Low alternator charging with Smart BMS 12/200

DIY
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1

Hi pwfarnell
I have a boat with 4 pcs. Lifepo4 12/200 bateries, Smart BMS 12/200 and 180A alternator. Since the alternator only charges with approx. 50A, I want to add an Orion XS 12/12-50 between starter battery and Smart BMS to boost the alternator voltage. The original Orion has a 125A fuse on the alternator side. Can I replace the fuse with 200A to charge the alternator with up to 180A
Thank you

2

Topic moved to its own subject.

You can not increase the Fuse size above 125A for 100A charging. The Smart BMS 12/200 is only rated for 100A on the alternator port. The 200A relates to the system port.

You might be able to add an Orion XS between the starter battery and the BMS, but I have not seen anybody doing this and you will not get anything more than 50A through the Orion XS so you will not increase your charging as you currently get 50A. I would also be cautious about this because the Orion works by having a battery on the output which will damp out the current response, the voltage control circuit in the Orion may interact with the BMS.

For you case I would suggest thinking about the following options, these are just thoughts, you need to do the research & system design to make sure the lithium safety is not compromised.

  1. Investigate if you can get a higher voltage regulator for your alternator. Pros, cheapest option, no wiring mods, will boost the charge current through the BMS, BMS remains in charge. You may need to take it to a rotating electrical / automotive electrical shop. Cons, a higher voltage regulator may not be available.
  2. Investigate an external controller such as the Wakespeed WS500 or Arco Zeus, you could then bypass the BMS for alternator charging as these regulators have a proper lithium charge profile and you can use the BMS allow to charge port to turn it off if there is a battery problem. These regulators monitor the alternator temperature and reduce charge current if it gets too hot. Pros, you would get very good control and much higher charge current. Cons, cost and extensive rewiring.
  3. Add an Orion XS from the starter battery to the lithium batteries direct with a lithium charge profile. Connect the remote terminal of the Orion to the BMS allow to charge port so that the Orion will shut down if there is a battery problem. Leave the BMS alternator circuit as currently set up. Hopefully you will then get 50A through the Orion and 50A through the BMS. Pros, moderate cost, moderate wiring mods, good boost in charge rate. Cons, if the extra current draw of the Orion makes the alternator voltage sag further you may not get the 50A through the BMS.
  4. Add 2 Orions XS units direct from the starter battery to the lithium and disconnect the alternator from the BMS. Wire the remote port of the Orions to the BMS ATC port to get control over the Orions if there is a battery problem. Pros, moderate wiring mods, definite boost to 100A charging. Cons, Cost.
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Thanks for the comprehensive answer. I like version 4 the most. In addition to the starter battery, I also have two batteries bank, each for the bow and stern thruster, or do they need to be connected to a battery isolator or some cytrix

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If the thruster batteries are lead acid like the starter then a voltage sensitive relay of some form to connect them when charge voltage is detected will suffice. That is how my thruster battery gets charged. Simple.