Trailer - Disable PIP for long term storage

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prepared1

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OGITC: if you switch the system off during a time when the PV panels are still getting input, will that damage the panels? It is a concern with typical hot water solar panels, so people put in some sort of dump load or a cover. Just curious. I have considered doing something similar to your project, would like to know.

Thanks for the interesting posts...
 

OffGridInTheCity

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OGITC: if you switch the system off during a time when the PV panels are still getting input, will that damage the panels? It is a concern with typical hot water solar panels, so people put in some sort of dump load or a cover. Just curious. I have considered doing something similar to your project, would like to know.

Thanks for the interesting posts...
Thank you for the thought. The 2s2p panels go to thru standard circuit breakers, are combined, and then on to the MPP. The disconnect procedure not only re-routes the AC around the PIP but also includes turning off the battery bank and disconnecting the PV input.
1614271636951.png
 

OffGridInTheCity

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Lately the sun is high enough to reach the 4 x 300w panels on the roof of the trailer. Mid day - there is band of shadow from the roof of the house, killing optimal performance but beginning and ending 1/3 of the day they are in full sun ....
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and producing pretty good power. Here's the kwh vs hours of the day from the PIP logs for yesterday. The dip in the middle is the shadow from the roof in the pic above. They're wired 2s2p length-of-trailer-wise - so 1 string is full sun and the other has shadow on both panels.
1622749460073.png


With the dip I'm getting 2kwh/day (June 2) and would expect to get 3kwh/day in full sun. I've been running the 9000 BTU heat pump maintaining 75F/24C 24hrs/day on a 48v@260ah 18650 battery bank and its keeping up.

The temp spiked this week to a few days of 100F/39C but will be back down to 80-90F/29C'ish soon. The system looses some ground at 100F but gains just a bit of ground at 85F. The trailer is 14x7 with 1" insulation + radiant tape *everywhwere* (ceiling, wall, floor, in the tail-gate, and all the nooks-crannies.

I'm really pleased at how well heat-pump / 1200 watts of panels / PIP / 14kwh battery is performing. With modest power management and good sun - this thing can actually run on Solar.

The DIY 18650 14s88p battery made of RING cells is performing very well. Sat for the last 4 months and just turned it on... and balance is holding at 20mv max difference same as 4 months ago.
1622750603618.png



**Lessons learned.
1) FLAT mounted panels means the rain/water pools on them due to the frame lip all around them and when the water evaporates the dust/dirt is caked on and is not washed off the way tilted panels are. Hadn't considered that... and would warn others to allow for some tilt for better self-cleaning.

2) The Honda EU3000is generator was converted to support Propane and it turns out you can still use Gasoline. The Gasoline mode will produce 2,200watts of continuous charging. The Propane mode will only produce 1,800watts... the motor isn't quit as powerful under load. and that's 20% less charging power.
1622751653360.png
 
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OffGridInTheCity

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I've been experimenting with the 120v is disconnected and the Trailer/PIP 3048LV has been running on solar + battery only. The mini-split has been maintaining a reasonable temp 24/7 - all good. However we've hit a hot patch - 106F/41C yesterday and projected 115F/46C today.

At these temps it can't maintain and the 48v (14s88p) battery is down to 51.8v this morning.

QUESTION: You can see my PIP settings below - what happens when the battery hits cut-off-voltage. with no 120v input?
I assume it will require external battery charge? and that it won't resume AC output until it hits "Back to discharge voltage"?
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R

robinkyle11

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Yes. I have a few scenarios with the trailer and I just need to know what to set for different modes. For example:

1a) One mode is using the onboard generator to charge the batteries while driving - e.g. the generator goes to the ATS / PIP sees 'grid' and I want it to do the 20a max charging.

1b) An Alternate to this is just using the solar panels while driving to charge. The trailer is in shade so I can't test this very well right now - and surprised to see 2a charging (10a max) when when the panels only creating 100w in "Solar->Utility->Battery" mode. The 2a must be coming from the grid but why 2a instead of 10a?

2) Another mode is boondocking with sun and I want the solar panels to have priority - but maybe run the generator an hour or 2 to assist (with max amps flowing).

3) And bypass - where I have grid at a campsite (or just parked at the house) and bypass the PIP/batteries and leave it all turned off ---
*You're 3-position switch advice has solved this for me - thank you again for that!*

The good news is I can adjust parameters - but want to work out the minimum set of adjustments :)
 

OffGridInTheCity

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I've got mine down to 1 setting for all the below.
1st up - I have Charger source prioirty = SBL&UCB + Output source priority = Utility->Solar->Battery. This works when AC input is off + when AC input is on it will still let the PV thru if I throttle the Max AC charging current so that Max AC charging current + PV <= Max charging current (to the batteries). In my case 2a + PV = 13a = 15a and is <= 40a.
1627151992184.png


I have a honda eu3000is and discovered that Max AC charging current = 20a (in conjunction with Max charging current = 40a) is the max the generator can sustain before the engine overloads / runs erratically. This gives me ~ 2,200w of continuous AC charging.

