My first solar generator build

[Power4life]

Here is my first attempt at building a solar generator. I have always been interested in electronics and how they function. I camp quite often (avid festival goer) and a few years back I wanted to have electricity at my site without paying for sites with hookups. I bought a few solar generators and quickly realized I would have to pay an arm and a leg to buy a generator that would meet my electrical demands (fridge, lights, BT speaker, etc.) After discovering DIY Solar, I became inspired by Will to build my own. I needed a battery that was somewhat light weight and powerful enough to get through the weekend without relying on panels. Not every festival or camp site is sunny which would often leave me dead in the water after a couple of days.

Parts list: 4s 12.8v 120ah 1536wh Lifepo4 cells from Lucky Electronics Aliexpress
Smart Bms 80amp 4s
Victron Smart MPPT 20amp
Victron 65amp Smart Battery Protect
12V to 19V converter to charge BT speaker and Suaoki G500
Eylar Hard Case
Anderson PP panel mounts for solar panels and AC charger

As of now I dont have an inverter installed because most of my electronics run off of DC (except for air mattress pump which the G500 takes care of). After a recent scare by Hurricane Dorian, my next project will be to add an inverter to power router, tv, etc.

 

[Craig]

These things look so cool. Very nice job.

 

[Will Prowse]

That is awesome!! I am envious. You crammed a lot in there. Any plans for adding an inverter? How will you hook it up?

 

[Power4life]

That is awesome!! I am envious. You crammed a lot in there. Any plans for adding an inverter? How will you hook it up?

Yeah things got really cramped towards the end of completion. Had a really hard time setting the footmans loops for the straps with only ~ 2 inches of clearance. Ended up temporarily moving the 19v converter out the way to have more room to work with. I do plan to add an inverter. A 300 watt inverter is all that will fit so I may end up building a separate case with a 700 watt inverter and have the two connected with a high amp Anderson Power Pole connector. Since I will be connecting and disconnecting often I will have to incorporate a bypass for the bms so I dont damage the mosfets on initial hookup. I did something similar with the mppt's connection to the bms. Flip one breaker to charge capacitor, flip the other to connect to the bms and then turn off first breaker. All is good. This bypass also allows me to charge even if the bms shuts everything down from over discharge. Had real fun building this and plan on doing more in the near future. Your expertise was greatly appreciated in this build. Keep up the good work my friend.

 

[Power4life]

Oh, and congrats on the Tesla and being a homeowner. Now I'm envious haha

 

[Supervstech]

Yeah things got really cramped towards the end of completion. Had a really hard time setting the footmans loops for the straps with only ~ 2 inches of clearance. Ended up temporarily moving the 19v converter out the way to have more room to work with. I do plan to add an inverter. A 300 watt inverter is all that will fit so I may end up building a separate case with a 700 watt inverter and have the two connected with a high amp Anderson Power Pole connector. Since I will be connecting and disconnecting often I will have to incorporate a bypass for the bms so I dont damage the mosfets on initial hookup. I did something similar with the mppt's connection to the bms. Flip one breaker to charge capacitor, flip the other to connect to the bms and then turn off first breaker. All is good. This bypass also allows me to charge even if the bms shuts everything down from over discharge. Had real fun building this and plan on doing more in the near future. Your expertise was greatly appreciated in this build. Keep up the good work my friend.

I looked at those type cases, but decided they were too small and expensive for my plans.
Homedepot sells rigid and husky and Milwaukee brand “pack out” cases in stackable sizes with a suitcase style pop up handle and wheels... I am steadily creating my battery bank... there is a short YouTube vid on my channel about it...
To be continued.

 

[Rider]

Homedepot sells rigid and husky and Milwaukee brand “pack out” cases in stackable sizes with a suitcase style pop up handle and wheels... I am steadily creating my battery bank

That's what I did. got one from BJs.

 

[kevfab]

Nice build Power4life. What are the dimensions of your case?

 

[Power4life]

Outer: 19.78" x 15.77" x 7.41" Inner: 18.06" x 12.89" 6.72".... Going for a revamp of my system at the moment. After watching Wills video on these cells, I realized that my cells are used and I could be getting more power out of the same size (150 ah).... rookie mistake haha.

