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Hi. I have a new install MP2 3kVA with victron gel batteries (4 x 220AH in series).
I did an initial discharge test down to what the system believed was 70% or 48.9V.
When I cut back power, the charger went straight into float, not bulk.
It has slowly charged back to 85% and is now in storage mode.
Any ideas why it would not have bulk charged?
Should I just run another (longer) discharge cycle and see if it corrects itself?
It can be a pain/issue for off grid setups, but there is a minimum voltage that the battery must fall below, in order to trigger a new charge cycle, after an initial charge cycle has been completed.
This is the case even when the AC input has been disconnected and reinstated days later - such as when charging with a generator.
For a 48V system the battery must fall below Float voltage - 5.2V (for lead acid batteries).
There is a work around, which is to switch the Multiplus OFF and then back ON. Then it will go into bulk charge phase immediately, regardless of the battery voltage.
What is the minimum charge value for 12v lead acid batteries and can it be altered in settings?
The 12v system re-Bulk voltage is in the screen image attached above: Float voltage - 1.3V (with a maximum of 12.9V).
Although the above is, in my experience, accurate there is a wrinkle that caught me off guard. It could fool anyone: the impact of a solar panel.
I have a Multiplus supporting a 300 AH 12-volt lithium system on a Cal 34 sailboat. After sailing for a week, I docked and hooked up shore power. Shore power takes over for the fridge, cabin lights, hot water -- in fact everything but AIS and the freezer. After motoring to the harbor and dock, batteries were 100% charged with the alternator. Multiplus went into "float" as expected.
Overnight the voltage drops slightly as the battery powers the freezer and AIS ... but not below 13.5 volts. In the daytime the solar panel gives a voltage of above 13.5 volts -- yet draws from -2.3 to -6 amps depending on the appliance draw and amount of light. The result was a house battery with less than 50% capacity remaining -- but a Multiplus still in "float". As mentioned, the workaround is to turn the Multiplus to "off" then either to "charge only" or to "on".
That assumes you are still at dock -- otherwise you have to start the engine to charge the battery.
Hello! I have the same problem with a Multiplus 24/5000. I have attached the diagram of the voltage. You can see that the first day, the systems enters bulk-absorption-float. The second day it is only on float! My batteries are OPZs and I noticed that the second day the voltage during the night did not fall under 24,2 V . So if you formula is correct, my float voltage is 26,8V, If we take of 1,3 V for a 12V system than for my 24 V system the rebulk volatge is 26,8-1,3*2= 24,2 V.
So it is normal to not trigger a new charging cycle?
The other work at wound is to turn off storage mode under charge I believe. Then it will go through the normal cycles when charging.
Thank you for your reply. Storage mode is not selected in the VEconfig.
I would label this a defect in the logic in the Multiplus. My float is 13.4V so using Victron's logic, I would not go to bulk charging until the battery voltage goes to 12.1V which is significantly discharged or under a heavy load. My typical voltage with a 20A or less load is 12.7V at 80% SOC. Having to reset the Multiplus to get to bulk charging when the battery bank is at 75% SOC doesn't make much sense. There needs to be a way to disable this arbitrary voltage setting so the charger will go to bulk mode. I have tried using the fixed charge curve and the unit does exactly the same thing. I can set a lot of values in the Multiplus, but can't specify when to start bulk charging.
I agree. Between this and the inability to end absorption based on tail current, the multiplus charge algorithm is significantly flawed. It's disappointing, considering the charge algorithm (and associated adjustments) on the SmartSolar MPPTs is quite good.
I have the same problems with my 600ah house bank of AGM Lifeline batteries. No bulk mode unless I turn the Multiplus II off/on. I've set the charging profile for my batteries up in ve configure.
Any other settings I can adjust to trigger it to start in bulk mode?
TIA,
Jack
