How does the alternator charge the batteries?

[serpa4]

To make the full jump to lithium is a little expensive. I'd like to make the jump in steps.
I have enough stuff now to do a partial conversion now I think with out engine mods.
I have a Lithium capable inverter/charger. Xantrex.
I have a Lithium capable solar charge controller (Victron SmartSolar 150/70) and 870 watts of solar.
I don't have the stuff for the engine alternator to charge lithium such as alternator temperature sensors, device to increase the alternator voltage to work with lithium, and programable battery charge relays, and alternator open circuit protection device.

I was thinking I could do the 4 house AGM batteries to 2x100ah lithium and not 4 right now and later add 2 more 100Ah lithium house for 4 total.
I'm very certain I could easily make due with solar charging the lithium and also the generator powering the inverter as backup. Currently with my AGM and solar, I did a 9 days without generator/engine charging. My solar tops off my batteries by 11am (making 55+ amps at 14volts).

If I disconnect the factory charge relay from house to thruster, then the inverter and solar set to Lithium would not charge the AGM thruster and AGM engine battery. This would keep the house lithium batteries higher charge voltage of 14.6 from trying to charge the AGM at their suggested 14.1-14.4 volts.

Again, I'd have to disconnect the charge relay from the house to thruster because the higher resting voltage of the lithium house would also keep the charge relay connected all the time due to the higher resting voltage of the lithium.
The charge relay would always be thinking the system is being charge and keep the circuit closed and connected. Anything above 13 volts, the factory charge relay would keep the batteries connected till the lithium hits 13v at 30% remaining capacity.

Battle born did say I could still use the combine engine/house switch for emergency starting though if required.

So, how does the alternator tie in to the system?
If it connects to the engine battery and then the engine to thruster battery charge relay would keep those charged all the time. However, since I'd remove the house to thruster charge relay, then the alternator would not try to charge the lithium. By having a lead acid attached to the alternator, I would not have a lithium battery BMS disconnect a fully charge lithium battery and thus not send a spike of voltage back to the alternator frying the diodes when the BMS disconnects the lithium house batteries.

Or does the alternator connect to the house batteries and then through charge relays to the thruster/engine? Then I'd have to rewire the alternator to the engine and not the house.

Anyone know where the alternator output for charging go into the system?

 

[BB marine]

Alternator to engine battery. Engine battery to thruster bank through ACR, Engine battery to House bank through ACR. You can wire it any way you want but that is the factory install on Cutwaters.

 

[Scottfree]

I am working with a Solar Company and am planning on doing a similar mix of batteries. In that the Lithiums have their own BMS he told me I would need Charger Controller between the Alternator and the Lithium Batteries. This is all new to me but I'm learning! I'm not suggesting this is "the" answer but only what I was told. I am very interested in your solution to stop the spike back to the alternator. I'm using Victron Controller and Monitor so would likely us a Victron Charger Controller if that does the trick.

Please post what you go with.

Cheers, Leon

 

[serpa4]

When I get to work tonight, I'll send you my part numbers of my plan to do the swap.

 

[Wee Venture]

According to my understanding, if you leave your alternator connected to your AGM engine battery (which is standard) the engine battery load will always be there as a buffer and you do not need to worry about protection for the alternator diodes in the event the lithium BMS suddenly shuts off the house bank. Then you can use a DC to DC charger (or two of them in parallel) to charge and isolate your lithium house bank. To do this you would need to disconnect the ACR between the house bank and engine battery. One other consideration is that you will need to install a separate shore power charger for your engine + thruster batteries, since your existing shore power charger connects to your house bank and you will have removed the ACR that shares the charge with your other banks.

John

 

[serpa4]

According to my understanding, if you leave your alternator connected to your AGM engine battery (which is standard) the engine battery load will always be there as a buffer and you do not need to worry about protection for the alternator diodes in the event the lithium BMS suddenly shuts off the house bank. Then you can use a DC to DC charger (or two of them in parallel) to charge and isolate your lithium house bank. To do this you would need to disconnect the ACR between the house bank and engine battery. One other consideration is that you will need to install a separate shore power charger for your engine + thruster batteries, since your existing shore power charger connects to your house bank and you will have removed the ACR that shares the charge with your other banks.

John

Yes, that is how I understand it also.
I will eventually do the engine to lithium, but the start engine lithium start (1500amps x 5 seconds) is $$$1,600. Then, at that time, I will also pull thruster AGM and connect the thrusters to lithium house. The thruster AGM is a waste of space/weight/complexity I don't need.
Eventual plan, next year, is Lithium start and lithium house only. SO, someday I will need the diode protection.
For shore power, you are correct, but I don't use shore power, ever (always trailered or anchored out). But I will use charge relays for lithium to lithium when I do the engine to lithium and will again want the waterfall charging with the relays. But that is also after I get a alternator to battery system for lithium.
For now, I don't see an issue with using the engine while running to charge only AGM engine and thruster and NOT the house. My generator/Inverter will keep house lithium topped off and 870 watts solar will also keep the house charged. Im wagering the engine battery is usually good enough for me to be charge only when running the engine and not ever from shore/inverter at this point... While boating, I'll just start my engine every 7 days for a few minutes, but realistically, I run my motor to move from beach to beach every other day now anyways.
The Lion 105 Ah lithium is on sale for $1,400 for two. They are like 10yr warrant and name brand. I just don't want to buy all the rest of the components, charge relay, alternator to lithium, temp sensor for alternator, etc right now. But CostCo sale ends today.

 

[serpa4]

What I want to do/buy is
Engine start lithium:
ChargeX brand, 150Ah CX150, 1500 amps for 5 seconds, $1,400

To charge all lithium house batteries and the lithium start using the alternator:
Sterling Power ProAlt-C - 130A Alternator to Battery Charger, up to 130 amp alternator, with battery and alternator temper sensor, $380.

To protect the alternator from feedback of all lithium boat (No AGMs or SLA batteries):
Sterling Power 12V or 24V - Alternator Protection Device. $66

To connect the engine lithium being charged by the alternator to connect to the lithium house batteries: $143
Sterling Power ProLatch-R Combining Relay. Programmable connect and disconnect voltages. 160amps

Already have :
Xantrex Pro inverter/charger. 150 amps charging of batteries, supports lithium, and 3000 watts for electric cooking stove, micro, bbq.

870 watts of solar.

Victron SmartSolar charge controller. 150v/70amps works with lithium.

Two Lion brand 105Ah (150amp continuous discharge/100 amp charge) Model UT1300. $700 each. I have 4. This gives me 400Ah usable, and 600 amps to run the thrusters. Since they have 200 amp fuses, it should be plenty.

 

[knotflying]

I love $97.00 flooded Walmart batteries. Every three years I replace them. No fuss no muss.

 

[Cutwater28GG]

The other option is to put a dc to dc charger instead of the acr between the battery types. It’s a cheap solution to protect the alternator. So alternator to engine agm. Dc to dc charger to house and solar to house.