250 watt / 36 v.

[patrickp708616]

I have a 250 watt Resenola panel with 36v output charging 3-12v marine max 114 ah each, in series. 1-cheapie MWP $10 12v / 24v controller. All New.

The only thing I have on it is a 12v at 5 amp Coleman cooler jumpered across 1-12v battery.

My problem is that the batteries after 6-8 hrs go dead. Do I need more panel or batts?

Everything is new so I dont understand the problem. The controller although just a 24v cycles just as it should.

[Shockah]

I have a 250 watt Resenola panel with 36v output charging 3-12v marine max 114 ah each, in series. 1-cheapie MWP $10 12v / 24v controller. All New.

The only thing I have on it is a 12v at 5 amp Coleman cooler jumpered across 1-12v battery.

My problem is that the batteries after 6-8 hrs go dead. Do I need more panel or batts?

Everything is new so I dont understand the problem. The controller although just a 24v cycles just as it should.

Wait. Lemme make sure I read this right...
you have (3)12v/114ah batteries in series, and you're charging the 36v battery pack with a 24v charge controller?

I would say you need to take one of the batteries out, so you'll be charging only a 24v battery pack with a 24v charge controller,
and you should be fine, granted you have a >10amp charge controller.

How many times have you cycled those 3 batteries to dead? You better pray you didn't do much damage to those batteries...

[patrickp708616]

Wait. Lemme make sure I read this right...
you have (3)12v/114ah batteries in series, and you're charging the 36v battery pack with a 24v charge controller?

I would say you need to take one of the batteries out, so you'll be charging only a 24v battery pack with a 24v charge controller,
and you should be fine, granted you have a >10amp charge controller.

How many times have you cycled those 3 batteries to dead? You better pray you didn't do much damage to those batteries...

Yes I have 3 12v batts in series. According to the sales person at Wholesale Solar he said the 24v and 36v ranges are very close to each other that yes for what Im doing would work due to the low amperage Im drawing at 5 amps. Theres no doubt the controller is cycling as it should because the led lights dictate this. If you think about it doesnt a 24 volt solar panel put out 30 plus volts under ideal conditions? Of course it does which is why you can use a 24v controller on a 36v panel. With all that behind me is why isnt the batteries lasting longer than 6-8 hrs??? Do I need more panel or battery???
5 amp x 12 vdc = 60 watts. The battery is 114 amp hrs, so why does the battery go down to 50% after 6-8 hrs? The fridge is only opened 3 times a day.

PS Everything is only 1 week old but (NEW) nor did I ever let the batteries go below 50%.

[greenHouse]

Patrick,

You need to start over from the very beginning. What you're trying to do can't work.

If your only load is a 12 volt cooler, you need a 12 volt DC battery pack. It can be 3 12 volt batteries in parallel, but it cannot be 3 of them in series.

Likewise, if you have a 36 volt panel, you must have a battery pack which is no more than 75% of that as the nominal voltage, or 27 volts. There's no such thing as a 27 volt battery pack, so you're back to 24 volts, except that your load is 12 volts, so 12 volts it is. The peak charging voltage for a 24 volt nominal battery is over 30 volts in the winter. For a 36 volt battery it is close to 46 volts. Your panel isn't up to that task.

[Shockah]

Yes I have 3 12v batts in series. According to the sales person at Wholesale Solar he said the 24v and 36v ranges are very close to each other that yes for what Im doing would work due to the low amperage Im drawing at 5 amps. Theres no doubt the controller is cycling as it should because the led lights dictate this. If you think about it doesnt a 24 volt solar panel put out 30 plus volts under ideal conditions? Of course it does which is why you can use a 24v controller on a 36v panel. With all that behind me is why isnt the batteries lasting longer than 6-8 hrs??? Do I need more panel or battery???
5 amp x 12 vdc = 60 watts. The battery is 114 amp hrs, so why does the battery go down to 50% after 6-8 hrs? The fridge is only opened 3 times a day.

PS Everything is only 1 week old but (NEW) nor did I ever let the batteries go below 50%.

Out of curiosity,
before you pull apart that 36v battery pack, is it possible for you to measure the amps out of the controller while in charge mode?
Do you have a clamp on amp-meter or digital multi-meter?

And ditto on greenHouse's comment about the 12 volt load.

However, with your PWM CC, I believe it would be more efficient to charge a 24v battery pack.
So, you may want to explore a 24v-to-12v transformer instead of switching to a 12v parallel pack.

Either is better than discharging just one battery.

[Shockah]

5 amp x 12 vdc = 60 watts.

Is the said "5 amp" the actual current draw or the total draw in a 24 hour period?

In other words, what is the wattage of that cooler, 60w? or 2.5w?

[Shockah]

5ah / 5 amp hour

Im guessing this is the cooler,

http://www.amazon.com/Coleman-40-Quart-PowerChill-Thermoelectric-Cooler/dp/B0014VSR90/ref=cm_cr_pr_product_top

^^^That is a 5ah cooler, meaning it draws 5 amps per hour, meaning it will draw 60ah x 12v = 720 watts in 12 hours.

12hours @ 5ah = 60ah.
114ah Battery x 3 = 342ah.
342ah x 20% = 68.4ah ... 20% is the recommended maximum, and you're below it @ 12 hours ... so you do not need more battery.

