Factory installed DC to DC charger

[Snackchaser]

I was recently asked about Oliver’s Email offering of a DC to DC charger, how long it takes to charge, and whether it’s worth it.  I can provide thoughts about the one I installed, but I don’t know anything about what Oliver is doing.  This seemed to be a good topic for the forum because it would nice to find out more details of what Oliver is installing, and what other folks think about it.

I think the DC to DC chargers are great if there is limited solar, no hook-ups, and you are frequently driving.  I don’t think they are good for regular battery charging while parked, but they are a great emergency back-up if needed.   If you use a lot of power like TV, internet, toasters, hair dryers, microwaves, cappuccino machines, etc., it’s nice to know that you will be charging on the way to the next camp.  

Charging times depend on a lot of factors.  But for a rough idea, a typical factory setup with 340 watt solar panels puts out roughly 26 amps, which theoretically can charge the 390 amp hour battery from 0% to 100% in about 15 hours, or 7.5 hours from 50% to 100%.   A 30 amp DC/DC charger would take about 13 or 6.5 hours respectively, if my math is right.  Of course I don’t know how many amps Oliver's DC to DC charger is.  

I installed a Victron 30 amp DC/DC charger because the solar was not keeping up with my old power hungry Starlink, and the battery would run down after a few days.  I originally assumed it was a lack of sun for the solar, but it later turned out that the solar charger had become disconnected somewhere in my travels.  After re-connecting it, I realized that the solar probably would have easily kept up with the Starlink, particularly with the new ones that don’t use that much power.  Please don’t ask me why I didn’t recognize this problem sooner. . . I don’t have a good answer.

My other justification for a DC/DC charger was air-conditioning.  Although the ac can run from the battery, it’s only for short periods.  We plan on doing some desert boondocking and my idea is to run the ac from the DC/DC charger while driving - so that the trailer will be cool when we get to camp.   It works, but it still uses a little battery juice also.  It’s nice to have a cool trailer for camp set-up, but a generator is still needed for long periods in hot weather.   IDK, it might be a bad idea.

FYI, I added cooling fans on my Victron DC/DC charger because it derates 3% for every degree over 104 to the point where it shuts down.  That would likely happen in the desert and I could end up draining the battery with the ac running while driving down the road.  See my “More DC to DC charger installation Tidbits” post for details on the fans.

Anyway, I’m interested to hear others thoughts on this because it's becoming a growing trend.

Cheers, Geoff

[Ronbrink]

18 hours ago, Snackchaser said:

My other justification for a DC/DC charger was air-conditioning.  Although the ac can run from the battery, it’s only for short periods.  We plan on doing some desert boondocking and my idea is to run the ac from the DC/DC charger while driving - so that the trailer will be cool when we get to camp.   It works, but it still uses a little battery juice also.  It’s nice to have a cool trailer for camp set-up, but a generator is still needed for long periods in hot weather.   IDK, it might be a bad idea.

Actually, great idea! I have a Renogy 40A DC-DC and run my a/c on LFPs via inverter while underway quite often; the total amp draw by the a/c is offset by the output of said charger. I should mention, no solar. In some instances, owners run for long duration to keep pets comfortable inside the Oliver when in transit. The only problem I’ve experienced was an aging alternator in my TV; the vehicle battery was not being properly maintained, but installation of a new high output alternator resolved that issue. 

Edited September 16, 2024 by Ronbrink

[jd1923]

20 hours ago, Snackchaser said:

Charging times depend on a lot of factors.  But for a rough idea, a typical factory setup with 340 watt solar panels puts out roughly 26 amps, which theoretically can charge the 390 amp hour battery from 0% to 100% in about 15 hours, or 7.5 hours from 50% to 100%.   A 30 amp DC/DC charger would take about 13 or 6.5 hours respectively, if my math is right.  Of course I don’t know how many amps Oliver's DC to DC charger is.  

I installed a Victron 30 amp DC/DC charger because the solar was not keeping up with my old power hungry Starlink, and the battery would run down after a few days.  I originally assumed it was a lack of sun for the solar, but it later turned out that the solar charger had become disconnected somewhere in my travels.

Your math is close enough in theory. Though roof-mounted panels, flat to the horizon, are not getting near 340W. Ours often charge at net 12A, even in the Arizona sun. Our new 400W Renogy Suitcase when aimed directly at the sun got 366W at best one time and more often was between 200 and 300W. The Victron 30A SC has showed 20+ amps charging, where theoretical max is 33A.

