Suggestions on a alternator for charging a single life04 that doesnt break the bank

I'm currently building my auxilary battery setup, which frankly is going to be overkill for what im wanting, but I think I have decided to go with a 100ah life04. From what I understand, they can be rough on alternators, and I think I may just isolate my entire charge systems with a second alternator custom fitted.

I was looking at balmar, but they are pretty dang expensive, and frankly, im not sure I need it. I'll basically be running a cfx75 fridge freezer, and maybe a laptop and some lights.

I guess, the question is, are there any decent reliable air or watercooled alternators out there with a good duty cycle in the 400 dollar range? Maybe change my mind on needing a second alternator as well :)
 

DiploStrat

Expedition Leader
For a 100Ah LifePO4 battery? Go with your choice of B2B (battery to battery) charger in the 50A range. Done. KISS
 

gungriffin

New member
What are you driving? What size is your alternator now? Some JK Jeeps were fitted with up to a 160 AH alternator. That would be plenty for a 100 AH battery. Ever though about a 100w solar panel? You can get one for under $200 from Renology on Amazon.

Be sure to fit a temperature monitor to cut charging if it is going to get cold where you are going. If it tries to charge the lithium battery below about 41 degrees, it could damage the battery.
 

john61ct

Adventurer
Yes no need to dedicate an alternator.

LFP's high CAR is only "rough" on one if you don't properly **regulate** the current between them.

And of course LFP requires precise voltage input.

A good DCDC will be fine in your case.

If you did want to add another alt, what matters more is fitting a good external VR, that allows Amps and Voltage output to be custom adjusted. Then you can get very high output without the bottleneck of the DCDC.

But can cost a grand or more, and as I said you don't need that
 
Thanks for the replies. It's going on a inline 4 turbo gasoline engine. It's just seemed easier for me to add a second alternator and seperate the wiring completely instead of reengineering 1980s wiring for way more load then the stock 65amp alternator was ever intended for. Basically, I either run a upgraded alternator, or a second in which I have no problem fabricating up a mount.

I still do need to do some research on a dcdc charger.
 

john61ct

Adventurer
OK, pick up a large-frame alt rated to put out 200A continuous, like for fire trucks. Cheap as chips to recondition or find on eBay.

Convert to use external VR like Balmat MC-614 or the new Wakespeed / APS-500 hotness.

No DC-DC required, much higher charge rate, in fact can derate a lot for longevity, cooler running.

Keep a lead batt in parallel for when your BMS takes the LFP offline.
 

Chris Boyd

Explorer
What DCDC charger do people recommend? Once you get over about 20A they seem to get quite expensive.

Redarc BCDC in either 25A or 40A. Has the lithium charging profile already on it. Seems the way to go... that’s what I’m getting ready to do with a Battleborn in my trailer.

Additional benefit is the solar charger MPPT built in as well with green priority.

E-Trailer.com has them in the US.
 

luthj

Engineer In Residence
There are plenty of ~200A small frame alternators installed on common vehicles. Many alternator builders have good selections. None are likely to be a bolt on for your application. The good news is that you can fabricate a mounting bracket, and likely mount a second alternator.

Is your belt system Vee style or serpentine style? If its Vee style you may be limited in alternator size unless you upgrade to a multi belt system.

There are several external alternator regulators available. Just about any alternator can be modified to use an external regulator with fairly easy work. This allows fine control over current and voltage.

LFP batteries will easily and rapidly charge from 13.8-14.2V. You may not need an external regulator, its worth some testing once you get the unit installed.
 

john61ct

Adventurer
What DCDC charger do people recommend? Once you get over about 20A they seem to get quite expensive.
A proper LFP system will rarely be cheap, I figure at least 7x the equivalent usable Ah compared to lead.

Sterling, maybe Victron's latest?

User-custom adjustment of the charge profile is critical IMO

Lower cost, maybe Kisae https://sprinter-source.com/forum/showthread.php?p=825984

Renogy is not adjustable.
 

john61ct

Adventurer
Yes anything over 80-100A actual continuous output, need a solid multi-vee belt, if not actual serpentine.

Anytime you see chronic belt dusting or have to keep tightening, you need to upgrade that part

(re-size your pulley to get higher amps output at lower rpm while you're at it!)

and start de-rating current output in the meantime.

Go large frame, continuous rated like first-responder vehicles use, if at all possible to fit.

In some use cases worth choosing the vehicle partly on that basis.

Sure small frame from Grasser, MaineSail, maybe Balmar etc will work "fine", but

heavy duty **cooling is critical**, otherwise you will constantly have to be de-rating current output based on the VR's overtemp protections.
 

john61ct

Adventurer
And of course Euro-style integration of alt control with the ECU throws this whole idea out the window.

But then they rarely have much room under the hood either.

Then a B2B / DCDC is best you're gonna do
 

rayra

Expedition Leader
Thanks for the replies. It's going on a inline 4 turbo gasoline engine. It's just seemed easier for me to add a second alternator and seperate the wiring completely instead of reengineering 1980s wiring for way more load then the stock 65amp alternator was ever intended for. Basically, I either run a upgraded alternator, or a second in which I have no problem fabricating up a mount.

I still do need to do some research on a dcdc charger.

Step back and reconsider what you are doing. You are talking about adding extra battery and extra generation. Why on Earth would you want to deliberately isolate those systems and throw away potential options of combining resources or cross-linking things or leveraging other options. Especially when you are considering sinking premium money for components.
I'd want a combiner / isolator option and maybe even some rooftop solar too, for passive power, which can extend the period of time between when you need to run the vehicle.

too, most alternators don't generate anywhere near their rated capacities at idle / near idle. So you'll need an ALT that's purpose built for that, as for police/emergency vehicles.
Properly configured, your batteries ought to be fully charged when you get where you are going. Then the issue is more to extend their useful charge without havign to run your vehicle often. Or you change your movement plan so you drive a good bit at moderate speeds between 1-2 day campsites. That way you are topped off before each stay.
If the plan is boondocking / extended stay, I'd say go more solar, instead of sinking money into an expensive battery and second / improved alternator solution. Throwing a lot of money at something is not always the answer.

I've got dual matching SLA batteries and a solenoid isolator / combiner and rooftop solar. I chose the matching 'stock' batteries so if the Starter batt fails on a trip I can just swap them. I've got your desired 100AH capacity and 5AH in solar and my trips in the desert southwest involve a lot of miles covered. It works for trips of a few days' duration. My whole setup cost less than that 100Ah LifePO4 battery alone. I'm not claiming poverty is a virtue. Just saying take a step back and look at what you are trying to really accomplish overall then pick the pieces that support that, instead of chasing one costly addition after another. Buying the most expensive parts is not a magic solution. In fact you are finding out that the fancier batteries aren't fully charged by most factory vehicle charging systems and are now having to double down on costs to make it work. That's what's called a 'type 1' error, an error in conception of design.

DiploStrat is right, go for the direct (no DC pun intended) solution and let your factory charging / battery system do its thing. And stop shoveling money at induced problems.
 

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