Large Scale Central

Who knew? Amps used to charge a battery.

Electronics Power and Sound
#1

In a conversation with club member Mike Williams, later confirmed by email from Jonathan Beliese, one should only charge a 2600 mah LIon battery using 1.5 amps.

No one ever told me this, including the person that I purchased the battery and charger from (Jonathan…)

Is this common knowledge?

Is there a special school that one has to go to to learn this stuff?

What does one charge a 4400 mah battery at, the same 1.5 amps, or some other, more esoteric number? How about a 5600 mah battery, what does one do then?

Is there a “Go-By?”

#2

Steve,

I hear you…there doesn’t seem to be any hard and fast rules to set the charging amps. I buy all my batteries and chargers from Jonathan. But when I first started in battery power, I ASKED Jonathan for advice on how to set the charger. That charger was a MAHA. He said something then about using half the value of the mah of the battery and go. His comments to me at that time were exactly as he posted above. I set the 2600 mah battery to charge at 1.3 to 1.5 amps. I have 4200 mah NiMH batteries in my Connie and a Accucraft C19 #346. I charge both of them at 1.5 amps because Jonathan said lower and slower is better. My Berlyn Work Goose #6 uses a 1400 mah Li-Ion and I charge that one at 0.5 to 0.7 amps. I must be doing something right because the Connie and C19 batteries are 7 years old and 6 years old respectively and still strong.

#3

I bought the chargers All-Battery recommended (the cheap “smart” chargers), one of which charges at .5 amps, the other at 1.5 amps. (The lower rate charger allows for multiple voltages.) Since they were the recommended chargers to go with the batteries I bought, it’s what I use. In reading about Li-Ion batteries, I read where 1.5 amps was about as high as you wanted to go on charging them, but never gave it much more thought than that since I never had a charger where I could adjust that. My battery packs (2200 - 2600mAh) charge up in around 90 minutes, which is plenty fast for my needs. I guess if you’re discharging them inside of 15 minutes, you might want to look for ways to cut that time down, but when I’m getting 2 - 3 hours run time out of a pack, I’m happy with 90 minutes. My packs are 5 years old and still giving me the same longevity they did when new, so I’m not going to argue with success.

Later,

K

#4

The safe value is to charge at a 10 hour charge rate That means you would charge a 5 amp/hour battery at .5 amp/hour. In most cases, a smart charger can usually charge at a higher rate. An example is the charger for the Tenergy 4400 MAH, 14.8 V battery pack. The vendor recommends a 1.5 amp charger for that battery. Go see what the battery manufacturer recommends.

#5

Wow, answers all over the place.

The amp hour rating is normally termed “C” in amps, i.e. a 4 amp hour battery would have a “C” of 4 amps.

The recommended charging rates, and more importantly charging profiles (meaning the current and voltage is not constant) varies greatly by battery chemistry.

then within a chemistry, there are often batteries that take a faster charge, can dissipate heat better etc.

Normally, you consult the battery manufacturer on the recommended charging rates and profiles.

But there are even variations on this, where, for example, a power drill manufacturer will have a charging profile that recharges the battery just as fast as possible, but the battery may not have as many charge cycles (life) as the same battery with a less aggressive charging profile.

Everyone seems to have their favorite setup, and also their own “balance” of agressive charging vs. battery life.

Charging modern batteries at “C” is normal, BUT this is normally for a short time and the charger tapers the current off pretty quickly.

Recommending 1/2 C, as Steve was told in the first post, is more conservative, but less heat built up initially and the battery will last longer (lifetime).

So Steve, a bit of research will give you your best answer. If you need a “pat answer” get a smart charger that automatically tapers the charge, and limit the initial max current to 1/2 C and you will get pretty much all the life the battery can offer.

If you need faster charging, try charging at C, but be SURE your charger is smart, and monitor the cell temps. You might get a few less cycles (lifetime).

Greg

#6

Who did you buy the batteries from, buy their charger! Each type of battery has a certain type of charger! ALWAYS use the correct one for the type of battery! I you don’t there could be a large BOMB or fire! These little devices can cause you a great deal of prain in the a_____!

Paul

#7

OEM’s recommend charge rate for the atypical 18650 Lithium-Ion cells typically utilized by G-scale model rail roaders for a standard charge rate is .5C and 1C for fast charge. This holds true for any capacity battery. Don’t be confused by ‘C’ C=capacity NOT amps/Ah’s.

The ‘C’ rating of a 2200mAh battery is 2.2Ah; 2200/1000=2.2Ah, 2.2/1=2.2A

C = C/1 hour; where C is the battery capacity expressed in A-hour or mA hour.

2.2Ah x .5C = 1.1 Amp charge rate

The ‘C’ rating of a 4400mAh battery is 4.4Ah; 4400/1000=4.4Ah

4.4Ah x .5C = 2.2 Amp charge rate

Most of these cells are nominally rated @ 2200mAh @ 3.7V, some claim higher numbers… Since the cells are stacked in series configuration for our voltage requirements capacity remains constant. 14.4V/3.7V=4 cells. That said higher mAh capacity batteries are wired in parallel/series configurations. In a nutshell a 4400mAh battery is two (4) cell batteries wired in parallel. This is known as a 4S2P battery (two (4) cell series wired batteries that are wired together in parallel). 2200mAh x 2 = 4400mAh

Michael