Sign up with GoogleGood point, but will this not break the whole link connecting to the transformer to get the inverter working.
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Modifying a RCT2000VA UPS with an External charger
- Thread starter KOPITE
- Start date
Good point, but will this not break the whole link connecting to the transformer to get the inverter working.
is to control the charging current
I think so
Gnome
Executive Member
- Joined
- Sep 19, 2005
- Messages
- 7,208
You are 100% wrong. That is the current sense transformer. It will almost certainly have nothing to do with charging.
Haha, I am watching this thread. Need to see what the end result is. This is going to be good.
This design was copied from the APC design btw. minus the true sinewave and safety circuitry before the first CT. Lower quality components (Chinese caps for example, relays look cheap, etc). But overall looks pretty decent tbh. Transformer is pretty cheap tho, so likely very inefficient. But considering it is low frequency it was going to be inefficient anyways..
So let's see:
1) This is a low frequency design. It is clear from the big ass mains frequency transformer. They clearly generate AC at low voltage then step it up using that thing.
2) They are running the inverter in reverse to charge the battery with the big ass transformer secondary being used as an inductor.
3) While this is happening the transformer primary is being used as a auto-transformer. Very classic APC design and really cool actually
They even say that in the manual you downloaded:
"Charger: The battery is charged by the mains through transformer and full-bridge inverter. "
The interesting bit is even though you are completely wrong about the current sense transformer, and I am super curious what will happen if you remove it (I suspect it will stop working but let's see), it does appear that there may be a way to disable charging.
This part for example has some very good nuggets of info:
"The flow chart of charger is described as follows: (Figure S-3-A & Figure S-3-B)
4.1 When UPS is connected to the utility, the control power (+5Vdc) will be established and the CPU will start to work.
4.2 When CPU turns on Main Relay (RY01), the AC power flows into Main Transformer.
4.3 Charging current will be generated from the inverter coil of the Main Transformer.
4.4 A PWM IC 3843 is used to adjust the charging voltage and charging current. (Refer to Figure S-3-A) The charging voltage can be set by changing the value of R87, R88, R46 and R65. The charging current can be set by changing the value of R14. "
So they are using a PWM chip to drive the transistors for charging. I haven't really got time to spend on this but if that PWM chip doesn't do anything other than drive the charge functionality I would considering removing VCC to the chip and see if that stops the charger from working.
Again. This. is. dangerous.
You are thinking of removing a current sense transformer to stop this thing charging when it doesn't even factor into it. It is actually there to prevent over current situations...
Are you are sure you should be doing this?
Last edited:
You are 100% wrong. That is the current sense transformer. It will almost certainly have nothing to do with charging.
Haha, I am watching this thread. Need to see what the end result is. This is going to be good.
This design was copied from the APC design btw. minus the true sinewave and safety circuitry before the first CT. Lower quality components (Chinese caps for example, relays look cheap, etc). But overall looks pretty decent tbh. Transformer is pretty cheap tho, so likely very inefficient. But considering it is low frequency it was going to be inefficient anyways..
So let's see:
1) This is a low frequency design. It is clear from the big ass mains frequency transformer. They clearly generate AC at low voltage then step it up using that thing.
2) They are running the inverter in reverse to charge the battery with the big ass transformer secondary being used as an inductor.
3) While this is happening the transformer primary is being used as a auto-transformer. Very classic APC design and really cool actually
They even say that in the manual you downloaded:
"Charger: The battery is charged by the mains through transformer and full-bridge inverter. "
The interesting bit is even though you are completely wrong about the current sense transformer, and I am super curious what will happen if you remove it (I suspect it will stop working but let's see), it does appear that there may be a way to disable charging.
This part for example has some very good nuggets of info:
"The flow chart of charger is described as follows: (Figure S-3-A & Figure S-3-B)
4.1 When UPS is connected to the utility, the control power (+5Vdc) will be established and the CPU will start to work.
4.2 When CPU turns on Main Relay (RY01), the AC power flows into Main Transformer.
4.3 Charging current will be generated from the inverter coil of the Main Transformer.
4.4 A PWM IC 3843 is used to adjust the charging voltage and charging current. (Refer to Figure S-3-A) The charging voltage can be set by changing the value of R87, R88, R46 and R65. The charging current can be set by changing the value of R14. "
So they are using a PWM chip to drive the transistors for charging. I haven't really got time to spend on this but if that PWM chip doesn't do anything other than drive the charge functionality I would considering removing VCC to the chip and see if that stops the charger from working.
Again. This. is. dangerous.
You are thinking of removing a current sense transformer to stop this thing charging when it doesn't even factor into it. It is actually there to prevent over current situations...
Are you are sure you should be doing this?
I'm not doing this myself. I asked an electrician today to see if he can maybe do it for me. Waiting on him.
BigEars
Senior Member
- Joined
- Feb 22, 2015
- Messages
- 533
An electrician is going to come up with an expensive "out of the box" solution. As in "out of the UPS box".
All that is needed is a very small disconnection inside the UPS. No extra parts or anything....
How do I do this
BigEars
Senior Member
- Joined
- Feb 22, 2015
- Messages
- 533
Electrician late? :erm:
Ok, so the way I understand this, because I don't have an extra battery pack, I only have the current batteries in series. What you saying I put a relay on the normal power plug and switch the relay to cut off power from the mains and then charge via the external charger. Is this happening while everything is on 24/7. I will only use the relay when I need to charge via external charger.
BigEars
Senior Member
- Joined
- Feb 22, 2015
- Messages
- 533
^^^You need to understand how a 3 stage charger works. It doe's not just float charge. It is constantly monitoring the battery/batteries under its supervision. They do crazy stuff..mine cycles from 14.4V down to 13.2V and keeps all topped up when floating the battery....
All that a normal float charger (internal cheap UPS) does is float the battery. Cannot think.
So, it's either one charger in control, or nothing. Otherwise they will end up fighting. You see it?
All that a normal float charger (internal cheap UPS) does is float the battery. Cannot think.
So, it's either one charger in control, or nothing. Otherwise they will end up fighting. You see it?
So is my explaination correct or not
Show that section to your electrician guy