Q&A Batteries

This Q&A section has general information pertaining to batteries and charging. There are several Q&A sections and you will find an index of them at Q&A Central.

General Battery Questions

How do I know which batteries are really the best?
Take a look at our AAA NiMH Battery Comparison Data for a side by side look at some very interesting data.

How do alkaline cells compare to rechargeable cells?
Of course alkaline cells are not rechargeable, and they last longer for their single use. But they cannot provide as much current as rechargeable cells. Rechargeable cells have more "Punch" than alkaline cells as they are able to deliver their voltage at a higher amperage due to their lower internal resistance. With alkaline cells, the voltage falls drastically under load, so the power being provided is much lower than with rechargeable cells.

What are NiCd batteries?
The NiCd (nickel-cadmium) battery is a popular type of rechargeable battery for portable electronics and toys using the metals nickel (Ni) and cadmium (Cd) as the active chemicals. They are sometimes used as a replacement for Alkaline cells, since they are available in many of the same sizes. Nickel-cadmium cells have a nominal cell potential of 1.2 V. This is lower than the 1.5 V of Alkaline cells, and consequently they are not appropriate as a replacement in all applications. However, unlike most Alkaline cells, NiCad cells keep a near constant voltage throughout their service life. Despite their lower nominal voltage and the requirement of discharging before recharging, NiCd cells are actually better suited for high current applications. Due to a significantly lower series resistance, they can supply high surge currents. This makes them a favorable choice for remote controlled electric model airplanes, boats and cars, as well as cordless power tools and camera flash units.

What are NiMH batteries?
A nickel metal hydride battery, abbreviated NiMH, is a type of rechargeable battery similar to a nickel-cadmium (NiCd) battery but has a hydride absorbing alloy for the anode instead of cadmium. Cadmium is an environmental hazard; therefore, the NiMH cells are less detrimental to the environment. Like in NiCd batteries, nickel is the cathode. A NiMH battery can have two to three times the capacity of an equivalent size NiCd and the memory effect is not as significant. However, compared to the lithium ion chemistry, the volumetric energy density is lower and self-discharge is higher. Standard NiMH batteries perform better with moderate drain devices such as digital cameras, flashlights, and other consumer electronics, but, because NiCd batteries have lower internal resistance, they still have the edge in very high current drain applications such as cordless power tools and RC cars.

Are Lithium camera batteries the same?
No. Although the Lithium chemistry is cimilar, the cells are generally not rechargeable. You could use them, but it would get very expensive. We know a guy who spent $300 on the Radio Shack non-rechargeable Tadiran brand cells before he found our rechargeable Lithium cells.

How do batteries Work?
Take a look at this article on how batteries work. It is very informative.

Battery Specification Questions

What do all of the specifications mean, Volts, Amps, mAh and IR mean?
A few practical cell measurements and how they pertain to RC car performance are:
V (Voltage) = Top speed or horse power
A (Amperage) = Torque
mAh (milliamp hour) = Run time or capacity
IR (Internal Resistance) = Lower = more punch

What does the mAh rating really mean in terms of run time?
Assuming a 1 amp load the following ratings would yield the following run times:
1000 mAh = 60 Minutes of run time at a 1 amp (1000mA) load
800 mAh = 48 Minutes of run time at a 1 amp (1000mA) load
780 mAh = 47 Minutes of run time at a 1 amp (1000mA) load
750 mAh = 45 Minutes of run time at a 1 amp (1000mA) load
700 mAh = 42 Minutes of run time at a 1 amp (1000mA) load
670 mAh = 40 Minutes of run time at a 1 amp (1000mA) load
600 mAh = 36 Minutes of run time at a 1 amp (1000mA) load

What are C Ratings?
How fast a battery can discharge is it's maximum current capacity. Current is generally rated in C's for the battery. C is how long it takes to discharge the battery in fractions of an hour. For instance 1 C discharges the battery in 1/1 hours or 1 hour. 2 C discharges the battery in ½ or half an hour. All RC batteries are rated in mAh (milli Amp hours). If a battery is rated at 2000 mAh and you discharge it at 2000mA (or 2 amps, 1 amp = 1000mA) it will be completely discharged in one hour. The C rating of the battery is thus based on its capacity. A 2000mAh cell discharged at 2 amps is being discharged at 1C (2000mA x 1), a 2000mAh cell discharged at 6 amps is being discharged at 3C( 2000mA x 3).

Presently, Li-Poly technology does not allow currents as high as NiCad or NiMH batteries do. Because of this, many Li-Poly batteries are put in parallel to increase the current capacity of the battery pack. When 2 batteries are wired positive to positive and negative to negative, they become like one battery with double the capacity. If you have two 2000mAh cells and you wire them in parallel then the result is the same as one 4000mAh cell. This 4000mAh cell has the same C rating as the original 2000mAh cells did. Thus if the 2000mAh cells could discharge at a maximum of 5C, or 10 amps, then the new 4000mAh cell can also discharge at 5C or (4000mA x 5) 20 amps. This method of battery pack building allows us to use Li-Poly batteries at higher currents than single cells could produce.