Starlink and other electronics, and the Oliver LED 12V lighting take so little power. Running cooking appliances, the A/C and a blow dryer is another story. I've been running A/C all week on only rooftop solar, but fall has broken up here at 5400 FT and the weather is wonderful lately. We do want to run A/C on inverter when it's hot after an efficient A/C upgrade. Running A/C when towing is a lot of drain, given sun and wind pulling the cool in your wake down the highway!

1 hour ago, Ronbrink said:

... installation of a new high output alternator resolved that issue. 

I worry about charging via the TV. I would only do so with the kind of upgrade that Ron made. OEM alternators are not designed to push out another 30-50A. Trucks today have complex ECUs and you don't want voltage-related error codes affecting fuel injectors and ignition.

@Snackchaser I read your DC-DC upgrade post (very nice work). I believe at the start of 2024 only the Victron 30A was available. The newer 50A is much more efficient, producing less heat, half the size, no large heat sink attached and likely no need for adding a fan. See video @rideadeuce added to my question post: Choosing a DC-DC Charger - Ollie Modifications - Oliver Owner Forums (olivertraveltrailers.com)

Lastly when traveling, we I go out of our way to drive only 2-3 hours between stops and generally not more. We like to maximize time at the campsite vs. time on the highway. Some of you drive a lot of hours in a day where this is more useful. I will likely add a DC-DC charger but went the suitcase route first because of this. When adding this capability, you should consider the cost of the charger, another $150+ for 4 AWG cables and connectors, plus the cost of an aftermarket high-output alternator, to do it right.

Victron Energy ORI121217040 Orion XS 12/12-50A DC-DC battery charger | Powerwerx 

[Cameron]

I'm definitely interested, especially since I think I might have the trailer serviced at OTT in January. I checked and they can't hold this month's special until then, but there might be another special. I'm thinking that OTT service would be a good place to get the trailer system installed. I don't use lots of power when boondocking, and usually am in a sunny place. But for times when there's not a lot of sun, and I'll either be running the AC or furnace, I'm wondering if the DC-DC charger option could take the place of me hauling a generator with me. 

[jd1923]

2 hours ago, Cameron said:

I'm thinking that OTT service would be a good place to get the trailer system installed.

This is the advertised special: "Charge your lithium batters from your tow vehicle.
*Camper system only. Truck must be outfitted by automotive shop for system to fully operate. Limited Supply. Sale Price: $1,350.00"

I zoomed in on the picture and can just see the '30' for the 30A on the charger. These go for $204 on Amazon: Amazon.com: Victron Energy Orion-Tr Smart DC to DC Charger (Bluetooth) - 12/12-Volt 30 amp 360-Watt - Battery Charger for Dual Battery Systems - Non-Isolated : Automotive

On 9/15/2024 at 1:06 PM, Snackchaser said:

I was recently asked about Oliver’s Email offering of a DC to DC charger, how long it takes to charge, and whether it’s worth it.

OTT will likely add a Bussman breaker (about $40, not shown in the picture). Say $100 for 4 AWG cable and parts (trailer side only), so they are charging about $1000 for labor! You would still have to wire the TV to connect at the hitch.

You really want this charger instead, for greater charge rate and less heat (watch the video in the link supplied above): Amazon.com: Victron Energy Orion XS Smart DC to DC Charger 12/12 50A (700W) - Advanced Battery Protection : Electronics There are a couple authorized sellers on eBay that accept $300 offers on this same charger for greater savings.

If I could not do this myself for <$500 in parts, I would purchase the components and get a trusted local installer or truck service company to install both sides at the same time. There are so many great examples here in mod postings from @Snackchaser, @Ronbrink, @MAX Burner, @rideadeuce, demonstrating this installation.

Don't forget an alternator upgrade! (also not included)

Edited September 19, 2024 by jd1923
Added last sentence

[Ronbrink]

3 hours ago, Cameron said:

I'll either be running the AC or furnace, I'm wondering if the DC-DC charger option could take the place of me hauling a generator with me. 

Furnace is not a problem, but running the a/c off battery for more than a few hours will be too tasking for the average battery bank. I carry a small dual fuel genny and use propane for overnight stays when a/c is needed off-grid. That said, lengthy travel stops for rest, lunch, shopping, etc. are prime times to use the a/c on battery since when back underway the DC-DC will likely recharge as you reach the day’s destination. 

[Snackchaser]

There are some good comments so far.  It was interesting to learn that some solar panels were not meeting their rated capacity, and the sun doesn’t always cooperate either.  This is a positive for the DC to DC charger because they have a more reliable output.  It was also good to hear that others run their ac off the DC to DC charger, this is a strong selling point IMO.

Yes I was disappointed when the 50 amp Victron charger came out after I installed the 30 amp, it’s way improved in efficiency, thus reduced heat.  I'm surprised that  OTT is not using it.  On the bright side, the 30 amp uses smaller gauge wire, but I think a cooling fan is still needed because it starts derating at 104 degrees.   This could be  less than ambient air temperature when you'd want to run the ac, and you could run down the battery faster if the charger output is not 100%.  From what I've seen with the 50 amp specs, this should't be an issue.

This raises another important point that trailer folks should be aware of.  Most of the DC to DC chargers are used in camper-vans and boats with short wire runs to the alternator, and the multitude of videos and wire specifications reflect that.  However, trailer installations have much longer wire runs, typically around 50 feet one way, so they will require larger wire to minimize voltage drop.  Even the Victron 50 amp is sized for maximum #4 wire, which would be too small for most trailer applications.

Alternator capacity was not something I've given much thought to,  because mine was something over 200 amps.  It’s good idea to check your'e alternator rating by looking up the alternator code or use an on-line VIN decoder.  I believe most newer trucks are at least a 100 amps or more.  TV voltage errors should’t be a concern because Victron has safeguards to shut down in low voltage conditions, and they are designed to work with smart alternators that are constantly adjusting output for better fuel economy.

Cheers!  Geoff

[jd1923]

On 9/19/2024 at 12:05 PM, Snackchaser said:

However, trailer installations have much longer wire runs, typically around 50 feet one way, so they will require larger wire to minimize voltage drop.  Even the Victron 50 amp is sized for maximum #4 wire, which would be too small for most trailer applications.

Planning on adding the Victron Orion 50A DC-DC charger in the new year. The Victron Amazon store just lowered price on these: Amazon.com: Victron Energy Orion XS Smart DC to DC Battery Charger 12/12 50A (700W) - IP65 Dust & Waterproof - Fully Configurable - Remote Management Possible - Advanced Battery Protection : Electronics

I will go with TEMCo 4 AWG cable. I measured distance from battery to rear bumper at 21 ft (long bed TV), then from hitch to rear dinette to my main busses another 15 ft, adding 10% for 40 ft total one-way. Wondering what Geooff, or @MAX Burner, @Ronbrinkand others did with the ground wire at the TV? It doesn't seem necessary to run the B- cable all the way up to the batteries. Could it not be grounded at the rear frame of the TV? The truck batteries are also grounded to the frame. This saves 18 ft of cable, so I'm planning on 60 ft total. Wire got more expensive in the last year!

BTW, I did upgrade to a Nations 180A HD alternator last summer which is about 50A higher than the OEM alternator.

Edited December 30, 2024 by jd1923

[Snackchaser]

Geez, I’m jealous!  If for not having to upsize the cable, I’d probably ditch my 30 amp for the 50 too!  Good on you for getting your total length down to 60’.   My ground is connected to the battery and I was closer to 90’ total with the 2500 RAM extended cab.  Have you done a wire size calculation for 50 amps at 60 feet?   #4 AWG is small for such length.

You got me thinking about using the truck frame for a ground, because logically it should be included in the wire size calculation.  It begs the question:  What is the frame resistance?  I couldn’t help myself, I had to try and figure it out. . .  in the wet cold dark.

Without an ohm meter that can measure such low frame resistance, I measured the voltage drop across an 88 ohm relay coil instead.  First measurement was through the relay and a jumper cable.  The second measurement included a loop from the jumper cable back through the truck frame.  After subtracting the jumper cable voltage drop, the frame resistance was calculated at 0.00295 ohms.   Given the resistance of #4 AWG is 0.000242 ohms per foot, the frame is equivalent to 12’ of #4 cable.  Of course there are many margins for error, but I think it’s a fair approximation.   

So it’s okay to use the frame as a ground, but it's prudent to add the frame resistance to your 60’ length when calculating wire size.

