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Second Alternator Charging Lithium Battery Bank

RAM5500 CAMPERTHING

OG Portal Member #183
Doesn't the LiFeBlue provide built in current monitoring (not control)? So you would know how much current it is drawing, and it will also shutdown charging if it is too high. To reduce the current, you can either dial down the alternator voltage, or add some resistance between the alternator and battery.
Technically yes, but their app is HORRIBLE
 

john61ct

Adventurer
+++ Sterling B2B+++

Very skeptical of any battery maker claim they can do without alt temp protection / current throttling, saying for now a pile of hooey until simeone shows how the sausage is made.

Def forget jury rigging resisters, thinner wires etc unless you are an elecktrickery wizard with decades of hands-on practical experience.

Note the Sterlings are sensitive to high heat levels themselves, def **not** into any normal engine compartment, their cooling system needs cool input airflow,or you may need to cut throughput in half

Their support is usually very responsive worldwide, even get Charles hisself sometimes.

Finally, forget any EV li-ion chemistry (3.6 - 3.7V nominal) in this application, 100x greater odds of thermal runaway one day, even with a vigilant expert constantly testing SoH.

Besides LFP, LTO only other lithium I'd consider if there are ever other fellow humans in close quarters.

Boom bad!
 

pugslyyy

Expedition Vehicle Engineer Guy
+++ Sterling B2B+++

Very skeptical of any battery maker claim they can do without alt temp protection / current throttling, saying for now a pile of hooey until simeone shows how the sausage is made.

...

Note the Sterlings are sensitive to high heat levels themselves, def **not** into any normal engine compartment, their cooling system needs cool input airflow,or you may need to cut throughput in half
I hear what you are saying, but we typically install the Sterling on trucks with 397A dual alternator packages, so overloading the alternator isn't an issue in our application.

Agree that even though they are rated for exposure it is better to install the DC-to-DC in the house. That also helps with sensing the correct voltage on the house batteries since you have less voltage drop due to shorter cables.
 

john61ct

Adventurer
I hear what you are saying, but we typically install the Sterling on trucks with 397A dual alternator packages, so overloading the alternator isn't an issue in our application.
Even a small say 400Ah LFP pack once depleted will pull thousands of amps if allowed.

It is the DCDC that is limiting the current thus preventing burning out the alt circuitry.

I was just warning not trying to do it without a DCDC, or a current limiting VR, as apparently LiFeBlue is claiming to enable.
 

pugslyyy

Expedition Vehicle Engineer Guy
Even a small say 400Ah LFP pack once depleted will pull thousands of amps if allowed.

It is the DCDC that is limiting the current thus preventing burning out the alt circuitry.

I was just warning not trying to do it without a DCDC, or a current limiting VR, as apparently LiFeBlue is claiming to enable.
I'm actually running an experiment on my personal camper with 400Ah of LiFePO4 batteries directly connected to the alternator. The chassis is an older RAM 2500, and it smoked the alternator within about a month. I've put a new alternator in and am going to see how well it holds up.
 

DiploStrat

Expedition Leader
I'm actually running an experiment on my personal camper with 400Ah of LiFePO4 batteries directly connected to the alternator. The chassis is an older RAM 2500, and it smoked the alternator within about a month. I've put a new alternator in and am going to see how well it holds up.
Use a 100% duty cycle alternator and you should be fine, assuming everything else is working correctly. I am guessing that you will use a key controlled relay or, perhaps, the Victron relay with higher, lithium settings.

Ever play with this: LiFePO4 Battery Isolation Manager (BIM) | Battle Born Batteries

But, that said, keep us posted! ;)
 
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chrshale

New member
The OP asked about a dedicated alternator for a large lithium battery bank. Winnebago and Coachmen are both offering this kind of system for their rv's without generators. They use either a Nations or Balmar high output alternator and a Balmar 614 standalone regulator. But those offerings are hardwired and never disconnected like a truck camper. I have asked both companies what device they use to limit the secondary alternator output but I have never gotten a straight answer other than Coachmen stating that they don't use a B2B charger in their Li3 rv's. I wouldn't want any alternator to run at more than 50% of max. I also don't know how such a system should be designed to accommodate disconnecting the camper. And there's this article...https://www.truckcamperadventure.com/ditching-the-generator-for-the-alternator/.
 

DiploStrat

Expedition Leader
... have asked both companies what device they use to limit the secondary alternator output ...
To your question:

-- Dedicated voltage regulator that also senses alternator temperature.
-- Special "marine" or 100% duty cycle alternators.

Absent these, most of us are better off with a B2B rated not much higher than about 50% of a regular alternator's output.

YMMV.
 

john61ct

Adventurer
Balmar MC-614 has current limiting built in, to protect the alt from burning up

and also a small LFP bank from being charged to fast

in fact much more adjustability than Sterlings

great flexibility for changing conditions.

Unfortunately not an option foe modern vehicles where the alt is tied into the vehicle computer
 

pugslyyy

Expedition Vehicle Engineer Guy
I've had good success with the Balmar regulators but ended up being pretty dissatisfied with their alternators. I had their fancy $900 alternator fail catastrophically. It wasn't rebuildable, so I replaced it with a GM 120A alternator that I paid under $100 for (GM because they are externally regulated) and haven't looked back. As a bonus I can now get a replacement alternator pretty much anywhere if I need it.
 

RAM5500 CAMPERTHING

OG Portal Member #183
I've had good success with the Balmar regulators but ended up being pretty dissatisfied with their alternators. I had their fancy $900 alternator fail catastrophically. It wasn't rebuildable, so I replaced it with a GM 120A alternator that I paid under $100 for (GM because they are externally regulated) and haven't looked back. As a bonus I can now get a replacement alternator pretty much anywhere if I need it.
Yes!

The reports of folks having good reliable luck for more than a year or so with aftermarket “high output” alternators exist, but are few and far between.

The reports of quick failure of big $$$ alternators making large amp claims are very plentiful.

This goes with ALL brands.

OEM alternators only, in my rigs, ever
 

john61ct

Adventurer
The large frame alts designed for emergency vehicles will run at rated output in hot conditiins continuously.

Leece-Neville is a good brand

also surplus military stuff, some Hummer units can put out like 13+ kW

Alternatively, a VR that derates the current output based on temperature sensing

But obviously such extreme mods can cost as much as some spend on their whole truck
 
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