Second Alternator Charging Lithium Battery Bank
- Thread starter brianjwilson
- Start date
RAM5500 CAMPERTHING
OG Portal Member #183
Yes sir
+++ 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!
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
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.
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
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
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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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
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.
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
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
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
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
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
OllieChristopher
Well-known member
What brands would that be? When you are running high amperage draw equipment (winches, lights, stereos, etc) beyond the rated output of your alternator the OEM one will die just like an aftermarket.
I have a Mechman brand. It is one of the best aftermarket alternators in the industry. You are not going to see one of those fail side by side with a OEM and the same power draw. The difference between a OEM alternator and Mechman cannot even be compared.
I do agree the aftermarket is flooded with junk. Mechman happens to be designed for performance and longevity over the OEM.
Mine was actually dyno'd at 198 amps idling and 257 ams at 1800 rpm cruising speed.
mechengrsteve
Most time adventurer
I was just looking for some info and found this forum and thought I'd chime in. I have a 2004 F350/6.0l with a custom flatbed adventure rig (see 'workingonexploring' on YT and workingonexploring.com for details). I've been running dual alts with one (135A large case 6G) dedicated to 12V operation of the vehicle and the other (220A DG Electric, 3G with external Traspo regulator) converted to 24V with an OEM second alternator mounting system, dedicated to charging my 17kwh Nissan Leaf 7S20P battery. I did this about 4 years ago before there were many B-B chargers out plus I wanted a lot more current than most B-B provide (plus then no one made a 24V B-B). I have some e-zine articles on 'truckcampermagazine' and 'truckcamperadventure' if you look for them. While B-B manages most of the demand well, its not the way I went and some of what I did may be helpful whichever way you decide to go;
1) Temperature control of the alternator is something few manufacturers concern themselves with but IMHO is a paramount concern any time you demand lots of power. Alternators have no form of thermal protection and an overload or high underhood temperature can contribute a burnout especially when charging lithium. As a safety measure, I use a thermostat, with the control and display mounted on my center console, that can automatically cut excitation to the external regulator (safely terminating charging). Because my second alternator is not connected to the truck electrical supply in any way, this does not affect truck operation. I believe this is also readily implemented to interrupt the 'ignition' lead of a B-B if the alternator over temps. You could also connect the interrupt in series so that if either alternator was over-temped, it would cut off B-B. My current thermostat (<$10) uses a 10k NTC thermistor, limits at 120C (extremely conservative) and I am soon replacing it with an industrial thermal controller (~$30) with type K thermocouple which will allow higher temps (plan to use 150C) cutoff.
2) I have a console-mounted switch in line with the regulator to shut off charging any time I don't want it such as if I expect to get enough solar, if I am driving a lot of hills, or if I am driving low speed (airflow cooling ls low). Again, a disable switch to the B-B on the 'ignition' line could do the same thing.
3) FYI; Alternators are rated at what they can produce at 6000 alternator RPM. That is nowhere near their continuous duty capacity. Continuous duty capacity is ~1/2 max rated and is much a factor of underhood temperatures which are a function of outside air temperatures, engine load and vehicle speed (airflow). Because of the large potential to overdraw the alternator capacity, I have amp, volt and temp displays on my console as well as an adjustment potentiometer wired into the regulator, to adjust the alternator voltage setpoint at any time (which directly alters amperage output). I can trim my charging to any output I want to suit my conditions and needs. If running several B-B in parallel, I could imagine having an 'enable' switch for each so the load could similarly be adjusted albeit in large steps.
4) Do not put overload protection on your alternator cable that can be triggered by possible alternator output. Short circuit protection within 7" of the battery (ABYC requirement) to any charger is expected but should be sized at 125% of the maximum circuit load/amperage. Also understand that OLPD typically functions at 130% of rating. If you have a 200A alternator, use a 250A device. A 250A device will function at (250A x 130%) 325A which will certainly happen if there is a short circuit but is otherwise impossible. IF the OLPD functions due to overload (even once), and not by a short circuit, it WILL destroy your alternator. If attaching a B-B, put protection between the B-B and battery only.
5) DO not locate any equipment (including fuses or breakers) in the engine compartment. Heat adversely affects their proper operation.
