SLA battery: Connectivity detection

Jason,
This is about as close I can get with the present circuit and information.

Look thru it, it hasnt been tried but it should be OK.

ericgibbs said:

Jason,
This is about as close I can get with the present circuit and information.

Look thru it, it hasnt been tried but it should be OK.

Click to expand...

Ok thanks, I'll check it out and get back to you.

Hi again,

Jason:
Dont loose heart now, we're almost there.

Eric:
I see in your new schematic that the power of the LM358 now comes
from the LM317. This is what i have been saying all along, and i
even thought this was the way it was going to be from the start.
Just one quick question now...
What does "Junction of R3 and R4" on the schem mean?

MrAl said:

Hi again,
Just one quick question now...
What does "Junction of R3 and R4" on the schem mean?

Click to expand...

hi Al,
Its where resistors R3 and R4 are joined together. ie : point 'B' on the dwg.

Hi Eric,


Oh ok i see now...that is a reference to the 'Existing Circuit' diagram.
It was a little confusing because there is an R3 on the new schematic too,
and there 'was' an R4 previously too, which i guess the 1k's can be called
now.

The more i look at these circuits and listen to Jason the more i think you
should sit down and design the entire circuit for him, making sure he
gets the right current and right trip points and all. I dont think he is getting
the charge current he wants, as you were pointing out before.
If he got an entire circuit schematic i think it would make things easier
for him. Just my last thoughts on this.

Good luck with it Jason.

MrAl: Thank you I was actually going to ask all of my questions for Eric or yourself later on (I have a small list, haha) once we get my initial problem solved. I am still testing Eric’s circuit under different scenarios to see how it behaves, and how (or if) it affects any other part of my existing circuit.

Hi Eric
I have been testing the circuit based on your latest schematic. I am still working on it, because I want to see how the whole system behaves overall under certain scenarios.
Last night one little thing was bugging me (one connection), so I made a very minor change, and so far it has been working better. I was prompted to remove the potential divider connecting to the R3/R4 junction (point “B”) and connect it to the junction of the two diodes instead. It definitely made a difference. **But**, I think it may be due to the lack of charging current for the battery, in which I was hoping you would shed some more light on… I just don’t understand the theory. I thought it was just R=V/I ??
Once we sort out the charging current issue, I will definitely re-test it with your original connection (back to the R3/R4 junction).

Other than that, I connected everything else like you said, and so far so good. The RV1 pot definitely requires “fine-tuning” I must say, so I have hooked up a 25-turn cermet trimpot… a lot better than a standard one.

Eric I don’t expect you to “re-design” my circuit as per MrAl’s kind suggestion. It’s working ok… just needs a few minor adjustments here and there as you previously mentioned (thank you for your advice) but not fully discussed.
I think you didn’t like the Charging LED operation, the charging current, and the 12-volt reg. I think I’m just going to eliminate the 12-volt reg and that’s it, but have a fuse connected in series with the Load output. Unless you have a better idea?

Much appreciated.
Jason.

jst3712 said:

I have been testing the circuit based on your latest schematic. I am still working on it, because I want to see how the whole system behaves overall under certain scenarios.
Last night one little thing was bugging me (one connection), so I made a very minor change, and so far it has been working better. I was prompted to remove the potential divider connecting to the R3/R4 junction (point “B”) and connect it to the junction of the two diodes instead. It definitely made a difference. **But**, I think it may be due to the lack of charging current for the battery, in which I was hoping you would shed some more light on… I just don’t understand the theory. I thought it was just R=V/I ??
Once we sort out the charging current issue, I will definitely re-test it with your original connection (back to the R3/R4 junction).

Other than that, I connected everything else like you said, and so far so good. The RV1 pot definitely requires “fine-tuning” I must say, so I have hooked up a 25-turn cermet trimpot… a lot better than a standard one.

Eric I don’t expect you to “re-design” my circuit as per MrAl’s kind suggestion. It’s working ok… just needs a few minor adjustments here and there as you previously mentioned (thank you for your advice) but not fully discussed.
I think you didn’t like the Charging LED operation, the charging current, and the 12-volt reg.
I think I’m just going to eliminate the 12-volt reg and that’s it, but have a fuse connected in series with the Load output. Unless you have a better idea?

Much appreciated.
Jason.

Click to expand...

hi Jason,
I used a multiturn pot to set RV1/RV2, I find the single turn pots are too coarse for comparators.

I dont mind anyone doing a pick and mix of my circuits, if by modifying it in anyway gets it doing the job for you, thats fine by me.


The reason I was concerned about the apparent low charge current etc, was the recharge time of the battery.
Ideally you want a float/standby battery back upto full charge asap.
You never know when the next mains out will occur.

I think the diode in the output of the battery when powering the LOAD is inefficient, you are losing 0.7V across this diode and all its doing is shunting the 39R current charge sense resistor so that the charge LED can light.
I would suggest a relook at that part.

Lets me know how it goes and if you want any areas reworking.

Just lets get the show on the road.

BTW: increasing the 1M0 feeback resistor will reduce the dead band [on/off] and likewise decreasing it will increase the dead band.
You may need to tweak the RV1 if you change the 1M0

ericgibbs said:

hi Jason,
I used a multiturn pot to set RV1/RV2, I find the single turn pots are too coarse for comparators.

I dont mind anyone doing a pick and mix of my circuits, if by modifying it in anyway gets it doing the job for you, thats fine by me.


