This is a very difficult question but a summary of the class of products available might help seek an answer. It is also hard to make a bad decision with a battery charger these days as all RTM battery chargers are “intelligent” types and cannot damage expensive batteries. Beware of chargers picked up at garage sales or chargers that seem quite cheap. They are probably old technology which does not shut off once charging in complete. This can seriously damage a battery.

General Purpose Types

General purpose workshop chargers. These are the ones that sit in your garage. They typically have jumper leads with alligator clips. They will generally give a discharged (but not crook) battery a top-up in 20 minutes to an hour. You should be able to start your vehicle on this. You may even be able to leave the charger connected to the battery when you crank the engine to help start the car. Every man cave should have one of these. 

Battery Maintenance Chargers

These are special low capacity chargers that you would use to keep the battery in that special car that spends months in the garage between outings, the ski boat in the garage in winter, etc. All lead acid batteries slowly go flat due to self

discharge. When the battery terminal voltage goes to about 11V, a process called sulphation starts to occur on the plates in the battery. This will slowly kill the battery. Stone dead. You may think that you can shock the battery into life but it will let you down. Best bet is to put a little “Battery Minder” charger across the neglected battery and keep it in tip-top condition. A battery minder is cheaper than the cost of a replacement battery, and better.

Multi-Purpose Jump Starter, Battery Charger/Inverter/Workshop Light

Very popular but not a heavyweight product. A handy thing to have on the road. The gell-cell inside has limited capacity and may start a petrol engine that has simply run out of fuel. They are very neat and compact but will not start a diesel over 2.5L on a cold morning.

Battery Chargers That Can Be Wired In

These are charger/battery controllers that manage the battery banks (house batteries) in boats, caravans & RV’s. They are very clever and can run banks from 12V to about 30V (for 24V systems). RTM specialises in these and all quality battery chargers.
See our staff for further advice.