What does 2S2P mean?
The naming convention that allows you to decipher how many cells are in parallel and how many are in series is the xSxP method. The number in front of the S represents the number of series cells in the pack. So 3S means it's a 3 cell pack. The number in front of P means the number of cells in parallel. So a 3S4P pack of 2100mAh cells has a total of 12 cells inside. It will have the voltage of any other 3S pack since the number of cells in series determines the voltage. It will have the current handling of 4 times the maximum C rating of the 12 individual cells. So say the 3S4P pack had a maximum discharge of 6C. That means that it has a nominal voltage of 10.8 volts (3x3.6) and a maximum discharge rate of 50.4 amps (2100mAh x 6Cx4P)

Charging Questions

My buddy has IC3 cells and they fast charge in 15 minutes, what's the deal here?
It should be noted that most any NiMH battery can be fast charged, you simply increase the C rating on your charger. It also has the effect of pushing the peak higher but reduces the quality of charge resulting in shorter runs. The higher peak voltage means the starting voltage is higher for early punch but this is bad for the batteries and greatly shortens life.

What's the deal with the IC3 15 minute battery?
There is nothing special about the IC3 batteries. Any battery can be fast charged. It is the charger that rapid charges the batteries so they are done in 15 minutes. There are several such fast chargers available of much better quality and features, but the Rayovac IC3 has been marketed well so many consumers identify with it. And while the Rayovac marketing says that fast charging does not reduce battery life, this is simply not true. Slow charging is and always will be better for battery life.

How do I charge the Lithium batteries?
With any Lithium battery charger. You will find several Lithium chargers here.

With XMODS and Mini-Zs it looks like you cannot remove the batteries from the car, how do you charge them?
All of our battery kits are equipped with a plug that matches up with our chargers. You simply unplug the pack from the car harness and plug it into the charger.

Can I use my existing Ni-Cad or NM-MH charger?
That's a big NO! Lithium cells should be charged at a constant current of 0.7C until 4.2V/cell is reached. Then constant voltage (CV) is to be used until current drops to 0.1C. At that time, the charging should stop. When the battery reaches 8.4v, it should no longer draw current. The charger should also be current-limited. Below about 75% charge, the limit current is reached. After about 80% charge, the current should decay toward 0. At about 95% charge the current should drop to only a few milliamps. In short, the closer to 100% charge, the less current is delivered to the battery.

Do I really need a the 12 Volt Adaptor?
The chargers we sell all require a 12 volt power source like a car battery or power supply. If you already have a convenient 12 volt source you are in good shape. If not, you will need to buy a 12 volt adaptor from the Chargers Page.

I have my own power adaptor, how do I connect it?
Simply cut the JST connector off the "INPUT" side charger. Use your Meter to determine which side of your power adaptor is positive. Connect the positive side of the power supply to the red "INPUT" wire on the charger. Put the heat shrink on the wires, twist them together and then solder them. Finally, use a lighter to shrink the heat shrink and you are done.

I'm too cheap to buy a 12 Volt Adaptor, can I use my dad's car battery charger to supply 12 volts to my charger?
No, you cannot use a battery charger, but you could use the car battery.

Can I just plug the 12 volt adaptor into the charging pocket to charge the batteries?
No, the 12 volt adaptor is not a charger, it outputs a fixed 12 volts and a fixed 500 mAH current. It will fry your batteries if you try to connect the 12 volt adaptor directly to them. You must use a charger.

How long does it take to recharge a 780mAh Lithium pack with the Lithium 7.4V, 500mAh Charger?
The Lithium Safe 7.4v 500mAh Auto Charger takes 90 minutes to charge up to 90% and another 30 minutes to charge to 100%. This assumes you ran them to the minimum voltage, which you probably did not.

Lithium Ion Batteries

What are the advantages of lithium ion batteries compared to other rechargeable batteries?
Lithium-ion batteries have several advantages:

They have a higher energy density than most other types of rechargeable cells. This means that for their size or weight they can store more energy than other rechargeable batteries.

They also operate at higher voltages than other rechargeables, typically about 3.7 volts for lithium-ion vs. 1.2 volts for NiMH or NiCad. This means a single cell can often be used rather than multiple NiMH or Ni-Cd cells.

Lithium-ion batteries have a lower self discharge rate than other types of rechargeable batteries. This means that once they are charged they will retain their charge for a longer time than other types of rechargeable batteries. NiMH and Ni-Cd batteries can lose anywhere from 1-5% of their charge per day, (depending on the storage temperature). Lithium-ion batteries will retain most of their charge even after months of storage.

