mashp39

My Feedback: (1)

I have a 4,8 volt 1500 mah receiver battery. Usually I use a 4.8 700 mah receiver battery. What will change if I use the 1500 battery? Will the battery be OK with 3003 and 3004 Futaba servos? Will the battery charge last longer? Will the battery take longer to charge with the standard charger?The plane is an old Big Stik that I have redone and so will be just a sport flyer.What can I expect?

flyinwalenda

My Feedback: (5)

hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhhhhh

Hydro Junkie

The servos COULD also act faster and have more torque with the extra power they could receive. Since you're planning on using the same voltage pack as before, it won't be very much. It would be very obvious if you were going to packs with higher voltages

mashp39

My Feedback: (1)

Thanks for your replies. This is what I thought would be the effect but I thought to check in first.I did not want to see smoke.

flyinwalenda

My Feedback: (5)

You will not see smoke. 4.8 volts is 4.8 volts no matter how large the capacity is. A larger capacity battery pack will not make the servos move faster. The only way it would appear to do that is if the old 4.8v pack had a bad cell and was not delivering its rated voltage.

Hydro Junkie

Thank you for clarifying that for me. Had three identical packs, one I could move the rudder by hand, two I couldn't. Wasn't until I got a better charger that I found the one pack had a cell that only took a partial charge, even though the pack indicated fully charged by the wall charger that came with my radio

BarracudaHockey

My Feedback: (11)

Unfortunately that is incorrect. There will be no extra torque or speed if the voltage is the same regardless of the size of the battery

BelAirBob

Think of mAh as fuel tank size. The larger the mAh rating, the longer it will last. But as having a larger gas tank in a car, it will not make it go faster or accelerate faster as Barracuda notes.

do not use a wall wart to charge. Get a real charger and charge at 150 mAh for 10 or more hours. You should charge at 1/10C

regards

bob

Rodney

There is nothing wrong with using a wall wart to charge. As long as it provides a current in excess of the self discharge current (which is usually in the micro ampere range) the battery will eventually reach full charge. As long as the charge rate is 0.1C or less, no damage will occur to the battery if you leave it on to long. If the current is quite a bit below 0.1C (but greater than self discharge current) no problem, you just have to leave it on charge for a much longer time. In fact slow charging (0.1C) is usually much better for your battery; i.e. more useful cycles of use than you will get by fast charging.

BelAirBob

If you have a 2000mAh battery and charge with a 50 mAh wall charger, you are probably looking for disaster. Maybe it will eventually charge after a few days, but sure you are going to keep track of it and how will you know it is fully charged? Another advantage of a real charger is that you can cycle the battery and find out what the real capacity is. Over time, capacity diminishes and after a point, you need to discard the battery. A Hitec or similar charger is a great investment if you are going to be in this hobby

buzzard bait

He didn't say 2000, he said 1500. Furthermore, the amount of current you put it is the same whether it is a 700 or 1500 mah battery so when you go to the flying field, no disaster. To continue the fuel tank analogy, if you put 10 oz of fuel in a 16 oz tank you still have 10 oz of fuel.

I bet you could leave the plane on the wall wart charger continuously and the 1500 mah battery will be fine, though I have not tried to. Some people do that with standard battery packs and claim that trickle chargers are unnecessary, but I can't speak from experience. However, double the Rx pack size and I would not hesitate to try just leaving it on all the time. Others weigh in on this?

Jim

600Bob

If the smaller pack voltage sags because of high current draw then the larger capacity pack would sag less so the servos would effectively be operating at a higher voltage and operating closer to their specifications. But yeah, unlikely to notice the difference in the real world.

warhwk

My Feedback: (3)

I have a computer battery cycler-analyzer and I was curious how a wall wart would work with larger capacity NiCad and NiMhrd batteries. I found that a fully discharged 2000 mah 4.8v took about 48 hours to get a full charge with most of the charge occurring in the first 24 hours. This makes sense as when the battery voltage rises, there is less voltage differential and less current. The 50 mah wall wart charged the discharged battery at closer to 75 mA in the first few hours and dropped off to less than 35 mA after 18 hours.
I then measured the average use during a day of flying. I rarely used more than 600mA. I was now comfortable is putting my 2000 mah on a wall wart for between 12 and 18 hours before flying. 12 hours on the wall wart charger was more than sufficient to replace what had been used on a typical flying session. I also use a loaded voltmeter and check the Rx battery voltage before every flight. I've been doing this for more than 10 years without any issue. In fact, the batteries that have been primarily charged with a wall wart have lasted longer than the batteries that get charged on the peak detect charger.

For the OP, the wall wart charger will work fine as long as you start with a fully charged battery. I would start with an initial 48 hour charge, then a 12 hour charge between sessions. An inexpensive loaded volt meter is the most valuable tool you can get. I recommend this one. http://www.dreamworksrc.com/catalog/V-300-Led-Voltmeter

Rodney

warhwk, as said before, as long as the charge current is greater than the self discharge current, the battery will eventually reach full charge. That is just a fact of physics. It is best if the current is about 0.1C but it does not have to be that high. How do you tell when the battery (NCad or NiMh) is fully charged when charging at very low currents? Hard to do with measurements although measuring under a load and reading about 1.3 to 1.4 volts per cell, you can be reasonably assured of a full charge. If you have an infra red temperature gauge, that will also help. If you read a few degrees above ambient when measuring cell temperature, chances are that the battery is near full charge. As soon as a battery reaches full charge, any energy pumped into it will raise the temperature rather than increase voltage.

warhwk

My Feedback: (3)

I agree completely Rodney. I have one 1500mA NiCd that still has 90% of its capacity that has primarily been charged from a wall wart. It is 11 years old now.

tazzzz

If the battery feels warm,not hot,,,,rule of thumb usually battery is charged and can take no more.

TAZZZZ

rt3232

My Feedback: (6)

The Ma is never a problem, as the receiver and servos will draw what ever they need per your flying style it will just get you longer flights between recharge.

Cheers Bob T
Ama13377

Stick 40

this is true, if a battery is warm, its over charged. If your battery is "HOT" you are way over charged! when a battery gets to full charge the extra charging has to go some where and that is heat. It is not good to over charge a battery. The small wall chargers work , but it best to get a better charger that will cut off when "peek charge" is reached. your battery's will last longer and you may not loose a plane over it.
I have had some very good chargers that cost as little as $39. they tell you how much Mah you are using and do a complete charge.
your doing the right thing , asking questions.
if your using a 1500 Mah battery and you put it on charge the nite before you go flying and let it charge all nite, you should be alright. 50 Mah charger at 10 hr. is 500 Mah put into the battery and one plane flying for 3 or 4 flights should use about 300 Mah. That is is the servos are not using more due to improper instillation.

flyinwalenda

My Feedback: (5)

No that is not true. All Nixx batteries get warm while being charged.. It's simple physics.

Yes it is true that a battery when very hot to the touch is being charged with too high a current setting (too high of a C rate) and that will damage a cell. That is why a good charger comes with a temperature probe to shut down the charge if the temp gets too high.

Using a wall wart or a charger with a 0.1C rate is good for new packs to "form " them(forming charge) for the first several charges. After that ,charge them at 1C.