Solar Panels to 2x battery banks ( Lithium and AGM )

[Marktla]

Hey guys,

I am trying to install solar panels on a boat and I want them to charge the boats existing 4x 95AH AGM batteries and 2x 200 AH Lithiums

I bought 5x 200w Renogy flex panels, 2x 200 AH Renogy Lithiums , 2x Renogy Rover 60A MPPTs and 1x Renogy 3000w inverter.

I like to charge both the AGMs and Lithiums with the 5x panels using 2 different MPPTs… I may split the panels and use 3x and 2x or something like that..

my question is…

may I connect 1000w of panels to both MPPTs at the same time.. and charge both battery banks at the same time ? If this is not possible then I guess I need to add a switch and route the current to the MPPT of my choice…

I know I have to program the MPPTs accordingly to the battery bank.

thanks / mark

 

[SamDeleted]

may I connect 1000w of panels to both MPPTs at the same time.. and charge both battery banks at the same time ?

Hi mark , no that's not ok sorry . The mppts will fight for the power , neither will win , both won't work right

I think a dual pole DC transfer switch is your best option

 

[timselectric]

You can not connect the same panels to two MPPT's.
3 and 2, or alternate between the SCC's.

 

[SamDeleted]

Or consider a DC-DC battery to battery charger.


Solar PV > mppt > LiFePo4 > dc-dc charger > AGM

 

[timselectric]

Another option is to solar charge the Lithium batteries. And use a DC to DC converter/ charger to charge the AGM from Lithium.

 

[SamDeleted]

Another option is to solar charge the Lithium batteries. And use a DC to DC converter/ charger to charge the AGM from Lithium.

Beat you twice in a row ?

 

[timselectric]

Or consider a DC-DC battery to battery charger.


Solar PV > mppt > LiFePo4 > dc-dc charger > AGM

Brilliant minds think alike.

 

[timselectric]

Beat you twice in a row ?

Yup
I'm a slow typer.
But I have a good excuse. I'm old. lol

 

[SamDeleted]

Brilliant minds think alike.

And fools seldom differ

 

[Marktla]

Well I also bought 2 DC-DC chargers.. one 60 Amps and one 40 Amps.

Can lithiums charge AGMs with no problem? I would wanna put a switch in between to cut the charging too... when I want.

also.. can I charge the Lithium from the started battery with the 2nd DC-DC charger?

 

[Marktla]

Actually my best scenario would be…

use 1000w solars to charge AGM or Lithium… not at the same time.

when needed ( at night, when there is no SUN and my AGMs are dying ) put some juice to AGMs from Lithiums

and also charge the Lithiums with the engine alternator.. via starter battery using another DC-DC charger.

will this work?

so I only need one dual pole dc transfer switch.. I have all the others already.

 

[Marktla]

one more question… kinda related.. I also bought the Renogy 1000w powerstation.. can I charge this directly with a solar panel? Or it has to via mppt or ?

 

[timselectric]

This is getting more complicated.
Those are all valid options. Just don't do them all at the same time. Charging in both directions, just sends power in a circle. And creating losses.

 

[Marktla]

It seems I can connect the solar panels directly to this guy… will 200w be too much?? I guess it has a built-in mppt or something.

 

[Marktla]

This is getting more complicated.
Those are all valid options. Just don't do them all at the same time. Charging in both directions, just sends power in a circle. And creating losses.

I mean… I can just charge the lithiums with only Solar… then if needed use a DC-DC to fill up AGMs.

 

[Marktla]

My Renogy panels have arrived… also the Rover 60A MPPTs.. how can I quick test the panels to see if they are working?

any quick fixes?

 

[Tomthumb62]

My Renogy panels have arrived… also the Rover 60A MPPTs.. how can I quick test the panels to see if they are working?

any quick fixes?

Quick fix for what problem?

To test the panels, you need a multimeter. Set it to DC volts in the 200v range. Place the meter's red lead into the tip of positive cable from the panel and the black lead in the negative cable. Make sure the panels are setup facing the sun. You should get a voltage reading somewhere less than VOC (number listed on the back of the panel) but in full sun, it will be closer to VOC than not. Probably between 19 and 22 volts in full sun, or 14-18v in clouds.

