MPPT Solar and Lithium Question

[uncle_bob]

Hi

If the panels are in parallel and you have diodes in your "hub" there really is no gotcha from tossing a blanket over one of the panels. No parasitic drop even with super crud panels.

If they are in series and you have shunt diodes on the panels, the same thing is true. Essentially zero drop across the dark panel. That's *if* you stay above the minimum voltage needed by the MPPT *and* it's an MPPT in the first place. With lesser controllers YMMV.

The math (assuming three panels):

Three in parallel supply 3X current at 1X voltage. Net 3 x 1 = 3 chunks of energy. Take one out and you have 2X current and 2 chunks of energy.

Three in series supply 1X current at 3X voltage. Net is 1 s 3 = 3 chunks of energy. Take one out and you have 1X current and 2X voltage. Net is 2 chunks of energy.

Why all the posts about trouble with series? It's not the panels .... it's the stupid controller they are using..... Unless your panel puts out 1/2V total, it already *has* series connected cells ....

So much fun !!!

======

Taking a day off from the trailer and roasting a whole pig while attempting (along with a number of friends) to put a measurable dent in the world's inventory of beer

Bob

[waninae39]

yum yum

hey bob, whats you addr. i want to come over for beer and BBQ pork );

BTW, still battling with vitron, maybe i have a bad controller

[daleyocum]

Originally Posted by waninae39

i broke down and ordered the mutiplus 3k. it was shorter than the 2k(wont fit in my 22FB)

i have two 100/30 Victron mppt ctrl and one BB 100AM lion battery now

i have two mppt ctr since i plan to get another set of SS for the roof, to complete the 160w panel on the rear . I am looking at the narrwo 90w am solar panels. 3 will fit on my 22fb roof, 2 on one side and 1 one the other



when down i will have 160+270W= 430W

plus 200AH with BB Lion



i am making room for the a 2nd BB 100AM lion battery along with the mutiplus 3k.



all will just fit under road side under the front bed.

i have to move one support board and will likely rewire the very messy As wiring and collocate the +ve and -ve bus bars



once the mutiplus 3k. comes in and i get it all setup, ill post pics of my setup.



i have two

I agree with the others that having two MPPT controllers may not be ideal. Besides the parasitic drain, monitoring the system will be more difficult. I’m not sure what the Venus does with displaying the outputs of two solar controllers and monitoring them. It might work fine, but you will be the pioneer, at least on this forum, getting it all to work. I find that more often than not, I just log in with bluetooth to the solar controller itself to see what’s going on. With two, that would be a pain.

I’d just put all the panels in parallel and let the diodes and MPPT controller do their job.

A single 30amp controller would be able to handle all your panels fine. As you know, seldom do all the panels pump out their full rated output as they are almost never pointed directly at the sun, at noon, on a crystal clear day. Even if that happens, your controller would just deliver the amount of amperage it can.

[uncle_bob]

Originally Posted by waninae39

yum yum

hey bob, whats you addr. i want to come over for beer and BBQ pork );

BTW, still battling with vitron, maybe i have a bad controller

Hi

We do pork and beer at New Years and July 4th pretty much every year. If you are in the Carlisle ( PA ) area drop by !!!!

======

One limit on the Venus is that it comes stock with two VE.Direct ports. One goes to the BMV (which is pretty important if you want to do stuff with the Venus). The other goes to the MPPT. Hooking in a second MPPT .... errr ... out of default ports. There may be a way to do it with a USB to VE.Direct adapter. Now you are into "pioneer" status in multiple ways ...

Bob

[uncle_bob]

Hi

Yet again with the double post ...

So, the new MPPT got here in the mail. Got it wired up and mounted in place. Fired up the phone. It connected to it and checked firmware. It first updated the main firmware and in a second pass updated the Bluetooth firmware. So far identical to the other unit.

Same old cable hooked it to the same old port on the Venus. Check the Venus control panel. *Surprise !!!!* it recognizes an MPPT !! No need to reboot or poke at the Venus. Always better when things actually work. Pretty conclusive that the old MPPT was weird in some way.

After some poking at this and that, pretty much all the things that should co-ordinate now seem to co-ordinate. It'll take a little time to see how things settle out. Everything at least makes sense at this point.

Later I'll play with the USB -> VE.Direct dongle and see if it will chat with the old MPPT on the bench. My guess is that it will not .... we'll see. Not quite clear what I'll do with it. A spare (even semi-functional) might be nice to have. I'll check the return-ability of it later. I suspect I'm past the "no questions asked" return period. Who knows what a warranty return entails....

So much fun !!!!

