7.3 Alternator and how much power I can steal for Victron Orion

bisonthecruiser · 02-21-2023, 02:51 PM

Hey Everyone,

Working on getting my dream power system full fleshed out and am looking for some help.

I'm looking at two Victron Orion's 30A Smart Isolated DC to DC's to charge my battery bank when on the road (600AH Lithium setup), but I'm not too sure if it makes sense with a stock alternator or if an upgraded alternator would even provide enough power.

I believe the stock alternator (mine is a rebuild) is good for 130a, so 1,560 watts, and I think I'd be lucky to get a consistent 800 watts combined while driving.

My questions:

1. Are these the right chargers for me to consider?
2. Thoughts on the alternator? I don't know what the alternator pulls for the engine/system at idle, but I'd imagine it's not insignificant.

Thank you!

Best,

Adam

boywonder · 02-21-2023, 05:31 PM

Just went through this with my 2008 5.4L 130A stock alternator.

Worst case is lithiums are at a low state of charge and the engine is idling.....

Here is the page from my 2008 service manual, not sure how the diesel alternators have changed over the years but if you are sure yours is 130A then look at the 130A gas alternator chart for the amps output at whatever rpm your engine idles at.

I would also measure the current coming off your alternator at idle with a clamp type ammeter.

Looking at the graphs you've got 60-70 amps available (certainly less than 80) around idle RPMs.....in my van the headlights are on all the time as is the stereo and a few other things, like the heater blowers (F+R)...they suck a lot of amps.

I didn't have much headroom once I subtracted the amp draw at idle with the curves above. I think a single Orion would have been very tight.

1der/Ray is running two 30A Orions but he has dual alternators..maybe dual 90's or 110's?? can't remember.

I picked up a 200A alternator that is rated for 136A at idle and it's happily running a single 30A Orion into a 280ah LiFePo4 battery, and there are plenty of higher output alternators readily available if you've got the $$.....they get quite pricey.

You could also change the pulley dia to get more output at idle but I'm sure there are downsides to that.

bisonthecruiser · 02-21-2023, 05:37 PM

Thanks a ton, boywonder. Sounds like I can upgrade the alternator if needed. These guys claim 200 amps at idle: https://www.mechman.com/320-amp-high...lue%20anywhere!

Scalf77 · 02-21-2023, 07:08 PM

So I agree with boywonder except on the part worse case being low state of charge on the lithium's. The DC to DC is going to put out full power right up to when the batteries hit the absorption target (unless they temperature throttle back). So the alternator will see the full input for most of the charge curve.

-greg

bisonthecruiser · 02-21-2023, 07:15 PM

Thanks, Greg. Sounds like I need to plan it out a little bit better than I had in my mind. Still need to order everything.

boywonder · 02-22-2023, 07:53 AM

Quote:

Originally Posted by Scalf77

So I agree with boywonder except on the part worse case being low state of charge on the lithium's. The DC to DC is going to put out full power right up to when the batteries hit the absorption target (unless they temperature throttle back). So the alternator will see the full input for most of the charge curve.

-greg

True.....I have a 12V converter charger connected to the starter battery side of the Orion, and when I plug in shore power the Orion regularly goes right to 30A after a few seconds of start-up delay. LiFePo4 batteries behave quite differently than those lead-acid antiques.

..and yes, forgot to mention the Orions run really hot. I've got a fan that turns on when it's running. The early units ran really really hot, then they changed a few things, now they just run really hot.

1der · 02-22-2023, 08:54 AM

Our alternator setup is the dual 110a units.

2x Victron 30A dc to dc.
2x206Ah SOK Lithium w heating pads added to bottom of battery.
400 watt panel

The Good re Victron SMART (bluetooth) is it is easy to enable /disable them
The Mediocre is you are capped at 60a input, if all is good.

Look at your energy use profile. How many amps are you using per night and per day?
Add it up - Scalf77 has a pretty good spreadsheet if I remember correctly. eg. Fridge is good for 40 to 50amps per day, plus lights, stereo, fans, water pumps, heater, etc. Not hard to approach 100A /day. At 50 to 60 A replenishing rate it will take a solid 2 hrs of driving/ day, or a bit less if you have solar contribution, as well.

Longer stay with no alternator input means more battery bank draw down.

I am experimenting with a third dc to dc charger to up the charging rate for our system. It is a Sterling 120. No bluetooth control but I do have the remote unit. I have it current limited to 40 for a combined total input of 100a (SOK charging limit )when combined w the 2 x 30 Victrons. It is not working the way I want as of yet. More tweaking needed.

Why not just go w the Sterling 120a unit? I thought the 2x30 Victron would be enough and bought and installed those. The Sterling was a lightly used unit acquired after I had already installed the Victron units.

If upgrading your alternator output take into consideration the amp capacity of the existing wiring. Also, some consideration should be given to passively charging your two engine batteries from solar or on board shore power based charger. That is not as straight forward as it is w AGMs and a separator.

boywonder · 02-22-2023, 09:14 AM

Quote:

Originally Posted by 1der

If upgrading your alternator output take into consideration the amp capacity of the existing wiring. Also, some consideration should be given to passively charging your two engine batteries from solar or on board shore power based charger. That is not as straight forward as it is w AGMs and a separator.

Good point on the Orions; they are not bi-directional. If your solar is connected to your Lithiums, you won't be charging the starting batteries without more hardware.

In the old days (lol) using Blue Sea ACRs you could charge both battery banks simultaneously since they work in both directions.

bisonthecruiser · 02-22-2023, 10:14 AM

I'm still running ACR's in my Land Cruiser. Won't give those up! Is there a preferred way to charge the starting batteries coming off of solar? Like Ray, I'm running 400watts up on the roof and would probably be best suited to keep both banks up and running....

Adam

bisonthecruiser · 02-22-2023, 10:16 AM

Quote:

Originally Posted by 1der

Our alternator setup is the dual 110a units.

Why not just go w the Sterling 120a unit? I thought the 2x30 Victron would be enough and bought and installed those. The Sterling was a lightly used unit acquired after I had already installed the Victron units.

If upgrading your alternator output take into consideration the amp capacity of the existing wiring. Also, some consideration should be given to passively charging your two engine batteries from solar or on board shore power based charger. That is not as straight forward as it is w AGMs and a separator.

I wasn't familiar with Sterling, but that clearly seems like the way to go. 120A for the cost of 60A with Victron. I'm running Victron for everything else, but Sterling seems like a better fit for this use case.