NiCD, NiMH, & Memory Effect

What is the difference between Nickel Cadmium (NiCad) and Nickel Metal Hydride (NIMH) batteries? What is “Memory Effect?”

Both NiCad and NiMH batteries are rechargeable. The main difference between the two is the fact that NIMH batteries offer higher energy densities than NiCads. In other words, pound for pound, NIMH delivers approximately 30% more capacity than its NiCad counterpart. What this translates into is increased runtime from the battery with no additional bulk. NIMH also offers another major advantage: NiCad batteries tend to suffer from what is called a “memory effect”. What this means is that when a NiCad battery is only partially discharged before charging, the battery “forgets” that it has the capacity to further discharge all the way down.

To illustrate: If you, on a regular basis, fully charge your battery and then use only 40% of its capacity before the next recharge, eventually the battery will become unaware of its extra 60% capacity which has remained unused. Your battery will remain functional, but only at 40% of its original capacity.

The way to avoid the dreaded “memory effect” is to fully cycle your NiCad battery at least once a month. In other words, fully discharge your battery and then fully charge it.

Batteries can be discharged by allowing the device to run on the battery until it ceases to function. This will insure your battery remains healthy. NIMH batteries are “memory free” – they do not suffer from this affliction. Thus, if you have a NIMH battery, the only time it is necessary to cycle it is during its initial use and after a long storage period. This is done to “exercise” the battery and bring it up to full capacity.

How to treat corroded battery terminals

Corroded battery terminals can prevent your vehicle from starting. You could have so much corrosion around your battery connections that the resistance is stopping the current from getting through to start your vehicle.

Battery corrosion is caused by hydrogen gas being released through the battery vents from the acid inside the battery. This mixture builds up over time and is the white, green, or blue tinted corrosion we see on battery terminals or cables.

Most often the corrosion occurs on the negative battery terminal, which is a sign of undercharging the vehicle’s battery. This typically happens when the alternator does not have enough time to replenish the lost battery capacity. Battery corrosion on the positive terminal is normally from overcharging. If this is what you are seeing in your vehicle, it may be best to have your alternator checked for proper output.

Once corrosion occurs, if the buildup is not too severe, the terminals can be cleaned by using a battery cleaner with sandpaper or a wire brush to loosen up the corrosion and scrub it away. Before doing this, you should turn your vehicle off and disconnect the battery cables from the vehicle. For safety the negative cable should be disconnected first, and hooked up last. A solution of warm water and baking soda will neutralize any acid on top of the battery or in the vehicle tray.

Sometimes, a corroded battery cannot be sufficiently cleaned, and it is time for a replacement. When inspecting your battery, be sure to check the condition of the case itself. If it is leaking or swollen, it is time to replace the battery instead of cleaning the corroded terminals and cables.

The best way to fight corrosion is to prevent it from ever starting. You can use a spray battery protector which is meant to prevent corrosion build-up on battery terminals and cables. Always start with a cleaned-up connection and read the manufacturer’s directions before use.

How to safely jump start a battery with booster cables

  • Always wear proper eye protection.
  • Never lean over the battery.
  • Do not jump start a damaged battery. Inspect both batteries before connecting booster cables.
  • Be sure battery vent caps are tight and level (if applicable).
  • Make sure both vehicles are turned off before jump starting. Do not turn on the assisting vehicle at any time during the jump starting process.
  • Make certain that the vehicles are not touching and both ignition switches are turned to the “OFF” position:
  1. Connect the positive (+) booster cable to the positive (+) terminal of the discharged battery.
  2. Connect the other end of the positive (+) cable to the positive (+) terminal of the assisting battery.
  3. Connect the negative (-) cable to the negative (-) terminal of the assisting battery.
  4. Make a final connection of negative (-) cable to the engine block of the stalled vehicle, away from the battery.
  5. Start the stalled vehicle. Leave the assisting vehicle turned off.
  6. Remove the cables in reverse order of connections.

Series & Parallel Battery Connections

You’ve probably heard the terms “series” and “parallel” before. What do these terms mean and how do they influence what charger you need? When discussing batteries that are connected in either series or parallel, it is important to take into consideration the proper charger select that should be made when charging your battery.

Series Connection

To make a series connection between batteries, use a jumper wire between the negative of the first battery and the positive of the second battery. Run your positive wire off of the open connector from the first battery and your negative off of the open connector on your second battery.

In a series connection, the individual battery voltages are added together. When charging your battery, it is necessary to account for the total voltage of the string.

For example, if you have (2) 100 amp hour, 6 volt batteries connected in series, the total voltage is 12 volts and the amp hour capacity of the assembly is 100. In this situation, you would use a charger that satisfies both 12 volts and 100 amp hours. Electric golf carts often use 6V, 8V, or 12V batteries connected in series to produce a total of 36 or 48 volts.

Parallel Connection

A parallel connection is made by connecting the positives of all the batteries in the string down the line with a jumper wire, and then doing so with all the negatives. Then, connect the last positive and negative to the application.

Batteries connected in parallel increase the amp-hour capacity of the assembly, but not the voltage. A parallel battery system’s voltage is the same as the individual batteries, but it will increase the run-time for which it could power an item.

When charging batteries that are connected in parallel, it is crucial to take into account the increased amp-hour capacity when selecting your charger. A good example of a parallel connection is diesel pickup truck with (2) starting batteries connected in parallel to maintain 12 volts, but double the available starting amps and reserve capacity.

Whether it is the increase in voltage from a series connection or the increased amp-hour capacity from a parallel connection, understanding how these are different and the appropriate manner of charging your battery system is important in maximizing battery life and performance.

Can I let my battery sit on a concrete floor?

Will storing my car or motorcycle battery on a concrete floor ruin it?

