Shake-down cruise with a Norcold compressor fridge

[alanmalk]

Originally Posted by dstreight

Mike, maybe you stated it but what tow vehicle are you using? If later model with "smart" alternator you may not be getting adequate current to your BB1230. Both of my TVs are older and getting sufficient current flow (I used 2AWG from battery to the nose box where the BB1260 is housed on our 15A) isn't a problem at highway speeds.

Not sure what your furnace draws using 12v but I have read ~15amps when its running...that can suck considerable battery current over 24-hours.

He mentioned Tacoma (Taco) but not the year. I don't think Tacomas have incorporated smart alternators yet - the upper management seems to hesitate on incorporating technology. (I might be tempted to upgrade my Tacoma if and when they move into the modern age.) But that aside - a B2B (DC-DC converter) should be immune to modest drops in voltage - that's one of the main selling points. "Low" voltage on the tow side is boosted to higher Lithium charging voltage on the trailer side. To achieve that, they pull more current in than they put out, but the wattage in is roughly the wattage out.

A number of years ago I measured the furnace draw at roughly 4 amps if memory serves.

[dstreight]

My understanding from Sterling: The BB1230/BB1260 needs 13.3v to turn on...so, in the case of a buddy's smart alternator LandCruiser 200-Series, when the alternator sees the OEM battery at full/near full charge it will taper output voltage in an effort to reduce engine load thereby increasing MPG; whatever % I don't know. I don't remember the needed work around but it wouldn't keep his 2nd battery fully charged all the time.

[rubicon327]

Originally Posted by alanmalk

A number of years ago I measured the furnace draw at roughly 4 amps if memory serves.

The nameplate amps on the older Atwood 8012-II furnaces is 1.8A. The newer Atwood AFSAD12 / Dometic DFSAD12 furnaces are 2.4A.

[Rossue]

Originally Posted by dstreight

My understanding from Sterling: The BB1230/BB1260 needs 13.3v to turn on...so, in the case of a buddy's smart alternator LandCruiser 200-Series, when the alternator sees the OEM battery at full/near full charge it will taper output voltage in an effort to reduce engine load thereby increasing MPG; whatever % I don't know. I don't remember the needed work around but it wouldn't keep his 2nd battery fully charged all the time.

Yes, that's the way the smart alternator works. Have a 250 amp smart alternator in the 2021 Transit T-250 and at idle the proprietary Goal Zero B-B charge is showing 750 Watts going into the Goal Zero 3000X. However, while driving it drops to 50 watts or even less. Fortunately that proprietary charger- called the Vehicle Integration Kit has two settings. One for Car Mode which one would use with a normal alternator and the other for Tank Mode- which allows for an additional battery to be added. The workaround is to run it in Tank Mode. While there otherwise would be some fear that the starter batteries would be drained; the CCP2 (Customer Convenience Point) shuts down after about 30 minutes or when the starter batteries(two 75 AH AGM) gets below 12V.

[dstreight]

^ good info & thanks! FYI/FWIW, the Sterling BB1230/BB1260 units shut off current flow from the parent battery at 13.0v and also perform as an isolator so not to syphon current either way.

An aside/hyjack of sorts: Like the OP, I wish programming the Sterling units was via BT or something easier than how they 'designed' it to be accomplished on these units. Otherwise my BB1260 functions to expectation.

[Mike Lewis]

Originally Posted by John in Santa Cruz

Do you have a Victron smartshunt or BVM? Monitor your batteries with their bluetooth app

Yes. I realized today that I could monitor the charging activity with the "Trends" screen of the SmartShunt app while revving the engine. Haven't tried it yet, though. Maybe tomorrow.

[Mike Lewis]

Originally Posted by alanmalk

He mentioned Tacoma (Taco) but not the year.

I have a 2013 Tacoma with a 4.0L V6 engine. I'll put that in my profile. There's nothing smart about it as far as I can tell. Its radio is particularly dumb imo.

[Mike G]

Originally Posted by Mike Lewis

My gut feeling was that the new fridge would work fine boondocking out West in the summer where the skies are not cloudy all day, .

Reminds me of a song:
Oh, give me a home
where the buffalo roam
and the deer and the antelope play;
where seldom is heard
a discouraging word
and the skies are not cloudy all day.

[John in Santa Cruz]

A DC compressor fridge draws 2-3 amps, and only does it about 20-25% of the time. My furnace fan is also about 2-3 amps.

[dstreight]

A 500 mile drive should have completely re-charged the LFP bank on the way to Florida using just the BB1230 given the starting SOC. Rough estimate: 10-hours of driving & 15A/hour from the Sterling should have resulted in 100% SOC upon arriving in Florida.

6AWG is probably OK to move up to 20amps of current at 14v the 50' electrical round trip, but definitely undersized for 20+amps. You should have seen at least 13.3v on the trailer's battery side of the BB1230 when driving.

Do you know what size alternator is on the Tacoma? Generally, per inter web, it looks like Tacomas, depending on the model year, came with 90-130A alternators.

Obviously, the BB1230 isn't contributing what it should be...

The good news: LFP is fine being discharged regularly 80%, so assuming your SOC measurement is accurate, your 52% of max upon leaving Orlando for the back home ride was OK.

I assume since the BB1230 is located in the trailer, the LFP bank is also located inside the trailer? The below freezing nights should not have dragged the battery bank's temp low enough to stop charging from the solar bank assuming you're using a Victron or similar solar charge controller.

For comparison: I have 800w rated PV atop our almost all electric (diesel heater) 15A with a 500A of LFP. From May to late October with full sun to mostly sunny days, our PV array easily replaces any/all electricity used from the LFP.

