Nerdvana
New member
Our yacht has a 24V Mastervolt MLI system with 2x MLI 12/5000s in series, Mastervolt 24/60 charger, Alpha Pro charge regulator and an SCM25 solar regulator. The system was installed by a very professional dealer in 2015.
There is a small PC connected to a Masterbus USB interface, which I can power up to give me remote access to MasterAdjust. There are a couple of webcams, 4G router and other kit that remain online and draw a total "steady state" power drain of ~45W.
We've spent the last few winters in Piraeus, and I've been leaving the shore power charger disabled so that the solar panels charge the batteries for a few hours every day. If SOC falls to ~35% the battery charger will start, or I can start it remotely. The batteries have needed a shore-power top-up every week or so through the winter.
However..... I noticed that one of the two MLI batteries reports a lower SOC than the other, and that the two SOC figures diverge over time. Towards the end of 2021 the difference increased to the point that the standard Mastervolt battery protection was preventing any charging (one battery was below 25%; charger would start but after ~1 minute the big battery isolation relay would pop out). The local Mastervolt dealer was able to override this and get both batteries up to 100%.
So, the batteries can get back to both reporting 100% SOC. But the constant ~45W load over 24hrs combined with solar charging for 4-6 hours per day results in a SOC difference between the two series-connected batteries, which increases over time.
The Mastervolt-specified "balance" cable between the two batteries is in place; the blade fuses in each battery have not blown, and (needless to say) nothing is connected "stand-alone" to either battery.
Has anybody else experienced this, or anything along similar lines?
Thanks
Sean
There is a small PC connected to a Masterbus USB interface, which I can power up to give me remote access to MasterAdjust. There are a couple of webcams, 4G router and other kit that remain online and draw a total "steady state" power drain of ~45W.
We've spent the last few winters in Piraeus, and I've been leaving the shore power charger disabled so that the solar panels charge the batteries for a few hours every day. If SOC falls to ~35% the battery charger will start, or I can start it remotely. The batteries have needed a shore-power top-up every week or so through the winter.
However..... I noticed that one of the two MLI batteries reports a lower SOC than the other, and that the two SOC figures diverge over time. Towards the end of 2021 the difference increased to the point that the standard Mastervolt battery protection was preventing any charging (one battery was below 25%; charger would start but after ~1 minute the big battery isolation relay would pop out). The local Mastervolt dealer was able to override this and get both batteries up to 100%.
So, the batteries can get back to both reporting 100% SOC. But the constant ~45W load over 24hrs combined with solar charging for 4-6 hours per day results in a SOC difference between the two series-connected batteries, which increases over time.
The Mastervolt-specified "balance" cable between the two batteries is in place; the blade fuses in each battery have not blown, and (needless to say) nothing is connected "stand-alone" to either battery.
Has anybody else experienced this, or anything along similar lines?
Thanks
Sean
