A proper forming charge takes at least 24Hrs @ C/10. NiCD cells benefit from this more than NiMH.
Leaving either technology on charge, even at trickle rates, is not advisable. One has to realize that the original circumstances that lead to trickle charging regimes was based on back-up power systems, this meant the primary powr source was used to maintain the backup system. Generally these packs were replaced before their service life was reached (which was significantly shorter than actual lifespan). Once again...trickle-rate charging form dendrites (crystalline cell growth from the reactive constituents), which can pierce the separator layer and cause soft shorts. Although (most of) these can be burned off by aggressive discharging or cycling, not always. Extended charging at trickle rates removes service life from NiMH and NiCD cells. Quoting Cameron <[EMAIL PROTECTED]>: > Jim, > > Does the charge HAVE to be stopped after 12~16 hours of charging? I have an > Alpha4 charger which charges until the NiMH battery peak had been reached > and then it switched to C/20 indefinitely. > > Thank you for the info. > > Cameron > > -----Original Message----- > From: Jim Laurel [mailto:[EMAIL PROTECTED] > Sent: Thursday, May 19, 2005 1:30 PM > To: Cameron > Cc: rcse > Subject: Re: [RCSE] GreatPlanes Triton charger > > Cameron, > Formation charges are required for preparing new NiMh packs. You > simply charge the pack at a current level equal to 1/10th of the pack > capacity for around 12-16 hours. For example, a 1000mAh pack would be > charged at 100mAh for 12-16 hours. A 2200mAh pack would be charged at > 220mAh. On my Hobbico charger, I use the 250mAh setting. It's not too > critical. Just try to get close. > > Due to manufacturing variances, all battery cells of the same type are > not truly identical. When put together in a pack and charged, some > will charge faster and peak early, which will fool most modern peak > detecting chargers, leaving the laggard cells in a state of partial > charge. Slow charging at capacity/10 allows all the cells in a pack to > get fully charged without causing a thermal crisis in the cells that > have peaked early. After 2-3 charge/discharge cycles like this, the > cells reach a sort of equilibrium, charging and discharging together at > relatively similar rates. This is what you are trying to achieve with > the initial formation charges. You want all the cells in your pack to > peak at the same time, and discharge at the same rate. Once the pack > is conditioned like this, you can use the peak detecting fast chargers > with no problem. > > Cheers, > > --Jim > > On May 19, 2005, at 10:12 AM, Cameron wrote: > > > Jim, > > > > What is formation charges? Does this relate to NiCad, NiMH, > > Lithium-Ion or > > Lithium Polymer batteries? > > > > Thank you. > > > > Cameron > > > > > > -----Original Message----- > > From: Jim Laurel [mailto:[EMAIL PROTECTED] > > Sent: Thursday, May 19, 2005 12:46 PM > > To: Jon Stone > > Cc: soaring@airage.com > > Subject: Re: [RCSE] GreatPlanes Triton charger > > > > Jon, > > Thanks for the tip on seeing total mAh! That helps. > > > > Yes, I set the timer, which goes up to 960 minutes (or thereabouts), > > which translates into 16 hours - perfect cutoff for formation charges. > > The downsides to using the Triton for this are: > > > > 1) You have to remember to reset the delta peak, or you will fry the > > next pack you try to quick charge! > > 2) The Triton only goes down to 100mAh, so you can only do formation > > charges on packs of 1000mAh capacity or more. It's useless for > > formation charges on, for example, handlaunch packs. > > > > I keep a Hobbico R/C Multi Charger around, which has current settings > > ranging from just 25mAh to 500mAh. I use it all the time for slow > > charging my RX packs and transmitters fitted with 2100mAh NiMh packs. > > Another plus is that it runs on 110VAC - very convenient! It's a very > > useful item at just $29.99 new from Tower. Everyone could make good > > use out of one of these simple inexpensive devices, IMHO. > > http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL331&P=7 > > > > You can use a timer with it, but the catch is that a small design flaw > > in the charger allows the pack to DISCHARGE into the charger itself > > when power to the charger is cut off. I made a few adapters with > > inline rectifier diodes from Radio Shack that solves the problem. > > > > --Jim > > > > > > On May 19, 2005, at 6:06 AM, Jon Stone wrote: > > > >> Jim, > >> > >>> The Triton is a great charger for the money. There are a few dumb > >>> things about the software, such as the way it erases the total mAh > >>> put > >>> into a NiMh cell after it goes into "top-off" mode, but by and large > >>> it > >>> is a very good unit. And again, you can't beat the price. > >> > >> You can press the right square button after the charge is done and > >> review the Mah the charger put into the battery, before the top-off > >> charge. Same way you can review up to 10 charge/discharge values. > >> Have to do it before disconnecting the pack, or before pressing the > >> left button, though. > >> > >>> I use it for all sorts of cells, including NiCd, NiMh, and LiPo. It > >>> can even be tricked into doing a formation charge on NiMh packs by > >>> rning the delta peak setting up really high. > >> > >> Thanks for the trick about forming packs. I had not figured that one > >> out. I had been keeping another charger around just for that feature. > >> I assume you also set the timer to the # of hours you want to charge. > >> > >> Jon > >> > > > > RCSE-List facilities provided by Model Airplane News. Send > > "subscribe" and > > "unsubscribe" requests to [EMAIL PROTECTED] Please note that > > subscribe and unsubscribe messages must be sent in text only format > > with > > MIME turned off. Email sent from web based email such as Hotmail and > > AOL > > are generally NOT in text format > > > > > > > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and > "unsubscribe" requests to [EMAIL PROTECTED] Please note that > subscribe and unsubscribe messages must be sent in text only format with MIME > turned off. Email sent from web based email such as Hotmail and AOL are > generally NOT in text format > Simon Van Leeuwen PnP Systems - The E-Harness of Choice Radius Systems Cogito Ergo Zoom RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
