Inverter load/Victron Gurus step inside.....

[7Gentex]

Is this normal?

ETI stock build (9/2022) configuration E19 with dual HubLion 100 a/h batts in the front storage box and 1500 watt inverter in the front dinette.

And, I'm new with this lithium/inverter/Victorn stuff. Not a sparky, but have some basic understanding...............I think!

The other day, I plugged in a 1500/750 watt /120v resistance heater to "test" the inverter, and the heater did not seem happy. Heater fan seemed to be running slow and unit was too quiet. Heater starts in a 1,500 watt configuration though I switched it to low immediately....Hmmmmmmmmm.....Victron showed almost 60 amps being pulled with the heater on "Low" (750 watts) and the batt voltage fell to the mid 12's immediately - from 14.3 ish. I was pressed for time do no more real data relating to such. Too many days ago for Victron history....Maybe the 1500 watt start up threw it a curve?

So today I hooked up a 500 watt/120v resistance heater, followed by a 500 watt/120v "scene light" for a bit more discovery.

Batts were around 13.8v at the start.

On the Victron graph below, you can see where I started with the 500 watt heater, which pulled around 35 amps or so. I turned it on and off a few times to see what the voltage reading would do as I was surprised by the voltage drop.

Then, I also turned on the 500 watt light which got the amperage draw to around 67 amps. Turned that on and off a few times as well to see what the voltage would do. Inverter fan kicked on immediately when the light was turned on. Low 70's F ambient temp.

The heater and light seemed "fine" though as compared to the original heater that I tried.

On full load after a bit, the voltage got down to around 12.9 volts via Victron and I thought that was a bit low, and was maybe approaching about a 20% SOC, though the Victron never showed less than around a 85% SOC?? Inverter indicator lights were all green the whole time.

When I would cycle the loads off, the voltage would immediately climb back up to around 13.3v.

What is going on here? Seems odd. Do I have to let the batts sit after pulling a load to get a good reading? Like after charging?

Normal, or undersized cables, bad connections, 200 amp fuse of the batt causing a loss? All the above? Operator error?

FYI - I doubt I will ever rely on the inverter for much of anything, I wouldn't have ordered one (and avoided the wonderful floor / hull holes!), but this was an inventory trailer "win".

Just curious about the voltage drop shown on the Victron while pulling the load versus the SOC% value?

[Effie]

This is not bad as long as the voltage stay at this level for 30-60 minutes. I tested two Lithium batteries in parallel, (100ah each) pulling just over 50amp. The voltage dropped from 13.3 to 13.1 when applying the load and after about 30min it was 13.00, it did not drop any further in the next 30min.
The Victron 712 is doing its job. In the short time you loaded the batteries they did not lose a lot of capacity, the SOC is calculated from the current, time and the device’s settings.
On a side note, many wrong readings are the result of a misconfigured shunt, that’s when a Bluetooth battery BMS can give a reliable reading.

[splitting_lanes]

Try a 120-130 amp load. Use an accurate volt meter and test voltage at the batteries, and at the inverter.

That will let you know if there’s a significant drop, then you can test at various points to find out where.

Lithium batteries will sag under a high load.

[rubicon327]

Voltage is not a good indicator of state of charge of a lithium battery. That is why something like the Victron with shunt is used to show % SOC. As said lithium will sag under high loads. I have seen my lithium voltage drop considerably when under load (i.e. 1,100 W microwave) especially when the battery is cold. If the load is only short duration the voltage returns to nearly the same voltage after the load is removed. What surprises me about the behavior you are seeing is that the voltage is not returning to as high of a value as I would expect after the load is removed.

[John in Santa Cruz]

Running a 15A/1800W hair dryer on my 2000W inverter, I saw about 150A draw on my 2 x 206AH Lithiums, and the DC voltage stayed above 12V the whole time.. My batteries + inverter + chargers are all my own wiring, lots of short AWG4 and AWG2 cables, and its all in the back of my E21C, under the dinette..

