How to Charge a Deep Cycle Battery With a Car
Deep cycle batteries are generally much bigger and more powerful than starting (cranking) batteries. As their name suggests, they’re used for deep cycling rather than quick bursts of energy needed to start a vehicle’s engine.
While starting batteries are designed to give large amounts of energy in short bursts, deep cycle batteries produce smaller amounts of power over an extended period of time.
They’re ideal for running power tools or other equipment that requires extensive use but doesn’t need the quick burst of current provided by a car battery. For example, if you have a home solar system and your panels aren’t sized correctly, you could damage or shorten the life of your main panel with only one or two small loads, such as standard car audio/video equipment.
But a deep cycle battery can last years on one charge or even be recharged using a solar panel setup. In this article, I will discuss how to charge a deep cycle battery with a car. So let us get started.
Step-wise Guide on How to Charge a Deep Cycle Battery With a Car
First, connect your car battery’s positive (+) terminal to the positive (+) terminal on the deep-cycle battery.
After this, you need to connect the negative (-) terminal of your car battery with the positive (+) terminal on the deep cycle battery and take care that these terminals are opposite each other.
Now, it is time to choose which one out of your charging options should be used under different circumstances. When using a shore power charger, select four to six amps as the current rating.
Alternatively, if you wish to use an engine alternator for charging, then make sure that you choose a twenty amp current only since anything more than this might damage your batteries.
When you are ready with the above step, then you need to connect the positive (+) terminal of your shore power charger or engine alternator to the positive (+) terminal of the deep-cycle battery, and this should be followed up by connecting the negative (-) terminal on your shore power charger or engine alternator to the negative (-) terminal on your deep cycle battery too.
After these steps are over, you can now turn on your car’s engine so that it could charge up both of them. If you start charging initially, there will be no significant difference in their voltage levels; however, after a while, they would go up gradually, and soon enough, they will attain full charge level.
Since you can’t give a specific time period, you should wait until the battery voltage on both of them becomes equal. While charging, ensure that they are not overcharged since this might cause damage to your deep cycle batteries and could even result in their explosion.
When the above steps are all done, then you need to disconnect the positive (+) terminal on your shore power charger or engine alternator from the positive (+) terminal on your deep-cycle battery as well as from the negative (-) terminal over here too. Also, make sure that you should be very careful with what wire goes where in this step since any error might damage something.
Finally, this needs to be followed up by connecting the negative (-) terminal on your shore power charger or engine alternator to the negative (-) terminal of your deep-cycle battery.
Now, you need to select either “the parasitic drain mode” or “external load mode”. If you are using a switch that has an off position in it, then connect that wire with the common ground of both your battery and car (car body).
This needs to be followed up by connecting any external load, for example, either a light bulb or something similar over here. Alternatively, instead of this, you can also use a second toggle switch to turn on parasitic loads like lights, etc., while charging. However, make sure that they do not exceed twenty-five watts only since anything more than this can lead to damage to your batteries.
After you are done with the above steps then you need to turn off the car engine so that it could stop charging for a while and thus allow you to make both positive (+) terminals on your shore power charger or engine alternator as well as negative (-) terminal of your deep cycle battery free from each other.
Precautions While Charging a Deep Cycle Battery With a Car
- The battery must be cooled down before charging. Use a low current charger and check the specific gravity at least once every 12 hours. Please do not charge the battery for more than 24 hours without checking its voltage or specific gravity.
- Connecting the wrong terminals of either car or battery will cause sparks to fly out between them, which might ignite hydrogen gas in an overcharged battery. Avoid making this mistake as it could lead to a serious accident involving fire. A failed attempt to remove spark may also damage sensitive electronic parts of your car’s electrical system like ignition coils, and wiring harnesses, relays, and battery cables, etc., which could again cost you thousands of dollars to repair your vehicle properly if damaged severely.
- Never use a car battery to charge a deep cycle battery unless the car battery is in good shape and has been diagnosed by a mechanic and certified non-leaking or dry.
- Never attempt to connect your car’s negative terminal to the positive post of the deep cycle batteries (and vice versa) as it could damage electronic parts in both your vehicle’s electrical system and that of its charger/solenoid valve. Sparks will also fly out between them, which might spark hydrogen gas in an overcharged batter while doing so.
- Failure to properly secure and create a connection between all connections involved in the charging process can cause sparks not only at terminals but also within cells, and their fluid electrolyte gasses may explode violently, causing serious property damages severe injury to humans.
So, these were some guidelines that would help you know how to charge a deep cycle battery with a car if you do not have any alternative source of charging like a solar panel or an electrical outlet at hand.
However, when compared to those two, the first option given here is considered much faster and efficient since it does not require much time and energy to charge up your batteries if you have the right kind of voltmeter. Thank you and have a nice day!
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