The reason I was concerned about the apparent low charge current etc, was the recharge time of the battery.
Ideally you want a float/standby battery back upto full charge asap.
You never know when the next mains out will occur.

I think the diode in the output of the battery when powering the LOAD is inefficient, you are losing 0.7V across this diode and all its doing is shunting the 39R current charge sense resistor so that the charge LED can light.
I would suggest a relook at that part.

Lets me know how it goes and if you want any areas reworking.

Just lets get the show on the road.

BTW: increasing the 1M0 feedback resistor will reduce the dead band [on/off] and likewise decreasing it will increase the dead band.
You may need to tweak the RV1 if you change the 1M0

Click to expand...

Hi again,
Yeah I need to consider another solution for the incorrect battery polarity protection. I got the idea of the diode off another schematic, and did notice the 0.7V loss... I thought I'd have to live with it. I will definately come back to that one... thanks!

As with the 5-watt 39R - based on your previous post - I was looking at a 4R7 instead. So then 0.31A would be the max (1.5V/4.7R=0.31A), better?, assuming the lowest voltage before it became 'isolated' from everything is 12V. What you think? Battery isolation will be something I'll need to add on, but one thing at a time.

I'll also look at the 1M resistor. I'll see if I have a 1M trimpot somewhere that I can add it series to the current 1M - see how I go

Calling Eric... Calling Eric...

jst3712 said:

Hi again,
Yeah I need to consider another solution for the incorrect battery polarity protection. I got the idea of the diode off another schematic, and did notice the 0.7V loss... I thought I'd have to live with it. I will definately come back to that one... thanks!

As with the 5-watt 39R - based on your previous post - I was looking at a 4R7 instead. So then 0.31A would be the max (1.5V/4.7R=0.31A), better?, assuming the lowest voltage before it became 'isolated' from everything is 12V. What you think? Battery isolation will be something I'll need to add on, but one thing at a time.

I'll also look at the 1M resistor. I'll see if I have a 1M trimpot somewhere that I can add it series to the current 1M - see how I go

Click to expand...

Hi Eric, haven't heard from you in a while.....
So, what do you think? (see my reply previous to this one).
The 4.7R better? I don't want to blow up my battery!

As with the diode, I think you meant the one at the diode-to-diode junction near my 'Charging' LED detector, right? (so when the battery is in use, power flows through the diode bypassing the 5W resistor, to the load). Well if so, I have fixed that issue up with a relay, so there will be no voltage drop. And I also got rid of the 12V reg.

Thanks so much for your help by the way. You and MrAl have both been great.

Jason.

jst3712 said:

Hi Eric, haven't heard from you in a while.....
So, what do you think? (see my reply previous to this one).
The 4.7R better? I don't want to blow up my battery!

As with the diode, I think you meant the one at the diode-to-diode junction near my 'Charging' LED detector, right? (so when the battery is in use, power flows through the diode bypassing the 5W resistor, to the load). Well if so, I have fixed that issue up with a relay, so there will be no voltage drop. And I also got rid of the 12V reg.

Thanks so much for your help by the way. You and MrAl have both been great.

Jason.

Click to expand...

hi Jason,
Been hanging back, following your other reverse battery protection thread, waiting see which you have decided.

I did look at the charge indicator upstream of the LM317, but IIRC you did have the 12V reg on the output side of the LM317.

Where are you taking the LOAD current from, when the battery is charging and also when the battery is powering the LOAD.?

The relay method is the I have used for rev/pol protection,
its also possible to drive the relay by a transistor and use base control, it gives more flexibilty.

ericgibbs said:

hi Jason,
Been hanging back, following your other reverse battery protection thread, waiting see which you have decided.
Haven't made any formal decision, I was getting ideas and to see what sort of discussion there'd be on each approach (pro's and cons).

I did look at the charge indicator upstream of the LM317, but IIRC you did have the 12V reg on the output side of the LM317.
What's IIRC?? Sorry, I don't understand this question

Where are you taking the LOAD current from, when the battery is charging and also when the battery is powering the LOAD.?
Why, no good? I'm not sure what you are trying to ask here, but when the battery is charging, I am assuming the load takes whatever current it needs (I will allow up to 1A, max.) from the LM317, and the battery grabs whatever is remaining... noting that the LM317 has 1.5A max current. You thinking I should reposition certain sections?

The relay method is the I have used for rev/pol protection,
its also possible to drive the relay by a transistor and use base control, it gives more flexibilty.
Well I need reverse polarity protection at both the INPUT side (power supply) and one at the BATTERY side. I'm thinking I should keep the crowbar one at the battery end (as per my past schematics) and perhaps a schottky diode in series at the input end - I'll just need to increase the voltage slightly on the LM317 to make up for all voltage drops. Prefer to use relay for something else.

I was thinking of posting my whole updated circuit to you, but I think we are moving away more and more from the initial thread topic. Therefore prefer not to have just anyone viewing it.

Click to expand...

Hi Eric, see above.
Jason.

jst3712 said:

Hi Eric, see above.
Jason.

Click to expand...

hi,

The IIRC is often used, it means If I recall correctly

I have read/saved your post, I'll go thru this and the earlier ones, see if I get inspired.!

I was thinking of posting my whole updated circuit to you, but I think we are moving away more and more from the initial thread topic. Therefore prefer not to have just anyone viewing it.

Click to expand...

I dont think there is anything novel in the circuit, so it should be OK to post it.

Just dont tell us what its going to used for.