Winter blues... quick question

[Davian7]

If you guys don't mind helping me with some math.... let's say I get that 6500 watt predator generator. I'll attach the specs. What size "iota" type charger would u suggest and what do u estimate the charge time would be for my four 200ah batteries? I'm sure this is a simple formula so forgive my ignorance but I have yet to catch on fully

 

[Davian7]

What I'm getting at is I don't wanna depend on the sun. I medically can't afford to. So I am trying to find a way to crank up a generator for a couple hours and be back up and running. Any ideas or combinations would be appreciated

 

[ShaneC]

It's something you asked about early on but I don't think you got an answer. If you have the ability to switch over to using the generator instead of solar then that will be much better in terms of efficiency than charging your batteries from the generator. You're looking at about a 20% loss because of inefficiencies in the charger and inverter.

The reason to get a charger is that you'll be able to have the gennie on for 4~ hours to charge the batteries and then switch over to using your batteries instead of needing the generator on standby all day. You'll have to do the maths on whether that's feasible.

 

[Zwy]

I have a renogy 800w solar panel kit with the 3000 w inverter and rover 60a charger; also a handful of 200ah 12v agm batteries.

This is my first winter or fall rather with solar and I am noticing it isn't going to get sustainable. During summer i get to like 100% on the high end, more often than not, and maybe like 65% on a super rare day... well in the past week its been more like 24% highest and maybe 16% on average.. i am aware this is well below the 50% discharge rec. I know there are inverters that are chargers as well or maybe controllers that u can use other things to charge.... forgive my ignorance but I am working with what I have.

Several problems with your current setup. One is the panel angle is probably not close to the sun horizon for winter. Second, the AGM batteries are lead acid technology and will require absorption over a long time period to get fully charged. If you don't hit 100% SOC often, the batteries will sulfate. This leads to decreased capacity, eventually killing the battery. Running below 50% SOC with any lead acid based battery will lead to increased sulfation, eventually killing the battery with accelerated sulfation. In order to reach 100% SOC, the absorption charge is slow due to the increasing resistance of the lead acid type battery as it approaches full charge. This is a problem with reduced hours of sun, you only get X number of hours and are only pulling X number of watts that are declining due to the increasing resistance.

First thing is split up your bank into 2 banks. You will have to use an external charger most likely to get one bank to 100% SOC using an absorption charge. The other bank can be charged off your MPPT while you use it. Most likely though you will find you don't have enough PV.

I just used the search feature to look up some of the posts I had for lead acid batteries using the term AGM. One was this post. https://diysolarforum.com/threads/renogy-100ah-agm-renogy-100ah-hybrid-gel.62240/post-790120 If I were you, I'd source a LFP battery or 2. Two 100Ah LFP batteries equals two 200Ah lead acid batteries for useable capacity unless you can't store the batteries above freezing and don't have a heating pad. There is a place for lead acid, an example might be a cabin used mainly in summer and occasional use of short periods during winter. When not there, the batteries can achieve 100% SOC with an absorption charge. But still, the 50% discharge rule applies so the bank size might be quite large. LFP doesn't care about partial charge, this is one of the main reasons the big movement to solar systems with battery storage has taken place.

I have a predator 2000 generator/inverter 1600 running watts. If I was to plug the male end of a heavy Guage extention cord into the generator and splice the other end and connect it into the PV- & PV+ of the rover 60a, pretending just as if the current was coming from the panels, would this be a huge mistake? Are there any alterations "off label" that I can do to make this work?

The generator outputs AC current while a charge controller runs on DC. Don't do this.

Using a generator to only charge a battery bank and not run loads is a waste of fuel. The battery bank can only accept X number of watts as 100% SOC is reached. If you want to use the generator, then again, split your batteries into 2 banks and use 2 battery chargers while running loads off the generator. One bank can be in absorption while the other might be just above 50% SOC. Running your loads at the same time allows for efficient use of the fuel.

Thanks for ur time yall

Kindly,
DM

 

[Zwy]

ya I didn;t realize how inefficient the chargers were. Looks like the 55amp might be better.

0.38 x 800ah / 55amps = 5.5 hours of generator time.

It will take longer than 5.5 hours with absorption slowing down the process. Lead acid internal resistance increases as full charge is approached.

 

[wme]

Solar isn't magic, well it sorta is. But its not purple pixie dust magic. Mother nature is a Bi*ch and with electricity not following her rules results in fire and smoke.
You are on a very limited budget and just can't whip out your wallet to resolve your problem and build a more robust solar setup.
SO if you can't make more power, then you have too use less power.
Questions
How do you cook
How do you heat
How do you cool
What kind of Fridge
What are your lights, a old skool light bulb uses the same power as 10 led bulbs

For max battery life you need to get them charged and keep them up. A wad of money when they fail or a wad of money now for solar.

Your looking for percentages to improve your power situation.

Did you know that your inverter uses power when its turned on, with nothing plugged in? It takes about the power of one solar panel each day to power nothing. So your batteries effectively have less panels to charge from.