I have a new battery pack consisting of 12, 1.2v NiMh sub C cells
The OEM charger for this pack is 21v, 250mA…but I was using a 24v, 400mAh charger
BUT…the OEM battery pack was NiCd cells (1.2v X 12 sub C)
Problem is, it seems the voltage is dropping instead of going up during the charge cycle. Full charge is indicated by a red light turning to green.
After 24hours charging it has not turned green and the voltage I measured this morning was higher than it it is now after about 5 more hours on charge.
Taking NiMh hot from charging they get about 1.5V, resting after a couple hours later at 1.4V then slowly get to 1.35V over next days
If you charge em with 21 or even 24V you cook the batteries dead
If you dont charge em with delta V you should use 1.5V tops per cell and only charge em
Time=capacity/charge current*1.4
Charging too long kills the battery quick by overcharging
So for a 12x2Ah battery pack simple charge at 400mA
18V and 7 hours
The batteries wont get 100% full but you avoid bad overcharging
You need to buy a proper battery charger…not just hook them up directly to a constant power source.
The batteries are probably already damaged from charging like that.
There is no difference between NiCd and NiMh charge characteristics or voltage
If you dont use a smart charger you damage the batteries and they wear out fast especially when overcharged
There is no fix voltage you can plug the battery to and it will charge to 100% and stop
A lead acid battery can be plugged on a fix voltage and it will not harm the batteries life
lithium can be charged with a constant voltage, but if the battery is full you need to unplug it otherwise it wears down the cell
NiMh batteries need a smart charger which can detect the voltage drop and terminating the charge, if not termination it will wear down the cell really bad
I think that’s an issue with the Chinese knock off ones and not the authentic SkyRC units.
I’ve had 3 of the authentic SkyRC units and never had that problem although the flimsy USB data ports failed on all 3
They do that so they save cost and you can buy a new vacuum after a few years.
Buy a hobby charger to charge batteries properly.
The closer the battery is to charged the less voltage it provides so that you can fully charge the battery without exceeding or damaging it.
You will notice that in the instruction for appliances like this (nicd or nimh powered hand vacuums, cheapo toy rc cars, bargain basement rechargeable drills) they ALWAYS say unplug the device as soon as it is charged. They cheap out on the charger and it will damage the battery if left on the charger. Hoover rechargeable floor cleaner falls into this category.
I see your point. Didn’t know SkyRC was just another knock off of someone else.
I do know that SkyRC will ignore you if you have a problem during the so called “warranty (joke)” period.
Unless you get the seller you bought it from to help you you’re SOL
Welp,
I tried using my hobby charger but no luck….
Every time I tried to charge the battery pack I got an error that said “Connection Error, Check Main Port”.
The User Guide says this error means the battery connection is wrong.
I tried NiMh and NiCd and got the same error. There is no balance port connection for this NiMh battery pack….(obviously)
It’s 12 NiMh cells connected in series. So the charger is thinking 1.2v but it’s actually 14.4v.
It might work if I charge it as a 4S LiFe because that is 14.4v
I checked it every way possible and everything was fine. My conclusion is that there is some circuitry in the appliance itself that is preventing the hobby charger from working with it. The only way I think I could use my hobby charger to charge this battery pack is to remove it every time I want to recharge the pack connecting directly to the battery pack…… and I’m not doing that.
When I plug in the OEM wall charger it charges normally.
So, I’ll just leave it plugged in over night after using it and unplug it in the morning. If it slow cooks the batteries oh well.
Usually hobby chargers are limited to 8 or 10 nimh cells…
You also do not need a balance port, nimh batteries only need to be connected with the + and - and the charger can auto detect what voltage to charge to.
so you plug the power supply in the wall charger, but connecting the Imax to the wall charger gives an error
there must be some sort of circuitry in it, but measuring lower voltage after 5 hours additional charging means it has no smart charger built in overcharging the battery
also the voltage drop of NiMh cells is 40% smaller than on NiCd ones so the charger may miss termination