So in summary; lithium-ion batteries can be smaller and lighter, have a higher voltage and hold a charge much longer than other types of batteries.

What are the disadvantages of Lithium Ion batteries compared with other rechargeable batteries?
Lithium-ion batteries are more expensive than similar capacity NiMH or Ni-Cd batteries. Lithium ion batteries are difficult to obtain in standard cells sizes (AA, C and D) like NiMH and NiCad batteries. Lithium-ion batteries also require sophisticated chargers that will carefully monitor the charge process. And because of their different shapes and sizes each type of Li-ion battery requires a charger designed to accommodate it's particular size. This means lithium ion battery chargers are more expensive and more difficult to find than NiMH and NiCad battery chargers.

Are the Lithium Ion cells dangerous?
Yes, all lithium cells are dangerous but Lithium Ion cells are inherently safer than Lithium Polymer cells because of their differing chemical makeup and steel case. Our Lithium Ion cells have a safety disc that ruptures to release pressure to avoid explosion. Follow the Lithium Safety Guidelines in the Q&A.

I was making my own Ion Pro 2S Pack and accidentally touched the wires together and the batteries and wires got very hot. What happened? And are my batteries OK?
You probably shorted the positive and negative ends together which creates a completed circuit and the energy must be dissipated. In this situation, it will dissipate in the form of heat. If this happened for only a second or two, the cells should be fine. But leaving them in a shorted condition for an extended period can ruin them. You should be careful when handling the cells as a shorted pack will generate enough heat to burn your fingers.

I heard that if you run them below 3 volts per cell they are ruined. Is this true?
It is true that you should not run the cells below 3 volts each. However, in this application it is not a problem if you pay attention, because the car begins to slow long before they reach this point. It will be very obvious that it is time for a recharge. As long as you don't discharge the battery below 3 volts per cell you won't have any problems. Below 2.9v/cell, the batteries will need to be trickle charged around 50 mAh until they reach 3 volts per cell. Discharge below 2.3 volts per cell can do permanent damage. So when the car slows down, stop and recharge after letting the batteries cool! If you keep running, there is the potential to damage the cells. We have cells we have been running hard for months now with no problems as do many of our customers, but you do have to pay attention to this issue.

OK, I didn't bother to read the Q&A before and have ruined my cells, now what?
This is not a product defect, so you will need to purchase another set. Think of it like the guys who drag race and push their engines too hard and blow them up (hope that helps ease the pain).

Do Lithium cells have memory?
None at all. What determines the life is the number of discharge/charge cycles.

How long will these batteries last?
Lithium-based batteries have a lifetime of 2-3 years. The clock starts ticking as soon as the battery comes off the manufacturing line. The capacity loss manifests itself in increased internal resistance caused by oxidation. Eventually, the cell resistance will reach a point where the pack can no longer deliver the stored energy; although the battery may still contain ample charge. Increasing internal resistance is common to cobalt-based lithium-ion. The speed by which lithium-ion ages is governed by storage temperature and state-of-charge. Figure 1 illustrates the capacity loss as a function of these two parameters.

What is the best way to store Lithium Ion batteries?
Lithium-ion batteries can hold a charge for many months. If possible, store the battery in a cool place at about a 50% state-of-charge. The most harmful combination is full charge at high temperature. This is the case when placing the cells in a hot car. If a lithium-ion battery with a very low charge is stored for a long period of time (many months), it is possible for the voltage slowly drops below the level at which it can be charged again. If the battery is going to be stored for several months it's a good idea to take it out and recharge it after a few months. Better yet would be to actually use the battery every few months and then leave it partially or fully charged.

On the page about the Lithium cells it says they are 8.4 volts together but it says the individual cells are rated 3.7 volts each. Isn't that 7.4 volts and not 8.4 volts?
The cells come off the charger at 8.4 volts and drain down to 6 volts with 7.4 being the nominal (according to plan or design) voltage. The 8.4 volts is significant because this is the maximum voltage that a stock XMOD or MiniZ can handle.

Why are Lithium cells more expensive than other battery types?
Mainly because they are much more complex to manufacture and are manufactured in much smaller quantities than NiMH or NiCad batteries. But they are worth it for the performance difference. Something to consider is this, the Lithium cells are the future of the Remote Control hobby and the support equipment you buy such as chargers and other equipment should be considered an investment. Even if you tire of RC cars, Lithium technology will benefit your future hobby endeavors.