Going to purchase and install new 150ah cells from BLS store aliexpress. Also, I'm going to upgrade the battery protect to the 100 amp version, add a coulometer shunt monitor, and run 4 awg wire to allow the connection of an external 1200 watt inverter. I will post when all is done.

 

[kevfab]

Sweet. That is going to be one powerful case.

So how are you dealing with the screws mounting the equip? How are you preventing them from going through the plastic?

 

[Power4life]

Sweet. That is going to be one powerful case.

So how are you dealing with the screws mounting the equip? How are you preventing them from going through the plastic?

The case is double walled so I used short screws to catch the inner wall and took extreme care not to puncture the outer wall. I wasn't exactly perfect with everyone of them. A couple of them went through just enough to raise the outer part of the case but barely noticable and no gaping holes. So far everything is holding in place quiet nicely.

 

[Justin Laureltec]

@Power4life , I'm a little concerned about that BP... what's connected to it, exactly? Asking because from the wiring (specifically from the SCC) it looks like there may be reverse current (Out post to In post) running through it, which is forbidden and can potentially result in a fire. The BP is unidirectional in operation only, so using it as a charge cutoff is acceptable only if it's installed in reverse (charge source to "in" post, battery to "out" post) and then in that instance there's really nothing else that can be connected to it.
Also worth noting that using a BP to directly disconnect the DC supply line of an inverter is also expressly forbidden. Not sure you were planning to do that, but you mentioned "inverter" and "upgrade to a 100A version" in the same sentence, so I want to make sure you're aware of these caveats of the BP.

 

[Johnmahon]

@Power4life - @Justin Laureltec and I were having this same conversation this morning as well regarding the BP. You can also see what he suggested for my system. It has been a great experience learning from him! Looking forward my completed system! https://diysolarforum.com/threads/need-some-help.1342/ - look towards the end of the post for the most recent comments.

Hope all goes well. it looks great!

Jm

 

[Power4life]

@Power4life , I'm a little concerned about that BP... what's connected to it, exactly? Asking because from the wiring (specifically from the SCC) it looks like there may be reverse current (Out post to In post) running through it, which is forbidden and can potentially result in a fire. The BP is unidirectional in operation only, so using it as a charge cutoff is acceptable only if it's installed in reverse (charge source to "in" post, battery to "out" post) and then in that instance there's really nothing else that can be connected to it.
Also worth noting that using a BP to directly disconnect the DC supply line of an inverter is also expressly forbidden. Not sure you were planning to do that, but you mentioned "inverter" and "upgrade to a 100A version" in the same sentence, so I want to make sure you're aware of these caveats of the BP.

So with the BP I am aware that it is unidirectional. On the In/battery side, I have two 10awg wires running to the battery, a single 10 awg wire running to the mppt, and another single 10 awg running to an auxiliary dc charge port (anderson pp where I connect a dc power supply to charge). I didnt have room for all those connections to take place at the positive terminal of the battery so I did it there. On the out/load side I have 3 wires going to their own 12v plug and one going to the 19v converter.
As for the inverter, I was planning to use the BP as disconnect in an under voltage situation whether it be the pack voltage (determined by BP) or cell voltage (determined by bms with the battery protect's negative connected to load side of the bms). Please explain to me why i cant use it as a low voltage disconnect for the inverter on the load side of the BP. I would not use the BP for over current situations or as a current limiter. I would have fuses/breakers to accomplish that. Please elaborate.

 

[Justin Laureltec]

As for the inverter, I was planning to use the BP as disconnect in an under voltage situation whether it be the pack voltage (determined by BP) or cell voltage (determined by bms with the battery protect's negative connected to load side of the bms). Please explain to me why i cant use it as a low voltage disconnect for the inverter on the load side of the BP. I would not use the BP for over current situations or as a current limiter. I would have fuses/breakers to accomplish that. Please elaborate.

