LiPo Noob - Need Some Help

RC_Noob

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Hi Guys,

I'm a complete RC Noob and after a bit of research I just picked up an AMP to get into the hobby.

I decided to go for LiPo batteries and received a Prophet Sport Mini charger and a Reaction 30C 4000 mAh battery this afternoon along with the car.

I'm trying to charge the battery but the charger flashes an error, 1 blink per second to indicate a bad connection.

From what I can see I've connected everything correctly (pictures below). The balance cable is inserted into the 2S plug, the EC3 connectors are in the appropriate sockets,, it's set to 3A for a 3C charge battery etc etc..

When I put a multimeter to the battery terminals I can see it has around 5.4 volts of charge, and when connecting the low voltage alarm to the balance cable it gives me a reading across both cells. Though the alarm is sounding as cell 1 seems to have much more charge than cell 2 - is that normal or should they discharge equally?

My initial feeling is there is a problem with the charger, although it is working ok for the stock NiMH battery. Before I send it back, am I doing anything stupid?

Thanks

charging_1.jpg

charging_2.jpg
 
Welcome @RC_Noob!

Firstly, the charge rate does not depend on the C rating. It is the capacity that you should be looking at. Also, to a lesser degree, how fast the manufacturer recommends charging it. This is usually 1c (this time for capacity). In the case of your battery, that would be 1 x 4000mA (4A), thus a charge of 4A. That will charge your battery in about an hour if the battery was discharged to an appropriate level. Usually around 3.7-3.8V per cell.

That brings me to the next aspect to look into. You mentioned that the cells did not measure the same, what voltage does each cell read? They ideally should be identical, but you may see a difference of .01-.02V difference sometimes. 5.4V across the whole battery is much to low. It should be atleast 6V (but ideally no lower than 7.4V), and even then you risk damage. I have a feeling you may have a damaged cell.
 
Thanks for the response.

According to the Low Voltage Warning device one cell was reading 3.x and the other was reading 1.x, can't remember the exact .x numbers but I suspect cell 2 is damaged from what you are saying. Attached is an image from of the multi-meter reading.

charging_3.jpg

Thanks for the information on the charge rate. I was just following the instructions for the battery and instructions which suggested 1A for each 1C, or perhaps I mis-read the manual, here's the extract:

charge_manPNG.PNG

The battery has 3C charge rate stated on the front as you can see in the above pictures.

Thanks
 
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Thanks for the response.

According to the Low Voltage Warning device one cell was reading 3.x and the other was reading 1.x, can't remember the exact .x numbers but I suspect cell 2 is damaged from what you are saying. Attached is an image from of the multi-meter reading.

View attachment 6024

Thanks for the information on the charge rate. I was just following the instructions for the battery and instructions which suggested 1A for each 1C, or perhaps I mis-read the manual, here's the extract:

View attachment 6023

Thanks

Yes, that instruction is what I listed, you just misunderstood the basis of the charger's instructions. There are two "C" ratings for the battery. The C you see on the label, which is actually a measurement of rate of charge/ discharge capabilities. The other, as I pointed out, refers to the capacity of the battery, listed on your's as 4000mAh. The instructions reference the capacity rating. 1C for your battery is 4000mA, or 4A. Hence charging at 4A.

There is a small possibility that you could bring that cell back up. But honestly, since the battery is brand new I would return it saying it is defective.
 
Yes, that instruction is what I listed, you just misunderstood the basis of the charger's instructions. There are two "C" ratings for the battery. The C you see on the label, which is actually a measurement of rate of charge/ discharge capabilities. The other, as I pointed out, refers to the capacity of the battery, listed on your's as 4000mAh. The instructions reference the capacity rating. 1C for your battery is 4000mA, or 4A. Hence charging at 4A.

There is a small possibility that you could bring that cell back up. But honestly, since the battery is brand new I would return it saying it is defective.

Thanks for clarifying on the charging rate. As I said I'm a noob to the world so it's good to build a better understanding. I assume I've not caused any damage by attempting it at 3A, it would just take longer to charge.

I'll contact the store to see if I can get a replacement.
 
I assume I've not caused any damage by attempting it at 3A, it would just take longer to charge.

Correct. You can certainly charge at a lower rate. With LiPo it is commonly accepted to charge at 1C, but there are some that can charge at greater rates. There really isn't a benefit to charging lower, in fact I believe there could be some detriments if too slow.
 
So will the 2S Lipo be OK with the AMP using the stock stuff, plus alarm? I was reading that a lot of folks had troubles with stripping gears and such on the forums here and elsewhere with stock and 2S? Any tips to be wary about? (about to do similar to as @RC_Noob )
 
So will the 2S Lipo be OK with the AMP using the stock stuff, plus alarm? I was reading that a lot of folks had troubles with stripping gears and such on the forums here and elsewhere with stock and 2S? Any tips to be wary about? (about to do similar to as @RC_Noob )

Breaking stuff largely boils down to use. For my own personal experience, my son and I have driven our Amp with 2s for many years without driveline failure. Your mileage may vary.
 
The replacement LiPo arrived today, gave it a go this morning and it's given a significant boost to the Amp. I also took delivery of a second battery.

How should I store these things at home, do they need to be kept in a LiPo bag (or is that just when charging?) - should I keep them at a specific voltage, my charger doesn't discharge or have a storage mode setting but I could part charge them and use the voltage alarm to check.

Thanks
RCN
 
My ammo tin arrived today for my battery storage should I drill some vent holes into it? There were some suggestions of that in the previously posted thread.
 
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