UPS and inverter questions

[PCBONEZ]

Re: UPS and inverter questions

Time to charge depends on a sundry of things.
amp/hrs of the battery.
How far down it is.
The charger makes a big difference too.
The charger you are using should take it to a predetermined voltage and then 'float' there to deepen the charge. It doesn't know it's not attached to a car battery.

[starfury1]

Re: UPS and inverter questions

PCBonez answer the charger question but I'll leave the below for ref anyway
(got 10 min then cant edit....post has moved on a bit since I wrote this)

Well On the battery charger, here's the blurb....I dont see mention of Gell cell only automotive and vehicle battery
So I suspect Not
I dont know for sure either way
chargers have moved on a lot these days

6 Amp / 4 Amp / 2 Amp Continuous Charge Rates - Smart Battery Charger™
Model # VEC1086BBD
3 stage, automatic, high-frequency charging technology
More efficient charging than conventional model chargers
Spark-resistant, reverse hook-up & overcharge protection
Digital Smart Control™ microprocessor
Automatic float mode monitoring


I'll let davmax answer this more in depth as he seems to familiar with the circuit and understand it a lot better then me

Generally speaking, On the Relays its depending on construction of contacts.

to put it simply
(and I think your probably beyond this stuff but I'll start at the beginning anyway)

Basically its a coil of wire that used magnetic force to switch physical contacts.

The voltage for the coil can vary 12 V 24 V 48 V

It I suppose you could call a digital action , it either ON or OFF.

The amount of contacts can vary
but it is more or less a "switch" of some kind
Like a "toggle switch" and the switch sort of follows those layouts
SPST SPDT DPDT (single pole /double throw etc)
(of course it depends on who made and and it purpose too, so could have more or be configured differently)

So you will have a "Control Circuit" that turns ON or OFF the voltage to the Coil (read as applies voltage across coil) this will then cause the switching action with the contacts.

Now these can be made one of two ways
"Normally open contacts" and "Normally closed"
(in other words the coil isn't energized the contacts are closed etc)

so the idea is its a "switch" and how it switches or how many isolated switchs can be in the relay depends on the relay

so just like a light switch and you
you are isolated from the mains but you switch on the light

So the "coil control circuit" (you) is not normally part of the "Switch" contacts
(light switch)

I guess now (if you haven't) you need to identify whats being switched via the relay contacts.

it appears you know that it "should switch" so therefore you need to check if this is happening on the coil

If you can, you could remove the relay and check it functioning correctly.

But possibly it not switching cause the "control circuit" is faulty or a signal it should receive to trigger the action is not being sent (or arriving where it should).
relays can and do fail so it a suspect component.

you may have to disconnect the coil to check the the voltage...also you will I suspect find a flyback diode near it across the coil, the idea being to suppress back EMF from the coil when the magnetic field collapses it generates a high voltage spike
(if memory serves me)


I think davmax is best to advise since he is more familiar with your problem

Hope what I've posted is of some help anyway

Cheers

[starfury1]

Re: UPS and inverter questions

K just looked at your attachment
"seems you understand relays well enough"
(so scratch the above)

[andrew77]

Re: UPS and inverter questions

K just looked at your attachment
"seems you understand relays well enough"
(so scratch the above)

Everything helps.

There are some SMD mosfets that are controlling these relays. The number on them is 702. I guess I need to check the one for the line switch over relay(RY4).

[andrew77]

Re: UPS and inverter questions

The mosfet for RY4 is shorted. Would this particular mosfet be controlled directly from the microcontroller?

[davmax]

Re: UPS and inverter questions

Andrew.

Re charging. What was temp 100C or 100F? The starting charge you quote is not dramatically too high, but above max. The important thing is that during charge this should drop right back to about 0.5 amp or less at full charge. The battery will be damaged if finishing current is too high. Heat is usually caused by finishing being too high, causes gas generation and internal damage. Strange that the two batteries were so different, on the face of it one appears to have had low charge, the cool one.

Looking at your circuit. It is clear that RY4 changes over from input AC to inverter out. Inverter out being selected when power fails. The HOT out must pass through RY1 and RY2. RY1 is strange in that it does a tap change on the transformer. I assume the status of the relay connections shown is with inverter OFF and no external power. This shows RY4 by default taking power from the inverter. RY1 should should remain in the default state for both inverter and input AC. RY2 should move to connect the hot line to the output for both inverter and line power.

Your drawing can be misleading re the tap on the transformer it can be either step up or down. This can be tested by running on battery and you need to measure the voltage between neutral and hot and then neutral and the tap connection. See if the tap voltage is higher or lower that Hot.

[davmax]

Re: UPS and inverter questions

This does not make sense with your circuit where (no power connects to inverter output). With MOSFET a short the relay would move to connect line power.ie no output from inverter would reach the output. Something confusing here.

[andrew77]

Re: UPS and inverter questions

Davmax the temp was 100F.

The relay states in the diagram are with the ups unpowered.

I measured power from the center tap on the AVR transformer and one side was 85 volts and the other was 75 volts.

Broken parts:
Q10 is the mosfet and the diode D7 is shorted also. It is driven by the microcontroller. The diode has KY3 on it.

Now we're really getting somewhere.


Here's a picture of both.

[davmax]

Re: UPS and inverter questions

I not sure that you have given the important voltage readings. You quote two sides. It is important that you measure and quote voltages with respect to neutral as previously defined.

I am glad the temp was 100F and not boiling.

D7 does not look like a diode compare with D6

[davmax]

Re: UPS and inverter questions

problem what made Q10 and D6 blow???? Does this mean a shorted relay coil? Compare with other inverter.

[andrew77]

Re: UPS and inverter questions

Sorry, from neutral to the center is 75 volts. Wasn't using my brain, I put it back together to test it after realizing it says on the board "AVR CNTR" and "AVR TOP". The center one was obviously lower.

The relay is not shorted. I unsoldered it and tested it earlier.

[hardwareguy]

Re: UPS and inverter questions

I don't know if this leads you anywhere, but I am aware of one feature of the 7812:

These things are thermally protected and overload protected. If they get too hot or try to pass too much current, they will shut off..... check too see if the load on the 7812 is excessive. Check whatever circuit is being fed by its output pin.

In fact, all the 78xx and 79xx regs have this as far as I know.

Full output current of 1.5A needs a heatsink. The greater the input voltage, the more heat it will dissipate...... it is after all a simple but terribly inefficient linear regulator! (which is why they don't make high current ones...3A is the biggest linear reg IC I have seen!)

[hardwareguy]

Re: UPS and inverter questions

The cheap APC units are stepped square wave ("modified sine"), the SmartUPS is sine wave.

Oh.... I'm a night owl college student so I'll be up till 2:00am CST or maybe later...... no homework tonight so I guess I'll be on badcaps forums!

[davmax]

Re: UPS and inverter questions

Thanks Andrew. Well that is very interesting. It is a centre tapped transformer. As you show RY1 connected this means the following. In the default position the AVR transormer receives 115VAC from both line and the inverter. The other relay position places 115VAC on the centre tap doubling the output voltage to HOT and also the output of the transformer secondary (charging circuitry). Why is this? It defeats me right now. Are you sure these connections are traced correctly?

[andrew77]

Re: UPS and inverter questions

The cheap APC units are stepped square wave ("modified sine"), the SmartUPS is sine wave.

Oh.... I'm a night owl college student so I'll be up till 2:00am CST or maybe later...... no homework tonight so I guess I'll be on badcaps forums!

Thanks for looking at the thread.

Are you sure these connections are traced correctly?

Only as far as I've taken components off that were in the way of the traces. And to the best of my ability, which isn't saying much.

Here's where I've been deciphering most of my SMD markings: link

[hardwareguy]

Re: UPS and inverter questions

Monitor the battery closely if using a car battery charger.... forget it and you will destroy the battery.

How big are these batteries? The Smart UPS batteries (assuming you have a 1400 or more VA unit) can be charged with a car trickle charger. Watch the temps though, these AGM batteries do not have any way to replenish water in the electrolyte if you overcharge them.

The 5-7AH units in small UPS units shouldn't be left on a car charger for long at all, 30mins tops at any given time or they get too hot.

[andrew77]

Re: UPS and inverter questions

Hardwareguy, it's a pair of batteries in series and they're 7.2AH.

I'm too tired to do anything else, it's past my bed time.

I'll be back at it in 8 or 9 hours.

[davmax]

Re: UPS and inverter questions

Here's where I've been deciphering most of my SMD markings: link

Funny I must be missing it. I could not pickup link to code book. Does one have to be a member?

[hardwareguy]

Re: UPS and inverter questions

I used to charge 7Ah batteries with a 6A trickle charger.... I left them on for 30 mins, let them cool and then put them on for another 30. I kept a close eye on them.

You don't get full capacity with this fast charge (the rating is for a 20hr charge!), but it works if you want to jumpstart the UPS.

[andrew77]

Re: UPS and inverter questions

Funny I must be missing it. I could not pickup link to code book. Does one have to be a member?

No, let me give you some more links.

http://www.tkb-4u.com/code/smdcode/indexsmdcode.php
http://www.marsport.org.uk/smd/mainframe.htm
http://www.the-foundation.be/smd_codebook.php