The reason I have Max AC set to 2a (right now) is that if I left it at 20a (for max generator charging) it would be 20a + load = overload on the 15a circuit I have the trailer plugged into at home. This might be true at a camp-ground as well. But with 100% generator = I can set it up to 20a for max charging.


Yes. I have a few scenarios with the trailer and I just need to know what to set for different modes. For example:

1a) One mode is using the onboard generator to charge the batteries while driving - e.g. the generator goes to the ATS / PIP sees 'grid' and I want it to do the 20a max charging.
I only need to alter the Max AC charging current from 2a to 10 or 20 or xxx till I reach the max the generator can do. But remember - its Max AC charging current + load - so you're situation may vary. While driving, you're load should be minimal so max AC amps your generator can handle.

1b) An Alternate to this is just using the solar panels while driving to charge. The trailer is in shade so I can't test this very well right now - and surprised to see 2a charging (10a max) when when the panels only creating 100w in "Solar->Utility->Battery" mode. The 2a must be coming from the grid but why 2a instead of 10a?
Just leave the generator off with settings above. The PV will surge in with no 120v input.

2) Another mode is boondocking with sun and I want the solar panels to have priority - but maybe run the generator an hour or 2 to assist (with max amps flowing).
Since you'll likely have load, you might want to pull on Max AC charging current - to 50% of your generator max to both charge and leave room for active loads.

3) And bypass - where I have grid at a campsite (or just parked at the house) and bypass the PIP/batteries and leave it all turned off ---
*You're 3-position switch advice has solved this for me - thank you again for that!*

The good news is I can adjust parameters - but want to work out the minimum set of adjustments :)

I hope that helps and I'm not sure this is the 'only way' - its just what I'm doing so far :)

A side note - I took the 7,000lb trailer out for a 1st 20mile run the other day. It only weighs 3,800lbs (good) and the PIP / mini-split ran just fine the whole time. The mini-split is silent inside and out. The surprise was the PIP is not that noisy - perfectly OK for inside the trailer!
 
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OffGridInTheCity

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I have a few scenarios with the trailer and I just need to know what to set for different modes.

For example:

1a) One mode is using the onboard generator to charge the batteries while driving

e.g. the generator goes to the ATS / PIP sees 'grid' and I want it to do the 20a max charging.

1b) An Alternate to this is just using the solar panels while driving to charge.

The trailer is in shade so I can't test this very well right now

and surprised to see 2a charging (10a max) when when the panels only creating 100w in "Solar->Utility->Battery" mode.

The 2a must be coming from the grid but why 2a instead of 10a?

2) Another mode is boondocking with sun and I want the solar panels to have priority

but maybe run the generator an hour or 2 to assist (with max amps flowing).

3) And bypass

where I have grid at a campsite (or just parked at the house) and bypass the PIP/batteries and leave it all turned off

*You're 3-position switch advice has solved this for me - thank you again for that!*

The good news is I can adjust parameters

but want to work out the minimum set of adjustments :)
Replied to these questions 2 posts earlier with a pic of my settings.
 

Korishan

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They were a spammer, they've been removed.
 

OffGridInTheCity

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After a year of work - "The Trailer" took it's maiden overnight voyage! Used 5-6kwh in 24hrs for full 24hr mini-split comfort + dinner (full range of appliances). The 14s88p (260ah) battery went from 56.0v down to 50.0v low (52% DOD per my chart) and back to 52.0v with a bit of sun on panels during travel home.

Overloaded the MPP Solar 3048 at one point (mini-split + hot-water + hot-plate + microwave) and had to turn it off + back on to reset as I didn't know what to do - but that worked. The system has 30amp AC circuit breakers (10awg wire) - so the the PIP overloaded before they tripped as it tops out at 25a@120v.

Really happy with the 18650 battery and the PIP :)
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1632495210589.png
 
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cak

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Mar 14, 2021
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How exciting! In my system I have noticed that the BMP low pack voltage protection is almost always what shuts off first from high voltage drop under full load, even with full packs. Once I upgrade to the DIY BMS I am hoping to be able to set it up to have a lower under load shutoff protection vs resting voltage protection.
 

