Tracer 40A CC

[mj52]

Hi,

Manual says CC accepts either 12 or 24V from panels with a max input of 400W.

Using 4 100W Renogy panels no matter how I wire them I get 400W.

My problem is with the 12 or 24V part.

Each panel is 18.9V @ 5.29A = 100W

4 panels in:

Series 75.6V
Parallel 18.9V
Series/Parallel 37.8V

I kinda get 18.9V and 5.29A is at 100% efficiency and not very likely so I can see how Parallel could be thought of as 12V and Series/Parallel could be considered 24V BUT the straight series with 75.6V doesn't click.

What am I missing?

Thanks, Mike

[mschulz]

What model are you using.

[mschulz]

If you bought the Renogy® Tracer 4210 40 Amp MPPT Charge Controller 12/24V 100VDC Input you will notice that they are giving you 100VDC volts of panels, so you could string them all together for 75.6 volts at 5.29 amps. This is the preferred way to do it since you bought the MPPT controller and your charge controller will convert the power to the batteries in 12 or 24 volt.

NOTE: If this is not the controller, disregard my recommendations.

[mj52]

Thanks,

There are 3 ways to wire these 4 panels and no matter which way I use I get an optimal output of 400W and you suggest the CC prefers high voltage and low amperage......5.29A @ 75.6V (a series feed).

Is there a particular reason why you chose this set-up? I ask only because this is my first solar project and I'm curious. I'm not in anyway trying to be argumentative. but I am curious.

Mike

[mschulz]

Thanks,

There are 3 ways to wire these 4 panels and no matter which way I use I get an optimal output of 400W and you suggest the CC prefers high voltage and low amperage......5.29A @ 75.6V (a series feed).

Is there a particular reason why you chose this set-up? I ask only because this is my first solar project and I'm curious. I'm not in anyway trying to be argumentative. but I am curious.

Mike

Higher volts and lower amps = less loss from panels to charge controller and smaller wire which saves you money.

You still need a large conductor from charge controller as you are going to have 33 amps from cc to batteries if you are running 12volt. 1/2 that if your bank is 24 volt

[mj52]

BINGO,

Less loss and smaller wire because of higher voltage from panels to CC. This sounds like a good thing.

As far as the battery/bank to inverter is concerned it was suggested I size the wire to the largest inverter I plan on using and use that same guage within the bank itself.

It was also suggested that the inverter may very well list what guage wire is best suited.

Thanks, Mike

[mschulz]

BINGO,

It was also suggested that the inverter may very well list what guage wire is best suited.

Thanks, Mike

A word of caution that this may not always be true. For instance, if your Charge controller is generating 400 watts at 12 volts, you are moving 33.3 amps from the charge controller to the battery. If your Inverter was only 200 watts, you are only working with 16.6 amps which would have a much smaller recommended gauge wire.

It is very important that you always match the size of wire to the amps that are traveling through it with proper overload protection (fuse or breaker).

Again, since you have not answered if your system is 12 volt or what exact model of charge controller you are using, I can not and will not give you any advise on what size wire should be used.

We still need more info from you.

[mj52]

Hi,

This project is simply in the beginning stages and I'm trying to get my facts straight.

It's going to be a mobile/storable 400W emergency battery backup system.

4 100W renogy panels wired in series (higher voltage, lower amperage, less loss) mounted 2 per tiltable base. The base will be on a 1 1/2 galv pipe and be removable for easier storage and movement.

A 40A tracer MPPT CC

4 Trojan T1275 FLA batteries (bought 2 this month (dated D-5 which stands for 4-15), 2 next month( probably dated E-5)) An 82lb battery weighs a ton.

All wiring up to and including the CC wil be #8 (Red and Black) oversized I know but the distances are quite short.

The wiring size in and around batteries to be determined since I haven't decided on how big an inverter yet? A small 300W for sure but not sure about large one

Everything including 2 panel mounts will be set in/on one of those industrial sized garden wagons w/ pneumatic tires (rated for 1000 lbs) with the 4 drop down sides. Most box stores sell something comparable and might even use them for customers


I'll lay it all out, build it, rough in the wiring, prove one panel doesn't shade the other (1 set will be X" off the deck and the other will need to be 2X +/- off the deck)

I figure I could go to night school someplace and slog along or I could just do it.

Grounding, fusing, inverters are still an issue.

[mschulz]

Hi,

This project is simply in the beginning stages and I'm trying to get my facts straight.

It's going to be a mobile/storable 400W emergency battery backup system.

4 100W renogy panels wired in series (higher voltage, lower amperage, less loss) mounted 2 per tiltable base. The base will be on a 1 1/2 galv pipe and be removable for easier storage and movement.

A 40A tracer MPPT CC

4 Trojan T1275 FLA batteries (bought 2 this month (dated D-5 which stands for 4-15), 2 next month( probably dated E-5)) An 82lb battery weighs a ton.

All wiring up to and including the CC wil be #8 (Red and Black) oversized I know but the distances are quite short.

The wiring size in and around batteries to be determined since I haven't decided on how big an inverter yet? A small 300W for sure but not sure about large one

Everything including 2 panel mounts will be set in/on one of those industrial sized garden wagons w/ pneumatic tires (rated for 1000 lbs) with the 4 drop down sides. Most box stores sell something comparable and might even use them for customers


I'll lay it all out, build it, rough in the wiring, prove one panel doesn't shade the other (1 set will be X" off the deck and the other will need to be 2X +/- off the deck)

I figure I could go to night school someplace and slog along or I could just do it.

Grounding, fusing, inverters are still an issue.