[7Gentex]

Thanks for all the replies, appears the DC voltage sag under load is normal - I wasn't expecting that much............

I pulled around 30 amps for about 30 minutes, then 66 amps for about another 20. After shutting down the batt voltage did immediately recover to around 13.3v and the SOC showed around 85%

[John in Santa Cruz]

when dealing with high amp loads, you'll likely measure different voltages at the load and at the battery terminals, too. Even heavy gauge wire has some resistance per foot, and Ohms*Amps = Volts. Rando example, AWG #6 wire is 0.4 ohms per 1000 feet, so 0.0004 ohms per foot. a 6 foot run is 12 feet round trip, about 0.005 ohms, and at 66 amps, thats a 0.3 volt drop...

[Perry Butler]

I noticed the 206 ah SOK has a 100 continuous amp current discharge rating, the same as the 100 ah SOK. My understanding is that two 100 ah SOK batteries in parallel will have 200 continuous amp discharge, or twice the discharge as the 206 ah SOK. Am I understanding this correctly? If so, I'm buying two 100 ah SOKs.

Thanks,

Perry

[John in Santa Cruz]

yes. if you want 200A total, do be sure to use heavy gauge wire.

I had AWG 4, so I wired each battery "Y" with its own + and - cable to a pair of 250A rated bus bars, one for +, and one for -. Each battery has a 150A ANL fuse in series with its positive lead. all this cabling is fairly short, its all under the rearmost bench of my U dinette.

the inverter has a pair of AWG 2 wires on each of + and ground, these are wired directly to my bus bars. The solar is also wired directly, everything else goes through the power center wiring.

if you choose to parallel the batteries, use bridge cables of the same gauge (+ to + and - to -), and connect the negative lead to one batteries negative terminal;, and the positive lead to the other batteries positive. For occasional sustained 200A loads, I would chose #0 aka 1/0 wire for short runs, or #00 aka 2/0 for longer ones.

the reason you cross wire the batteries is so that each battery has the same total resistance in its wiring... say the + to + wire is 1 foot, the - to - wire is 1 foot, and the leads from load to battery are each 4 feet. one battery has 4 feet to its plus terminal, and 5 feet to its -, while the other battery has 5 feet to plus, and 4 to minus, in other words, each battery has 9 feet total in series. If you wired both power cables to the same battery, then one battery woudl have 8 total feet, and the other would have 10 total feet in series with it at the load.

[John in Santa Cruz]

p.s, I got the stuff to rewire what I did to true parallel with 0 gauge, and I still might. instead of the 2 120A ANL fuses, I got a single 225A class T (fast blow) fuse in a holder. I have enough 1/0 gauge black and white to redo the cables to the Renogy 2000W inverter, too. As I said, the inverter is around 160-170 amps DC at max output, but I don't intend to ever run it above 15A/1800 watts, which will be 150 ADC.

[Perry Butler]

Originally Posted by John in Santa Cruz

yes. if you want 200A total, do be sure to use heavy gauge wire.

I had AWG 4, so I wired each battery "Y" with its own + and - cable to a pair of 250A rated bus bars, one for +, and one for -. Each battery has a 150A ANL fuse in series with its positive lead. all this cabling is fairly short, its all under the rearmost bench of my U dinette.

the inverter has a pair of AWG 2 wires on each of + and ground, these are wired directly to my bus bars. The solar is also wired directly, everything else goes through the power center wiring.

if you choose to parallel the batteries, use bridge cables of the same gauge (+ to + and - to -), and connect the negative lead to one batteries negative terminal;, and the positive lead to the other batteries positive. For occasional sustained 200A loads, I would chose #0 aka 1/0 wire for short runs, or #00 aka 2/0 for longer ones.

the reason you cross wire the batteries is so that each battery has the same total resistance in its wiring... say the + to + wire is 1 foot, the - to - wire is 1 foot, and the leads from load to battery are each 4 feet. one battery has 4 feet to its plus terminal, and 5 feet to its -, while the other battery has 5 feet to plus, and 4 to minus, in other words, each battery has 9 feet total in series. If you wired both power cables to the same battery, then one battery woudl have 8 total feet, and the other would have 10 total feet in series with it at the load.

