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Old 11-09-2024, 12:10   #1
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Lithium conversion setup

I have a 12v starter and 2 pair of 6v house batteries. A 150 amp alternator and a balmar mc614 regulator. The batteries are combined by a BEP voltage regulator. I also have a 1800w inverter which is not lithium compatible, so I am upgrading that to a 3000w.

I am not sure the best way to charge starting battery with the new system. The balmar can switch to charge the lithium no problem, but then the starter battery will need power. I'm trying to figure a way to put enough power to the starter battery for it to have enough power and the rest get dumped into the lithium.
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Old 11-09-2024, 13:14   #2
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Re: Lithium conversion setup

The typical setup today is to charge your house bank with alternator, solar, etc. Then use a DCDC charger to charge the start battery which can remain lead acid based. Install an alternator protection device from either Balmar or Sterling to protect the alternator in case the BMS shuts down the lithium bank.
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Old 11-09-2024, 13:23   #3
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Re: Lithium conversion setup

how do you determine how man amps your dc/dc need to keep starter battery charged? My balmar regulator can get set up for Lithium profile so that shouldn't require new hardware. I'd run alternator to balmar regulator to house. then dc/dc to starter.
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Old 11-09-2024, 14:11   #4
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Re: Lithium conversion setup

Most factory alternators are around 60A for something like a 50hp diesel. They seldom put out more than half of that and that is when charging house batteries too. I would expect something like a Victron 12/12/18 DCDC charger would work if starting is all the battery needs to do. Starting uses very little power and the start batteries charge quickly.

The only other consideration is whether you have a windlass or bow thruster that will run off of the start battery. If so, going up one size to a 30A model might make sense.

Check with a Victron distributor and they can probably help size for you.
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Old 11-09-2024, 18:11   #5
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Re: Lithium conversion setup

I use a small 120v 5amp Victron charger connected to the start battery and is its only source for a charge. The charger is powered by the inverter while underway and with shore power at the dock.
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Old 13-09-2024, 07:53   #6
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Re: Lithium conversion setup

Quote:
Originally Posted by hlev00 View Post
Most factory alternators are around 60A for something like a 50hp diesel. They seldom put out more than half of that and that is when charging house batteries too. I would expect something like a Victron 12/12/18 DCDC charger would work if starting is all the battery needs to do. Starting uses very little power and the start batteries charge quickly.

The only other consideration is whether you have a windlass or bow thruster that will run off of the start battery. If so, going up one size to a 30A model might make sense.

Check with a Victron distributor and they can probably help size for you.
Even 5A DC2DC will do it. A start needs less then 1AH. I would get the 20A renogy DC2DC charger, cheap and works well, no need and advantage to get a victron here, no communication or integration into venus OS on the 18A or 30A victron heating bricks anyhow.
Your 3000W inverter I assume you get a victron multi also has a 5A trickle charge output, so when at shorepower the multi keeps lead starter in float if you connect that, no need for a seperate charger

Connect the windlass to the lifepo4 and not the starter, it has much less voltage sag and supports the motor better.
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Old 13-09-2024, 08:49   #7
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Re: Lithium conversion setup

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Originally Posted by CaptainRivet View Post
Even 5A DC2DC will do it. A start needs less then 1AH. I would get the 20A renogy DC2DC charger, cheap and works well, no need and advantage to get a victron here, no communication or integration into venus OS on the 18A or 30A victron heating bricks anyhow.
Your 3000W inverter I assume you get a victron multi also has a 5A trickle charge output, so when at shorepower the multi keeps lead starter in float if you connect that, no need for a seperate charger

Connect the windlass to the lifepo4 and not the starter, it has much less voltage sag and supports the motor better.
I have a cheap 5a ac/dc I could set up to charge off the inverter to starter battery. That would provide power whenever inverter is on. I guess I'd just need that on whenever the motor is running to provide power to the start battery I'm guessing? Or use a 20 amp dc/dc to feed start battery from house and dump atternator power to house battery.
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Old 13-09-2024, 11:23   #8
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Re: Lithium conversion setup

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Originally Posted by Brian Cope View Post
Or use a 20 amp dc/dc to feed start battery from house and dump atternator power to house battery.
Do that and forget your first solution.
A lot of cruisers with lithium when leaving boat for a longer periode completly disconnect the LFP and switch all to lead starter which is kept in float by a small shorepower charger that also covers the permanent loads, in case of a shorepower outage the lead provides power to bilge pumps etc it's that for a long time only the start battery dies and easy/cheap to replace. To avoid that you can connect the starter to a small solar panel that always keeps it floating even if there is no shorepower.
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Old 17-09-2024, 07:37   #9
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Re: Lithium conversion setup

Quote:
Originally Posted by Brian Cope View Post
I have a 12v starter and 2 pair of 6v house batteries. A 150 amp alternator and a balmar mc614 regulator. The batteries are combined by a BEP voltage regulator. I also have a 1800w inverter which is not lithium compatible, so I am upgrading that to a 3000w.

I am not sure the best way to charge starting battery with the new system. The balmar can switch to charge the lithium no problem, but then the starter battery will need power. I'm trying to figure a way to put enough power to the starter battery for it to have enough power and the rest get dumped into the lithium.
I am thinking of doing it in stages and adding solar and connecting it to new batteries via mpppt. I can do that independent of current system, as new batteries are going at a different spot. then I was going to connect the inverter to the new batteries and disconnect the old house batteries. I would at that time separate the house from starter completely and have the starter battery only connected to alternator. The shore power would be connected to inverter and charge house as well as solar. I can then later add a dc/dc if i feel i need it to keet the house batteries charged.
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Old 17-09-2024, 10:37   #10
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Re: Lithium conversion setup

Quote:
Originally Posted by Brian Cope View Post
I am thinking of doing it in stages and adding solar and connecting it to new batteries via mpppt. I can do that independent of current system, as new batteries are going at a different spot. then I was going to connect the inverter to the new batteries and disconnect the old house batteries. I would at that time separate the house from starter completely and have the starter battery only connected to alternator. The shore power would be connected to inverter and charge house as well as solar. I can then later add a dc/dc if i feel i need it to keet the house batteries charged.
Why not just use an argofet, connect the alternator to it and output to lead starter and lifepo4 house. When the alternator runs it charges both and when the house is full and disconnects then the lead starter is always there.
Simple and cheap, the 200A argofet is around 170Euro.
Doesn't make sense to waste 140A charge when your engine is running. You have a fully external regulated alternator, use what you have and its always handy if you just maneuver into anchor spot when your alternator puts in 50% of your daily use in 30-45min you need the engine anyhow.
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