Need help adjust bulk voltage on 16 year old non-VE.Bus Victron Multiplus 24/3000

[Maast]

Looks like the inverter I got for $400 was a lot older than I thought. According to Victron support the serial number says it was made in 2006. Be interesting to see how it does when I put some real loads on it.

At any rate, after a lot of manual studying and head scratching I figured out how to change the absorption and float voltages & times using the dip switches - but there's nothing in there about what dip switch selection I'd use to adjust the bulk voltage. It's set for 3.6V per cell which is .5V higher than I'm comfortable with. I'd also like to adjust the low voltage disconnect - it shuts down the inverter at 2.25V per cell which is WAY too low. I can rig a external LVD though so thats not that big of a problem.
I've got another support request email going to Victron but no reply so far.

Anybody have a idea? There are no pots on the mainboard that I see but I can't imagine it's not adjustable when just about everything else is.

The numbers on the board are: 1842012-HEX on the big chip, and
PMP 24/3000
2021070053
06130800006
On the stickers

 

[Maast]

Got a response from Victron Support: There is no "bulk voltage" it charges up to whatever the absorption is set for and switches over to that for whatever you have it set for (minimum of 1 hour) and then down to the float voltage. I can rig a external low voltage disconnect so it looks like this'll work for me.

 

[Ampster]

Anybody have a idea?

The bulk currrent is the important value because once charging in Bulk gets to Absorb voltage it should go no higher.

 

[Ryang]

Quality Hardware lasts forever.... Nice.

 

[ghostwriter66]

Got a response from Victron Support: There is no "bulk voltage" it charges up to whatever the absorption is set for and switches over to that for whatever you have it set for (minimum of 1 hour) and then down to the float voltage. I can rig a external low voltage disconnect so it looks like this'll work for me.

So YES technically it will work - guess it just goes full on charge until it hits the magic number then switches to float .... is there user defined parameters to tell it to charge to a certain point that you can set??

I was in the 3rd grade when this came out ... wow ... they built them good ...

 

[Maast]

So YES technically it will work - guess it just goes full on charge until it hits the magic number then switches to float .... is there user defined parameters to tell it to charge to a certain point that you can set??

I was in the 3rd grade when this came out ... wow ... they built them good ...

According to them thats what it supposed to do and the settings I put in via dip switches and the testing I've done it appears thats the behavior, but what I see with the tiny little 5AH mostly dead UPS batts I'm using to test with is it'll charge and momentarily hit 28.8V (3.6v/cell) and immediately drop to the 27.6V (3.45v/cell) absorption voltage and then drop to the 27.2V (3.4V/cell) float voltage I set. It charges so fast (about 90seconds) with these tiny batts though that the 28.8 might simply be overshoot. Need to carry it downstairs to hook up to one of the BYD modules for a real test. Think I'm going to drop the float to 3.35v/cell.

3rd grade..... groan. I'd been retired for a year from the Air Force in 2006.

I'm actually thoroughly impressed that it still works so well so far, have to do a full load test tho. Can't edit my OP, its ONLY 14 years old.