Thanks, glad to hear it will be 200 amp when paralleling the two 100 ah SOKs. I was pretty sure I had read that somewhere, but always pays to ask. I figure the 900 watt microwave will be using 85-90 amps, depending on efficiency, too close for only a 100 amp continous draw battery. I can also see us making toast with our 700 watt toaster at the same time. I'll be running 10 gauge romex from the inverter to the distribution panel.

2/0 equal length cables will be used for my parallel batteries and for my 2000 watt Progressive Dynamics inverter/transfer switch. I also will be using a 250a T fuse for the inverter. The extra cost for 2/0 wire is negligible.

Thanks,

Perry

[splitting_lanes]

Originally Posted by Perry Butler

Thanks, glad to hear it will be 200 amp when paralleling the two 100 ah SOKs. I was pretty sure I had read that somewhere, but always pays to ask. I figure the 900 watt microwave will be using 85-90 amps, depending on efficiency, too close for only a 100 amp continous draw battery. I can also see us making toast with our 700 watt toaster at the same time. I'll be running 10 gauge romex from the inverter to the distribution panel.

2/0 equal length cables will be used for my parallel batteries and for my 2000 watt Progressive Dynamics inverter/transfer switch. I also will be using a 250a T fuse for the inverter. The extra cost for 2/0 wire is negligible.

Thanks,

Perry

Perry, I thought you sold your 5.0. What’s this setup for?

BTW - I only lose a tenth of a volt in my 1/2 AWG at 140 amps, but the total length of it is 18 inches of 2 awg, and a foot of 1 awg. Keep it as short as you can for maximum efficiency at low voltages (12 volts).

[Perry Butler]

Originally Posted by splitting_lanes

Perry, I thought you sold your 5.0. What’s this setup for?

BTW - I only lose a tenth of a volt in my 1/2 AWG at 140 amps, but the total length of it is 18 inches of 2 awg, and a foot of 1 awg. Keep it as short as you can for maximum efficiency at low voltages (12 volts).

Next Saturday we start our trek to Sidney, BC to pick up our 25RQ Bigfoot. Two days later we travel to Portland to camp two nights with Oldwave and his wife, and then head to Death Valley to start our winter camping in Arizona, New Mexico, and Utah.

Progressive Dynamics states 2/0 wires at a minimum for their 2000 watt inverter/transfer switch. My inverter will be installed on a platform so the 2/0 wires from the battery will only have a slight but straight incline to the 2,000 watt inverter. 2/0 wires, not over 18" total, including the Victron BMV-712 shunt on the negative, and a a Blue Sea 4 way shutoff with a 250a T fuse on the positive, so five cables total.

Enjoy,

Perry

[splitting_lanes]

Originally Posted by Perry Butler

Next Saturday we start our trek to Sidney, BC to pick up our 25RQ Bigfoot. Two days later we travel to Portland to camp two nights with Oldwave and his wife, and then head to Death Valley to start our winter camping in Arizona, New Mexico, and Utah.

Progressive Dynamics states 2/0 wires at a minimum for their 2000 watt inverter/transfer switch. My inverter will be installed on a platform so the 2/0 wires from the battery will only have a slight but straight incline to the 2,000 watt inverter. 2/0 wires, not over 18" total, including the Victron BMV-712 shunt on the negative and a Blue Sea 4 way shutoff and 250a T fuse on the positive, so five cables total.

Enjoy,

Perry

NICE! And I mean all of it. The inverter, wiring, and trailer. Hope you’ll swing through some escape/fiberglass gatherings to humblebrag. Lol.

That inverter is insane. 4000w peak.

[Perry Butler]

Originally Posted by splitting_lanes

NICE! And I mean all of it. The inverter, wiring, and trailer. Hope you’ll swing through some escape/fiberglass gatherings to humblebrag. Lol.

That inverter is insane. 4000w peak.

We have every intention of attending the Mississippi River Rendezvous next fall.