Bob

[fran&frank]

Glad to hear thinks went smoothly with the new mppt and venus Bob, that's pretty much the way my install went.--Frank

[waninae39]

i wired the bmc 712 using the usb adapter to free up 1/2 VE.Direct ports on my colour display.

thus i will have two mppt on the two VE.Direct
and the 712 on the usb

also, usb port supports a USB hub . thus you can have many more USB connections

[uncle_bob]

Originally Posted by waninae39

i wired the bmc 712 using the usb adapter to free up 1/2 VE.Direct ports on my colour display.

thus i will have two mppt on the two VE.Direct
and the 712 on the usb

also, usb port supports a USB hub . thus you can have many more USB connections

Hi

There is a maximum number of devices (however connected) that the control brains will support. At the moment that number is around 5 or 6. They push it up with various firmware updates.

While it's a minor issue to some, I still am bugged by the parasitic power these systems consume. Tacking expansion hubs and usb gizmos on just adds to the power.....

====

I got the system buttoned up today. Main issue was a couple of times the VE.Direct cables popped out of one end or the other. Something that mates in a more positive fashion would be nice.

Next on the todo list is to work out a more rational way to turn the inverter on and off. I never want the converter side turned off so it's really going from "on" to "converter only" rather than on to off. The inverter pulls about 1.7A when idling. That's more than I can afford to support in an environment where solar may max out in the 1,2 or 3A range.

Bob

[Paprika]

"I agree with the others that having two MPPT controllers may not be ideal."

I tried that with a Victron 100/30 and a 75/15. It didn't work well. One or the other would "back off" when it saw the other charger's voltage, and go into float. Result: wasted solar power. Victron tech support first claimed that it should work, then admitted it was less than ideal. I gave up and replaced all my panels with identical ones, so I could use one controller.

[uncle_bob]

Hi

Ok, so I got the "old" MPPT out of the trailer and hooked it up to a bench supply. I configured the Mac as Windows under Bootcamp and got the VE Connect app downloaded and installed. Plug in the VE.Direct <-> USB adapter and ... hmmmm.... it connects fine and does it's thing talking to the MPPT. One would *guess* that it will now talk to the Venus. Why it did what it did .... no idea ... My only advice to anybody who hits the same roadblock - pull it entirely out and hit it with the USB adapter ....

Bob

[SilverHouseDreams]

Originally Posted by uncle_bob

Coming home today the Orion DC / DC gave up part way through the journey. No idea why ... yet.

Bob

Bob, I PM'd you on this but thought it might be useful to get input from others and share our findings. I actually had my Orion stop working as well, during initial testing it seemed OK...but then for the actual trip it wasn't powering on. In my course of troubleshooting it doesn't appear that the Orion was powering on during a normal connect sequence (load always connected, input connected when 7-pin is connected). I was able to get it to power on by manually disconnecting the load and then connecting the 7-pin.

Did you find a resolution to your issue? Did they ship a replacement and it solved the issue entirely?

[uncle_bob]

Hi

Sorry, I missed the PM. The Orion seems to be doing fine. It powers up if I put a battery on the appropriate wires. I also checked the little jumper that does the remote control. It seems to be ok.

The issue appears to be on the Ford side of things. There was a blown fuse in the truck. After replacing it, the Orion still does not seem to get power on the 7 pin. It's a 30A fuse which should be OK for an 18A converter. I'll get it over to Ford when we aren't busy using the AS ....

Bob

[daleyocum]

Originally Posted by uncle_bob

Hi

Sorry, I missed the PM. The Orion seems to be doing fine. It powers up if I put a battery on the appropriate wires. I also checked the little jumper that does the remote control. It seems to be ok.

The issue appears to be on the Ford side of things. There was a blown fuse in the truck. After replacing it, the Orion still does not seem to get power on the 7 pin. It's a 30A fuse which should be OK for an 18A converter. I'll get it over to Ford when we aren't busy using the AS ....

Bob

I also have a F150 with the Orion. I was baffled by the Orion not getting power for some time. Ford, for reasons known only to them, decided to make the pin 7 “smart.” It only engerizes it when your trailer is connected to the truck, ignition is on, you’ve pressed the brake, and put it into drive. It’s current limited. I’m not sure at what value but there’s only a small gauge wire going to it so it couldn’t be much. It’s seems to be able to drive my 9A Orion fine but I’m not sure how much further it could go.

[uncle_bob]

Hi

Yup, it only turns on after you go a bit nuts with putting things in drive and playing with brakes. One nice thing abut the Victron gear is that you can Blutooth or WiFi into it while in motion. That lets you "see" if the Orion is putting out anything or not.

The fuse on the wire to the 7 pin is a 30 amp fuse. That would suggest that they have a run of 10 AWG back to the connector. If it's much less than that, the fuse would be smaller. If you figure 10 feet to the connector and 10 feet into the trailer, that's 40 feet round trip. That gets you 40 mili-ohms of resistance. At 30A you would drop 1.2 V through the loop of wire. More or less, you loose 10% on that trip.

If the alternator / battery drops to 12.6V at idle, you are at 11.4V on the connector at 30A. If the Orion is trying to get to 14.4V, that is a 3V step up. Instead of pulling 18A to get 18A out, it likely is pulling a bit under 24A. That makes a few assumptions about how it current limits and it's efficiency. Still, it is a long way below 30A. The fuse should not blow ....

.... yes, I've pondered this a bit

Bob

[SilverHouseDreams]

Thanks for the feedback, I need to do some more testing with mine to narrow down the issue. Perhaps I ended up blowing the charge line fuse during the previous trip, I wasn't looking to spend time crawling under my mattress with an interior temperature of ~99 degrees the other day. I'll have to go visit it at the storage lot soon after the replacement for my noisy PD4655LV arrives and will do some more testing, I am also adding a disconnect relay on the charge output in my TV so that it won't draw the TV battery down during a long stop with the fridge in 12V mode.

[uncle_bob]

Originally Posted by SilverHouseDreams

Thanks for the feedback, I need to do some more testing with mine to narrow down the issue. Perhaps I ended up blowing the charge line fuse during the previous trip, I wasn't looking to spend time crawling under my mattress with an interior temperature of ~99 degrees the other day. I'll have to go visit it at the storage lot soon after the replacement for my noisy PD4655LV arrives and will do some more testing, I am also adding a disconnect relay on the charge output in my TV so that it won't draw the TV battery down during a long stop with the fridge in 12V mode.

Hi

Before you go to crazy with relays to protect the TV, check how yours works. A lot of trucks these days have a built in disconnect for trailer power once the truck is turned off. I *do* understand just how much fun crawling around in 100+ degree heat doing this is .... I now have a *lot* of personal experience at it ...

Bob

[uncle_bob]

Hi

Well, the thing that I suspected would be the weak link in my installation has proven to be just that. After a few months of driving down unpaved interstate highways in a number of states .... the LAN cable between the Venus and the Mulit gave up. I ran it under the trailer along with the battery cables. My guess is that it got crushed be the big bad battery cable at some point under the floor and above the belly pan. In any case the Venus no longer can control the Multi.

If anybody else gets into this fix ... the trick to remember is the first two DIP switches. They go one way for remote and the other way for running manually on the local switch.

We're having FUN .... and to think I was worried about the tail end of a hurricane just an hour or two ago .... such minor issues ....

Bob

[rmkrum]

Originally Posted by uncle_bob

Hi

----------------snip---------------------

We're having FUN .... and to think I was worried about the tail end of a hurricane just an hour or two ago .... such minor issues ....

Bob

Yup, when you are comfortable, on the road, and the weather is FAR behind you, it's time to relax and enjoy the trip.

DW is thinking about retiring and moving to Florida, and getting a slightly bigger Airstream. I grew up on the east coast, and having a ready-to-roll Airstream is the ideal solution to bad/dangerous tropical weather...you don't have to hunker down, just board up the house, and run for it.

Sat through some seriously big hurricanes in the 1960's. Family had no good way to run for it, so we had to stay and take the beating. Fortunately the house was built to take a lot of wind and rain. Still very scary for us kids.

[waninae39]

Originally Posted by SilverHouseDreams

Thanks for the feedback, I need to do some more testing with mine to narrow down the issue. Perhaps I ended up blowing the charge line fuse during the previous trip, I wasn't looking to spend time crawling under my mattress with an interior temperature of ~99 degrees the other day. I'll have to go visit it at the storage lot soon after the replacement for my noisy PD4655LV arrives and will do some more testing, I am also adding a disconnect relay on the charge output in my TV so that it won't draw the TV battery down during a long stop with the fridge in 12V mode.

I replaced the PD4655LV with the victron 12v/3000w/50A converter/inverter + remote control panel . i also added a victron orion 12v-12v one way islolator so that the TV can charge the As , but no reverse flow.
with my BB lion battery the output of the orion can be higher that the TV input

[SilverHouseDreams]

Originally Posted by waninae39

I replaced the PD4655LV with the victron 12v/3000w/50A converter/inverter + remote control panel . i also added a victron orion 12v-12v one way islolator so that the TV can charge the As , but no reverse flow.

with my BB lion battery the output of the orion can be higher that the TV input

I already have the Orion 12/12 converter, but I keep having issues with it not powering on.