Battery charging question.

ojstinson · April 22, 2013, 09:33:33 PM

Can you leave a car/motorcycle battery hooked up to a charger even when the charger is unplugged from the AC power source? I'm thinking an internal diode would prevent a DC leakage from the battery back through the charger. This is more of a general question. I have an automatic gate opener that is on a gate that is about 100 yards from my house, it runs on a heavy duty car battery that I need to charge every week or so. It's kind of a hassle to go out and fiddle around with the battery connections because I have it strapped in a protective container. I was thinking it would be so much easier to just flip the main breaker in my garage on or off as needed and just leave everything hooked up as is.

yamahonkawazuki · April 22, 2013, 09:56:49 PM

hmmm not sure tbh. if anything can leave the hot connected and pull the neg. after a charging. never considered whether it would drain or not via the charger

Kiwingenuity · April 23, 2013, 12:12:53 PM

Hi there,

Not all lead acid battery chargers have a diode fitted to prevent the battery discharging back through the system. If you add one, any sort of regulated charger is not going to know about the forward volt drop across the diode (unless you open it up and have a gander at how the feedback circuit works - or even if it has one). Pulling it apart may yield some clues.

If you add a diode, the forward volt drop is going to reduce the float voltage by between 0.7 to 1V (depending on diode). This would extend the charge time, and ultimately would never get to full voltage on the battery.

EDIT
I would suggest a series relay / contactor which is powered from the AC line ~~or even the charger~~ when it is active - that way you can automate the "unplugging" of said battery from the charger terminals. Edit - if you do the line side, you won't need as bigger a relay - just have to have a ferret around for something already in a box.

let us know if you have any queries.

Janx101 · April 23, 2013, 03:42:57 PM

Hmmm ... I got a bit lost with that one... And it's not even my orig post!

..... I saw ... Blah blah blah blah blahblahblah ...

Blah blah blah ...

... Blah blah BLAH blah

.... I've got a ferret in a box!!

Bahahahahahaha....... Nah I got the idea... Just stirring....

But why do you keep your ferret in a box?

ojstinson · April 23, 2013, 05:32:45 PM

Me to, I believe we have a legit electrical engineer in the house, good point though about possibly not having a diode to prevent backup. Someone suggested a small solar panel made for that purpose, that would likely be sufficient for maintaining a fully charged battery.

Kiwingenuity · April 23, 2013, 06:58:35 PM

Quote from: ojstinson on April 23, 2013, 05:32:45 PM
Me to, I believe we have a legit electrical engineer in the house, good point though about possibly not having a diode to prevent backup. Someone suggested a small solar panel made for that purpose, that would likely be sufficient for maintaining a fully charged battery.

So you caught me - my job title certainly has electrical engineer in there..

Solar panel can work pretty well for maintaining charge - if you live in an area not subject to vandalism / theft. From various remote site projects we have found that you may need to give batteries the odd manual charge once in a while. Father in law uses one for a small power barrow - keeps it topped up nicely.

Kiwingenuity · April 23, 2013, 07:54:06 PM

Quote from: Janx101 on April 23, 2013, 03:42:57 PM

But why do you keep your ferret in a box?

Thats the best place to keep a ferret - beats your pocket..

but the real question - is the ferret alive or dead inside the box..

Janx101 · April 23, 2013, 09:09:58 PM

hmmmm.. very good point... and then we could add a 3rd option....

Shake the box like crazy ... then .. Is The Ferret Dead? .. Is The Ferret Alive? ... Is The Ferret BLOODY FURIOUS ..

yamahonkawazuki · April 24, 2013, 11:38:00 AM

ever consider adapting a moto tender ( battery tender?)

mister · April 24, 2013, 01:40:57 PM

Um... ok, silly question....

1 - Wire runs from garage to battery near gate.
2 - Wire charges battery
3 - battery powers gate opener

So, why not do away with the battery and wire right into the gate opener, if you're going to run a wire down there anyway?

ojstinson · April 24, 2013, 02:19:13 PM

Yama, I think I'll go with the Solar thing for now, but that would be next option.

ojstinson · April 24, 2013, 02:25:45 PM

Mister, I have house currant and a box at the gate that is connected to my breaker panel in the garage, the gate will only operate with straight DC battery Voltage, the AC can only be utilized to keep the battery charged. The only alternative would be self contained solar charging devices. They could make gates to operate on AC but if your power went out you would be S O L.

yamahonkawazuki · April 27, 2013, 08:46:27 PM

Quote from: ojstinson on April 24, 2013, 02:19:13 PM
Yama, I think I'll go with the Solar thing for now, but that would be next option.

would be cheap Eh? on the tender. run the gate once. it dips hte power, tender kicks on, tops it off, shuts off. OR if it came down to it and none of these were doable, a pwoer supply which could handle hte amperage of the gate motor, and run from a power supply in garage. or inside battery box/mechanical room of gate

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Battery charging question.