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Black Forest
02-27-2017, 02:17 AM
On my sheep release pen the receiver is 12v and I have already 24v solenoid valve and was wondering if I take two 12v batteries and hook them up in series to get the 24v is it ok to connect to one of the batteries in the series to pull the 12v needed for the receiver? I was planning on using two motorcycle batteries to keep the size down.

BCRider
02-27-2017, 02:47 AM
It will work. BUT!...... It will draw down the battery used for the receiver faster than the other. How much faster depends on the current draw of the receiver and how often you use the whole 24v for the solenoid. If the receiver draw is small and you use the solenoid a lot the batteries will run down pretty well together. But if the receiver draw is a little more or the solenoid is only used occasionally the battery powering the receiver will run down earlier than the other.

MattiJ
02-27-2017, 03:04 AM
It will work. BUT!...... It will draw down the battery used for the receiver faster than the other. How much faster depends on the current draw of the receiver and how often you use the whole 24v for the solenoid. If the receiver draw is small and you use the solenoid a lot the batteries will run down pretty well together. But if the receiver draw is a little more or the solenoid is only used occasionally the battery powering the receiver will run down earlier than the other.

Very much true. But not necessarily any problem, just charge the batteries independently with 12v charger. That way you don't cook the less drained battery or leave the receiver battery half-empty.
Could even select bigger battery for the receiver.

------
How much current the solenoid valve takes?
Maybe you could slap in step-up dc-dc converter to get the 24 volts required.

MattiJ
02-27-2017, 03:09 AM
ie. One of these:
http://www.ebay.com/itm/150W-DC-DC-Boost-Converter-10-32V-to-12-35V-6A-Step-Up-Voltage-Charger-Power-/171907240597?hash=item2806785295:g:Is4AAOxy86RSX-g5

Probably good for the rated 6amps on short duty like control solenoid valve, for continuous use I wouldn't use these for more than 3A or so.

PStechPaul
02-27-2017, 04:26 AM
Probably better to use a buck converter from the 24V to 12V for the receiver which probably draws little current. Here's one for less than $2:

http://www.banggood.com/DC-DC-Adjustable-Power-Supply-Buck-Converter-Step-Down-Module-p-922049.html?rmmds=search

http://img.banggood.com/thumb/gallery/upload/2014/04/SKU104062/1.jpg

Black Forest
02-27-2017, 05:35 AM
I ordered a solenoid valve with a 12v solenoid. Problem solved. Thank you for the replies.

A.K. Boomer
02-27-2017, 07:04 AM
Just out of curiosity is there a way to get both worlds of 12 and 24V by just using some diodes? so that not just one battery is involved in the 12 volt part but so both can be ran in a parallel sequence and therefore does not drain just one? - maybe takes it down to a certain level and then as soon as it's lower than the other it draws the 12 volts off of the other?

my electronics "minds eye" tells me yes but when I try to draw up a diagram things don't seem to be working out...

might also produce complications with trying to charge batteries?

EVguru
02-27-2017, 07:36 AM
You may not be able to pull in a 24v solenoid with 12v, but you should be able to hold one with 12v once it is pulled in.

If you use a DPCO relay, you can generte a pulse of 24v from 12v.

Connect the solenoid between 0v and the NO side of both contact pairs. Connect the COM connection of one contact pair to +12v via a forward biased diode (anode to +12v).

Connect the COM connection of the second contact pair to the negative terminal of an electrlytic capacitor. The NC connection of the same contact pair connects to 0v and the positive terminal of the capacitor goes to +12v.

When the relay is de-energised, the capacitor is connected between +12v and 0v and charges. When the relay is energised, the capacitor is connected in series with the relay coil and adds to the supply voltage untill it has discharged. The holding supply then comes via the diode, which was reverse biased untill this time.

Size the capacitor to pull in the solenoid.

Seastar
02-27-2017, 08:51 AM
Clever Paul, very clever.
I had not seen that one before.
Bill

lakeside53
02-27-2017, 11:41 AM
Unless you have a multi-bank charger (one that senses and charges each series battery, not just the parallel types) it's not a good idea to draw different power from each. Why? When you charge in series the lessor discharged battery (s) ends up getting overcharged each charge cycle. Even different aging of batteries has this effect. Multi-bank/battery chargers are common on boats and on devices like forklifts, golf carts etc. I use them on a battery powered barges - 24v with 4 6V batteries, but the aux power (radios, lights, boom boxes etc) is 12v.

6PTsocket
02-27-2017, 02:04 PM
Very much true. But not necessarily any problem, just charge the batteries independently with 12v charger. That way you don't cook the less drained battery or leave the receiver battery half-empty.
Could even select bigger battery for the receiver.

