance to accept charge - their responses are the opposite of each other.
Secondly, at low voltage a lithium battery can only tolerate low current, but a discharged lead-acid battery can accept high current charge - again, the opposite of each other.
So how come a charger such as the OptiMate 1 DUO works on both battery chemistries? Well, the DUO is a safe compromise. It does not deliver high voltage recovery, simple - and at low voltage it delivers only very low current. That said, it does still have plenty of 'smarts' - for example, its 24-7 maintenance program adjusts to the connected battery.
For dealers it is important to sell the right OptiMate battery charger to their customers. Use the table seen here to navigate your way through the different customer habits that you have to allow for.
The GOOD option is for the conscientious riders who never forget, i.e. always maintain the battery of their parked vehicle, with the BETTER or BEST options for those riders who may forget and need, on occasion, to save their battery or who simply prefer a battery charger with more features.