Hi everyone you may have seen this request on many forums from me, over the last 2 years I have been trying to monitor and switchover 2 12volt batteries.
I have a motor that runs on 12 volt lead-acid battery and needs about 2 amps but I want to rate the circuit about 4 amps so has not to over load things. Now if the voltage drops below 10.5 volts it just comes to a full stop but the motor at this point is still drawing some current that completely flattens the battery if left unattended. The motor will free run at this voltage but not under load so I need to restore the 12-volt supply. The motor runs a small pump that just circulates water for my pond. Now I dont want the pump to stop at all but if it does I want to be able to start it ASAP. So that means 2 batteries one in use and one on charge, by solar panel, But the sun doesnt like to play ball some days this has happened many times.
Yes I could use both batteries in parallel and charge them at the same time. But if the sun dont play ball I have both batteries under 12 volts and no motor running. Now that seems to happen a lot when the batteries are in parallel, I know that should run just fine but it doesnt.
My system at the moment as 2 switches, switch 1 (primary switch) if I flick this one every day or so it seems to keep going but only with my input and for most of the time its fine on the switch. Switch 2 (secondary switch) puts the batteries in parallel regardless of the position of switch 1.
Now lets say I go away for some time which happens, I cannot throw the switch so motor will stop. Yes I can put the batteries in parallel with the flick of a second switch just for such occasions and this will all most double the run time. Now in the ordinary world that would be fine. But my job means I get a call and whatever Im doing stops and off I go regardless. When I get a call I dont have the time to go and set things up. So I get the wife to go and flick the parallel switch, this will last about 4 days.
Now if the wife uses the primary switch daily it seems to run forever.
The location is in a remote-ish wooded area and I dont want the wife do go to it unless absolutely necessary, all though keeping the pump running is a priority, but not as to put the wife at risk.
Just to note I have run both systems independently without any switchers to see which would be the most suitable for my needs. And the results of these tests were to switch the batteries and not to parallel them.
Tests carried out over 12 weeks, 6 weeks on changing the batteries over daily and the next 6 weeks with batteries in parallel. Now I know that the solar panels output will have a big deciding factor on this but I have been running the same tests over a 3-year period and its always the same result.
Test 1.
Week 1: running on primary switch, all runs ok.
Week 2: running on primary switch, all runs ok.
And so on for 4 weeks all ok when using the switchover. Switch 1.
But maybe stopping at night, I ant stopping there all night to watch a pump, no thanks its just too spooky.
Test 2.
Week 1: running on secondary switch, mostly ok but pump starting to run slow by 4th day.
Week 2 run on secondary switch pump running intermittently.
And the same for the next 4 weeks when using the secondary parallel switch. Switch 2.
So the next test was to use a timer circuit so every 8 hours or so it flips over the batteries this seemed to be OK, looked like it was sorted!
NO, it would change regardless of the battery condition resulting in intermittent running of the pump.
I played around with this one a lot, it does work to a degree.
Next test light activated switch when it gets dark it flips over batteries, so the one that as been on charge all day now runs the pump all night, sun comes up and the other one that charged overnight now runs the pump all day.
Doo! Solar panels dont work to good in the dark. Well it seemed like a good Idea at the time.
So as you may now start to understand my frustration with this maybe someone will help.
So my worst case scenario, I left the system on one battery I get the call and off I go, maybe for weeks. Now maybe the solar panels will run things ok. More batteries would be in order or a different motor but I dont want to do that the system works well but only with my involvement. Now for relays I have used all different manor of then but had nothing but problems, some of the problems were sticking on or not switching on, getting hot even one that had melted. I dont want to go in to depth on this, I want to keep well away from them I just cannot express this enough so please no relays.
Now I paid my local electronics company to build me something to do the job it cost me £150. I installed the unit it worked fantastic for weeks and completely solved my problem. So why am I looking for help well someone broke in to the shed and it got damaged the electronics company that built it sealed it with resin and I cannot get it repaired and they want another £150.
I know properly need a voltage comparator and a current comparator, and reset flip-flop circuit.
The outputs of the flip-flop drive will drive a Mosfets that connect the solar panel and disconnect the pump.
But I dont have a clue how to set the above out. Build it yes.
