Modifying a RCT2000VA UPS with an External charger

[BigEars]

The problem here I understand is the cheap ups charger even though it may be a 10amp charger is most probably a 2 stage charger
Current limited to x amps
Voltage limited to 27.6 volts
It does not charge battery to 28.8 v for an hour and then drops down to 27.6

As far as I know the RCT 2000 comes standard with two series connected 9Ah batteries..
MAX charging current for a normal 9Ah SLA is 2.7A.

How can it have a 10A charger?

See pdf below

View attachment RT1290.pdf

 

[thehuman]

As far as I know the RCT 2000 comes standard with two series connected 9Ah batteries..
MAX charging current for a normal 9Ah SLA is 2.7A.

How can it have a 10A charger?

See pdf below

View attachment 218522

I realy wish someone will take an amp meter to see current flow

 

[BigEars]

I realy wish someone will take an amp meter to see current flow

Agreed absolutely. I have been using logic only without any real hard physical facts on the unit.

 

[KOPITE]

Can someone please try and get a diagram circuit for the ups. This will help us to bypass the internal charger.
Which company can we ask to maybe get the manual or diagram

 

[KOPITE]

As far as I know the RCT 2000 comes standard with two series connected 9Ah batteries..
MAX charging current for a normal 9Ah SLA is 2.7A.

How can it have a 10A charger?

See pdf below

View attachment 218522

Is this the batteries that the rct ups takes.

 

[BigEars]

Is this the batteries that the rct ups takes.

9Ah SLA is 9Ah SLA. Quality varies from brand to brand but they essentially have similar charging specs.

Here is how the battery charge/discharge stuff works. Pdf below:

 

[KOPITE]

http://www.manualslib.com/manual/702858/Fsp-Technology-Ep-1000-Series.html#product-EP 2000 Series

This is the 2000va one. This looks the same if not identical. Anyone an spot any differences

 

[BigEars]

Got the Manual. Thanks. It's 2.72A MAX charging current. As I predicted. Not 10A....

They have made allowance for bigger Ah batteries though...they have an option of an additional current sense resistor in parallel with R14...more current then...

Interesting design. Love to get my hands on one

 

[thehuman]

Again loadsheding for me will switch pc on 18:00 and take a look
Ok
Check figure S 3 B
R71 and r14 is parallel can increase the value of both to limit current to nothing

 

[BigEars]

Note to KOPITE.

Send the thing here to me. Let me sort out and do the simple mod and check it out. You take internal batteries out and pay postage both ways. Done and dusted. Any work I do on the thing I will share here on MBB. And the labor is free.

We all need to learn here. Plus I have equipment that can monitor and do stuff.

Ball is in your court.

 

[thehuman]

Note to KOPITE.

Send the thing here to me. Let me sort out and do the simple mod and check it out. You take internal batteries out and pay postage both ways. Done and dusted. Any work I do on the thing I will share here on MBB. And the labor is free.

We all need to learn here. Plus I have equipment that can monitor and do stuff.

Ball is in your court.

This i think will be the safest

 

[BigEars]

Again loadsheding for me will switch pc on 18:00 and take a look
Ok
Check figure S 3 B
R71 and r14 is parallel can increase the value of both to limit current to nothing

Those two resistors are in parallel. And they are both 3W low Ohm resistors. That tells me they are handling the actual current going from internal charger to internal battery/s. Design probably has a transistor base emitter junction waiting for 0.6V to switch on...and then current limits. Gut feeling.

 

[BigEars]

Or maybe I should just buy a RCT 2000. Don't need it though. Check it out properly. Mod it and sell it to a Customer here that hates blackouts...problem is I will not have any takers.

Enough.

 

[KOPITE]

Got the Manual. Thanks. It's 2.72A MAX charging current. As I predicted. Not 10A....

They have made allowance for bigger Ah batteries though...they have an option of an additional current sense resistor in parallel with R14...more current then...

Interesting design. Love to get my hands on one

I had a close look at the circuit board and I noticed there is a resistor missing. Looks like they left it like that intentionally.

 

[KOPITE]

Note to KOPITE.

Send the thing here to me. Let me sort out and do the simple mod and check it out. You take internal batteries out and pay postage both ways. Done and dusted. Any work I do on the thing I will share here on MBB. And the labor is free.

We all need to learn here. Plus I have equipment that can monitor and do stuff.

Ball is in your court.

I can send it, but the Mrs will complain for a few days.
If you can send me something to go on with or if anyone in cpt can donate something to me in a few days then i will ship it off to you.

Any takers........

 

[thehuman]

Some components sometimes optional . What is the resistor id ?

 

[KOPITE]

Those two resistors are in parallel. And they are both 3W low Ohm resistors. That tells me they are handling the actual current going from internal charger to internal battery/s. Design probably has a transistor base emitter junction waiting for 0.6V to switch on...and then current limits. Gut feeling.

Do you actually do these electronical components work as a day job?

 

[KOPITE]

Some components sometimes optional . What is the resistor id ?

Will send you a pic now, is it not in the pics i already send.

 

[KOPITE]

sorry, watching the rugby first. will send after the game.

 

[thehuman]

Do you actually do these electronical components work as a day job?

A person need a understanding how electronics work ,
Electronics is a hoby of mine