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Choosing the right battery charger for any application

Voltage, and Wattage, and Amperage (Oh My!)

I want to go on record and say that electricity may just be the most difficult thing to "DIY" (at least you can see lions, tigers, and bears coming). Portable electricity is no exception, and there is the added caveat that your batteries discharge themselves over time and require more maintenance than your standard yellow brick road. If the batteries in your motorcycle need topped up in the off season, your ATV needs a pick-me-up to make your weekend getaway all that much more fun, or your RV is going into storage for the winter and you want to make sure it's ready to go immediately after it warms up, here are some things to consider when you are selecting your battery charger.
How to Speak Battery
Here are some of the basic terms and units of measurement you will find when researching a battery charger. This isn't everything that there is to it, but if you understand these things you are well on your way to becoming an accomplished battery whisperer.
The rate at which your battery charger will fill your battery. Quite simply, a charger with higher amps charges a battery faster.
More amps = faster charging time
Volts (in the scientific sense) are the difference in electric potential between the negative and positive terminals of the battery (higher difference = higher voltage). What that means for you is that some chargers are compatible with some voltages of batteries and not compatible with others. So make sure you are getting the right voltage for the battery.
Volts determine compatibility
This term is used to describe the battery in question. It refers to the maximum capacity of a battery. The higher amp hours of a battery, the longer it will power your things.
More amp hours = more power so your stuff runs longer
Step 1: Why Do You Need a Charger?
The first thing you should ask yourself when considering a battery charger is, "What am I charging?" The best charger will vary greatly based on what you're using your battery for. Some batteries will need to be charged up after a heavy use, like your golf cart battery after a long day of use, and some will only need a trickle charge to keep it topped off, like your RV batteries when you're storing them for the off season.Your charger's amps (which we now know is the speed of charging, yay for learning!) will vary depending on whether or not you want to trickle charge or charge a battery from a depleted state. Note:Trickle charging is when you give a small amount of power (just enough to compensate for the battery's natural depletion) to your battery to keep it good for storage.If you are exclusively trickle charging, then the amps of your charger are less important. It is highly unlikely that your battery will drain faster than even the smallest trickle charger can replenish. The average battery only discharges roughly 5% a month, so replenishing that doesn't require significant effort from your battery charger.However, if you are charging from a depleted state then you will want to make sure your battery charger's amps are roughly 10-20% of the total amp hours (Ah) of your battery (for example, a 100 Ah battery would perform best with a 10-20 amp charger). If you want to calculate how long it will take to charge your battery, use the following formula for a good estimate:
(Battery Ah / Charger Amps) x 1.10 = Charge time (in hours)
trickle charging
This battery is safe throughout the year, because not only will it stay charged up throughout the off-season, but this NOCO battery charger can charge it up after a hard day of use.
Step 2: Check the Voltage and the Battery TypeVoltage (v) will be a primary concern when you determine if a battery charger is compatible with your batteries (can you imagine how boring the movie would have been if the ruby slippers were 2 sizes too small?). Many vehicle batteries are either 6 volts or 12 volts (with some lesser common exceptions such as 8 volts), and while many chargers can work with both, some are only compatible with one or the other. You will often find this information on the charger itself, but this information should be readily available on the packaging, manual, etc. There are also systems that utilize multiple batteries that can have 36, or even 48 volts. These are generally a series of 6 volt, 8 volt, or 12 volt batteries that have been installed in the same system, and can be charged with a compatible charger (for example, 36 volts is six 6 volt batteries, 48 volts is four 12 volt batteries). The voltage required of a charger should be listed on the battery bank itself.It is also important to know the type of battery you have, such as lead acid, AGM (absorbent glass mat), gel-cell, or lithium batteries. Many battery chargers will only be compatible with certain types. So to determine compatibility, make sure the voltage and the battery type work with the charger you are looking to use.
volt toggle
Many battery chargers display the voltage options directly on the charger itself.
Step 3: Special ConsiderationsThere are a couple extra things to keep in mind when you are picking out the trickle charger of your dreams.
Solar charging capability is worth considering depending on your situation. Access to a wall outlet is easy to come by if your vehicle/RV/boat/bike is parked in a garage, or near an external outlet. But for many of us, we like to keep our vehicles outside, and these sorts of indoor accommodations aren't feasible. This is especially true for boats and RVs, which are difficult, and often impossible, to get into a covered space for storage easily (and without spending a pretty penny on storage fees).For these applications, a solar-powered battery charger is the way to go. The Bright Way Solar Battery Charger is a great alternative to a traditional trickle charger, and only requires regular access to sunlight to keep your batteries charged all year long.
Smart charging is a feature that you may need if you alternate between trickle charging and standard charging frequently. Smart charging battery chargers will modify their output when the battery is full to prevent it from overcharging. If you plan on leaving a battery charger on all season and don't use a dedicated trickle charger, we suggest a charger with the smart charging feature.This feature is great for your applications where you may use a lot of your battery power in use, and need to give your battery a quick boost. But you then have to store your battery during the off season, and have to keep it trickle charged using the same charger. The ability to give your battery a full-strength charge when it needs it, but ease off the charging when it doesn't is what makes a battery charger a smart charger.
smart charging
The NOCO Genius is one of the many smart chargers that will modify how it charges your battery based on the battery's current status, protecting it from overcharging and damage.
DC to DC charging is a feature that some battery chargers are capable of. It allows other batteries to be the power source for your battery charging. The best way to utilize this is to use a car while it is running to charge or jump-start a smaller battery. This is fantastic if you are charging your batteries in a vehicle that isn't easy to keep near an outlet, but also isn't easy to mount a solar charger to, such as an ATV or a motorcycle. This is not ideal in a trickle charging scenario, but for that quick boost to get your bike back on the road or your ATV back on the trail, this might be exactly what you're looking for. You might also see a DC to DC charger on a dump trailer, or on a boondocking setup.
dc to dc
DC to DC chargers allow you to use your car battery, or any other battery, to charge your dead battery. This is great if you need to charge things from your vehicle.
To Wrap Things UpIf you ever need to remember some important questions to ask yourself, and things to remember when picking out a battery charger, remember the acronym WIZOZ:
  • What am I charging?
  • Is my voltage compatible?
  • Zero maintenance with a trickle charger
  • Overcharge protection with a smart charger
  • Zero other words that start with the letter 'Z' (cut me some slack here, two z's?)
We hope that we have been able to clear up some of the battery charger purchasing process. Because, unlike Dorothy, who had to learn her lesson for herself, we would be happy to help you. There is nothing scarier than getting your ATV out the first warm weekend of the season, only to have it fail to start because the battery is dead (with the obvious exception of the flying monkeys). If you have any further questions don't hesitate to reach out to us, and for our selection of battery chargers, tap your heels together three times and say, "There's no place like the battery charger page. There's no place like the battery charger page. There's no place like the battery charger page."
its jacob alright
About Jacob JTo say that my path to etrailer was complicated would be an understatement. I have always had a passion for helping others, and throughout my education and career as a social worker or community liaison, I have loved writing as a hobby. When I found etrailer and was given the opportunity to turn something I enjoyed doing into a career that helped people access information and products they need to live the best life they possibly could, I was instantly interested. I am a lover of the outdoors, have been loading and unloading trailers since I before I was old enough to drive them, and have spent my recent years working in and around the automotive industry. And I am excited to share all of the things I have learned (more often than not the hard way). I consider myself a perpetual student, and etrailer gives me the opportunity to learn something new every day and share my findings with others. Which is something I am extremely grateful for. I look forward to continuing to help people find the answers they need to make memories for a lifetime.
Related Articles:Related Products:Written by: Jacob JLast updated: 4/24/2023