OK, lets slow down hear a little. When you say "mobile/storable 400W emergency battery backup system" and "Everything including 2 panel mounts will be set in/on one of those industrial sized garden wagons w/ pneumatic tires" - what are you using this for - A cabin? SHTF? or other. How far are you going to be moving all this? How Often?

I think you are going to regret your battery choices as those are 12 volt batteries and you will have 4 wired in parallel which is not ideal. Still you need to answer, are the batteries going to be wired to be 12 volt or 24 volt - both of these not ideal with 4-12volt batteries.

[mschulz]

Also, stop buying stuff. If you use those batteries you bought, you only have enough panel wattage to charge 2 of them. If you want to run 4 of those batteries, you will need 400 more watts of solar. You need to do more design work here. What are you loads etc.

Read the stickies on this forum.

[mj52]

Hi,

This is my plan

a dedicated pair wired in series to run the 12V inverter.

The other 2 (used 1 at a time) will power 12V items around the house. A 1/2 dozen 12V LED lights (commonly used in RVs), a 12V fan (endless breeze) to move either warm air or create a cooling breeze (place a porous air filter over the front of the fan and drip water onto the filter. Amazing how well this works.) An emergency radio, a couple of cigarette lighter outlets. We will be roughing it but with a certain amount of creature comfort.

I don't expect this to be perfect right out of the box but as long as the only thing that operates is a fuse i will be able to deal with that and move forward. With a meter and a hydrometer I should be able to monitor the batteries.

I don't plan on charging 4 batteries at a time. What I do plan on is moving the batteries to the job. thats why 82lbs wieghs a ton.

The 2 feeding the inverter I think will need the most tending too. This inverter will only be used as needed and disconnected when not.

The other 2 (used 1 at a time) will be swapped out and charged as needed. Again they will be brought to the job.

There wil only be the inverter batteries or 1 of the other 2 charging at any time for a maximum of 2 charging at once. Once the spoilables are exhausted the large inverter is a paperweight and the 300W should be able to cover most other needs and the 2 inverter batteries can be repurposed to other things.

This wagon will only be dragged around our yard following the sun during the 4 seasons and then be put away each night.

Don't forget if I'm really using this as intended I have no reason to be anywhere else and if I build it I'll know how to take it apart.

The wagon will allow me to move a lot of weight where and when i need. It'll keep everything in a central location. If nothing else it'll be a hell of a learning experience. Granted not a cheap class but an education that may well become invaluable.

Respectfully, Mike

[mj52]

Here's a question regarding the 40A Renogy MPPT CC.

I've read that batteries seem to like charging at between 15-18% of their 20 hr Ah rate.

For the T1275s the 20 hr rate is 150Ah 15-18% of 150 is 22.5 to 27.

A T1275 has a sweet spot between 22.5 and 27A but the CC is listed at 40A

Renogy hawks their 4 100W panels with their 40A CC

What happens if you try to charge one T1275? The CC is going to see its a 12V system, is it going to send 40A when 60 to 70% of the Max may very well be the best charging level? Something stinks.

What about 2 batteries?

The 2 batteries would be wired in parallel and used to feed a 12V inverter. Wouldn't you charge them in parallel as well. In this case the CC would see a 12V system and be undercharging the batteries slightly. 20A per battery rather than the ideal rate of 22.5 to 27A. I've been led to believe this only means it'll take longer at a slightly lower rate.


Something else I've noticed from all the videos. Some take a great deal of pride in their workmanship, others not so much.

Mike


When the panels arrive I'm sure they'll be in fine shape but how to I proof them? I'll tag them 1,2,3,4 and measure their voltage but what about the amperage? Can I measure the amperage like I would the voltage across an open panel or do I need to put the meter in series with a load?

Could the load be the charge controller? Could I wire 1 panel at a time to the CC and measure the amperage that way? I WILL WIRE A BATTERY TO THE CC FIRST.

Mike

[paulcheung]

Here's a question regarding the 40A Renogy MPPT CC.

I've read that batteries seem to like charging at between 15-18% of their 20 hr Ah rate.

For the T1275s the 20 hr rate is 150Ah 15-18% of 150 is 22.5 to 27.

A T1275 has a sweet spot between 22.5 and 27A but the CC is listed at 40A

Mike

For FLA batteries, the ideal charge rate is C/8 to C/12 on 20 hours rate. That is 8.34% to 12.5% of the 20 hours rating. 10% be the best spot. For two 150 amp hours batteries in parallel that is 300 AHs the ideal charge rate would be 30 amps.

[mj52]

PC, Thank You.

So this 40A will easily take care of the 2 batteries when charged in parallel. So as a good general rule (15 hr rate/10) will get you where you're going. and in my particular case 300Ah/10 = 30A.

just for giggles I'd like to know what the charge rate is for my 40A CC? It's rated at 40A but is that a "Max" under ideal conditions? I'll be calling Renogy.


Mike

[mj52]

Hi,

Charging time?

Is this correct ?

Batteries are at 100% verified by meter but this is not the correct way to measure battery SOC. Test again using hydrometer and specific gravity says batteries are good to go.

Use the batteries and draw batteries down to 80% SOC, this means a DOD of 20%. DOD +SOC = 100%

I thought i saw something about needing to charge to 130% in order to store 100%.

20% x 1.3 = 26%


Math Example:

I used 100Ah of a 500Ah bank. 20% DOD & 80% SOC

100Ah x 1.3 = 130Ah (amount needed to put back in order to store 100Ah)

130Ah/40A = 3.25 hours

Math example assuming 100% efficiency. We all know what happens when we assume anything.



Mike