Can I solder directly to Lithium Ion cells? In other words, can I solder to cells without tabs?
No you cannot. The extreme heat (we solder at 660 degrees) will disrupt the cell chemistry and permanently damage them. They may still work, but the output will be greatly reduced. If you are going to make your own Ion Pro 2S Pack, you must buy tabbed cells. We have seen many kits sold on eBay and other sites that were direct soldered. These will have greatly reduced capacity.

How many times can you charge a Lithium Ion battery?
Our Lithium Ion cells are rated for 500 discharge/charge cycles, whether its a half cycle or full doesn't matter. This rating goes out the window if the cells are abused.

Lithium Polymer Batteries

Is Li-Po and LiPo the same as Lithium Polymer?
Yes it is, Li-Po or LiPo are common abbreviations for Lithium Polymer cells.

What is Lithium Polymer?
Lithium Polymer batteries are used in many electronic devices. Cell Phone, Laptops, PDA's, Hearing Aids just to name a few. Most ,if not all, lithium polymer batteries are not designed for RC use, we use them in different applications than they were designed for. They are similar to Lithium Ion batteries in that they each have a nominal voltage of 3.6 volts, but dissimilar in that they do not have a hard metal casing but rather a flexible material encloses the chemicals inside. The "normal" lithium polymer batteries are thin rectangle shapes with two tabs on the top one positive one negative. The reason we use Lithium cells is that they are significantly lighter than comparable NiCad or NiMH batteries, which makes our cars run longer and better.

How do the Lithium Polymer cells compare to other batteries on the market?
The Lithium cells are lighter and more powerful than any other technology on the market. Bottom line is, nothing comes even close.

What is the voltage range for Lithium Polymer Cells?
Li-Polys act differently than NiCad or NiMH batteries when charging and discharging. Lithium batteries are fully charged when each cell has a voltage of 4.2 volts. They are fully discharged when each cell has a voltage of 3.0 volts. It is important not to exceed both the high voltage of 4.2 volts and the low voltage of 3.0 resting volts or 2.5 during discharge. Exceeding these limits can harm the battery. You will know it is time to stop driving if you experience a sudden drop in power.

What is your quality control procedure for Lithium Polymer cells?
Every single cell is voltage tested before shipping and all Packs are voltage tested and load tested at 1 amp after assembly to verify correct pack assembly.

Lithium Safety Guidelines

Warning: Li-Ion (Lithium Ion) and Li-Poly (Lithium Polymer cells require special handling. Improper usage and charging of Lithium based batteries can result in explosion and or fire. Always follow the safety guidelines below.
Only Use Lithium Safe Chargers!
Lithium cells require a special charger specifically designed to charge lithium cells. In general any charger that can charge lithium ion can charge lithium Polymer assuming that the cell count is correct. You must NEVER charge lithium cells with a Ni-Cd or NiMH only battery charger. This is dangerous. Charging cells is the most hazardous part of using lithium batteries. EXTREME care must be taken when charging them. It is important to set your charger to the correct voltage or cell count. Our Lithium Safe 7.4v 500mAh Auto Charger is safe for all of our 2S and 2S2P packs.

Double Check Charger Cell Count!
This is the most common mistake people when charging Lithium cells. It is safer to have a fixed charger like our Lithium Safe 7.4v 500mAh Auto Charger which is fixed at 7.4v which is the correct setting for our 2S and 2S2P packs. If you charger cell count is selectable make certain that it is right.

Use a Conservative Charge Rate!
You can charge below 1C, but should never exceed it. For example, charging a 500mAh battery with our Lithium Safe 7.4v 500mAh Auto Charger would be charging at a 1C rate and is safe. Charging a 1000mAh battery with the same charger would be .5C and is even safer.

Charge in a Safe Area!
Use a fireproof surface to charge your batteries on. A Pyrex dish with sand in the bottom is a good option. Only charge your batteries in a open ventilated area. If a battery does rupture or explode hazardous fumes and material will spew from the battery. Keep a fire extinguisher or a bucket of sand nearby when you are charging batteries.

Always Monitor Charging!
This is the most important safety measure you can take, so please take it seriously. A damaged cell may balloon during charging. If the batteries show any sign of swelling, discontinue charging and remove them to a safe place outside as they could erupt into flames.

Inspect Cells for Damage After Crash!
The steel case of the Li-Ion cells is tough and hard to damage physically, but Li-Poly cells as they have a soft skin and can be damaged easily. Inspect your cells for physical damage after a crash and if you find any sign of physical damage discontinue use immediately. So you should keep a close eye on your batteries after a serious crash for the next 20-30 minutes.

Safe Disposal!
Put the cell or pack in salt water (outside of course) and wait until the cell has discharged completely which could take a day or two. Check the cell voltage with a MultiMeter and when it is at 0 Volts it is safe to puncture the outer casing with a non metallic object. Place it back in the salt water solution for a day which neutralizes the chemicals and makes it safe to throw in the garbage.