OffGridInTheCity

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How exciting!
Thank you :)

In my system I have noticed that the BMP low pack voltage protection is almost always what shuts off first from high voltage drop under full load, even with full packs. Once I upgrade to the DIY BMS I am hoping to be able to set it up to have a lower under load shutoff protection vs resting voltage protection.
Yea... a high voltage drop under full load would mean the battery is smaller and load is larger. For example, if an 18650 battery drops from 4.0v to 3.6v 'instantly' on a load, I'd say the load is extreme for the battery size. Can you increase the size of your battery or lighten the load?

For example, the trailer battery is 14s88p @ 260ah and is subject to a max of 3000w which is about 700ma/cell. On average things are running at 350ma/cell... so voltage drop is not consequential as this is within standard discharge specs of the cells.

I have the PIP set at 49v low (3.5v/cell) whereas the BMS is at 3.3v low and the PIP hi is 4.0v/cell where the BMS hi is 4.17v/cell. I use the PIP min/max as the operational control for low DOD... and can change it a bit as needed like going up to 4.1v/cell for more DOD if I boondock. The BMS is fixed and offers the full-stop shunt-trip protection.
 
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cak

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Yep I agree my battery is too small/poor quality for my desired peak load. I am currently building a 100p7s pack with fully tested cells and am hoping that will work better although I am also hoping to upgrade to a bigger inverter so for that I think I will need the second pack I have tested but not assembled yet. I am designing the packs to operate at about 1A per cell.

My current setup is one I inherited form a fellow hobbyist and I don't plan to keep up the design and am retesting all the cells since they have sat at full charge for a couple years since the last testing and there are lots of ones I would consider B grade for my standards, Under 1800mAh, Sony cells... I haven't done supper detailed tests since this current setup is "temporary", I think we all know how that goes :) Based on my basic calculations I am pulling about 3kWh AC so about 120A DC and it shouldn't be more than 1.5A per cell peak(I think there are about 180 cells in series assuming I haven't blown too many cell level fuses yet). I am actually thinking a not insignificant part of the voltage drop is from wire losses. Most of it I am sure is do to the bad cells drawing down the pack but I currently only have two parallel 10AWG wires from the batteries to the inverter and while the distance isn't long I am pushing past the design specs of the wire and it does get warm(but not hot) to the touch when at peak load. Again that whole "temporary" thing but I plan to have 1/0AWG wire for my new packs and inverter so that should handle 250A.

As a side note you are always talking about PIP and I have been to lazy to figure out what exactly you are talking about. It is pretty easy to deduce it is some sort of protection circuitry though.
 

OffGridInTheCity

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Yep I agree my battery is too small/poor quality for my desired peak load. I am currently building a 100p7s pack with fully tested cells and am hoping that will work better although I am also hoping to upgrade to a bigger inverter so for that I think I will need the second pack I have tested but not assembled yet. I am designing the packs to operate at about 1A per cell.
1a / cell is pretty hefty for regular laptop cells - most are more in the 0.5a standard discharge range. What cells are you planning to use?

My current setup is one I inherited form a fellow hobbyist and I don't plan to keep up the design and am retesting all the cells since they have sat at full charge for a couple years since the last testing and there are lots of ones I would consider B grade for my standards, Under 1800mAh, Sony cells... I haven't done supper detailed tests since this current setup is "temporary", I think we all know how that goes :) Based on my basic calculations I am pulling about 3kWh AC so about 120A DC and it shouldn't be more than 1.5A per cell peak(I think there are about 180 cells in series assuming I haven't blown too many cell level fuses yet). I am actually thinking a not insignificant part of the voltage drop is from wire losses. Most of it I am sure is do to the bad cells drawing down the pack but I currently only have two parallel 10AWG wires from the batteries to the inverter and while the distance isn't long I am pushing past the design specs of the wire and it does get warm(but not hot) to the touch when at peak load. Again that whole "temporary" thing but I plan to have 1/0AWG wire for my new packs and inverter so that should handle 250A.
Just take your load and divide it by the number of cells in one of the series packs. For example, let's say you have 7s100p and you're max load is 3000w. 3000w/24v = 125a. 125a/100p = 1.25a/cell. Unless a cell has specs for this (standard discharge) it will pull down the voltage.
I would guess it's the amps/cell that is dropping your voltage rather than wiring or a few cells.

As a side note you are always talking about PIP and I have been to lazy to figure out what exactly you are talking about. It is pretty easy to deduce it is some sort of protection circuitry though.
PIP is a (loose) short-hand term for an MPP Solar Off-grid unit. https://www.mppsolar.com/v3/pip-series/
Although it has been pointed out to me in the past that PIP(s) are not all off-grid and in the link above - they are 12v/24v whereas my MPP Solar 3048 is 48v.

I think I just like the term "PIP" because of @hbpowerwall and that bit of Australian envy over their the cool accent and figures of speech. :)
 
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