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RailPro => RailPro Specific Help & Discussion => Topic started by: Josephbw on March 31, 2017, 10:16:26 AM

Title: Battery powered idea
Post by: Josephbw on March 31, 2017, 10:16:26 AM

While replying to another post, I had an idea and thought I would run it past you guys for your opinion. What if you took a 12V thin quarter sized battery and wired it up instead of a capacitor to use as a "keep alive" alternative. It wouldn't take much to get you past those pesky hiccups in the trackwork, and should last quite a while, I think.  ;D

Joe

Title: Re: Battery powered idea
Post by: G8B4Life on March 31, 2017, 11:18:45 AM

If it was that simple it would have been done by now.  :(

It could possibly be made to work but for these reasons and possibly more (I don't have the cognitive ability to think this through properly at 3am) it hasn't been done.

• Those coin batteries come in a maximum of 3v, so you'd need at least 4 of them anyway (so there goes the space saving) or
• a voltage step up module like is used for deadrail.
• You'd need to prevent the track voltage from getting to the battery and prevent the battery from discharging (power being drawn from it) while track power is present. To do this you'd need some sort of circuit that switched the LM's power between track power and battery "Keep alive" accordingly when track power is lost and restored.

You'd need to do the third point as there is a reason they say not to recharge non-rechargeable batteries which is essentially what you'd be doing if you wired one in like a standard keep alive; even with a rechargeable battery you'd still need a proper charging circuit for it; and you'd want to prevent the battery from being used when track power is present as this is just a waste of the battery.

- Tim

Title: Re: Battery powered idea
Post by: Alan on March 31, 2017, 11:21:35 AM

Batteries require charging "management". You can't simply supply unlimited power to a battery. Here is a document that explains in detail: http://www.ti.com/lit/an/snva557/snva557.pdf (http://www.ti.com/lit/an/snva557/snva557.pdf)

Battery management circuits of a size that will fit in models are available. Finding one that is appropriate for a keep-alive replacement may prove tricky. Batteries are not commonly used in high frequency charge/discharge applications due to the short life of batteries when used this way.

Title: Re: Battery powered idea
Post by: Josephbw on March 31, 2017, 04:48:08 PM

Well in my defense, I didn't say it was a GOOD idea. ;D Thanks for straightening me out.

Joe