Charging large lithium bank through a high output alternator

Q&A and troubleshooting
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1

Question regarding charging a large lithium bank (2×200Ah 24 v) through a high output alternator on a sailboat. Does an Argofet limit the current ? Can it be used as a current limitor between alternator and lithium ? Or is orion the only / best way to go. Or is an exterbal alternator regulator. Trying to avoid multiple orions in parralel which would need an extra agm between alternator and orionsas well. Basically whats the simple but right way to do it. Prduct advice for alternator and regulator is also appreciated

2

What is the output and voltage of the alternator? Is it / Will it be adjustable? are you still in the process of setting up the drive/generator system?
You won’t be able to reach the maximum charging capacity of 0.5C anyway.

3

In this case It’s not about protecting the battery but about protecting the alternator against overcharging it.

4

Can you regulate the output voltage of the alternator?
A DC/DC converter would be a good solution as protection… but it has far too little power to quickly charge a larger battery bank.

An Argo FET does not protect against overcurrent … only against “back current” from other voltage sources …

5

Good experience here with a Wakespeed WS500 external regulator controlling a 175A alternator charging a 600Ah lithium battery bank. Limits the charge current to 120A to avoid overheating. You still have to consider load dump if the BMS shuts of charging. If the BMS has an ATC contact then that can be used to shut down the WS500 but you can also add a Balmar Alternator Protection Device. However these are not 100% guaranteed to avoid alternator damage on load dump. DC to DC chargers with a buffer lead acid battery avoid this problem.

6

I see no AGM 24 volt from victron though.

7

I guess that’s the real question.

Is it ok to connect an alternator with a proper external regulator directly to lithium ? Removing the buffer battery and dc-dc chargers. ?

Or would you still add a small agm in parallel separated with an argofet. To absorb the eventual spike.

Although something like the alternator protect module of Balmar could suffice (Or not).

It seems I’ll be putting the alternator, the external regulator, the protect module as well as the buffer battery and the dc-dc convertor. And stuff is being controlled by the bms’s AOC allow to charge as well.

Surely that’s overkill.

8

Normally either

  1. External regulator direct to lithium with alternator protection and ATC

Or

  1. Buffer lead acid battery and DC to DC.

Victron Lynx BMS can be set up to shut down alternator before the BMS disconnects.

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9

I would definitely recommend a DC DC charger, because your generator does not provide a suitable charging voltage for a LiFePo… the rotational speed of the engine also changes and the BMS should not be constantly responding.
The Orion XS 1400 DC-DC battery charger would probably be the best choice with up to 50A.

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10

I have a Balmar 100A alternator connected to a Balmar ARS-5 regulator. I will be installing a 300AH lithium house battery and keeping my lead-acid starting battery. I plan on upgrading the regulator to a Bamar MC-618, which is lithium-friendly, and connecting it directly to the lithium. The starting battery will be charged by the lithium battery with an Orion 12-12/30 DC-DC charger.

11

I have a RV with 660ah battery bank and Lynx BMS. It charges with a Wakespeed regulator and 160 amp Balmar alternator. The Wakespeed is connected to the Victron bus to a Cerbo. It works great. You can see it here.