dracekvo avatar image
dracekvo asked

Bluesolar jumping bulk/absorption/float


I`m newbie with victron. Before I have Tristar MPPT 60A.
Now I have Bluesolar mppt 150V/60A (no-smart), BMW-700 and rapsberry pi 2 with CCGX OS.

Ask 1:

I set absorption 55.2V, maximum time 5 min, float voltage 54.4V. Temperature compensation off, Equalize off. Why mppt charger jump bulk/absorption/float all day? See in screens.


Solar charger show voltage 55.2. But BMW show woltage 54.9V. Why charger not read voltage from BMW to compensate wire lost?
There is problem, becasue my ballancing module in each battery cells need 3.45V to corect battery balanced.

BlueSolar PWM
state.png (8.1 KiB)
batt.png (52.7 KiB)
2 |3000

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

wkirby avatar image wkirby ♦♦ commented ·

Can you also tell us what is happening with the weather at these times. Is it partly cloudy with the sun coming and going?
Also, what sort of loads are there? Are the loads constant or are these loads switching on and off a lot?

0 Likes 0 ·
dracekvo avatar image dracekvo wkirby ♦♦ commented ·


Yes. it was partly cloudy with the sun coming and going.

Loas was mobile heater with on/off regulation.

0 Likes 0 ·
ac.png (48.2 KiB)
2 Answers
wkirby avatar image
wkirby answered ·

So if your generating capacity (solar) is going up and down and also you have a load that is going high and low then it makes sense that the battery cannot stay in float all the time for a day like that.
When the load is high or the the solar is low (or both) then the battery Voltage will fall below the Float limit and it will jump back to Bulk. When the load is low and the solar is good (or both) then the battery will charge nicely again and go through Absorb and Float again.

1 comment
2 |3000

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

dracekvo avatar image dracekvo commented ·

Ok. I understood.

Tristar MPPT make absorbtion only one time in day regardless on that battery drop down under float.
I mean that was better. Because lifepo4 don't need ballancing several times during the day.
I will try equalize for ballancing only one time in day.

But now I have another problem :)

Absorption today was too short. Why? I set 55.2V and time 5 min in bluesolar setup.

0 Likes 0 ·
today.png (52.1 KiB)
offgridsa avatar image
offgridsa answered ·

I am having the same issue and was going to start a new thread but because My issue is almost identical I thought it better to bump this one.

I have had many years experience with previous offgrid system using Midnite solar classic 150 charge controllers and I was able to have them go through a bulk - absorb then float stage each day.

Once in float the charge controller would do its best to cover fluctuating loads throughout the day and maintain float Voltage. There was a rebulk voltage setting in the controller that you could set real low to say 48v so it wasn't triggered over a typical day.

It is absolutely possible for a charge controller to cover loads in float I ran my last lithium based system for 6 years like this with many large loads cycling on and off all day. Battery's held same soc % by end of day that they where when float was triggered earlier in the day.

What I am finding with the Victron charge controllers is they keep wanting to do a (rebulk) after the initial bulk - absorb- float if there is a large load or passing cloud and the voltage slightly drops the controller switches back to bulk followed by another absorb stage (though usually its only a shortened absorb after the initial one) I also no the Victron controllers have pre-set voltage drop trigger point for this rebulk feature to activate. something like .8v drop from float voltage ( 3.2v - 48v system)

So I have also found on days with large loads switching on and off my batterys can go through many bulk-absorb stages and trigger balancing of my cells several times a day this is unacceptable. I cant imagine anyone wanting this feature with lithium batterys.

Is there any way to disable this rebulk? Or does Victron actually sell any controllers that are user configurable. Not just a bunch of preconfigured one size fits all lead acid legacy settings that you cant change. A pre-set fixed absorb time is another one with a user adjustable tail current that ties into the BMV to cover active loads befor float trigger...that's another topic...

I have two bluesolar 150/85 controllers that I unfortunately might have to replace with midnite classic 150s that have detailed user configurable setting rather than all this preconfigured non adjustable nonsense.

Sorry if I come across frustrated I guess I am a little.

2 |3000

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

Related Resources

Additional resources still need to be added for this topic