New system lasting less than an hour.

[Beavo]

Hi everybody, thank you for the gold mine of information here on the forum.

I was hoping someone could give me some advice on my inverter/battery setup which is charged by 4 x 160watt solar panels..

I have a new Renogy 2000w inverter fed by 2 x new Eco-Worthy 280ah Lifepo4 batteries in parallel.

I have been using them to run a 150w TV and a 12w monitor.

The problem I have is that about an hour after it gets dark the batteries go down to around 11.5v, and if I don't turn off the inverter before I go to bed (after switching the TV and monitor off), the batteries dip down to around 10v and the inverter alarm sounds.

I'm obviously not doing the maths right as I worked out (from some calculation on the web) that the batteries should run my 150w TV for about 30 hours.

Am I doing something wrong or is this normal??

Thanks in advance for any advice.
Cheers
Beavo

 

[Tomthumb62]

Without doing the math, I can tell already that you likely don’t have enough charging power. You’re using more power than is being replaced, most likely.

I used to have that Renogy inverter. It’s a hog of idle power. My math says it uses about about 677Wh per day.

Now your two 280Ah batteries gives you a total of 7160Wh. Seems like a lot, yes? With no charging source, the inverter alone (if left on 24/7) will drain those batteries in about 10 days.

It’s winter in the northern hemisphere. If you’re there and it’s cold where you are, then solar production is extremely low this time of year. Your batteries probably have slowly getting lower and lower in charge each day and have been basically tanked for some time now. Do you have an AC power source you can plug in an AC charger? Or your can do a proper energy audit, do the math and figure out just how many panels you’ll need to sustain your needs year round.

How many hours a day are you using the TV? And the monitor?

Edit to say I now see you’re in Bristol, at 51 degrees north. Yep, you’re getting not enough sun hours per day this time of year. And if it’s cloudy, then even less. You’ll need probably 2-4x as many panels and more charge controllers to make it a go. But proper math would tell you exactly how many.

 

[Crowz]

Well as mentioned your not getting enough charge. There is no way that charge controller would ever be enough to charge those batteries back to full in a day from 11 volts.

You need more controllers and panels or a much larger charge controller and panels.

How many panels do you have now?

Plus which model of controller is that. The largest I see in that model is 40amps.

 

[MisterSandals]

What are the alligator clips for?

It the main negative to your inverter connected to the battery on the right?

 

[Crowz]

What are the alligator clips for?

It the main negative to your inverter connected to the battery on the right?

I betting the clips go to that meter he has at the top.

 

[MisterSandals]

I betting the clips go to that meter he has at the top.

Could be, I dunno.
A little odd that there are 2 wires coming off each battery positive.

I am betting on wiring causing battery imbalance and waaay too little charging.

 

[Beavo]

Do you have an AC power source you can plug in an AC charger?

How many hours a day are you using the TV? And the monitor?

Proper math would tell you exactly how many.

Thank you for that fantastic response.

1. I have ac power in the garage but not sure what type/model of charger I'll need and if I can charge the batteries in parallel.
I have an Avon smart charger but I don't think it's suitable for Lifepo4 batteries.
I do have a "normal" charger too but again not sure it's meant for Lifepo4.

2. I was just hoping to use it all day until we go to bed. Then everything gets switched off. (I've never switched the inverter off though)

3. I'll try and find out the "proper math equation"

Cheers

 

[Beavo]

You need more controllers and panels or a much larger charge controller and panels.

How many panels do you have now?

Plus which model of controller is that. The largest I see in that model is 40amps.

Thank you for the great reply.

1. Is there a specific controller you'd recommend as I was just about to get this one.

2. 4 x160w Photonic Universe panels.

3. Epever Tracer A 40amp.

Cheers

 

[Beavo]

What are the alligator clips for?

It the main negative to your inverter connected to the battery on the right?

Thank you for the reply.

They are just for the volt meter at the top. It makes it easier to see.

The main negative to the inverter is connected on the right battery. The positive is connected on the left.
Vice versa for the charge controller.

Cheers

 

[Beavo]

A little odd that there are 2 wires coming off each battery positive.

I am betting on wiring causing battery imbalance and waaay too little charging.

Thanks for replying.
1. One of them is going to the inverter from one battery and one to the charge controller from the other battery. The batteries are in parallel hence the two cables off each terminal.
I hope that's right, I've been doing it that way for years. I used to have 6 x 130ah Deep cycle lead acid batteries in parallel and only used the two end batteries for connections to inverter and controller.

2. I'm not sure how else I could wire them. I just filled some guys method on YouTube about six years ago. Sounds like I do need more panels though.

Cheers

 

[Beavo]

I betting the clips go to that meter he has at the top.

Thanks for reply.
Exactly right, my knackered old eyes struggle to read the charge controller.
Cheers

 

[Crowz]

That victron controller is a good one. Your going to need a good bit of panels to feed the controllers.
4 160w panels are not going to cut it.

• A 100-watt solar panel will charge a 100Ah 12V lithium battery in 10.8 peak sun hours (or, realistically, in little more than 2 days, if we presume an average of 5 peak sun hours per day).
• A 400-watt solar panel will charge a 100Ah 12V lithium battery in 2.7 peak sun hours (or, realistically, in about half a day, if we presume an average of 5 peak sun hours per day).
• A 10kW solar system will charge a 100Ah lithium battery in 6.48 peak sun minutes. That’s quick!