6) Be sure to understand the ampacity of your chosen cable 'in engine spaces' (use ABYC charts). DO NOT ASSUME to use NEC (residential/commercial) ratings. Do not use a cable with insulation rated 60C or below in engine spaces. Automotive manufactures use GXL (cross-linked thermoplastic) which is 75C rated. Many 'battery cables' or primary wires commonly found in automotive stores, are thermoplastic insulation (GPT) which is 60C rated and not suitable. Welding cable (105C rated) is best.
7) If you have a 2015 or later truck, you should also develop an understanding of the operation of your 'smart alternator' and how it works which will significantly affect your decisions.
8) The boat world has been dealing with this problem for quite a while and has some solutions but you need to understand how they will work on your truck, esp if you have a smart alternator. (Balmar, Mastervolt and Wakespeed to name a few).
I am a retired mechanical engineer with experience in high-tech manufacturing including conenctors, wireless power and RVs. I have a pretty in-depth understanding of this topic and would be happy to help anyone in need.
1) Temperature control of the alternator is something few manufacturers concern themselves with but IMHO is a paramount concern any time you demand lots of power. Alternators have no form of thermal protection and an overload or high underhood temperature can contribute a burnout especially when charging lithium. As a safety measure, I use a thermostat, with the control and display mounted on my center console, that can automatically cut excitation to the external regulator (safely terminating charging). Because my second alternator is not connected to the truck electrical supply in any way, this does not affect truck operation. I believe this is also readily implemented to interrupt the 'ignition' lead of a B-B if the alternator over temps. You could also connect the interrupt in series so that if either alternator was over-temped, it would cut off B-B. My current thermostat (<$10) uses a 10k NTC thermistor, limits at 120C (extremely conservative) and I am soon replacing it with an industrial thermal controller (~$30) with type K thermocouple which will allow higher temps (plan to use 150C) cutoff.
2) I have a console-mounted switch in line with the regulator to shut off charging any time I don't want it such as if I expect to get enough solar, if I am driving a lot of hills, or if I am driving low speed (airflow cooling ls low). Again, a disable switch to the B-B on the 'ignition' line could do the same thing.
3) FYI; Alternators are rated at what they can produce at 6000 alternator RPM. That is nowhere near their continuous duty capacity. Continuous duty capacity is ~1/2 max rated and is much a factor of underhood temperatures which are a function of outside air temperatures, engine load and vehicle speed (airflow). Because of the large potential to overdraw the alternator capacity, I have amp, volt and temp displays on my console as well as an adjustment potentiometer wired into the regulator, to adjust the alternator voltage setpoint at any time (which directly alters amperage output). I can trim my charging to any output I want to suit my conditions and needs. If running several B-B in parallel, I could imagine having an 'enable' switch for each so the load could similarly be adjusted albeit in large steps.
4) Do not put overload protection on your alternator cable that can be triggered by possible alternator output. Short circuit protection within 7" of the battery (ABYC requirement) to any charger is expected but should be sized at 125% of the maximum circuit load/amperage. Also understand that OLPD typically functions at 130% of rating. If you have a 200A alternator, use a 250A device. A 250A device will function at (250A x 130%) 325A which will certainly happen if there is a short circuit but is otherwise impossible. IF the OLPD functions due to overload (even once), and not by a short circuit, it WILL destroy your alternator. If attaching a B-B, put protection between the B-B and battery only.
5) DO not locate any equipment (including fuses or breakers) in the engine compartment. Heat adversely affects their proper operation.
6) Be sure to understand the ampacity of your chosen cable 'in engine spaces' (use ABYC charts). DO NOT ASSUME to use NEC (residential/commercial) ratings. Do not use a cable with insulation rated 60C or below in engine spaces. Automotive manufactures use GXL (cross-linked thermoplastic) which is 75C rated. Many 'battery cables' or primary wires commonly found in automotive stores, are thermoplastic insulation (GPT) which is 60C rated and not suitable. Welding cable (105C rated) is best.
7) If you have a 2015 or later truck, you should also develop an understanding of the operation of your 'smart alternator' and how it works which will significantly affect your decisions.
8) The boat world has been dealing with this problem for quite a while and has some solutions but you need to understand how they will work on your truck, esp if you have a smart alternator. (Balmar, Mastervolt and Wakespeed to name a few).
I am a retired mechanical engineer with experience in high-tech manufacturing including conenctors, wireless power and RVs. I have a pretty in-depth understanding of this topic and would be happy to help anyone in need.