BTW, who is your supplier for the TEMCo wire if you don’t mind?  I used BatteryCablesUSA in the past, specifically their jumper cable which I noticed Oliver used for the solar panel.  It was comparatively inexpensive a year ago, and has doubled since.

I hope this helps you out.  Cheers!  Geoff

[Ronbrink]

14 hours ago, jd1923 said:

Could it not be grounded at the rear frame of the TV?

It could if you know there will be a really good ground, but why take a chance with sensitive electronics?  That said, 1) best practice is to have a dedicated cable from the battery and 2) many DC-DC manufactures recommend it. I paid $115 for cable in 2020, here’s the current price. I used every bit of the 50’ cable with the Renogy 40A mounted under the rearward dinette seat hatch, your 60’ calculation should suffice. 

Edited December 31, 2024 by Ronbrink

[jd1923]

16 hours ago, Snackchaser said:

Geez, I’m jealous!  If for not having to upsize the cable, I’d probably ditch my 30 amp for the 50 too!  Good on you for getting your total length down to 60’.   My ground is connected to the battery and I was closer to 90’ total with the 2500 RAM extended cab.  Have you done a wire size calculation for 50 amps at 60 feet?   #4 AWG is small for such length.

You got me thinking about using the truck frame for a ground, because logically it should be included in the wire size calculation.  It begs the question:  What is the frame resistance?  I couldn’t help myself, I had to try and figure it out. . .  in the wet cold dark.

Without an ohm meter that can measure such low frame resistance, I measured the voltage drop across an 88 ohm relay coil instead.  First measurement was through the relay and a jumper cable.  The second measurement included a loop from the jumper cable back through the truck frame.  After subtracting the jumper cable voltage drop, the frame resistance was calculated at 0.00295 ohms.   Given the resistance of #4 AWG is 0.000242 ohms per foot, the frame is equivalent to 12’ of #4 cable.  Of course there are many margins for error, but I think it’s a fair approximation.   

So it’s okay to use the frame as a ground, but it's prudent to add the frame resistance to your 60’ length when calculating wire size.

BTW, who is your supplier for the TEMCo wire if you don’t mind?  I used BatteryCablesUSA in the past, specifically their jumper cable which I noticed Oliver used for the solar panel.  It was comparatively inexpensive a year ago, and has doubled since.

I hope this helps you out.  Cheers!  Geoff

Thanks Geoff, yes I'm certainly going to use the frame at the rear, so will only need 2 ft of ground cable there. I will add additional frame grounds to both truck batteries and perhaps to the alternator frame. This will add another 2 ft here and there. I went with TEMCo direct on Amazon, upped my number to 65 FT:

https://www.amazon.com/dp/B00LIB6F86?ref=fed_asin_title&th=1

Not sure on the resistance or voltage drop of a 10x4" steel double C-beam truck frame, but one thing is certain, it will not overheat when amped up! It is important to grind the paint off the frame at every ground connection. I love mechanic work, almost more than camping trips! Currently rebuilding the PS pump (was leaking) on my 1992 Lexus SC400 and installing new Tien struts on all 4s I got myself for Christmas!

I went with the Orion XS 50A for its efficiency, smaller unit, less the 3LB heat sink, etc. This is quoted from the Victron datasheet: "The charge current is adjustable with a minimum stepsize of 0.1 A. via VictronConnect." I went with 4 AWG, not wanting to spend more and the Victron Orion XS 50 terminal takes 4 AWG max (reason)? If there is an issue at 50A, I will merely set it down to 30A or somewhere between.
https://www.victronenergy.com/upload/documents/Datasheet-Orion-XS-12-12-50A-DC-DC-battery-charger-EN.pdf

Our Oliver is now 90% Victron (less the legacy Blue Sky SC). Victron Multiplus II inverter/charger, SmartSolar MPPT 30A for the Renogy 400W Suitcase, now the Orion XS 50A, SmartShunt, SmartDongle, VE.Bus and proud to say I don't need a screen mounted to the interior of the Oliver. Love the VictronConnect App! I should be able to read DC-DC charge voltage while towing.

I will post a new thread on my install, though it will likely be a couple months out when I  get to it!

[Snackchaser]

21 hours ago, jd1923 said:

Love the VictronConnect App! 

Yea, I love Victron stuff too!  If not for my Xantrex inverter, I’d have all Victron stuff including the Cerbo with all it’s features to play around with.  I just can’t justify replacing the perfectly good stuff I already have.  But if I only I knew then what I know now, I’d have never bought the lithium package.  It would have been much more fun building my own system.

