I have a 7 month old system on my Catamaran. First couple of months all was perfect and able to get close to 2,000 watts of charge when running engines. Now down to 400ish after about 5 minutes down from 2,000. Installer thinks it could be the sensor that needs to be moved. Not sure why after a couple months that would now be the issue. Any help greatly appreciated!
Hi Nick,
Please can you post more information about your system, in particular how the charging is connected and set up. Also the battery details. This would help with diagnosis.
I second @MikeD in asking for a bit more information.
What Voltage is the system? What sort of alternators are they? Do thy have external regulators? If so, what type? What sort of batteries are they? Do you have solar? How much and what are the regulators? What is the sensor you are referring to? What Victron systems are on board? What is the State of Charge of the Battereis when this reduction in power occurs?
Sorry kind of newbie… Secondary alternators added by Fountain Pujot at the factory and no brand listed. 125a and it’s a 12 volt system with solar and 4 LifePO4 330a batteries and not sure on external regulators, does have a Lynx M10 distributor.
The tech indicated a wire that was connected to the second alternator may be the issue. He said to clip it to a different spot on the alternator which is the sensor I am referring to.
Systems also include the Lynx Smart BMS. State of battery hasn’t made a difference weather it’s 25 percent or 75 percent.
Too bad I can’t include pictures.
Hello Nick,
One of the problems with having alternators connected to Lithium batteries is the ability for the Lithiums to take all the current the alternator can give. This can cause grief if the alternators don’t have external regulation. The sensor referred to is probably a temperature sensor to ensure if the body of the alternator gets too hot, it reduces the excitation current and lets it have a rest.
If the batteries are full of course the alternators will not charge the batteries because they are full. Is it possible your solar has already charged the batteries and you are trying to charge full batteries?
No I understand that if full or close to full then they will reduce the charge. In this case it happens even at 25 percent battery level.
Yes that is a temperature sensor and will be at the boat tomorrow so will disconnect and reattach to see if it helps but can’t image that would be the issue as reduces from 1,900w to 400 after less than 10 minutes and wouldn’t think it would heat up that quick?.
If you have two alternators providing that charging current it would be quite rare for both alternators to exhibit the same faulty behavour at the same time unless the external regulators are controlled by let’s say a CerboGX. Do you have a CerboGX in the system? If the CerboGX has DVCC enabled that could happen.
Are you sure the batteries are at 25 percent SOC? Where does that information come from? Does the battery terminal voltage seem reasonable for that level of SOC?
In the case of Balmar, the external regulator has a temperature sensor that is atttached to the body of the alternator so that if the body of the alternator reaches 100 degrees C, the excitation current from the external regulator drops to 50%.
Yes we do have a cerbo unit I am certain.
I have the battery percentage from the remote panel that displays the incoming and outgoing amps (GX Touch). Yes the levels of SOC seem reasonable. After lots of sun will be upwards of 85 percent and in the morning drops to around 30-40 percent.
Yes he thinks that the sensors are causing the charge to reduce but I find that hard to believe as both sensors for the first few months worked perfectly and now for some reason both sensors are showing alternators to be too hot? Seems unlikely.
Disconnect both sensors and see if it improves. I
Am not sure of your configuration but check the voltage on the output of the alternators and make sure it is the same voltage as on the batteries.
If the external regulators are working, I guess it is possible the alternators could be shot. That would be a bit unusual but possible I gues.
Hi Nick,
I apologize in advance for the deluge of questions, they are really intended to help you sort things out. You will also find all this to be very useful over time. And I am sure with additional information, more suggestion to resolve the matter will emerge from the community.
Check for any label on the alternators, take pictures and note all references. What is the brand and model of the engines?
Follow the cables from the engine to the batteries, including starter battery and draw the wiring with the equipment you find on the way. Does it agree with the electrical plan provided with the boat?
With the huge LFP battery bank that you have, I would imagine that without some form of current limitation, the alternators would have failed rapidly. If you had an externally regulated alternator, chances are it would be easy to read the brand. And 125 A seems very low for the purpose. I would therefore expect (but could be wrong) internally-regulated alternators, but then feeding into DC-DC chargers, or DC Buck Boosts…
Is this a new-boat installation done by the yard, or a retrofit on an existing boat? Did anything change during the first before you saw the charge current suddenly (?) drop from some 150 A to 30 A? Or did anyone work on the system that could have “improved” it? As other suggested, temperature regulation is a good lead - I just don’t see why it suddenly kicked in.
Other lead: were the LFP batteries properly charged at the start? Were they fully charged thereafter, at least once a month? It is easy to get SOC totally off unless the batteries have been fully charged and the parameter settings are appropriate. Do you have Smart Shunts to measure current consumption?
Check the batteries individually (on your phone with with Victron Connect). Anything suspicious?
Finally, is your Cerbo GX setup to send all the data to VRM? If you have everything on VRM, it is useful to build a few custom plots (very simple) to review data and troubleshoot before going back under the floorboards.
I hope this helps. Good luck!
Hi Nick,
It is quite easy to include pictures on this forum, and they are a great help in troubleshooting remote systems.
you can either drag and drop the picture (subject to size and format constraints - try it &see), or upload the picture file.