Suggestions for good battery chargers for Sanyo Eneloop rechargeable batteries.

[blr_p]

heh, you're gonna have to give us more info, how many times has it been used ?

what did you do to find out its 200mah only ? since you have the c9000, did you use the break-in mode to find this or other ? nice 39hr wait for the result.

 

[apextwin146]

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:

I dont find this comparision really worthwhile.
lowest cost New laptop - 10K
Lowest cost batteries - 100 Rs Duracell
So while i can buy new batteries while travelliing i certainly cant buy a New laptop while travelling. Apart from that all the important data is on your laptop while a battery charger just charges. So portability is affected by priority of its primary function too. Though its quite pointless to discuss on this point any further

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.
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.

Thanks for providing a wealth of information in there. Repped you for the same .
Also what are your views on Maha MH-C800S . I am getting quite a Good deal on this one but cant seem to find proper functional information regarding this. Frankly no offense but i somehow find Maha MH-c900 a bit difficult to use based on the user reviews hence i need to knw if Maha MH-C800S is easier to use. It also charges 8 in a row so thats a plus point too.What do you think?

 

[blr_p]

Also what are your views on Maha MH-C800S.

its 20% cheaper than the MH-801D

The only differences i can see are the 800S takes twice as long to charge than the other and does not come with a backlight. The power adapter as you can see is much smaller than that of the 801D. Otherwise everything else is the same.

Your're still going to need your BC-900 periodically for cell matching as the 800 series just charge and tell you when done, they do not tell you how much capacity a battery actually has. Now if you start with a new batch of batteries chances are they will all be of a similar capacity but as time goes the differences will become more pronounced, its recommended to pair batteries that are within +/- 5% of each other otherwise the weaker gets reverse charged and the stronger works harder, thereby spoling both. The other point is your app will work as long as the weakest cell so one bad cell amongst good will result in shorter app time.

I am getting quite a Good deal on this one but cant seem to find proper functional information regarding this.

See this. The 800S interface seems similar to the BC-900, place first battery in, decide whether you want a default charge or a soft charge or a recondition then place all the rest and the same program will run for the lot.

So it defaults to a 1000ma charge which is 0.5C for a 2000mah battery or 500ma on the 'soft' mode which is 0.25C. Usually all you would need is the default mode, even if the batteries are old or not good quality and heat up too much then you would use the default mode as the 'soft' or 0.25C might be too low to detect termination and the bigger risk is the charger does not stop charging and overcharges. I think the only time you want the 'soft' is for AAA.

You would need to babysit them on these different settings to see whether it terminates properly. The major problem is not terminating in time rather than higher charge rate. Higher charge rate is recommended as it gives a clearer termination signal to the charger to stop and then switch over to trickle.

Frankly no offense but i somehow find Maha MH-c900 a bit difficult to use based on the user reviews hence i need to knw if Maha MH-C800S is easier to use. It also charges 8 in a row so thats a plus point too.What do you think?

Initially, c9000 is little harder to use compared to the bc-900 but i accepted that in exchange for more accurate reporting and safety. This always happens when engineers get more say than designers. My philosophy is form follows function. It's often you don't get pretty products with this philosophy but the products do the job and do it well.

Having said that there are a cpl of improvements that could be made
- if there was a way to log data via a serial or USB port it would be nice.
- the biggest problem with these chargers is the lack of any flash memory whatsoever, so if you're in the middle of a long cycle and have a power cut then everything is lost and it restarts from the beginning :|

So its essential you have uninterrupted power to operate them if your power is erratic. Quite a few seem to think that any APC UPS like that used for a PC will suffice, but most of these ppl are referring to an interruption of a few seconds to say 5 minutes as opposed to running the charger on the UPS for hours together which is a different issue.