The Great Big Lithium Lie

I’ll try the can trick when I get a change I just positioned the panels in the same direction and angle that I see on telephone poles in my area in NJ. They have helper solar panels tied to the grid on all the telephone poles

Parallel then. Yes.

If you are asking me? My 6 panels are 2 strings of 3 panels in series going into a Victron 100/20 MPPT controller.

i Forget it’s been so long since I set this up. So I guess the panels are like 9 v and I’m doubling them.
I get confused about that. But I think I have correctly

Ya. I was hoping to get away the the old cheap Chinese MPPT. But I may bite the bullet

If you are using the app for the Overkill bms, just change the capacity to that of your battery, 200 Ah. With the Android app go to 'parameter setting ' page , select the nominal capacity and change to your battery capacity, there is no need to set all values.

Mike

I do have these on a hing. I just just never messed with them

Sundog33 said:

I do have these on a hing. I just just never messed with them

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I could never get away with that mounting. I have 2 foot roof overhangs around my house. My panels would be shaded for a good portion of the day likely starting in early summer. Besides, these 600 watts of panels will eventually go on my RV. I am planning a pergola/patio cover or possibly a carport that can hold 2K - 3K of panels. It depends on what I can fit. I probably need to get rid of one tree to make it all work.

I don’t have any android devices. I am not seeing parameter setup.
only Config at the default screen. Then BMS settings inside of that?

mikefitz said:

If you are using the app for the Overkill bms, just change the capacity to that of your battery, 200 Ah. With the Android app go to 'parameter setting ' page , select the nominal capacity and change to your battery capacity, there is no need to set all values.

Mike

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I think it's a good idea to also set the cycle capacity. I checked all the other default settings in mine when I first installed it and one of the temp settings was off. Same thing when I upgraded to the latest app on Overkills website. So it's probably good to review all the settings and to test the BMS to make sure the HVD and LVD work. Other than that it is basically plug and play...lol

Yep. I realize the mounting is not optimal. But it is convenient. I’ll take the loss. Just wish I was getting more when I should. Maybe better Victron.

Sundog33 said:

Well. I’m just going on suggested usage. If indeed I can cycle them fully and get what I got out of my AMGs then I am ahead of the game. I couldn’t believe when I disconnected them and one AMG was still showing 96% capacity from my car CCA tester after 10 years. I was amazed.

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Have you gone over the spec sheet for your cells? And compared it to to the spec sheet of your AGM's?

im using an iPad by the way

A lot of the lead acid vs lithium is different expectations. I think it is a crime that they advertise a lead acid batteries at 100 AH and you are told to never use more than 50%. With Lithium batteries, they rate them from a full charge to a safe discharge level. You can use from a full 3.65 down to 2.5 and get the rated number of cycles. That is their test criteria. You CAN pull them even lower, like a lead acid going below 50%, but it will drastically shorten their life, just like a lead acid going below 50%. Used in their rated range, an LFP battery will last much longer than lead acid, to the point of actually costing less in the long run. Then add in the much more efficient round trip. You get much more of the power that you put in, back out of an LFP battery. Well over 90%. My Li NMC cells are measuring something like 96% efficient. Lead acid is about 80%.

The BMS should be set to just protect the cells from an overcharge, or discharge situation, and also temperature limits. It is there to protect the cells if something goes wrong. The charge limit and low voltage cut off should be handled by the inverter and charger not pushing the cells to the limits. The BMS should only ever have to shut it down if the cells go far enough out of balance that one cell hits the limits, even though the full pack voltage is still in range. The BMS is not the charge controller.

Solar panel ratings are based on STC or Standard Test Conditions. That is not realistic in normal conditions, but it is consistent for comparing panels from different manufacturers. It is typical to be able to get about 80% of the STC rating on a clear day with the panel facing directly at the sun. My 300 watt panels top out over 240 watts on any cool but sunny day. On the "perfect" days, It looks like they hit close to 260-270 watts. I have them on microinverters, and those clip out at 240 watts. I have seen them flat top at 240 for up to 3 hours. It is obvious the production falls a bit when it is very hot in the summer. But the day is longer, so it trades off, and I still get a bit more overall production.

Getting the most power out of a solar panel is not an easy thing. If it is just a fixed mount, you should have it facing south and tilted close to your latitude angle. There are web sites for finding the best angle depending on the time of year. Flatter works better in the summer, and more upright works better in winter. Mine are just on my roof at that about 20 degrees angle, and it is pretty good, just 15 degrees off of due south. I have hit as much as 7 sun hours in the summer. Using a cheap PWM charge controller, it is rare to get better than 70% of the panel rating. An MPPT will get more from the panel, as long as the voltage is high enough for it to work. With any type of controller, you will find that the power coming from the solar panel will drop off drastically when the battery is full. This is how they keep the battery from over charging. So you need to be sure the battery is able to accept charging current to see how much the solar is actually able to push in. If the system has little load on it, it will top up and look like it is not making power.

Ya. I understand. Lithium is better. Just bitching about the added cost. I was proud of my build... and love the tech of the app monitor

Sound like I need to contact Steve over at Solarkill and find out how to change to 200ah. And if it makes a difference form the default.

Thanks for the info GX !

Sundog33 said:

Sound like I need to contact Steve over at Solarkill and find out how to change to 200ah. And if it makes a difference form the default.

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It's all in the very well written informative manual you can download from his website.

Thanks all for the input. I know it’s not a huge system. I never really abused the system I had. Just ran the fish tank and hoped for a power outage.
I have more faith talking to you guys that I may be able to run a 10” dc fan all night long in the summer as I do now with with a plug in. And not have any issues.
I’ll see if I can straighten things out.

little help please.
I figured out how to update the Overkill BMS to 200ah. just let it “Read” and changed to 200000 and 16000
but look at my readings for today Charging over 3.65 and still at 67%

Is this normal? or am I about to blow up my battery?
got the Victron today. But havnt installed yet