I’m considering the new 50 amp DC-DC charger upgrade too, because of its impressive efficiency.  We really taxed the 30 amp charger while running the AC during our recent Joshua Tree boondocking trip, it was sucking a lot of battery juice even with two cooling fans to minimize heat derating. 

I could'n't watch the Victron App while driving, but the shunt log appeared to indicate that it intermittently dropped out and I believe that the 90’ of #4 wire was a contributing factor.  I knew the #4 was a little undersized when I installed it, but I wanted use the smaller Anderson connectors.  That was a regretful decision for running the AC, otherwise the charger works great to charge the battery.

So I did some wire size calculations for 50 amps . . . and learned conservatism is not your friend for long runs.  I used 13 volts as a fair charging value with a general accepted maximum 3% voltage drop.  For comparison, I also calculated with Victron’s more conservative values of 12 volts and 2.5% (results in parenthesis.)  The lengths are total for both the positive and negative wires:

• #4 up to 30’ (23’)
• #2 up to 48’ (37’)
• #1 up to 60’ (46’)
• #1/0 up to 76’ (58’)
• #2/0 up to 96’ (74’)

WOW!  As you can see, your modified 65’ length calls for size 1/0 wire, and that’s without adding the frame resistance.  It’s 2/0 for my 90’ length.   The cable size calculations are to safeguard from overheating the wire and to avoid unacceptable voltage drops, the same reason why Oliver disconnects the #10 TV charging circuit for amp hungry lithium systems.  But as you pointed out, the charger output can be derated 😂

I agree with @Ronbrink thats its better to run all copper rather than using the frame because it’s a known resistance, and a more reliable connection with less termination losses.  If you go with larger cable then it’s a wash as far as resistance goes and an extra 18’ would not be a significant cost increase.  But I feel the pain if upsizing the wire, it would more than double the already steep cost.  Tough call if trying to save money!

21 hours ago, jd1923 said:

the Victron Orion XS 50 terminal takes 4 AWG max (reason)?

I think the Aussies use #4 sized terminals because the majority of  Victron chargers are being used in smaller European RV’s, Explorer Vans, and Boats with much shorter cable runs.  Our longer rigs are probably the exception and a small part of their sales.  If they used larger terminals, then more customers would be scratching their heads wondering why!  Snipping strands or necking down to smaller wire at the termination point is a common and accepted practice when using larger wire to limit voltage drop in long runs, and it does not reduce the ampacity rating.

More food for thought!  Cheers!  Geoff

[jd1923]

2 hours ago, Snackchaser said:

I agree with @Ronbrink thats its better to run all copper rather than using the frame because it’s a known resistance, and a more reliable connection with less termination losses.

Keep in mind your TV alternator is chassis ground. Run extra #4 cables, both B+ and B- cables from your alternator to your battery where you have your charger cables connected.

Have you ever checked charging amperage at idle with a clamp-on amp meter? Would the reading be the same on +tive and -tive sides? Is reading the same before and after the DC-DC charger (should be less after, the Orion XS 50A is advertised at 93% efficiency). Great thread, thanks!

[jd1923]

5 hours ago, Snackchaser said:

But if I only I knew then what I know now, I’d have never bought the lithium package.  It would have been much more fun building my own system.

I imagine our system is low cost vs. the "Lithium Package." This is the second full solar/inverter system I have built into an RV. Love the work and each time the technology and prices have improved.

I added the Victron Multiplus II that with Power Assist which is perhaps a better product than an equally powered Xantrex inverter today. Also added 600AH in Epoch batteries. My cost was $3400 plus my labor. When doing so, I moved all the awlward under-streetside-bed breakers, fuses and bus to the rear dinette location. I sold the LA batteries and 2KW Xantrex inverter for a total of $650, net total cost $2,750.

Yes, I would not replace a working 3KW Xantrex inverter/charger. Glad I found our old hull, not so old anymore, after 18 months of improvements. It fits us nicely now! 😂 

Edited January 2 by jd1923

[jd1923]

3 hours ago, jd1923 said:

Keep in mind your TV alternator is chassis ground. Run extra #4 cables, both B+ and B- cables from your alternator to your battery where you have your charger cables connected.