The Progressive Dynamics inverter was suggested by Oldwave. He had one in his Escape 21 with great results. It has everything I want in a inverter/transfer switch and at only $623 is within our budget.

Enjoy,

Perry

[DGLP]

Originally Posted by Perry Butler

We have every intention of attending the Mississippi River Rendezvous next fall.

The Progressive Dynamics inverter was suggested by Oldwave. He had one in his Escape 21 with great results. It has everything I want in a inverter/transfer switch and at only $623 is within our budget.

Enjoy,

Perry

Good price compared with the Go Power 2000 watt pure sine wave inverter (without transfer switch) at $660.34 on eTrailer. Enjoy the trip and trailer! Looking forward to seeing you at the Mississippi River Rendezvous.

https://www.etrailer.com/RV-Inverter.../34278156.html

[sameo416]

Originally Posted by rubicon327

Voltage is not a good indicator of state of charge of a lithium battery. That is why something like the Victron with shunt is used to show % SOC. As said lithium will sag under high loads. I have seen my lithium voltage drop considerably when under load (i.e. 1,100 W microwave) especially when the battery is cold. If the load is only short duration the voltage returns to nearly the same voltage after the load is removed. What surprises me about the behavior you are seeing is that the voltage is not returning to as high of a value as I would expect after the load is removed.

Exactly what I was going to say. I did a similar test with a 1,500W heater and saw similar results. The only way you can accurately gauge charge state in Li batteries is using a totalizer, a shunt that tracks charge flow. Our 5.0 was early in the Li fitments, and only included the GoPower charge controller. I realized quickly that it said zero about charge state, and installed a Thornwave shunt.

(totalizer isn't an electrical term - it's from aviation, referring to a fuel system that doesn't gauge what's in the tanks, but measures flow to the engine and subtracts from the total entered based on fuel fill...a memory from my CT-133 T-Bird days)

[tedtucci]

I am trying to follow this thread
We built our 2022 5.0 with 2 6 volt 260amp silicon dioxide batteries and two 180 watt roof top solar panels
We did not purchase an inverter when we built it

We would now like to add an inverter to charge our laptop toothbrushs snd perhaps supply power to an electric kettle

Is the progressive dynamic discussed below what we would want?

Would we ever be be able to use a small electric heater when boondocking with this configuration should we have the dreaded sail switch failure?

Thanks heaps electrical stuff is a foreign language to me
Mary

Ps Perry did you buy a Bigfoot

[John in Santa Cruz]

Originally Posted by tedtucci

I am trying to follow this thread
We built our 2022 5.0 with 2 6 volt 260amp silicon dioxide batteries and two 180 watt roof top solar panels
We did not purchase an inverter when we built it

We would now like to add an inverter to charge our laptop toothbrushs snd perhaps supply power to an electric kettle

Is the progressive dynamic discussed below what we would want?

Would we ever be be able to use a small electric heater when boondocking with this configuration should we have the dreaded sail switch failure?

Thanks heaps electrical stuff is a foreign language to me
Mary

Ps Perry did you buy a Bigfoot

Electric Toothbrush, Laptop charging, thats all sub 100W stuff, you can use a small portable inverter, like a 150-200W one, that plugs into a cigar lighter outlet.

the electric kettle is probably more like 1500 watts, maybe more, that will require a large inverter which has to be hard wired to your batteries with heavy gauge cable... My 2000W inverter draws about 180 amps when its outputting 1800 watts to my wife's hair dryer.

Electric heat would flatten your batteries in an hour or two. you can get away with the electric kettle or a coffee maker or hair dryer because those only run for a few minutes then you're done.

[Vermilye]

As John pointed out, using an electric heater as backup for a failed furnace is impractical - while the efficiency of an electric heater is high (close to 100%) the process of getting that energy from the batteries and the amount of energy stored in almost all battery installations limits the amount of heat available.

If you need a back up for the furnace, a catalytic heater such as one of the Buddy heaters makes far more sense, although there are cautions & considerations with them.