This rule of thumb at one time used to ring true in the early days of automotive battery technology.

The earliest examples of automotive batteries were lead acid batteries that were composed of glass cells and encased in a wooden box. When these were left on the garage floor the moisture from the concrete would be absorbed by the wooden box causing it to swell or warp. This would cause the glass cells to move and eventually break leaving you with acid on the floor and a ruined battery – not good.

As technology evolved car batteries had changed, but the concrete issue still remained. Car batteries eventually progressed to being built using a hard rubber case. The problem was these cases were very porous, and as with the wooden cases they would absorb the moisture from the floor and allow current to flow between the cells discharging the battery.

But fear not! The batteries we find in our modern cars use cases that are made of hard plastics like polypropylene. These cases are able to block any moisture from coming through preventing the previously mentioned discharge issues.

We can finally put this age old myth to rest. Storing your car or motorcycle battery on a concrete floor will not ruin it. Keep in mind that a lead acid car battery will self-discharge if left sitting unmaintained over time. This, however, has nothing to do with where or what the battery is sitting on.

Recycling Batteries at Battery Mart

If you don’t know what to do with your old batteries, we have a solution: Send them back to us for recycling!

We are currently accepting batteries of these types:

  • AGM / Gel / Sealed Lead Acid / Maintenance Free
  • Lithium Ion (Li-Ion) & Lithium Polymer (Li-Poly) Cell Phone Batteries

All you need to do is ship your old batteries to us by any carrier of your choice (UPS, FedEx, etc.) to the address below:

Battery Mart
ATTN: Recycle
1 Battery Drive
Winchester, VA 22601

If you’ve purchased from us, we recommend using the same box and packing materials your new battery arrived with to ensure the battery makes it to us safely. Shipping costs will be your responsibility.

You will be helping the environment by not only recycling batteries, but the packaging as well!

If you have any questions, please call us at 1-800-405-2121.

Please note that we DO NOT accept these types:

  • Alkaline & Carbon Zinc Batteries
  • Cordless Phone, Two Way, Cordless Power Tool, Rechargeable Consumer Type Cells (AA, AAA, C, D, 9V)
  • Large NiCd Cells from Standby Power or Switchgear applications.

We can provide contact information for companies that accept these. Please call us at 800-405-2121 or email us at [email protected] for more information and return procedures.  NiCD and NiMH batteries should be recycled properly. Do NOT throw these batteries in the trash. NiCD batteries are composed of approximately 20% cadmium, an extremely hazardous element and environmentally detrimental. While NiMH batteries are environmentally friendly, the higher capacity NiMH cells still contain trace amounts of cadmium.

Hearing Aid Batteries: Answers to Common Questions

While there are rare instances that a hearing aid will use a rechargeable battery, the majority of them use one of the standard Button Cell Zinc-Air batteries. These batteries all operated at 1.35 Volts (sometimes rounded up to 1.4 Volts). Typically, one would differentiate between batteries with their size.

Here you can find answers to some of the most common questions. Hearing aid batteries are extremely valuable items, and hopefully the answers here will help you understand a little more about them.

How can I tell what battery size I need?

Some time ago, hearing aid batteries sizes were standardized and assigned with a color code system to help you remember your battery size. You can check this color on tabs found on the back of the battery. The packaging usually has the color code displayed on it, too. So, even if you can’t remember your size, you can keep the color in mind.

  • Yellow Tab = Size 10
  • Orange Tab = Size 13
  • Brown Tab = Size 312
  • Blue Tab = Size 675

How long do the batteries last?

Depends on your hearing aid. Some require more power, and will drain the battery faster. Digital hearing aids generally use up batteries faster than an analog one, due to the more complicated circuitry in the digital ones.

So, while it’s not definite, your battery life should range from 5 to 7 days. If you’re consistently experiencing shorter life, you should be safe and have your hearing aid checked out. There’s a chance that it may not be working properly. Your hearing health care professional should be able to help you out, and send in your hearing aid for repair if needed.

What happens when I take the tab off my battery?

Zinc air batteries work by mixing zinc with the outside air. When you pull the tab, the battery activates and continues to stay active. You can’t deactivate the battery, so don’t pull the tab if you’re not ready to use it! If you keep the tabs on your battery, you should expect a shelf life of about 3 years (when stored at room temperature). After three years, the batteries probably won’t perform as well as normal.

How should I dispose of hearing aid and zinc air batteries?

Easily: You can throw them away with your normal trash. You shouldn’t accumulate them, though, as this can lead to a fire risk.

Our First Ever Commercial!

Introducing the first ever Battery Mart commercial!

We’re proud to display on our website the first ever commercial for Battery Mart. We’re really excited about it and think it turned out really cool. If you have 30 seconds, we’d encourage you to check it out!

And, in case you’re wondering, the storefront shot is from our Winchester, VA store, and the outside shot is from our Martinsburg, WV store.

You know that feeling… out of energy, running low, when your zip has lost it’s zap. Get back your get up and go with a fresh new battery from Battery Mart.

Whatever battery you need. Batteries for
cell phones, laptops, cameras, golf carts, boats, and cars. Power tools, watches, and hearing aids, and much more.

There’s a good reason why Battery Mart has sold over one million batteries. Get Battery Smart… Go with Battery Mart. In Martinsburg, Winchester, and online at

Everstart Battery Cross Reference

In this post you’ll be find powerful replacement batteries for your original Everstart battery.

We have sold batteries replacing the Everstart brand for many years.  Our recommendations come from our experience working with customers online and in our stores to get their vehicles back on the road.

Please be sure to review the replacement battery for terminal polarity, dimensions, and cranking power to ensure that the replacement options will work in your specific application. Battery manufacturers do change specifications without notice, so we always recommend comparing any replacement against your original battery.

Select your Everstart battery below: