Victron - Only Charge from Solar

Inverters Victron
101

I looked at your data again now. It looks like your float voltage is set to 53.8V or 53.9V? Look carefully at your data, the moment the voltage reaches that point, the MPPTs start limiting. They have to, they have been instructed to. If the battery won’t accept more charge current than it does at that voltage, the MPPTs are going to limit.

This “deadlock zone” exists for all batteries, it exists because SOC and voltage does not necessarily correlate. Even with a good LiFePO4 battery, if you tell the system not to discharge below 99%… it’s going to accept very little charge current, and the Multi is not going to feed any of that energy to the AC side because you told it not to.

What surprises me is that the deadlock zone is that large for your battery. That is assuming you’re using the right float voltage.

53.8V does seem like a very low float voltage. That’s less than 3.4V per cell. I prefer to float my cells at 3.45V per cell, which for a 16-cell battery should be 55.2V. Also a quick consult of a voltage/soc chart (at rest) seems to suggest that the SOC estimate is not too far off for the voltage you have there…

In other words, for the voltage you’ve chosen… 85% is essentially “full”, and the MPPTs are limiting because the battery is full according to what they have been told.

So normally I would advise you to raise your charge voltage. But I vaguely recall that if you do that, the BMS disconnects in protest and you end up with ripple warnings/alarms.

Which leads me to the next question: What’s wrong with your battery pack? It should not be doing that… it should allow you to charge your cells up to 3.55V per cell without complaining…

Edited to add: A good BMS will also reset its SOC estimate once it sees that the cell voltages are getting up there. This also pulls the system out of that “deadlock” zone within a few minutes and resync things. A BMS will usually only reset its SOC if the voltage goes high enough. Which again makes me question your very low float voltage.

A Pylontech battery, for example, wants to see 3.485V on almost all its cells before it resets to 100%.

1 Like
102

AHA … have I ever mentioned before the Daly as a potential culprit?

The Daly IS the problem BECAUSE the only voltages I can use, are Bulk of 54.6v and Float of 53.8.

I’m told: But other Victron people don’t have the same problem with the same BMS.
I say: a) BS. and b) they don’t use the system to its full potential.

ANYTHING higher ito bulk and float volts and I WILL get a DC Ripple, even with very short 50mm2 cables.
And yes, I checked every single connector and connections … as you explained to me in great detail with a lot of patience … I crimped the lugs damn good. :smile:

The issue stems from the max of 60v the Daly can handle … if I up the bulk/float, the margin gets to small and wham, even with small loads, the BMS will protect itself/the batts, when the MPPT has to throttle back. One has to have at least 75v “headroom”.

Replace the Daly … I’m onnit … the new one is coming with allegedly (negotiating from Eng to Chinese back to Eng is a challenge) with a CANbus, Bluetooth AND UART PC port.

This one: This product is no longer available.

Core reasons:

  1. Can ask the manufactuter to add what ports I want, and they give the specs.
  2. BMS is totally programmable via Bluetooth or UART.
  3. Balancing amps are more than 30mA. :smile:
  4. It has a proper shunt built-in.
  5. Min operating volts: 75v
103

Makes sense, for in that bracket, I’m seeing the MPPT “switching off” for all practicality.

104

It almost sounds like it was meant for a 15s battery… except that is a tad high for 15 cells.

The trouble with LiFePO4 is that it has a very very flat voltage curve. The entire curve from 30% to 90% spans a mere 2V over 16 cells, and from 90% to 100% spans around the same voltage delta.

I believe Daly does make a higher end model that works quite well. Ask @Louisvdw.

105

I think @justinschoeman is using the new smart Daly with the communications. It’s comms protocol looks very close to what my BMS use and it does look very capable, but I have not tested/used it.

My BMS is the same brand as the new one that TTT has bought.

106

Have asked the Daly manufacturer/supplier: What are the max operating volts?
For this BMS: SMART BMS LifePo4 250A 16S common port with uart/RS485/CAN communication
It is still max 60v.

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They also said, the Daly I have, can only have “charger for 58.4-60V”.
Upon mentioning the 72v spikes, they said: That’s why there is causing huge problems for u. I suggest you choose a larger cells than 16s of BMS, otherwise same issue would happen.

I instantly liked the ones @Louisvdw pointed out to me, maybe having made a mistake due to translation, I MAY get one without a UART port, if not, @justinschoeman said maybe there can be a CANBus connection, to which end I asked for the CANBus port to be Galvanicly isolated.

In any case, the older version could do 85v, the new ones max 73v.

So now it is a wait and see what I get. :laughing:

My CORE goal is to have a BMS that can use any lithium cell from any supplier, where this BMS “talks” more to the Venus than a lead acid battery and a BMV. The parmeters are there for me to set, on BMs and system, and not forced by the BMS/Vnus software integration … same as we did all these years with lead acid banks, we tuned the shiite out of them. :smile:

In the mena time I have read on the web that some people say that having a float voltage differ from the bulk volts are not necessary on lithiums.

Question: What if I make the float and bulk the same?

107

Yeah that could help… or make float 0.1V lower.

1 Like
108

Let’s see what Bulk of 54.6v and Float of 54.5v does.

Plonkster, I think we’ve gotten to the bottom of this one now. Our suspicions are now confirmed, the volts are too low so the MPPT does what the MPPT does.

Once I’ve gotten the new BMS installed, made sure there are no more DC Ripples, this should be-gone.
And can make them Dc Ripples happen on-demand. :wink:
All I do is switch on the option to feedback …

And Jaco is making me up some 70mm2 cables, 4m return length so that I absolutely remove any doubts I may still have ito cabe sizing, i.e. spot on the specs Victron recommends for <5m.
2 x 50mm are 4 lugs too many for my liking.