Trying to keep this brief, let me know what other info might be needed.
Config:
2x300 AH off brand lifeP04 batteries
1 550w rigid solar panel
Victron Smartshunt
Victron 50/100 Mppt charge controller
Victron 50a DC/DC charger
System works great and provides our boat a lot of power but 2 problems/things I would like to optimize:
They system stops charging (either solar or alternator, and sometimes a mix) at about 65% of the combined average battery charge level (see 2) meaning it goes from Bulk to Absorption and pulls in from the input sources about exactly the current draw from there on.
The batteries, wire in parallel, have become distinctly different in charge level (51% vs 70%)
I’ve attached the battery settings for each of the devices to see if anyone can narrow down on what might not be setup properly.
I have tried connecting to the batteries with a standard bms management app, but it didn’t see them (other bluetooth connectivity works fine). Can anyone suggest an app?
It seems there is a setting (settings) that are limiting the victron devices from charging to a voltage that will get the batteries to a full charge. I have done reading and watched videos to try to nail that down, but I’m cautious to screw anything up.
Please tell us more about the batteries as this seems to be more of a problem with those. How does the SOC of the SmartShunt compare with the batteries. What voltage and current is the smartshunt showing, post a history screenshot and status screenshot. The mppt settings look OK, the link for the shunt fails. The SOC reported by some drop in batteries is not very accurate until they have had a full charge discharge cycle. Get us the shunt info and we can help.more.
Ok, to try to simplify things I have disconnected one of the parallel batteries. (Victron reseller mentioned the stopping charging issues was due to the batteries being out of sync) but there is still a problem.
To further isolate I have the system focused just on charging from solar. But again before the battery is fully charged it stops charging and starts discharging.
This link should now have the victron dashboard, battery dashboard and the battery settings screen for each of the components.
First off, correctly set up the SmartShunt should be much more accurate than the SOC in some of the cheaper battery brands, so once working, rely on that.
Secondly, paralleling batteries needs uniform connection wire lengths to work along with equally made crimps, bolt torques etc., see Victron wiring unlimited
Thirdly, with standalone batteries if they get badly balanced cells one battery can stop charging and the other can carry on charging so the batteries get out of synchronisation with each other. Once the cells are balanced then they should remain synchronised reasonably well as long as your wiring is equal.
I can not see anything that would stop your batteries being fully charged. Reasons for not fully charging.
They are being charged and the SOC is not right. Does the voltage get to 14.2V and the current below 12A for 1 battery or 24A for 2 batteries at the same time. Your SmartShunt settings are not very good and will.not easily reset to 100% on a full charge.
The batteries are not balanced and they are stopping charge. If it is the latter then try charging at 14.0V or slightly lower to give them chance to balance.
You have a high resistance between your chargers and your batteries. When the charger is outputting 14.0V say, the battery should ideally be quite close to this, say 13.8V. If it is much lower then you need to investigate this. Do you have DVCC set up to compensate for voltage drop.
MPPT
Set float to 13.5V
Smartshunt
Set charged voltage to 14.0 or 14.1V. This is not a control, it is a monitoring voltage.
Set tail current to minimum of 2%, preferably 4%.
Set charged detection time to 3 minutes.
Set Battery SOC on reset to “Keep SOC”.
GX device
In Settings / System Setup / Batteries / Battery monitor choose your SmartShunt.
In Settings / System Setup / Charge Control
Set DVCC to on / enabled
Set SVS and SCS to on / enabled
SVS and SCS may need you to select a source of info, either leave ad automatic or select the SmartShunt. This then sends the battery voltage and current to the chargers to counteract voltage drop.
To help me build my experience and simplify the initial problem I have isolated down to 1 lithium battery.
It still only charges to 46%, at which time the smart shunt has auto set to 99% soc. I get you say the SS is more accurate but surely they shouldn’t differ to this degree?
Are you saying all of the MPPT, SS and GX device setting you have suggested are needed for the system to charge the battery to 100? I’m open to changing them, but can you give me a bit of rational behind these changes? I don’t need a setting by setting break down, but given many are different from the recommended victron settings I am just trying to get a feeling for the strategy here.
As I said, I would always rely on the SOC from a Smartshunt once set up properly compared to a basic low cost drop in lithium battery. The other caveat is also that the system is functioning, if you have poor connections causing incorrect voltage readings then all bets are off. You still need to do some basic trouble shooting with a multimeter and basic trouble shooting on battery balance. If the battery is getting to >14.0V and <12.0A then it is full regardless of the SOC. If it gets to such conditions the battery SOC should reset to 100%. You need to be talking to your battery supplier.
MPPT
It is well accepted tjst the float voltage for lithium should be 13.5V which equates to 99 to 99.5% SOC to avoid long term.over charging. Discussed profusely on the web.
SmartShunt
Many of your current settings are not the default settings. Most of what I have described are the default settings or slight mods to these. The major difference is the charged voltage as discussed in the link below. Your current setting is the same as absorption and if there are voltage errors will not work.
Still some work to do here on my end, but so far the most likely issue is pointing the BMS not stating SOC accurate to the voltage level which was mentioned as a possibility by pwfarnwell. This appears to be happening on both batteries and I am working on getting support from the battery manufacturer for their recommended reset procedure.
One of my learnings here is how varied the SOC vs voltage algoritum can be, and so stated SOC can vary much more than I would have thought.
I’m going to mark this closed for now. Thanks to klim8skeptic and especially pwfarnwell for your valuable comments.