Please help with full diagram even if it has relays. Im so desperate to get this done.
thanks Ron
I have a motor that runs on 12 volt lead-acid battery and needs about 2 amps but I want to rate the circuit about 4 amps so has not to over load things. Now if the voltage drops below 10.5 volts it just comes to a full stop but the motor at this point is still drawing some current that completely flattens the battery if left unattended. The motor will free run at this voltage but not under load so I need to restore the 12-volt supply. The motor runs a small pump that just circulates water for my pond. Now I dont want the pump to stop at all but if it does I want to be able to start it ASAP. So that means 2 batteries one in use and one on charge, by solar panel, But the sun doesnt like to play ball some days this has happened many times.
Yes I could use both batteries in parallel and charge them at the same time. But if the sun dont play ball I have both batteries under 12 volts and no motor running. Now that seems to happen a lot when the batteries are in parallel, I know that should run just fine but it doesnt.
My system at the moment as 2 switches, switch 1 (primary switch) if I flick this one every day or so it seems to keep going but only with my input and for most of the time its fine on the switch. Switch 2 (secondary switch) puts the batteries in parallel regardless of the position of switch 1.
Now lets say I go away for some time which happens, I cannot throw the switch so motor will stop. Yes I can put the batteries in parallel with the flick of a second switch just for such occasions and this will all most double the run time. Now in the ordinary world that would be fine. But my job means I get a call and whatever Im doing stops and off I go regardless. When I get a call I dont have the time to go and set things up. So I get the wife to go and flick the parallel switch, this will last about 4 days.
Now if the wife uses the primary switch daily it seems to run forever.
The location is in a remote-ish wooded area and I dont want the wife do go to it unless absolutely necessary, all though keeping the pump running is a priority, but not as to put the wife at risk.
Just to note I have run both systems independently without any switchers to see which would be the most suitable for my needs. And the results of these tests were to switch the batteries and not to parallel them.
Tests carried out over 12 weeks, 6 weeks on changing the batteries over daily and the next 6 weeks with batteries in parallel. Now I know that the solar panels output will have a big deciding factor on this but I have been running the same tests over a 3-year period and its always the same result.
Test 1.
Week 1: running on primary switch, all runs ok.
Week 2: running on primary switch, all runs ok.
And so on for 4 weeks all ok when using the switchover. Switch 1.
But maybe stopping at night, I ant stopping there all night to watch a pump, no thanks its just too spooky.
Test 2.
Week 1: running on secondary switch, mostly ok but pump starting to run slow by 4th day.
Week 2 run on secondary switch pump running intermittently.
And the same for the next 4 weeks when using the secondary parallel switch. Switch 2.
So the next test was to use a timer circuit so every 8 hours or so it flips over the batteries this seemed to be OK, looked like it was sorted!
NO, it would change regardless of the battery condition resulting in intermittent running of the pump.
I played around with this one a lot, it does work to a degree.
Next test light activated switch when it gets dark it flips over batteries, so the one that as been on charge all day now runs the pump all night, sun comes up and the other one that charged overnight now runs the pump all day.
Doo! Solar panels dont work to good in the dark. Well it seemed like a good Idea at the time.
So as you may now start to understand my frustration with this maybe someone will help.
So my worst case scenario, I left the system on one battery I get the call and off I go, maybe for weeks. Now maybe the solar panels will run things ok. More batteries would be in order or a different motor but I dont want to do that the system works well but only with my involvement. Now for relays I have used all different manor of then but had nothing but problems, some of the problems were sticking on or not switching on, getting hot even one that had melted. I dont want to go in to depth on this, I want to keep well away from them I just cannot express this enough so please no relays.
Now I paid my local electronics company to build me something to do the job it cost me £150. I installed the unit it worked fantastic for weeks and completely solved my problem. So why am I looking for help well someone broke in to the shed and it got damaged the electronics company that built it sealed it with resin and I cannot get it repaired and they want another £150.
I know properly need a voltage comparator and a current comparator, and reset flip-flop circuit.
The outputs of the flip-flop drive will drive a Mosfets that connect the solar panel and disconnect the pump.
But I dont have a clue how to set the above out. Build it yes.
Please help with full diagram even if it has relays. Im so desperate to get this done.
thanks Ron