For anyone in the know, I need to replace a lead acid battery from a sierra sound board. I have read that a NiMH 6v battery can be and does get used with success. This loco has the optional charge jack as well. Everyone says that the NiMH 6v can be used as a direct replacement and the sierra board will charge it but no one covers the optional charge jack. Is it safe to assume that the the lead acid 6v wall wart charger will charge a 6v NiMH battery as well?
Thanks
Terry
I got fed up with those batteries going dead or forgetting/neglecting to charge them, so I’ve done away with them entirely. Instead, I replace them with three 2.7 (2.85 volt peak) 6 - 10 Farad supercaps wired in series. You can leave the charging jack in place or not because you will never use it again.
Initially, you get no sound until ~9 volts on the rails. Then the cap begins to charge and the sound kicks in. If you cut the power the engine, or run below the charge voltage, it will continue to produce sound for ~1-1/2 minutes (with 6 Farad caps) before it makes a couple whoops then goes quiet.
The charging system in the Sierras seems robust enough to handle this. I’ve done a few with no failures.
That’s a cool idea.
But, its not my loco and they want the battery replaced.
I’ve changed out my lead acid for a NiMH. See here:
http://tjstrains.com/1019/replace-gel-cell-with-nimh-battery/
Best,
TJ
After you install the NiMH battery can you still use the wall wart charger to charge the battery off the track?
Terry, maybe. NiMH batteries should not be charged too fast nor overcharged. A wall wart probably will not do either, but since its a “dumb” charger you won’t know for sure. I bought an inexpensive “smart” charger when I replaced those pesky lead acid batteries for NiMH batteries on my Sierras. It will only charge at the set rate (controlled by a knob) and when the battery is charged it switches to a trickle charge mode.
Terry… I’ve used this battery as a replacement for the Sierra 6 volt gel cell. it needs the small plug replaced or just wire it negative to pin 2 and positive to pin 4. It may heat up a bit when charging but it does work…
http://www.megabatteries.com/item_details2.asp?id=14011&cat_id=158&uid=1315
Also, this is the one I now use… It works just great as most of my R/C installations are done in follow box cars where there’s lots of room… And it’s a lot less expensive than the smaller 6 volt gel cell… Been using these for years and have never had to replace one yet…
http://www.allelectronics.com/make-a-store/item/gc-612/6-volt-1.2-ah-battery/1.html
Yes, it may be a bit of overkill, but it works extremely well… Again, I connect negative to pin 2 and positive to pin 4 and not use the small green plug. Polarity is most critical…
I’d worry using a 4.8 volt battery in a charging circuit designed for 6v. That has got to kill the battery pretty quick.
The bigger 6v gel cell might take longer to charge up from flat, but it probably gives you a lot of run time.
Greg
I’ve been using these as a direct replacement for the Sierra gel cells for a couple of years now with no problems. I use the same charging jack that came with the system but use the recommended charger for the NiMh batteries. I rewired the Sierra charging plug to the new charger. They last much longer and I am very happy with them.
http://www.all-battery.com/6v2000mahnimhsidebysiderxreceiverbatterypackswhitecconnector11106.aspx
Doc Watson
Todd, where did you get the capacitors? this sounds like a good option.
ebay
Don Watson said:
I’ve been using these as a direct replacement for the Sierra gel cells for a couple of years now with no problems. I use the same charging jack that came with the system but use the recommended charger for the NiMh batteries. I rewired the Sierra charging plug to the new charger. They last much longer and I am very happy with them.
http://www.all-battery.com/6v2000mahnimhsidebysiderxreceiverbatterypackswhitecconnector11106.aspx
Doc Watson
I bought the same style, and rating, battery at Radio Shack several years back. My F3 and RS3 don’t seam to have a problem with them. But I do use a smart charger for them, to top them off before a run.
I applaud all of you who have the good sense to use a smart charger externally.
I do wish to make a point clear, though, there is a “charging circuit” on board, which should recharge the battery when running… that circuit is not “smart” and when you change the battery system radically (like the voltage) then you can run into issues, like over charging or under charging, or too much or too little current.
Regards, Greg
Greg, that’s why I tried to match the voltage, and use a smart charger. But I find with my NiMh batteries that I have to “top them off” before a run. Either the Sierra isn’t charging them fully while underway, or they are slowly discharging in storage, or both. I suspect they aren’t getting a good charge during a run, since my trains do not come anywhere close to traveling at Mach 1
NiMh batteries have fallen from favor due to a high self-discharge rate. That, combined with easier damage from over-charging sent people either back to nicad or forwards to li-ion.
Yeah, I think there’s only significant charging close to mach 1 !
Since it’s not a smart charging circuit, it’s most likely low current… I have the circuit diagram here somewhere, but only checked it to see that it was “dumb”.
Greg
Todd Brody said:
I got fed up with those batteries going dead or forgetting/neglecting to charge them, so I’ve done away with them entirely. Instead, I replace them with three 2.7 (2.85 volt peak) 6 - 10 Farad supercaps wired in series. You can leave the charging jack in place or not because you will never use it again.
Initially, you get no sound until ~9 volts on the rails. Then the cap begins to charge and the sound kicks in. If you cut the power the engine, or run below the charge voltage, it will continue to produce sound for ~1-1/2 minutes (with 6 Farad caps) before it makes a couple whoops then goes quiet.
The charging system in the Sierras seems robust enough to handle this. I’ve done a few with no failures.
I like this idea. Just before I left Florida for the summer I picked up a used Aristo Pacific that had a Phoenix sound board in the tender. I believe the battery is shot. I wonder if caps would work for the Phoenix? Also, I run DCC at about 20v and wondering if this approach would be compatible if I included a diode bridge to rectify the situation? Todd/Greg any comments?
Since I have constant current on the rails, the battery or caps would only be for those pesky quick pickup dropouts due to dirty track or plastic frogs.
I’ve never tried it in a Phoenix.
If you are running DCC, you should not need the battery at all, as I understand…
Yes, if you get sound dropouts, you could certainly use a set of supercaps… you might want to put a surge limiting resistor setup on the caps if they are high in capacity, I don’t think anyone has really validated the max current draw from a “depleted” battery that the charging “system” can handle.
(I never get dropouts on my layout, but then I use a different and more modern sound decoder).
In your case, in my opinion, it beats the heck out of a battery that will eventually crap out.
Regards, Greg
Thanks guys!
The really weird thing about this tender is that each truck has two pickup wires connected to the same rail. i.e. the front truck both wires are left rail, the rear truck, both wires are the right rail. Is that standard on the Aristo long tender? When I received the Pacific, it shorted out on both DC and DCC. I rewired it and the sound is working, but I only had a couple days with it before leaving for the summer, and the tender power pickup had a couple dropouts.
When I return to Florida after the summer, I will try and figure this out and add a cheap low amp decoder to the tender sound, and a more robust decoder in the loco. May even share power pickups between the two.
Mike McLaughlin said:
Thanks guys!
The really weird thing about this tender is that each truck has two pickup wires connected to the same rail. i.e. the front truck both wires are left rail, the rear truck, both wires are the right rail. Is that standard on the Aristo long tender?
That became standard practice on a lot of their stuff including the revised heavyweights. Other manufactures have also done this (e.g., my Accucraft galloping goose).
Many a person has created a short by removing and replacing AristoCraft axles (the wrong way) without realizing this.