question

simonmtl avatar image
simonmtl asked

100/20 goes thru charging cycles many times in 1 day !?

Hi!

Just got my installation done yesterday! Fun to look at and check the statistic on the app :)

My system is 100/20 mppt, 2 x 225 ah 6v, 295w solar panel and bmv712 installed in a sprinter van


Yesterday got the charger to charge and everything looked fine, but this morning I went to work parked the van under the sun, it was in bulk mode at that time. 8 hours later, after work I come back to the van, check the mppt status light it shows it’s in absorption, which I though was normal. Then I check the app and it shows it did went thru the float mode for a part of the day...


So I drive back home, once there it was now in float mode, thought it was weird. Went inside my house get a snack, and now it’s back in bulk mode


Is that normal?

I thought the cycles was to happen one after the other and it was not going to cycles thru them. Maybe I’m confused...


Just to make it clear, I have a 12v refrigerator hooked on the system, duty cycle is about 15minutes and it roughly draw 50w while on


Also I have checked the plates they look clean without sulfatation

MPPT ControllersHelp
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Mark avatar image
Mark answered ·

What do you have your float voltage set to & during that time was the float voltage able to be sustained or did it drop?

Depending on which firmware you are running in your MPPT, the 're-bulk' voltage will be either 13.7v or 13.4v - so if the float setpoint voltage happens to be set below this voltage or if the battery voltage drops below the 're-bulk' voltage (due to loads + lack of solar power) then it will trigger a new charge cycle starting with the bulk phase again.

If this happens late in the day it will most probably never reach absorption before dusk & finish the day in bulk phase.

In the upcoming firmware release, it is intended for the 're-bulk' voltage to become user configurable.

2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

simonmtl avatar image simonmtl commented ·

Ok! I didn’t know it could do a rebulk, I thought charge mode were happening one after the other with no coming back, but it makes sense that it can do rebulk


So my batterie are Magnacharge GC225 which are six volt and from what I understood is a de-branded Trojan T-105


My firmware is the latest version, so I don’t know what is the rebulk voltage is!?


My setting is

Abs 14.8v

Max abs time 6hrs

Float 13.20v (might be too low)

Eq 15.5v


Those are data I took from a T-105 data sheet but I found another one on the web for the t-105 that has different float and eq (13.50 and 16.20). I didn’t use them cause I thought maybe that was for a newer version of the T-105 and I wanted to play safe using lower number. I don’t want my batteries to explode :/


I will be contacting Magnacharge directly to have real spec from them since I can’t find it on their website :(


In the meantime, should I increase float?

Any danger if I put numbers too high??

Thanks

0 Likes 0 ·
Show more comments
simonmtl avatar image
simonmtl answered ·

thanks again.

so I got the data sheet from the manufacturer today, good news is that my setting was correct

now, i think I will be contacting my distributor to have some advice over the phone..


trojan-gc-225-1.png (359.3 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

MPPT Product Page

MPPT Error codes

MPPT 150/60 up to 250/70 Manual

Additional resources still need to be added for this topic