Critique my LiFePo4 Plan!

[Qismat]

Hi all!

I'm hoping you can critique my wiring schematic for my LiFePo4 setup. I don't think its complete and I'm hoping I'm not missing anything important. Though if I am, please let me know.

My biggest worry is that my alternator isn't protected against a voltage spike - Any ideas for solutions for this? I know I want to charge the LiFePo4 bank with the alternator and all charge sources. I don't want to go through the engine/windlass battery to charge the lithiums. So what are my options? A sterling Alternator Protection Device?

Please let me know what you would add or change... no matter how small.

Thanks, everyone! Please excuse my awful drawing, I don't know how you all make such nice ones.. please let me know!

[Qismat]

See photo here: https://imgur.com/a/KNAznar

[mikedefieslife]

The ultimate is to have the alternator converted to be externally regulated and then use a balmar regulator. I believe it also has canbus so could be controlled/shut off by some BMS units.

In lieu of that, since for older engines it's difficult to find externally regulated alternators that will just bolt on, and even harder to find someone to convert an existing one, many people use a Sterling Battery to Battery charger, but you've said that's not what you want.

I have the Sterling B2B charger and it is pathetically woeful. Sterling told me it would replace the Sterling Alternator to Battery charger, and it doesn't it's a much inferior product. Unfortunately the A2B charger doesn't have custom profiles, so is a no go with an LFP bank.

Others will better be able to explain the Sterling Protection device, but I don't think it's the ideal solution.

[Qismat]

Originally Posted by mikedefieslife

The ultimate is to have the alternator converted to be externally regulated and then use a balmar regulator. I believe it also has canbus so could be controlled/shut off by some BMS units.

In lieu of that, since for older engines it's difficult to find externally regulated alternators that will just bolt on, and even harder to find someone to convert an existing one, many people use a Sterling Battery to Battery charger, but you've said that's not what you want.

I have the Sterling B2B charger and it is pathetically woeful. Sterling told me it would replace the Sterling Alternator to Battery charger, and it doesn't it's a much inferior product. Unfortunately the A2B charger doesn't have custom profiles, so is a no go with an LFP bank.

Others will better be able to explain the Sterling Protection device, but I don't think it's the ideal solution.

I do have an external alternator regulator, as you can see in the photo, there is an MC-614 wired in there. However, if something were to happen where the switch got flipped or the BMS caught a catastrophic event, I want to make sure the alternator is protected rather than have a load dump.

I would be using the Sterling B2B charger simply to charge my FLA engine and windlass battery.

[mikedefieslife]

Originally Posted by Qismat

I do have an external alternator regulator, as you can see in the photo, there is an MC-614 wired in there. However, if something were to happen where the switch got flipped or the BMS caught a catastrophic event, I want to make sure the alternator is protected rather than have a load dump.

I would be using the Sterling B2B charger simply to charge my FLA engine and windlass battery.

Ah I see now. In your case I would separately switch the load bus from the charging bus. That way all charging can be switched off whilst still allowing loads useful when you want to bring the SOC down quickly.

The BMS can control the MC-614, disconnecting either the brown or the red wire from the MC-614 will shut it down. In such instances there is no need for any other device. The alternator is safe.

you could then if you wanted, have the solar controllers run though a Vetus Battery Protect, which can also be shut off by a bms.

[Qismat]

Originally Posted by mikedefieslife

Ah I see now. In your case I would separately switch the load bus from the charging bus. That way all charging can be switched off whilst still allowing loads useful when you want to bring the SOC down quickly.

The BMS can control the MC-614, disconnecting either the brown or the red wire from the MC-614 will shut it down. In such instances there is no need for any other device. The alternator is safe.

you could then if you wanted, have the solar controllers run though a Vetus Battery Protect, which can also be shut off by a bms.

How would the wiring of the BMS work with the MC614? I have the BMS monitoring only the loads, not the charging. Can I have the BMS control the load and the charging as well, since the BMS is wired into the negative side of the disconnects?

I'm not sure I understand how that would work.

[witzgall]

Looks good. Since I work for Balmar, I cannot resist suggesting a few alternatives:

1. SG200 for battery monitoring. It works very well with LiFePo4, and we are working on some tweeks to the lithium chemistry profile to make further improvements.
2. The Digital Duo Charge products are great for charging starter batts from a house bank. It is the same size as the MC-614 (Small). I would not use one for the Windlass batt. I myself used that setup (With an older MC-612) cruising with a LiFePo4 house and sealed LA starter for two years with great results.

Chris

[MikeFergie]

Looks very much like my plan but I have broken my 6p4s into 2 batteries of 300 amp hours each at 3P4S format. If one shuts down I hope the other will run still and the alternator should not spike it.

