axeman said:
If in Mumbai, call up JJ Mehta, he used to stock Panasonic Fast Chargers, very small, slim and perfect for the camera toting traveller. Charges my 2100 NIMH units in 4 hrs flat. Charge 4 AA or 4 AAA or any combination at a time. Can charge single units also.
4 hrs flat means it does 0.25C, does it do any trickle charging beyond the 4 hrs ? or is it 0.5 C with 2 hrs on trickle.
TechHead said:
Picked up a 15 minute Sanyo charger from Bangkok. Quite nice.
Cost around 2.6k with 4x2500mAH batteries.
This is the ultra-fast charger, don't expect your batteries to get beyond 75% capacity with them. Also as its designed for 2500mAH make sure you don't use it with batteries of lower capacity as they will be overcharged, not a good thing and is the #1 killer.
apextwin146 said:
Though your point about voltage is correct but the size of this thing would be a obstacle in achieving the portable functions as you mentioned.
Dunno, its bigger yes, but thats because the designers wanted to have an adequate air gap so that the batteries could stay cooler at higher charging rates. Any avg laptop is much heavier and bigger than this charger yet its never considered not portable is it, so why the hangup :huh:
apextwin146 said:
The default charge rate of 1000mA is pretty high i think. Again its very theoretical that High rates decrease the life of battery but still i would want something like 200-500 which is provided by most of the chargers.
The battery manufactuers recommend a 0.5-1.0C charge rate. Now what the 'C' stands for is the capacity of the battery, let's say you have a 2000mAh battery,
- a 0.5 C charge rate means a current of 1000mA and it would take 2 hours to charge up,
- a 1.0C charge rate means a current of 2000mA and it would take 1 hour to charge up.
- a 0.1C charge rate means a current of 100mA and it would take 10 hours to charge up.
The same applies of course during a discharge in an app as well, if you run with a constant load and the batteries are done in 2 hrs, your load is 1000mA.
Now whats missing in this scenario is the charging efficiency, upto 70% capacity the battery accepts charge very efficiently, once you cross the 70-75% mark it becomes harder to charge it at higher currents so that's when the 'intelligent' chargers switch down to a trickle charge, say it was charging at 0.5C , the charger would then drop to 100mA for a cpl of hours to increase capacity from 75% to 95%. This is why when someone posted here earlier that with a 1-2 hr charge rate he got fewer pics than with a slower charge rate.
Now a lot of chargers out there are 'dumb' chargers, they work with a timer and are very small as there is nothing else to detect an end-of-state charge. They tend to be gentle taking anywhere from 2 hrs to 16hrs and this is primarily a 0.5C - 0.1C. What needs to be realised is these chargers should only be used with batteries of the same capacity they came with, if you get a charger with your new 2300mAH or higher batteries, you do not want to use it with older sets of lower capacity as it would be overcharging them. This is where the flexibility to set the charge rate of an intelligent charger comes in.
When a NiMH rechargeable battery approaches full there is a slight drop in voltage across its terminals, the higher the charge rate typically 0.5C -1.0C the more noticeable it is to a charger looking for this sort of drop. This is known as a negative delta V, the maha uses this method to detect a battery is full and is why they recommend a higher charge rate not to go below 0.5C on charge rates. The BC-900 uses this as well too.
apextwin146 said:
I cant comment on the number of steps required to set the individual charging rates as i dont have one. I just wrote what i read from the reviews. Maybe you can shed some light on that.
There are 5 modes, if for some reason you want to use 100ma either to charge or discharge or cycle for all four then there are 40 presses. But the buttons have good feedback and response is almost instant so you can punch those in quite quick.
adder said:
@blr_p
Where did you buy it and what was the damages
Had a friend bring one over from the US, it worked out to $58 shipped to his place from thomas distributing.
eneloop battries are available locally, other batteries with higerrating sitll crap out in a month max! even if u dont use them! I gota La Crosse from KMD long back!
