How to Trickle Charge the Toyota Prius 12V Battery.

Electric or hybrid cars like the Toyota Prius need to have their battery charged if you plan to use them. And like most batteries, if you leave them long enough they’ll lose their charge.

So if you are going on a long trip where your Prius won’t be driven for some time, you may be interested in trickle charging.

What is Trickle Charging?

The idea behind trickle charging is simple: if you charge a full battery at the exact same rate the battery loses power, it will maintain its charge.

If you replace the 1% power loss as soon as it happens, the battery never dies.

This is important because you don’t want to overcharge a battery, which can harm its overall integrity and longevity.

But you don’t want the battery to be losing charge while you’re gone either, resulting in a dead or depleted battery when you get back to your car.

This is the value of trickle charging: keeping your battery fully charged when you’ll be unable to carry out a regular charge cycle for an extended period of time. 

When is Trickle Charging Appropriate?

Trickle charging is very useful under the right circumstances, but there are times when it isn’t the right answer to a problem. So, when is trickle charging appropriate? More importantly, when is it not appropriate?

Charging a Dead Battery: No

If the name “trickle charging” didn’t give it away, the trickle charging process is not designed to charge flat dead batteries.

In fact, it’s not designed to really charge batteries in the conventional sense at all.

Rather, the process is intended to maintain a charge, not build one.

Technically speaking, trickle charging could eventually charge a dead battery with the proper settings, but it would take an immensely long time to get the job done.

So if your battery is dead, trickle charging isn’t the answer.

Charging a Battery At All: No

So, even if your battery isn’t dead, and it’s actually just in need of regular charging, trickle charging isn’t the answer to this either.

Much like trying to charge a dead battery, while you could technically do it, it would take a very long time.

This means trickle charging is pretty much useless for regular charging like you would be doing between daily drives.

There’s really only one situation where trickle charging is useful that’s to maintain a constant level of charge.

Maintaining Charge Between Significant Breaks in Driving

The one time trickle charging is useful is when you need your car battery to maintain a charge over a long period of time, where you aren’t driving it.

Because trickle charging recharges the battery very slowly, to match the rate of battery drain, that’s the only time you would consider using it.

So if you plan on leaving your car undriven for a few days or even several weeks, trickle charging is the way to go.

But how exactly do you do it?

How to Trickle Charge Your 12V Battery

The good news is that it’s not really a complicated process to trickle charge your Toyota Prius. There are special chargers designed to trickle charge your battery specifically.

All you have to do is connect them to your battery, much in the same way you would when jumping a car.

Some chargers are special, in that they charge your battery normally to full charge, then switch to an automatic trickle charging mode to avoid overcharging the battery.

These types of chargers tend to be decently expensive, but they are very easy to use.

Of course, this doesn’t mean you can just plug in any trickle charger to your Prius and expect everything to be fine. There are many factors to take into consideration. First of all, there are manual and automatic trickle chargers.

Manual Trickle Chargers

These chargers continuously charge your battery until they are disconnected. That’s fine if you do a bunch of math to determine how much power your battery is losing an hour and how much needs to go back into every hour.

But if you don’t do that, a manual trickle charger could overcharge your battery and damage or destroy it. It’s not a good option if you are going to be leaving your car unattended for a very long time.

Automatic Trickle Chargers

These chargers consistently monitor your car’s battery level and only charge it when it actually needs it. This means there is no risk of overcharging, and you can leave the charger connected to your battery effectively indefinitely.

This of course means it is the right choice if you are going to leave your car unattended for some time and want to maintain a charge. However, because auto trickle chargers monitor battery levels, they can’t be used to charge a dead battery.

It’s a connect and forget type deal, and the easiest to use: simply connect the charger to your battery via the power cables, and turn it on. There’s no risk of overcharge.

Final Considerations

Always read your owner’s manual for specifications about charging your car. Improper charging practices can lead to major damage and serious risks. Follow all instructions in the manual and for your purchased chargers.