Ahhh excellent on the unidirectional bit... I couldn't tell if you were just using the "in" stud as a power post or if things were actually running through it. So no problem there.
The BP product line cannot be used to directly disconnect the main DC supply of an inverter for two primary reasons: first, the inrush current of the inverter charging its caps will exceed the BP's rating and cause a "short circuit" error... this is resettable but over time and repetition it will damage the BP's internal logic and the BP will cease to reliably function. Second, the inrush current can overheat the FETs and cause premature (and sometimes instantaneous) failure of the device.
The only permitted connection method for using the BP to disconnect an inverter is to use the inverter's remote on/off pins (if so equipped). The inverter main DC line connects directly to the batteries and a secondary POS line from the BP "out" post runs to the remote on/off pins of the inverter, thus when a low voltage condition is triggered, the BP disconnects the remote line and the inverter is turned off (but the main DC line remains connected).
Direct connection/disconnection by the BP of the main DC line of any inverter is expressly forbidden. For reference, please see the (relatively) recently updated user manuals on Victron's site... here is the Smart BP65 manual.
The good news is that you don't need to upgrade your BP to a 100A unit, since you can just as easily use the 65 you already have for your remote turn off.

 

[Power4life]

Ahhh excellent on the unidirectional bit... I couldn't tell if you were just using the "in" stud as a power post or if things were actually running through it. So no problem there.
The BP product line cannot be used to directly disconnect the main DC supply of an inverter for two primary reasons: first, the inrush current of the inverter charging its caps will exceed the BP's rating and cause a "short circuit" error... this is resettable but over time and repetition it will damage the BP's internal logic and the BP will cease to reliably function. Second, the inrush current can overheat the FETs and cause premature (and sometimes instantaneous) failure of the device.
The only permitted connection method for using the BP to disconnect an inverter is to use the inverter's remote on/off pins (if so equipped). The inverter main DC line connects directly to the batteries and a secondary POS line from the BP "out" post runs to the remote on/off pins of the inverter, thus when a low voltage condition is triggered, the BP disconnects the remote line and the inverter is turned off (but the main DC line remains connected).
Direct connection/disconnection by the BP of the main DC line of any inverter is expressly forbidden. For reference, please see the (relatively) recently updated user manuals on Victron's site... here is the Smart BP65 manual.
The good news is that you don't need to upgrade your BP to a 100A unit, since you can just as easily use the 65 you already have for your remote turn off.

I remember Will briefly mentioning the change to the Victron BP in rush issue and thank you for letting me know about the issue. I like the remote on/off solution to the problem but for my purposes I rarely have the need for an inverter as I use this case for camping and festivals. The only time I really have the need for an inverter is during hurricane season or power outages. Since my use is limited and the inverter would only be connected on a need basis, couldn't I just pre charge the inverter caps directly from the battery terminals and then hook up inverter to the load side of the BP. If low voltage occurs, all is shut down and I disconnect my inverter because the battery is dead leaving no chance of hitting the BP with surge.

 

[Justin Laureltec]

Hmmmmm well... poop. I'm at a bit of a loss here because I don't see why that wouldn't work, but given that I work at a Victron distributor and I'm a Victron Product Expert I'm really not allowed to advise you to connect these devices in any way that's not expressly supported by Victron.

So, for the technical record, attached is the one and only way to use a BP to control an inverter that is allowed, supported, and safe. Any other connection method may or may not work, but it also may or may not immediately void your warranty and/or cause device failure. Honestly my only real concern is that these things can get bloody HOT if they're not connected correctly, and that's a genuine safety concern.

Off the record, I can't think of a reason why that wouldn't work. On the record, "that's not a supported connection method, please see the manual" :-/

 

[Power4life]

Hmmmmm well... poop. I'm at a bit of a loss here because I don't see why that wouldn't work, but given that I work at a Victron distributor and I'm a Victron Product Expert I'm really not allowed to advise you to connect these devices in any way that's not expressly supported by Victron.

So, for the technical record, attached is the one and only way to use a BP to control an inverter that is allowed, supported, and safe. Any other connection method may or may not work, but it also may or may not immediately void your warranty and/or cause device failure. Honestly my only real concern is that these things can get bloody HOT if they're not connected correctly, and that's a genuine safety concern.

Off the record, I can't think of a reason why that wouldn't work. On the record, "that's not a supported connection method, please see the manual" :-/

Thanks for your help and insight. This is what I love about working with electrical components. There is most often an exception to the rule or a workaround as long as you know what you are doing. Now, to decided if its worth the cost of a new BP or just run a remote on/off switch. Most likely the latter haha