I am researching a Lithium install using the Smart BMS 12/200. The documentation states that, "the input current is electronically limited to approximately 90% of the fuse rating". How is this accomplished? It almost implies that it somehow senses the fuse rating, but I can't see how that's possible.
There seems to be zero documentation on the configuration options available via bluetooth, so I can't figure out if that setting is in the app.
The resistance of the fuse is measured. The lower the resistance of the fuse, the higher its current rating will be.
The current flowing through the fuse will be known, so the Voltage drop over it can also be measured and then the resistance can be calculated. Given that this product accepts the Littelfuse MEGA range of fuses, the resistances for different ratings across the range will be reasonably predictable.
Thank you for that answer. That gives me some peace of mind to know how it works, as I am planning to use my existing alternator which will need to be current limited to avoid the alternator burning itself up.
As an aside, do you know if it is possible to configure the current limiting even lower than the 90% of fuse rating manually via Victron Connect?
For what it's worth, during my installation, the Smart BMS 12/200 did not detect the fuse. There is a menu option to set the correct fuse manually via Victron Connect, which is what I did.
On my sailing boat I have installed Smart BMS 12/200 with 330Ah Smart Battery. Works fine.
My alternator regulator has a sense wire, and I found out it has to be connected to the "input" of the fuse and not to the battery directly. If you connect it to the battery, the Alternator will continue to deliver high current and Voltage (voltage drop 2V between input and battery) which results in BMS switching of due to overheating.
To your second question, I think the answer is no. The limit is determined by the fuse. Although my alternator (installed on VolvoPenta) can deliver 115A, I decided to be conservative and used the 80Amp fuse.
Hope this helps
Hello,
Bumping this subject, because I'd like to have an authorised answer to that question "can we limit the alternator current flow by setting a lower fuse value from the BMS menu than the physical fuse ?". The manual says that the menu should reflect the physical. What happens if it is lower in the menu.
What I don't understand is, since the BMS can sense the intensity (from Kirby's answer), changing the fuse rating is only a simple way to set up the Amp limit, but I should be possible to set it from the menu too.
When I ordered the BMS I had information that our alternator was 120A so standard fuse was ok. Now it turns out that the alternator is weaker than expected, and until I can have a 60 or 80 A fuse, I'd be interested to set the limit from the menu.
I have a sneaking suspicion that the only function setting the fuse value has is to calculate the charge current on the Victron Connect App. When I set mine to the lowest value, it didn't change or limit the current, it just changed the percentage. It would be great to get an official answer from Victron!
Hi, I have the same question : "the input current is electronically limited to approximately 90% of the fuse rating".
How is this accomplished ? But how is this accomplished from a technical point of view on the limitation side of the electronics ?
I thought a BMS could only turn ON or OFF the connection between the battery and the alternator. How is it technically possible to limit the current ? Is it by diverting the alternator current to resistors ?
Is it also possible to get more than 40A with the ATO-fuse-holder installed? Does it work when I install 2x40A-fuses on the ATOfuse-holder? The manual says nothing about it and I dont want to remove all the screws and cables to put in a Maxi-fuse...
ok thanks! The problem is that I only get a maximum of 23A and 300W with 2x30A fuses installed and I dont know why? The alternator in my Ducato 250 (luckily no smart alternator!) can charge with a maximum of 120A and 13,7V. I switched off everything (vehicle lights and DC loads like fridge etc), but nevertheless I only geht 23A and 13,7V from the alternator...