I have read this article before and there is one part that concerns me. The use of the word “trickle” charger. I worked close to 25 years on standby generators and ran into many instances where a well meaning owner used a trickle charger. A trickle charger, in time will destroy a battery. Even within a months time, depending on the battery and the charger. The better alternative is a float charger. What’s the difference? I’m glad you asked. A trickle charger will not stop pushing against the battery. When a battery is new, it will push back against the charger and at some point the charger and the battery will hold each other at a given voltage. Your comment was that the trickle charger only charges at the rate of natural battery drain. The problem with that thinking is that every battery is different, even within a given size rating. And as a battery ages, its drain characteristics change. Eventually the battery will start getting weaker and the trickle charger will keep pushing the voltage up, destroying the battery. Without a huge scientific explanation as to why this happens, I’ll explain the float charger. A float charger will work similar to a trickle charger, except when it reaches a set voltage, it backs off the “pushing” and just “holds” the voltage. The ultimate storage battery voltage for a 12 volt lead acid battery is 13.3 volts DC. A good float charger will maintain close to that voltage, where as, I have seen trickle chargers get pretty close to 15 volts DC, which destroys the battery. I need to add here, there is a difference between lead acid batteries and lithium batteries as well. It’s essential that a person charges the lithium batteries according to the manufacturer’s recommendations, unless of course you like uncontrolled fire. There are chargers that are switchable for both types and there are chargers that are specific for the lithium batteries as well. Some lithium batteries are built to protect themselves if charging is wrong, but some out there are not. A lithium charger will totally destroy a lead acid battery if it’s not the switchable type as well. Unfortunately/fortunately, the battery industry is changing and the consumer needs to be aware, so they don’t create a worse than a dead battery situation. Back to my original reason for writing, for long term storage (anything over a week) a float charger should be used instead of a trickle charger. And the charger needs to match the type of battery that’s being charged, whether long term or short term. I do read the articles that etrailer puts out and I get good information from them. And like Jacob, I like learning and I also like passing on info, especially if it can help someone that might unknowingly be going down the wrong path.



That was pretty funny WIZO man or wise old man, two Zs who could have ever believed.

Etrailer Expert

Mike L.


@Clint HA!



@MikeL I can never purchase sulfuric acid for my battery’s when water level get low distilled water evaporates and am constantly adding why and where can I purchase what I want
Etrailer Expert

Mike L.


@Larry We don't offer sulfuric acid, but we did a Google search and found many different sources, so do a search and you'll easily find some. Losing the water is a normal occurrence that's caused by the charge/discharge process that turns the water back into hydrogen and oxygen.
See All (4) Replies to Clint ∨



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