To test the amperage output, setup your multimeter to test DC Amps. Verify first how many DC amps it can test (if you try to test more amps than your meter can test, you will likely fry your meter...smoke will come out). You will need a meter than can measure at least 15 or more amps, since the short-circuit amperage of the 200W Renogy panel is about 11A. Same thing, place the red lead to the positive cable and black lead to the negative cable. If you have full sun, try tilting or shading your panel and notice the immediate effect this has on amperage output.

 

[Renogy Solar]

Hey guys,

I am trying to install solar panels on a boat and I want them to charge the boats existing 4x 95AH AGM batteries and 2x 200 AH Lithiums

I bought 5x 200w Renogy flex panels, 2x 200 AH Renogy Lithiums , 2x Renogy Rover 60A MPPTs and 1x Renogy 3000w inverter.

I like to charge both the AGMs and Lithiums with the 5x panels using 2 different MPPTs… I may split the panels and use 3x and 2x or something like that..

my question is…

may I connect 1000w of panels to both MPPTs at the same time.. and charge both battery banks at the same time ? If this is not possible then I guess I need to add a switch and route the current to the MPPT of my choice…

I know I have to program the MPPTs accordingly to the battery bank.

thanks / mark

This is not recommended, it is recommended that you install the PVs separately on the 2 MPPT controllers

 

[Marktla]

This is not recommended, it is recommended that you install the PVs separately on the 2 MPPT controllers

So… don’t use a dual pole transfer switch?

split the panels into 2 groups and feed to AGM and Lithium separately with 2 different MPPTs.. ?

 

[Marktla]

I opened the batteries.. DC home app finds one of the batteries but not the other one. Both batteries show 13.22 V.

What could be wrong?

 

[Renogy Solar]

So… don’t use a dual pole transfer switch?

split the panels into 2 groups and feed to AGM and Lithium separately with 2 different MPPTs.. ?

That's what we recommend.

 

[Renogy Solar]

I opened the batteries.. DC home app finds one of the batteries but not the other one. Both batteries show 13.22 V.

What could be wrong?

Can you send me a video of the connection in action? So that I can determine the problem.

 

[Marktla]

I was able to see both batteries together. I used the HUB mode. please see attachment.

one question, when can I connect them in parallel and make them as a battery bank? currently they have a slightly different state of charge and voltage… charge them full first?

I don’t have a Lithium charger to charge them from AC , shore power. I have DC-DC Renogy chargers ( 40A and 60A ) and 2x Rover 60A MPPTs. I guess I can charge them with solar..

I have the 3000w renogy inverter… what thick / rated cable I need to use between the batteries? They are 20-30 cm from each other.. side by side.

I wanna use kitchen appliances, washing machine over the inverter. I guess I will pull 50-100 Amps from the batteries in normal use and possibly 150-200 amps when using the washing machine.

are the cables came with the inverter good enough for these amps? Inverter will also be next to the batteries.. 20-30 cm away.

 

[TimE]

First question, why do you have AGMs? Is this a legacy from pre lithium? If the answer is yes, then you are very unlikely to use those batteries once you have the lithium set up. Charge the lithium with all the solar. It will have way more efficiency than the lead batteries. Wasting some of your solar to charge the AGMmakes no sense. You won't be using those batteries in my experience so charge them with DC DC. You will live of the lithium bank and the solar efficiency will be nearly double compared to using solar and AGMs. The main reason for this is that on lithium you will rarely get off the bulk cycle of charging. The solar will work hard.
We used to harvest just over 2kw of solar a day off 720w of solar and lead batteries. Those same panels harvest 3.5kw per day on lithium.

 

[Tomthumb62]

I was able to see both batteries together. I used the HUB mode. please see attachment.

one question, when can I connect them in parallel and make them as a battery bank? currently they have a slightly different state of charge and voltage… charge them full first?

I don’t have a Lithium charger to charge them from AC , shore power. I have DC-DC Renogy chargers ( 40A and 60A ) and 2x Rover 60A MPPTs. I guess I can charge them with solar..

I have the 3000w renogy inverter… what thick / rated cable I need to use between the batteries? They are 20-30 cm from each other.. side by side.

I wanna use kitchen appliances, washing machine over the inverter. I guess I will pull 50-100 Amps from the batteries in normal use and possibly 150-200 amps when using the washing machine.

are the cables came with the inverter good enough for these amps? Inverter will also be next to the batteries.. 20-30 cm away.

No time to answer all your questions, but for the sake of all things holy, don’t use the cables Renogy sent with the inverter.

Yes you can charge up each battery to full then connect in parallel. An AC charger is best for this.