Witgall if I can ask you a question on installing the balmar 614 units on a cat with the centre fielder unit. Can I mount the centrefielder on one side next to the 614 and wire the other one across the bridge deck to the centrefielder ?

[Qismat]

Originally Posted by MikeFergie

Looks very much like my plan but I have broken my 6p4s into 2 batteries of 300 amp hours each at 3P4S format. If one shuts down I hope the other will run still and the alternator should not spike it.

Witgall if I can ask you a question on installing the balmar 614 units on a cat with the centre fielder unit. Can I mount the centrefielder on one side next to the 614 and wire the other one across the bridge deck to the centrefielder ?

That seems like a decent idea for redundancy sake - You're hoping that if one BMS breaks, you'll have the other one monitoring the other battery bank? If not, then whats the rationale there?

[mikedefieslife]

Originally Posted by witzgall

Looks good. Since I work for Balmar, I cannot resist suggesting a few alternatives:

1. SG200 for battery monitoring. It works very well with LiFePo4, and we are working on some tweeks to the lithium chemistry profile to make further improvements.
2. The Digital Duo Charge products are great for charging starter batts from a house bank. It is the same size as the MC-614 (Small). I would not use one for the Windlass batt. I myself used that setup (With an older MC-612) cruising with a LiFePo4 house and sealed LA starter for two years with great results.

Chris

Can share how the OP could use the MC-614, and perhaps his BMS to cut the ignition line on the MC-614.

In my mind, a solid state relay would be used and triggered via the BMS or even battery monitor alarm circuit.

[witzgall]

Originally Posted by MikeFergie

Looks very much like my plan but I have broken my 6p4s into 2 batteries of 300 amp hours each at 3P4S format. If one shuts down I hope the other will run still and the alternator should not spike it.

Witgall if I can ask you a question on installing the balmar 614 units on a cat with the centre fielder unit. Can I mount the centrefielder on one side next to the 614 and wire the other one across the bridge deck to the centrefielder ?

Yes you can do that, and you can even mount both regulators and the centerfielder in on location. This can actually simplify wiring. If they are all mounted next to each other, with the centerfielder in the middle, it makes for a nice, clean installation. This is actually how Balance cats does it on their builds. I can send a drawing I made up, that is good but slightly flawed in that I did not put wire "jump over" curves to show when two intersecting wires are not connected. For this reason I don't want to just post it here.

Chris

[witzgall]

This is pretty simple, the BMS must just directly or indirectly (using a relay) cut the ignition wire to the regulator. This powers down the regulator, and the field is dropped gracefully protecting the alternator diodes.

If you are at all unsure about how to do this, please contact our technical support, they can help.

Chris

Originally Posted by mikedefieslife

Can share how the OP could use the MC-614, and perhaps his BMS to cut the ignition line on the MC-614.

In my mind, a solid state relay would be used and triggered via the BMS or even battery monitor alarm circuit.

[MikeFergie]

Originally Posted by Qismat

That seems like a decent idea for redundancy sake - You're hoping that if one BMS breaks, you'll have the other one monitoring the other battery bank? If not, then whats the rationale there?

Yes a separate BMS for each battery

[mbartosch]

Originally Posted by witzgall

2. The Digital Duo Charge products are great for charging starter batts from a house bank. It is the same size as the MC-614 (Small).
Chris

This is interesting. I had the Digital Duo in the original design for Entropy but replaced it with a Sterling B2B charger after Balmer tech support confirmed via email that the Digital Duo is more or less an intelligent switch, not a battery charger. It does not step up voltage.

In my opinion the Digital Duo is not a proper product to charge a traditional lead acid battery bank from a LiFePO4 bank. The LA bank will never be fully charged and will be destroyed over time due to sulfatation.

[leandroflaherty]

Personally, I like keeping things simple and isolated. I keep the starting battery lead acid as they are reliable, cheap and available anywhere with cars around. If you have cruising aspirations, good luck sourcing a lifepo4 battery in some impoverished and remote island, car batterys are everywhere. My boat (80s build) also has some chargers etc onboard for leadacid, always good to not eliminate working parts.


The starter battery is kept off and isolated with an on off switch, only used when motoring. Likewise the housebank, a renogy lifepo4 with built in bms, is turned off when motoring keeping the chemistry separate.



The housebank gets wind and solar charging when not motoring. When motoring I turn on a renogy 20amp battery to battery charger but to top off the housebank. They make one in 40 and 60amps as well. I like to keep demand low on the alternator.



What I like about this setup is that my super cheap and easy to find alternator (yanmar 3ym30) only charges the starter lead acid, no need for fancy and expensive external regulators. I carry a spare alternator just in case, $60 on ebay, serviceable the world over and its used in automotive applications so in good stock.



Keeps it simple, cheap and isolated if i run into any issues between the engine and home electrical systems. Only need to hit two battery switches to start and turn off the engine.