You're going to need these kind of battery terminals!

https://www.ebay.com/itm/235227033422

Edited January 2 by jd1923
Added picture

[Snackchaser]

3 hours ago, jd1923 said:

Sorry but the OTT Lithium package is for those made of money who pay for maintenance and services! That's not our household. 🤣

 End price was $3400

I was reminded of my favorite post in this forum by @Dave and Kimberly and @Ronbrink about the Solar Tax Credit.  With their information, we amended our 2022 tax return and received a handsome refund check for 30% of the cost of the lithium package.

In case you're unaware; I believe you could do the same!  Our friends did!   The entire system cost is eligible, batteries, solar panels, chargers, inverters, shunt, wire, and all the associated bits and bobs.  We didn't have to submit receipts, just have them available.   With 30% of the $3400 spent and the DC to DC charger cost, you're looking at some serious change brother!  It would pay for that DC to DC charger with properly sized wire, some new tools, and a night on the town with the misses. 🤙  

Cheers!  Geoff

[Ronbrink]

9 hours ago, jd1923 said:

You're going to need these kind of battery terminals!

Good advise! Here’s the Amazon alternative I used:

[jd1923]

11 hours ago, Snackchaser said:

With their information, we amended our 2022 tax return and received a handsome refund check for 30% of the cost of the lithium package.

Yes Geoff, I took a tax credit when I added a solar/inverter system to our Bigfoot Class-C in 2020. I plan to do the same here. The Oliver or any RV is considered a second home for tax purposes. That's also why I purchased the DC-DC charger, TEMCo 4 awg wire and Anderson SB175 connecters on New Years Eve, so that I would write off all my Oliver solar improvements for the 2024 tax year.

5 hours ago, Ronbrink said:

Good advise! Here’s the Amazon alternative I used:

This is the way to go! Much better price than the ones I bought.

[jd1923]

Got the goodies yesterday. The 50A Victron DC-DC charger is much smaller than I would have thought! It’s 5x5” with mount height at 1 1/2”, only 1 1/8” thick with 3/8” feet.

The SB175 Anderson connectors, which as pictured, added $79 to costs. They are larger than the charger! Why did I need 175A terminals for a 50A max system? It’s for 4AWG wire and larger. I purchased a similar SB50 10 AWG Anderson with “Environmental Connectors” for our 400W Renogy Suitcase solar. Very nice product!

Makes me think about heavier cables. Go from 4 to 2 AWG, add $55 on my frame grounded 65 run. Make it 1/0, why not add another $135 for $230 plus tax. Need near 100 ft battery to battery 1/0, plan to spend $350, more if you like fancy brand names!

[Geronimo John]

 

On 1/1/2025 at 4:00 PM, jd1923 said:

Have you ever cheeked charging amperage at idle with a clamp-on amp meter? Would the reading be the same on +tive and -tive sides?

JD:  Not for our Orion 12/12-30.  I ran #4 Battery Cables USA Premium cables B+ and B-.  Total length for F-150 Crew Cab was right at 108' out and back.  Fortunately my purchase was when copper was much less expensive than it is now.

I typically only get abut 23 amps on the B+ cable, and about 75% of that on the B- cable. 

Where did the other 25% go?  Appears to be Ollie frame to Bulldog and Anderson WDH, to F-150 frame to the frame/ battery cable to the B- TV battery terminal. 

I would think this is a much higher resistance path.  As such, one would think that all the B- amps would use the cable path back, but that's not what my amp meter is telling me.

Would not bother me much if I was seeing closer to 30 amps, but it is not performing at that level.  

Reading the great posts above, my next check this summer is to monitor the temp of the Orion.  Thinking of adding a fan.

GJ  

 

[Snackchaser]

1 hour ago, Geronimo John said:

 

JD:  Not for our Orion 12/12-30.  I ran #4 Battery Cables

Where did the other 25% go?  Appears to be Ollie frame to Bulldog and Anderson WDH, to F-150 frame to the frame/ battery cable to the B- TV battery terminal. 

I would think this is a much higher resistance path.  As such, one would think that all the B- amps would use the cable path back, but that's not what my amp meter is telling me.

Would not bother me much if I was seeing closer to 30 amps, but it is not performing at that level.  

Reading the great posts above, my next check this summer is to monitor the temp of the Orion.  Thinking of adding a fan.

