Let us wake everyone up ;)
So we know that lipos are to charged at 1C (which means you charge a 2200mah lipo at 2.2Amps max). The known exception is the new Hyperion lipos, which can be charged at up to 5C (users have not posted any long term side effects of the same, if any).
The question is, how fast can we charge the other types of batteries like regular NiCDs and NiMHs that we routinely use in RC. NiCD charging instructions typically say charge at 15mA overnight or something like that. If one's charger allows it, can we charge it at say, 1A ? (This is handy if you forgot to charge overnight, and you have only 1 hour before you head out to the field for flying!).
So what is the safe method for fast charging these (if any) ?
NiCds will tolerate some abuse but the down side is that slowly would loose thier life. The best charge rate is 1/10 C for NiCd and NiMh.
Having said that you can fast charge them upto 1.5 C which means you get a charged battery in an 1 hour. The thumb rule in slow charging being that you need to inpuit 1.5 times the Mah capacity of the pack/cell
The biggest ememy for NiMh is heat, if you cooked up your NiMh cells say good bye to them sooner or later.
Great ! Now let us take this a bit further (along with summarizing/clarifying what was said).
So it is OK to fast charge a NiCD around 1C once in a while ?
For NiMHs, did you mean the heat due to fast charging, or due to (say) keeping them in the sun ?
Sun will also heat up and you have a solution for that by keeping them in shade. But what is more important is the internal heat build up due to fast charge.
Yes once in a while it is ok to fast charge your NiCd
Also, what about fast charging NiMHs ?
What are delta peak chargers, and is it important to use them for these type of batteries ?
i have MAHA battery analyzer/charger for nimh/ni cd batteries,from my experiece i can say the better way to charge nimh/ nicd is 1/10 th of the battery capacity. my charger can charge the batterey in one hour, conditioning of the battery can take upto 48 hours, not much difference in performance after putting the battery in the conditioning mode.... heating up the battery is the main problem, always go for standard charging.
santhosh
more info abt maha chargers
www.mahaenergy.com
santhosh
QuoteSo it is OK to fast charge a NiCD around 1C once in a while ?
This would be acceptable if the battery was - at least - close to being fully discharged. Charging an almost fully charged battery would certainly cause it to overcharge and therefore overheat.
Fast charges for NiCd or NiMh at 1 or 1.5C should only be used if the charger has some sort of detection (e.g. peak). Or the battery should be discharged before starting.
Sanyo fast charge Nicd can be easily charged at 2c and higher and so can some high discharge Nimh like the Intellect Battery 3600 .
this is my story and I am sticking to it.
Shortening of battery life is largely irrelevant to rc'ers who will sooner get bored of the same
old pack and dump it for the latest brand of XYZ super batteries.
Quote from: saikat on September 04, 2009, 05:16:16 PM
this is my story and I am sticking to it.
Wow :o Sahil is in a bad mood today :P ;D
Updated: I meant to say Saikat !
How many packs have we seen made of Sanyo fast charge cells, and BTW I still fly with my old packs which are well taken care off.
And then when you are putting in facts it applies to majority of the case there would always be exceptions to the rule.
For eg the rule with most LiPo is to charge them at max 1C but then you also have latest packs which can be charged at 5C. Then again a slow charge never harms but fast charge has the potential to do so
BTW This is my story and I am sticking to it through thick and thin ;D ;D ;D ;D
QuoteSahil is in a bad mood today
is saikat's name also sahil 8-)
how many of you guys still use Nicds or Nimhs ?? i have been charging my lipos at 1.5c n problems still get the same run time and i have personally observed that a slow charged Nicd/Nimh will have more rum time then a pack charged at .7c or higher rate.
sahil
Quote from: sahilkit on September 04, 2009, 06:52:49 PM
QuoteSahil is in a bad mood today
is saikat's name also sahil 8-)
No I am Saikat - although you can call me "James Bond" if you wish ...
Re: Flyingboxcar's post ...... I am unable to think of an effective rejoinder at the moment
so I concur ..... for now......
QuoteSanyo fast charge Nicd can be easily charged at 2c and higher and so can some high discharge Nimh like the Intellect Battery 3600 .
As flyingboxcar says, exceptions are just that. Both of us are referring to common usage. For example, Sanyo ENELOOP NiMh cells have a very low self discharge rate - 15% over 6 months as compared to typically 5% 1st day + 1%/day after that for what most of us use. Would you say that NiMh have a low self discharge rate, therefore?
