I want to hook up a fast charger to my JR Sport S400 using the external charging jack. The internal battery connection is very weak and almost looks like it was intentionally designed to break off, so I would prefer to use the external jack. Does anyone know for sure if this can be done safely without damaging the charger?
I cannot answer your question specifically...but...the one thing that my Spektrum DX6 manual makes extremely clear .......is that the center-post on the charging circuit is the OPPOSITE polarity of "normal" chargers.
I think JR and Spektrum are built by the same company...Sooooo...I'd be very careful to check out the polarity of your setup...prior to adding any non-standard charger. regards, Rich
I was going to wire this part myself, the main issue that I need to verify is whether or not feeding 3000 ma though this connection could damage anything designed for 50 ma. The loest setting on my fast charger is 500 ma.
Fast charging is often thought to be "harder" on transmitter and receiver batteries and could cause a premature end to the usuable life of the battery.
My personal experiences have indicated that there is no real practical problem with quick charging at rates from .5 to 1.0 amp with normal 600Mah or 700Mah 4.8v and 9.6 NiCd packs.
I have a number of transmitter and receiver batteries that have been quick charged frequently for the last four years, and these batteries still discharge at or above their rated capicity. Quick charging them at 1000Mah hasn't reduced their useful life.
I haven't tried quickcharging these batteries at 3000Mah charge rates, however, but I suspect that tripling the quick charge amperage might be more likely to damage the batteries.
On Sun, 03 Aug 2008 08:32:39 -0500, Peter Olcott wrote these words of wisdom:
Fast charging Nicads or NiMH's generates heat. The faster you charge them, the more heat is generated. Charging a 600mAh battery at 1amp will not generate enough heat to degenerate the batteries internal makings. Charging a 600mAh battery at 3 amps will generate enough heat to make the battery start breaking down. Eventually the battery will develop an internal short rendering it useless. It won't hold a charge if it will take a charge at all. 1 amp charge rate is only 1.6 times the batteries capacity you can actually safely charge a battery at 2 times it's capacity which would be 1.2 amps for the 600mAh. 3 amps is 5 times a
600mah batteries capacity. Much too high.
If you have a NiMH battery pack in your radio, then look at the pack and see what it's rated capacity is, then multiply that by 2 and that would be the maximum I would charge it at. So for example, if your pack is 1800 mAh , then 3.6 amp charge rate would work. IIRC, JR radios have a fuse in them to prevent high amperage damage, or was it to attempt to prevent damage from a charger being hooked up backwards since JR wired the charge jack backwards from everyone else.
I have a couple Futaba Tx, and a Hitec, all with the standard nicad 600 milli amp hour batteries. I simplify by using a Hobbico quick field charger for everything. I think it charges at about 1 amp.
I have not seen any problem with using this exclusively for all TX's and Rx's for the past several years, and have not found the need to change any battery packs. I fully discharge, cycle, then discharge each pack while charting each battery's capacity every other year or so at the start of the season, and they are all still close to full specs.
IMHO, using a low amperage fast charger that .... (important stuff coming next) .... _shuts off at peak charge_... is way better for the cells than putting them on a slow charger, then guessing how long they need to fully charge, but yet not over charge.
So, go for it, use a lower setting on your charger, use standard jacks with attention to how the polarity is rigged.
If it were me with different transmitters with different charge configurations, I would make up a different adapter for each radio, plainly labeled and even color coded with the style and polarity required for the particular radio it goes with.
You only would have to let the magic smoke out of just _one_ Tx (by hooking the charger up wrong) before the parts for the adapters and the effort to make and use them would look very cheap, and very attractive.