Geronimo, JD,  

I also have the 30 amp Orion with around 90' of #4.  With the TV at idle, and the lithium batteries around 60%, the average TV input to the Orion was  42.5 amps, and the Orion's output to the battery was 35.8 amps.  Decent efficiency!

Amperage flows equally in a loop, so the B+ and B- will always be the same value.  Knowing that, the 25% difference that you were seeing between measurements was most likely due to the Orion auto adjusting the battery charging current, or changing the output current due to low voltage, or even the smart alternator searching.  It's really hard to get a consistently stable amp reading with all that going on.  The Victron smart shunt has a log feature that might provide a better overall picture of its performance.

You have 18' more wire than me, and that will increase resistance and voltage drop more than it may seem.  It sounds like you might also have some added resistance from using the frame through the hitch for B-.   That can cause the Orion to reduce the output amperage, which reduces the voltage drop, which brings it back within the default set points.  So it might help to change your Orion's default “Start Voltage” from 14 to 13 volts, and the “Shutdown Voltage” from 13.1 to 12.8 volts.  I get into  more detail in my post "More DC to DC charger Installation Tid Bits."  You might also re-check the battery type settings while you're at it.

A cooling fan would be good for the 30 amp Orion, especially considering it ramps down 3% for every degree above 104 F.  I described a way to install fans using a 104 degree thermo switch so that it doesn't create a parasite draw.  It's also in the afore mentioned post.

FYI, I was checking into adding parallel wires with the existing #4 for a 50 amp Orion upgrade.  Geez, I'd have to add at least a #1, but better a #1/0 to stay within acceptable voltage drop.  That's a lot of trouble and expense so I'm going to stick with the 30 amp for now.  I'm very pleased with its battery charging performance, but not so much for running the AC.  

Hope you will find this useful!  Cheers!  Geoff

[jd1923]

12 hours ago, Geronimo John said:

Appears to be Ollie frame to Bulldog and Anderson WDH, to F-150 frame to the frame/ battery cable to the B- TV battery terminal.

So GJ, are you really grounding through the hitch this way? I plan to ground to the truck frame at the rear bumper, but not through the hitch. I will use the Anderson connectors shown above and have a 2 ft ground lead from the Anderson connector to the frame. 

[Geronimo John]

Geoff:

Good info for sure.  Was not aware of the Victron SS log.  I'll check it out next summer. Some follow-ups:

13 hours ago, Snackchaser said:

I also have the 30 amp Orion with around 90' of #4.  With the TV at idle, and the lithium batteries around 60%, the average TV input to the Orion was  42.5 amps, and the Orion's output to the battery was 35.8 amps.  Decent efficiency!

From my understanding of the 30 amp Victron Orion 12-12/30 charger, the unit is specifically designed not to overamp the draw from the TV battery.  As such, the max draw to the Lithium batteries in the RV would by design be 30 amps.  How is it possible you get 35.8 amps out of the Orion as it acts as a TV battery 30 overamp "fire wall"? 

5 hours ago, jd1923 said:

So GJ, are you really grounding through the hitch this way? I plan to ground to the truck frame at the rear bumper, but not through the hitch. I will use the Anderson connectors shown above and have a 2 ft ground lead from the Anderson connector to the frame. 

Not by design.  My 4AWG cables run:

• B+:  TV battery to Circuit Breaker, an Anderson 175 plug, to Orion to Ollie Lithium (via outside terminal of Orion). 
• B-:  Ollie Litho's to Orion to Ollie trailer ground (Center Terminal of the Orion), and then (Outside terminal) to Anderson plug to B- at TV Battery 

But my 712 Smart display says 22 amps or so, and my clamp on amp meter only shows 16.5 amps.  I therefore conclude that about 5.5 amps are going along a metal path of the TV/Ollie team.

13 hours ago, Snackchaser said:

Amperage flows equally in a loop, so the B+ and B- will always be the same value.

  Yes.  That's correct and it is what I am seeing in my system.   But in this case the B- has two loops in it's path.  The 4 awg cables and the metal path of TV/Ollie.

13 hours ago, Snackchaser said:

 It sounds like you might also have some added resistance from using the frame through the hitch for B-.  

Your statement is true.  But I fully expected to see both B+ and B- cables as measured at the hitch area to show the same amperage as you also stated.  But the meters don't validate my expectation.

The return paths of the B- each has it's own resistance.  Per my meters and assumptions, the resistance of the two paths look like the metal path has a higher resistance than the cable path.  Specifically, the ratio balances the current measured by their flows.  Since less current is flowing in the metal path, it must have a higher resistance than the cable path.  