------
How much current the solenoid valve takes?
Maybe you could slap in step-up dc-dc converter to get the 24 volts required.
I like the reverse of that. Put the two batteries in series. and use a 24 to 12 converter for the reciever. Actually a simple 3 pin voltage regulater is all that is needed from the 7812 series. It is easy to hook up. The IN pin goes to + 24, ground goes -24 and the - 12 on the reciever and OUT goes to + 12,on the reciever. It would be helpful if he knew how much the reciever draws and how big the batteries are. Generally recievers use very little and his first idea would probably work fine.

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6PTsocket
02-27-2017, 02:11 PM
Probably better to use a buck converter from the 24V to 12V for the receiver which probably draws little current. Here's one for less than $2:

http://www.banggood.com/DC-DC-Adjustable-Power-Supply-Buck-Converter-Step-Down-Module-p-922049.html?rmmds=search

http://img.banggood.com/thumb/gallery/upload/2014/04/SKU104062/1.jpg
Unbelievable how cheap that stuff is. It approaches the cost of a simple 3 pin,12 volt regulator. Since he is on batteries the decision for me would be the one with the lowest regulator/ buck converter power consumption.

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6PTsocket
02-27-2017, 02:22 PM
Just out of curiosity is there a way to get both worlds of 12 and 24V by just using some diodes? so that not just one battery is involved in the 12 volt part but so both can be ran in a parallel sequence and therefore does not drain just one? - maybe takes it down to a certain level and then as soon as it's lower than the other it draws the 12 volts off of the other?

my electronics "minds eye" tells me yes but when I try to draw up a diagram things don't seem to be working out...

might also produce complications with trying to charge batteries?
No practical way with diodes unless you consider leaving the batteries in series and feeding the reciever through 17 diodes in series, a workable solution. Each diode has a forward drop of 0.7 volts. There are solid state regulators for under a buck that will do the same thing.

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6PTsocket
02-27-2017, 02:26 PM
You may not be able to pull in a 24v solenoid with 12v, but you should be able to hold one with 12v once it is pulled in.

If you use a DPCO relay, you can generte a pulse of 24v from 12v.

Connect the solenoid between 0v and the NO side of both contact pairs. Connect the COM connection of one contact pair to +12v via a forward biased diode (anode to +12v).

Connect the COM connection of the second contact pair to the negative terminal of an electrlytic capacitor. The NC connection of the same contact pair connects to 0v and the positive terminal of the capacitor goes to +12v.

When the relay is de-energised, the capacitor is connected between +12v and 0v and charges. When the relay is energised, the capacitor is connected in series with the relay coil and adds to the supply voltage untill it has discharged. The holding supply then comes via the diode, which was reverse biased untill this time.

Size the capacitor to pull in the solenoid.
A one shot voltage doubler.That is clever

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6PTsocket
02-27-2017, 02:36 PM
Unless you have a multi-bank charger (one that senses and charges each series battery, not just the parallel types) it's not a good idea to draw different power from each. Why? When you charge in series the lessor discharged battery (s) ends up getting overcharged each charge cycle. Even different aging of batteries has this effect. Multi-bank/battery chargers are common on boats and on devices like forklifts, golf carts etc. I use them on a battery powered barges - 24v with 4 6V batteries, but the aux power (radios, lights, boom boxes etc) is 12v.
It is a matter of battery size vs reciever current draw. In the real world, that reciever probably consumes zilch. It is not an entertainment radio that has to supply audio. With any reasonable size battery it hardly matters. Your car can go for months supplying the less than 50ma for the radio presets and the remote control reciever. Self discharge of a lead acid battery probably wastes more power.

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A.K. Boomer
02-27-2017, 02:45 PM
No practical way with diodes unless you consider leaving the batteries in series and feeding the reciever through 17 diodes in series, a workable solution. Each diode has a forward drop of 0.7 volts. There are solid state regulators for under a buck that will do the same thing.

Sent from my SM-G900V using Tapatalk

Thanks - sometimes my electronics minds eye is nothing more than a dysfunctional cyclops

what a vast field and although my brain does not thrive in this area I know enough about it to have allot of respect for people who are good at it...

it's also become apparent to me that there's dozens of ways to get the job done and some are way more cost effective and others maybe way more dependable ---

I bet every electrical engineer leaves behind his/her personal trademark in all the methods used and soldered into the board as total confirmation....

6PTsocket
02-28-2017, 03:50 PM
Thanks - sometimes my electronics minds eye is nothing more than a dysfunctional cyclops

what a vast field and although my brain does not thrive in this area I know enough about it to have allot of respect for people who are good at it...

it's also become apparent to me that there's dozens of ways to get the job done and some are way more cost effective and others maybe way more dependable ---

I bet every electrical engineer leaves behind his/her personal trademark in all the methods used and soldered into the board as total confirmation....
The same with writing software. There are usually many ways to get there. There are programs for laying out parts on a PC board, too.

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