QuoteShortening of battery life is largely irrelevant to rc'ers
Can we take a poll on this one?
I will be getting a 3000Mah battery with my e revo 1/16.Any idea on how I should charge it?IT says that it will take approximately 6 hours to charge it.ANd I don't think that the stock charger is adjustable.How can I do six hours of watching over the battery when I go to school at 9 and come back at 4??? :help: :help: :help:
Set an alarm and ask your parents to switch it off when you are away. Note that some charges discharge the cells if cells are not removed from them.
Another way is to buy a simple accucel 6 which is accessible from HC for 1500 bucks including shipping and discounts. Or buy one locally if your customs office is strict / you dont have access to paypal or CC.
These charges help you set up the charging current and help you charge in less than 2 hrs safely. Though cells charge cycles reduce if you charge fast. But since cells are cheaper these days, you dont have to worry abt charge cycles. :thumbsup:
hi everyone.
Any nicad or nimh battery has a standard charge rate of 1/10 of the capacity, so if u have a pack which is 2,000 mah, u can charge it at 200mah for 10 to 12 hours, this is standard, If any pack does not have "FAST CHARGE" stamped on it, u cannot exceed that standard charge rate mentioned above, u r damaging u pack, and one day u will loose ur plane. Now, in the recent past, nimh and nicad fast charge have entered the marked, and they will have fast charge positivey printed on it, cause if u fast charge a standard battery, and it catches fire and burns ur house down, u cannot take the manufacturer to court. that is the legal implication. for the rc guys, if fast charge not printed, follow standard charge settings.
happy charging
Ramesh Tahlan
But dosent High Discharge nicd generally means they can be fast charged? I have never come across any nicds/nimh that mentions fast charge printed on the battery(probably I havent bothered to find one), But I have fast charged them(1/3 C charge basically) w/o problems and used them till I got hold of LSD Nimhs.
May be I Am wrong. Lets see what others who have used NICDs have to comment on this...
The problem Iam aware of is that one should not Over Charge Nicd or especially NIMH. which will hamper the life severely.
Vinay,
nimh and nicad batteries that can be fast charged have it written on it specifically, to keep the user safe from explosin and fire. So take care and be safe. i have nimh pack Hydramax ultra, 4200, high discharge, and specifically written STANDARD CHARGE 11 HOURS ST 420 MAH. So high discharge does not automatically mean high charge, now look at DuraTrax 9.6V 5000mAh, it has specifically printed on it that u can charge it at 4,000 mah. So please be careful. if fast charge figure no written, the default it 1/10 of the capacity at is universally understood, not required to be written.
Ramesh Tahlan
Quote from: iamahuman on July 15, 2010, 06:11:36 AM
I will be getting a 3000Mah battery with my e revo 1/16.Any idea on how I should charge it?IT says that it will take approximately 6 hours to charge it.ANd I don't think that the stock charger is adjustable.How can I do six hours of watching over the battery when I go to school at 9 and come back at 4??? :help: :help: :help:
Unfortunately this discussion is not for your charger, If you are using the Traxxas included charger. You cannot select the charge rate. Best to get a basic charger like a Hobbycity or something
I always use 1C current rate.
I follow the recommendations on the battery. Many/most NiMH and NiCD cells specify the rate and time, and it is usually in the 1/10C range as Ramesh sir mentioned.
Fast charging is OK every once in a while, but following the recommendations would keep the battery in top shape for much longer.
Quote from: rameshtahlan on July 15, 2010, 10:01:02 AM
hi everyone.
Any nicad or nimh battery has a standard charge rate of 1/10 of the capacity, so if u have a pack which is 2,000 mah, u can charge it at 200mah for 10 to 12 hours, this is standard, If any pack does not have "FAST CHARGE" stamped on it, u cannot exceed that standard charge rate mentioned above, u r damaging u pack, and one day u will loose ur plane. Now, in the recent past, nimh and nicad fast charge have entered the marked, and they will have fast charge positivey printed on it, cause if u fast charge a standard battery, and it catches fire and burns ur house down, u cannot take the manufacturer to court. that is the legal implication. for the rc guys, if fast charge not printed, follow standard charge settings.
happy charging
Ramesh Tahlan
Sorry, but NiMh or NiCds do not - normally -catch fire if charged at an excessive rate for too long. They have vents which will release the internal pressure when the cells become very hot due to the high rate. This will at least reduce battery capacity/life, but thats about it.