However, during the shoulder months, even with full sun, it can be a challenge to replenish what we use in electricity each day and I have to be judicious with electric use. I carry a 170w foldable Merlin during these months to help. The PV contribution you were effectively getting with your 355w rated solar at the shortest days of the year wasn't able to cover what you used while you were camped.

[Mike Lewis]

Originally Posted by dstreight

6AWG is probably OK to move up to 20amps of current at 14v the 50' electrical round trip, but definitely undersized for 20+amps. You should have seen at least 13.3v on the trailer's battery side of the BB1230 when driving.

If this is the problem I am dismayed, as that wire was expensive and installing it was quite a chore. And the BB1230's terminals will not accept wire larger than AWG 6.

Do you know what size alternator is on the Tacoma?

No.

I assume since the BB1230 is located in the trailer, the LFP bank is also located inside the trailer?

Yes. The Sterling is adjacent to the battery bank, both near the rear of the trailer.

[Mike Lewis]

Originally Posted by dstreight

6AWG is probably OK to move up to 20amps of current at 14v the 50' electrical round trip, but definitely undersized for 20+amps. You should have seen at least 13.3v on the trailer's battery side of the BB1230 when driving.

The Sterling B2B charger's manual has a chart of recommended wire sizes for a given length of wire. The longest length given is 30 feet -> AWG8. I must have referenced this when I ordered the 50 ft of AWG6 wire. I was thinking one way though, not round trip.

[Mike Lewis]

I made the electrical connections from my Tacoma to my trailer. My solar panels were disconnected and everything in the trailer shut down, so I had a parasitic load of less than 0.5A. I started the truck and let the engine warm up. Then I measured a three-minute period: one minute idling, one at 2000 RPM, and the third at idling again. I recorded the charge with the Victron Connect app on my laptop.

After an initial climb it shows at least ninety seconds of a steady 22 amp charge. That's not bad IMO. See attached screenshot. The width of the graph is five minutes and the tick marks seem to be at thirty second intervals.

[BobG]

Originally Posted by Mike Lewis

After an initial climb it shows at least ninety seconds of a steady 22 amp charge.

That is really neat being able to easily verify your SOC and how charging is progressing as you travel to a your next stop.

[dstreight]

Well, 22 amps is good! Do you have a multi-meter? If not, its good to have one around and include in your truck/mobile rig. The clamp style that can read DC volts & amps are worthy as it allows easy/quick reads for same...

FYI/FWIW here's one of many wire gauge calculators out there on the web: https://www.omnicalculator.com/physics/dc-wire-size

I had to make up a 2AWG to 6AWG, which is only 4" or so long, 'adapter' to my BB1260; easy enough and fine given the short length so not to create an electrical 'bottle-neck'/undo resistance relative to current max.

[alanmalk]

Originally Posted by Mike Lewis

...
After an initial climb it shows at least ninety seconds of a steady 22 amp charge. That's not bad IMO. See attached screenshot. The width of the graph is five minutes and the tick marks seem to be at thirty second intervals.

The amp charge sounds good. The other half of the equation is the voltage at the battery terminals. If below (approximately) 14.4 VDC, then two possible complications. First, the charge will taper off to near zero before the battery is 100% full, and second, the cells won't be balanced by the BMS. (Balance doesn't need to happen every cycle, of course.)

I believe your alternator (and mine) are the 130 amp size. I think this comes with the V6 engine.

Reducing wire size for the last foot or two is a trick I have used. Yes, there is a bit more resistance added, however since the distance is short, and the effect is linear, the total voltage drop is only a fraction higher.

And for anyone following this conversation: When trying to figure out wire size and voltage drop - this is always done on a round trip basis. For example, total distance of wire, battery to inverter to battery, or alternator to B2B and back to alternator. It does hurt the pocketbook but there is no choice.

[Selkirk]

Originally Posted by alanmalk

I believe your alternator (and mine) are the 130 amp size. I think this comes with the V6 engine.

The 2nd Gen Tacoma came with a 130 amp alternator when equipped with both the V6 and towing package. Otherwise is it a 90amp unit.

This is an interesting thread. I'm in the process of configuring my trailer and been considering the compressor fridge option. This provides some real-world insight into the power storage/solar/charging requirements to support a compressor fridge while boondocking in the shoulder seasons with less-than-ideal solar conditions.

It might be a moot point for me anyways, since the compressor fridge option is temporarily unavailable from ETI.

[dstreight]

I don't have a smart shunt on my system but this might be worth a look for those that do. Seems there is set-up "tweak" that might be needed when using solar + B2B charger.

https://community.victronenergy.com/...s-lithium.html

[alanmalk]

Originally Posted by Mike Lewis

...

If this is the problem I am dismayed, as that wire was expensive and installing it was quite a chore
...

I'm not convinced - yet - that this is the problem.Ampacityof 6GA is 55 amps, so the wire can "take the heat". Voltage drop may be an issue since it is roughly 80 feet round trip - alternator to B2B to alternator. But I am guessing the B2B can deal with the voltage drop since that is one of its main purposes. But only some actual voltage measurements can prove or disprove this. And in the worst case you might need to upgrade some of the wire. A partial section that is easiest to reach since the whole system is linear. But don't jump the gun on that.

[Mike Lewis]

Originally Posted by BobG

That is really neat being able to easily verify your SOC and how charging is progressing as you travel to a your next stop.

At this point I think the B2B charger is charging the batteries intermittently. I have a trip coming up. On the first day of that trip I'll leave the laptop running in the trailer to record the charging activity.