I snagged the above off a site to help it make more sense.

Now using the above numbers to keep it simple lets go this route.

You have 560ah worth of batteries to maintain.

So if 100 watts takes 2 days to charge 100ah. Then 100 watts takes 10 days to charge 500ah.
200watts is 5 days to get to 500ah
400watts is 2.5 days
800watts to charge in a day roughly.

Now this is prime time solar aka not winter, not cloudy, everything is perfect. So not real life.
For 500ah I would want 1600 watts worth of panels minimum. Especially since your going to using power while its trying to charge.
Since I don't know how much load your pulling I can't really give an exact amount of panels needed.

But 1000 watts might do if you don't have a string of cloudy days.

 

[Crowz]

Another example is what I have on my 12volts system that runs my cameras.

I have 2 100ah lifepo4 batteries power it and 600 watts worth of panels on it right now.
On a pretty day it can charge the batteries back up fully with them at 30% charge at the start of charging.

But if its cloudy at all they do not fully charge. If it rains they don't even get close.

I have a victron battery charger that is powered by the grid that kicks in if the charge gets below 26% and charges them back fully. This is probably the ideal solution till you get your solar setup sized right if you have access to the grid.

https://www.amazon.com/gp/product/B08TRRLD4W/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You can also use a generator to run the battery charger to fix things when needed to if that is your only power source.

 

[Partimewages]

Any of the Victron equipment is good equipment.

 

[Beavo]

That victron controller is a good one. Your going to need a good bit of panels to feed the controllers.
4 160w panels are not going to cut it.

• A 100-watt solar panel will charge a 100Ah 12V lithium battery in 10.8 peak sun hours (or, realistically, in little more than 2 days, if we presume an average of 5 peak sun hours per day).
• A 400-watt solar panel will charge a 100Ah 12V lithium battery in 2.7 peak sun hours (or, realistically, in about half a day, if we presume an average of 5 peak sun hours per day).
• A 10kW solar system will charge a 100Ah lithium battery in 6.48 peak sun minutes. That’s quick!

I snagged the above off a site to help it make more sense.

Now using the above numbers to keep it simple lets go this route.

You have 560ah worth of batteries to maintain.

So if 100 watts takes 2 days to charge 100ah. Then 100 watts takes 10 days to charge 500ah.
200watts is 5 days to get to 500ah
400watts is 2.5 days
800watts to charge in a day roughly.

Now this is prime time solar aka not winter, not cloudy, everything is perfect. So not real life.
For 500ah I would want 1600 watts worth of panels minimum. Especially since your going to using power while its trying to charge.
Since I don't know how much load your pulling I can't really give an exact amount of panels needed.

But 1000 watts might do if you don't have a string of cloudy days.

Thank you for that marvellous reply.
Gonna take me a while to digest all that.
Cheers

 

[Crowz]

Your welcome and good luck with it.

 

[Beavo]

I have a victron battery charger that is powered by the grid that kicks in if the charge gets below 26% and charges them back fully. This is probably the ideal solution till you get your solar setup sized right if you have access to the grid.

Just to make sure I understand, this plugs in to the house ac and turns on if my battery back gets too low.
That sounds perfect.
My house has professionally installed panels on the roof so it'll be free solar charging free solar.

Cheers

 

[Hedges]

What controller you get depends on what panels you're going to connect, and vice versa.
Design the PV array to meet SCC voltage and current limits (including elevated Voc on cold weather, typically +15% or less, can be calculated more accurately if it looks too close.

 

[Crowz]

Just to make sure I understand, this plugs in to the house ac and turns on if my battery back gets too low.
That sounds perfect.
My house has professionally installed panels on the roof so it'll be free solar charging free solar.

Cheers

Yep.

 

[Tomthumb62]

(I've never switched the inverter off though)

Turn it off anytime you’re not using the monitor or TV. That will be an easy place to start to reduce your battery usage. That Renogy inverter is too big for your needs and thus uses a lot of battery simply to be powered on. I sold mine and got a smaller Victron instead, which dramatically slashed my battery usage, using the ECO mode.

1. I have ac power in the garage but not sure what type/model of charger I'll need and if I can charge the batteries in parallel.
I have an Avon smart charger but I don't think it's suitable for Lifepo4 batteries.
I do have a "normal" charger too but again not sure it's meant for Lifepo4.

Sometimes you can get away with using a normal charger to charge lifepo4, but it’s not ideal. I would recommend getting two of these. You can hook up one to each battery to get a total of 60A of charging, which will take 9 hours to go from 0% to 100% for your entire battery bank.

Sorry for the USA link but it gives you an idea:

BPC123047102 Blue Smart IP22 Charger 12/30(1) 120V NEMA 5-15 | eBay

Find many great new & used options and get the best deals for BPC123047102 Blue Smart IP22 Charger 12/30(1) 120V NEMA 5-15 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

The single output model seems hard to find at the moment. Maybe it’s easier in the UK. InvertersRus.com sometimes has used/open box models fora good price but they’d be the North American version. Maybe there’s a good Victron dealer in the UK.

There are cheaper chargers out there but the Victron would be the last you’d buy. Fully programmable and easy to use. I love mine.