The 0.1 C rates is a "safe" figure that will not cause problems even if left to charge indefinitely. Maximim rates vary significantly with different manufacturers. Also, I have found that the SANYO "Eneloop" cells do not take kindly to even a 1C rate. Their "normal" ones ar OK.
I had a pack that i forgot to remove from slow charge and it melted its shrink tube around it and there were black deposits around that place
Then you had something wrong with the charger or battery.
Would you give details of the charger and battery? (Current rating of both).
It was a chinese battery 6v 700mAh and the charger came with it (It was from a nitro buggy)
Quote from: Sahevaan on July 15, 2010, 08:59:00 PM
It was a chinese battery 6v 700mAh and the charger came with it (It was from a nitro buggy)
There you go! Obviously not intended for 0.1C charge! I am sure there would have been NO specs with the charger. How have you assumed/deduced it's charging rate?
never forget the golden rule, if it is not printed fast charge, u r only to charge at 1/10 of the capacity, and if they r designed for fast charge, the fast charge rate will be printed, so just follow the convention, and u will never go wrong.
Ramesh.
oh thanks vinay, that was exactly what I was thinking of.An alarm.Just one more question.Do the batteries get damaged after one 'bad' charge cycle?say, overcharging?
No. But they reduce the charge cycles and slightly reduce the capacity each time you BAD charge them. But if you BAD charge them way too much, then its a goner.
EDIT: AFAIK overcharging NIMH will reduce the Cycles greatly.
I've checked the Turnigy accucel chargers in HK site,they have mentioned the charger input voltage as 11-18 v tat means can't we connect tat in our normal home electric plug? And also mentioned as power supply not included..
You cant, U need a minimum 5 Amps power supply at 12 V or Use a UPS battery if u have.
Krish,
this is obviously a DC charger, and why they say power supply not included, is cause, u do get seperate power supplies, which let u plug ur DC charger into the wall outlet. Now AC/DC chargers are available. and the AC part in placed inside the charger. So u could have a DC charger, and take it to the field plug it to ur car battery, and when u at home, just plug in the power supply and use the wall outlet.
Ramesh
Ramesh, I had a Thunder AC6 Charger and the AC to DC switched supply was bad out of the box. It was spitting out 106 V AC instead of 12 V DC. I used to get shock when I used to touch the charger. The earthing part of the built in supply was good, but the switched supply was bad. Thank god Lipos didnt explode. Now I use a computer power supply to power the AC6 charger.
My Bad Luck with it >:(
Could not send it back to NitroPlanes.com as shipping back would become expensive.
With 106V coming out of the supply, it would be the charger that would blow up first. How did you discover this?
Digital voltmeter. Touching the charger body or the pin outputs was giving me slight juice. Then I opened the charger removed the smps and measured it independently and it still showed the same >:(
Sorry it was around 86 V. Here is the thread for the same
http://www.wattflyer.com/forums/showthread.php?t=52223
http://www.rcgroups.com/forums/showthread.php?t=1157627
So the power supply is an AC to DC converter?
Yep, it is same/similar to the one used in many laptops (for the 5A ones).
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6256 (as a sample)
Then can I use my Dell laptop's power supply with the turnigy accucell charger?
You have to check the ratings... output 12V at around 5A. If that is satisfied (most/many do), you can just add the right connector and use it.
I have a printer (670C) adapter which says output = 30 V 400 mA 12 VA
Any idea what this means and can this be be used with the Turnigy accucel charger http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11444&Product_Name=Turnigy__A-6-10_200W_Balance_charger_&_discharger
doc
Looks like NO. The rated input voltage for that charger is 12V to 18V, and the adapter output seems to be 30V, which i way over the range.
ok's. Then will look at something else. ;D ;D
Quote from: flying doc on July 17, 2010, 12:06:34 AM
I have a printer (670C) adapter which says output = 30 V 400 mA 12 VA
YOu need atleast 5 Amps for a 50 watts charger. here it says only .4 Amps which is way way less. I dont understand why they again mention 12VA :headscratch:
That is just the product of volts and amps 30V x 0.4A = 12VA. For DC, that is the same as wattage, right ? So they wanted to specify wattage/power also ?
No, that cant be true. 12VA means 12 V at 1 Amps and cannot be 30V at 400 mah. Both are different. They may be of same wattage, but whats the meaning is specifying it in terms of wrong voltage.
I don't see the point about "wrong voltage" :headscratch:
http://whatis.techtarget.com/definition/0,,sid9_gci539345,00.html (quick search result to refresh my memory)
VA is just the product of current and voltage, that's it ??!?!?
My mistake, You are right. ;D