Could it be possible that my Victron Orion non-isolated unit ground wire (Center wire of the cable connection) is the source of our observation?  If so, are others with this set up seeing similar same amp flows?  

13 hours ago, Snackchaser said:

So it might help to change your Orion's default “Start Voltage” from 14 to 13 volts, and the “Shutdown Voltage” from 13.1 to 12.8 volts.  I get into  more detail in my post "More DC to DC charger Installation Tid Bits."  You might also re-check the battery type settings while you're at it.

A cooling fan would be good for the 30 amp Orion, especially considering it ramps down 3% for every degree above 104 F.  I described a way to install fans using a 104 degree thermo switch so that it doesn't create a parasite draw.

Roger.  I think that most of us that have the older 30 amp Orion's would benefit from both of your suggestions.

GJ

Edited January 6 by Geronimo John

[Snackchaser]

4 hours ago, Geronimo John said:

From my understanding of the 30 amp Victron Orion 12-12/30 charger, the unit is specifically designed not to overamp the draw from the TV battery.  As such, the max draw to the Lithium batteries in the RV would by design be 30 amps.  How is it possible you get 35.8 amps out of the Orion as it acts as a TV battery 30 overamp "fire wall"? 

John, good discussion!

The Orions protective features are based on voltage rather than amps, and alternator voltage will drop in an overcurrent current situation.   Thats one of the Dropout Voltage functions, it protects the alternator from overcurrent.  The Orion allows you to adjust the Dropout Voltage enough to compensate for cable voltage drop, but not enough to lose the alternator protection or engine-on detection features.

I was pleasantly surprised  when getting 35.8 amps output from the Orion, but it is capable of 40 amps.  With the 42 amp input, it equates to 85% efficiency, where Victron claims 87%.  The difference in my output / input amps can be attributed to both efficiency and cable voltage drop because even with #4 we are undersized.

4 hours ago, Geronimo John said:

Since less current is flowing in the metal path, it must have a higher resistance than the cable path.  

Could it be possible that my Victron Orion non-isolated unit ground wire (Center wire of the cable connection) is the source of our observation?  If so, are others with this set up seeing similar same amp flows?  

Okay I see whats going on, you have a “non-isolated” Orion!  So the b- current is divided between the #4 wire and your frame.  Those angry pixies will always take the path of least resistance, so as you rightly pointed out, the wire is taking 75% of the load because the frame resistance is higher.   I hadn’t considered that because I use an isolated Orion and it carries the full input current on the wires only.   I don't think it's a problem for you, if anything, it's helping. 

Humm?  The 50 amp Orion is non-isolated too, so JD would be well served to buy an additional 12' of wire for the truck b-, and get a performance boost at little extra cost🤙

Good stuff man!

[jd1923]

16 hours ago, Snackchaser said:

Those angry pixies will always take the path of least resistance, so as you rightly pointed out, the wire is taking 75% of the load because the frame resistance is higher.

That's one way of looking at it. Another is 25% is going through the frame because it has less resistance than pushing more current through the 4 AWG wire at that amperage. Yes of course, the path of least resistance.

My plan it to use the truck steel frame only. One solid piece of frame steel, not the back path of Oliver Aluminum frame through the Bulldog and Anderson hitch, etc. What will allow for more current, 4 AWG of copper or the huge beam of frame steel? I do not know this answer, but I believe it will be fine as every automotive system is body or frame grounded, with ground straps connecting body to frame (including the Alt).

Notice the grounds in the wiring diagram. Also notice the bottom left corner of the diagram showing the truck alternator. Running B+ and B- 4 AWG wire to the truck battery only as good as the B+/B- wiring between alternator and battery. Your truck alternator is only grounded by contact through the engine casting and then a ground strap to the body. Your truck battery is also grounded by a ground strap to the body. I suggest running 4 AWG cables from battery B+ to Alt output and a B- cable to one of the Alt mounting bolts directly. This alone should improve your numbers (decrease resistance in the charge circuit). 

An interesting test would be to see @Geronimo John's number with and without the hitch connected running the truck at idle. It appears the frame ground is helping and without it charge numbers should drop. Another good test would be to see improvement after adding the additional cabling to the alternator. Make sure you have purchased a HO alternator which I believe everybody here has done.