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Need info, simple priority based load switching | 19 comments (19 topical, editorial)

Re: Need info, simple priority based load switchin (3.00 / 0) (#10)
by frackers (g8ecj at *nospam* gilks dot org) on Sun Jul 20th, 2008 at 07:39:48 PM MST
(User Info) http://www.gilks.org

If the shed is a much larger distance from the genny than the house then the extra cable required to get there may provide enough voltage drop that the house batteries get charged first anyway. If not, a series high current diode in the shed cable to 'loose' 0.7 volts will probably be enough to ensure that the house batteries are fully charged before the shed batteries take a significant amount of power.

For running the pond fountain, a simple voltage sensor (eg a zener diode driving a transistor/relay combo) to turn on the pump when the shed batteries reach full charge or maybe monitor at the genny so that if the voltage rises significantly due to a high charge current then the extra load is turned on (using the pump as a dump load in effect!!)
Robin - Down Under (or are you Up Over)

Re:Need info, simple priority based load switch (3.00 / 0) (#12)
by mukesh13 (mukesh ##remove this part ## at b2a.in) on Mon Jul 21st, 2008 at 04:30:01 AM MST
(User Info)

Hi frackers,
I noticed you are in new zealand. First time I went there, I thought I landed in paradise... The feeling remains same still, if and when I get chance to be there.

Any circuit references to to achieve :
" For running the pond fountain, a simple voltage sensor (eg a zener diode driving a transistor/relay combo) to turn on the pump when the shed batteries reach full charge or maybe monitor at the genny so that if the voltage rises significantly due to a high charge current then the extra load is turned on (using the pump as a dump load in effect!!)"

Thanks and enjoy the paradise.

-> No is not the answer. Just a challenge. <-
[ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#13)
by DamonHD (d@hd.org) on Mon Jul 21st, 2008 at 05:04:29 AM MST
(User Info) http://www.earth.org.uk/

Hi,

I use my main Internet server/laptop as a dump load, see:

http://www.earth.org.uk/low-voltage-drop-out-circuit-design.html

This involves an LVD with higher-than-usual voltage thresholds to only divert power to the laptop when the battery is pretty full and being charged and I also have some monitoring and software tweaks on the laptop to ramp up power consumption further if the voltage continues to rise. This makes a variable dump-load of between about 20W to 60W for my small system.

Rgds

Damon

[ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#14)
by mukesh13 (mukesh ##remove this part ## at b2a.in) on Mon Jul 21st, 2008 at 07:18:25 AM MST
(User Info)

Hi Damon,
It looks good. Any idea on adapting it to 24V ?
Thanks again for sharing.
-> No is not the answer. Just a challenge. <-
[ Parent ]

Re:Need info, simple priority based load switch (3.00 / 0) (#15)
by DamonHD (d@hd.org) on Mon Jul 21st, 2008 at 10:32:02 AM MST
(User Info) http://www.earth.org.uk/

I think that the control IC is good up to 30V, but check the data sheet. I think that the P-MOSFET I happened to use would also be OK, but (a) check and (b) there's nothing magic about it.

Then all you have to do is adjust the resistor values for the voltages you want. Easy.

Rgds

Damon

[ Parent ]

Re: Need info, simple priority based load switchin (3.00 / 0) (#18)
by Ungrounded Lightning Rod on Tue Jul 22nd, 2008 at 08:22:13 PM MST
(User Info)

Adding a diode drop means the shed batteries will never achieve full charge. Meanwhile the house batteries will require a dump load that goes on even if the shed batteries aren't yet fully charged.

[ Parent ]

Re: Need info, simple priority based load switch (3.00 / 0) (#19)
by mukesh13 (mukesh ##remove this part ## at b2a.in) on Wed Jul 23rd, 2008 at 08:28:06 AM MST
(User Info)

Hi,
I tried this. It won't happen the way you noted.
If I add a diode and then keep the shed batteries connected too, AC, not the DC connection, then the voltage at the batteries in house, after conversion, is more than the voltage in the cattle shed, so the house batteries end up getting charged first. Though not exactly a clean solution, since both systems are connected effectively in parallel and there is a trickle charge in anycase to the shed batteries almost all the time.

the way the site is organized :

AC to DC conversion is done at the batteries location.

Not a very good site design above but should be enough to give some idea.
Overall capacity of generation is much above what I need so keeping some lights for cattle all the time doesn't seem to hurt me...
I need to watch the results over next few days.

Thanks for the inputs.

-> No is not the answer. Just a challenge. <-
[ Parent ]

Need info, simple priority based load switching | 19 comments (19 topical, 0 editorial)

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