However, I'd say you are stretching that (250w Panel / PWM CC) combo pretty thin in the effort to replenish the spent 720w, whether you wire it into a 36v, 24v, or 12v battery.

In order to determine if you have enough components as is, you need to first wire the 3 batteries into a 12v parallel pack.
(Note: Parallel 3pack is not the most recommended for long battery life)
Now @ 12v, you need a 20amp CC for that 250W panel.
If you don't already have a 20amp CC, get an MPPT for maximum efficiency.
Even at that, you may still need more panel. The actual amount of peak sun hours in your area will dictate that for you.

My humble 2¢

[patrickp708616]

Im guessing this is the cooler,

http://www.amazon.com/Coleman-40-Quart-PowerChill-Thermoelectric-Cooler/dp/B0014VSR90/ref=cm_cr_pr_product_top

^^^That is a 5ah cooler, meaning it draws 5 amps per hour, meaning it will draw 60ah x 12v = 720 watts in 12 hours.

12hours @ 5ah = 60ah.
114ah Battery x 3 = 342ah.
342ah x 20% = 68.4ah ... 20% is the recommended maximum, and you're below it @ 12 hours ... so you do not need more battery.

However, I'd say you are stretching that (250w Panel / PWM CC) combo pretty thin in the effort to replenish the spent 720w, whether you wire it into a 36v, 24v, or 12v battery.

In order to determine if you have enough components as is, you need to first wire the 3 batteries into a 12v parallel pack.
(Note: Parallel 3pack is not the most recommended for long battery life)
Now @ 12v, you need a 20amp CC for that 250W panel.
If you don't already have a 20amp CC, get an MPPT for maximum efficiency.
Even at that, you may still need more panel. The actual amount of peak sun hours in your area will dictate that for you.

My humble 2¢

Finally a guy with facts, figures, ideas & math to boot. Thanks!
Thats all I wanted was a sense of direction.

Ive got money to get what ever I need. I bought this panel and controller for $20 un-opened at a yard sale so I was just working with what I already had. The batteries I had to buy anyway for my boat thats now been put away for the winter. I live in Indiana but down here in Ft Myers, Fl for the winter. The 250w panel I installed on my roof RV where theres plenty of space so no harm there. I bought a watt meter from ebay but it hasnt arrived yet. The 5 amps is what is on the fridge data plate so I dont know the actual charge controller current yet. Ive had a blast with this project so far but Im simply not gonna pitch the panel for the heck of it. What is the 36 v panel traditionally for anyway? Could I simply add more panels like this to do something else? What would you do? I can get more matching Renesola panels here in Ft, Myers.

What is a 36v panel for anyway? How much different is it from a 48 volt system if the same rules apply? Ive got the money to get a $700 controller so no biggie there either because I am not restricted financially like some others on here.

[patrickp708616]

Finally a guy with facts, figures, ideas & math to boot. Thanks!
Thats all I wanted was a sense of direction.

Ive got money to get what ever I need. I bought this panel and controller for $20 un-opened at a yard sale so I was just working with what I already had. The batteries I had to buy anyway for my boat thats now been put away for the winter. I live in Indiana but down here in Ft Myers, Fl for the winter. The 250w panel I installed on my roof RV where theres plenty of space so no harm there. I bought a watt meter from ebay but it hasnt arrived yet. The 5 amps is what is on the fridge data plate so I dont know the actual charge controller current yet. Ive had a blast with this project so far but Im simply not gonna pitch the panel for the heck of it. What is the 36 v panel traditionally for anyway? Could I simply add more panels like this to do something else? What would you do? I can get more matching Renesola panels here in Ft, Myers.

What is a 36v panel for anyway? How much different is it from a 48 volt system if the same rules apply? Ive got the money to get a $700 controller so no biggie there either because I am not restricted financially like some others on here.

What if I paralleled my existing 250 watt panel with a matching one, added 3-more matching batts and bigger controller? What would that give me and is it ok to do? If so, what controller should I get as well as well as wiring method?

[paulcheung]

If I were you, I will get a 40~60 amps Mppt charge controller and get 1 more 250watts match panel. wire the panels in series and set the controller to 40 amps max charge. wire the batteries in parallel, connect the cooler direct to the batteries.

Cheers

[Shockah]

What if I paralleled my existing 250 watt panel with a matching one, added 3-more matching batts and bigger controller? What would that give me and is it ok to do? If so, what controller should I get as well as well as wiring method?

When you get your current set-up working well for your cooler, study the "math" of it, and then you'll be able to know what more equipment will do for you.

However, it is better to build for a particular need than it is to just build.

[patrickp708616]

Mppt Controller Question with 250w Panel.

*In regards to MPPT Controller?

If I were you, I will get a 40~60 amps Mppt charge controller and get 1 more 250watts match panel. wire the panels in series and set the controller to 40 amps max charge. wire the batteries in parallel, connect the cooler direct to the batteries.

That sounds great and the advise Ive recently received is far from the advice I had received earlier saying "Start-Over or Pitch The Panel".
1.) What was a 36 volt solar panel ever used for anyway?
2.) When you said 40-60 amp MPPT Controller I take it that with the 2-36v panels in series will output 72v, so are you telling me the controller has adjustable voltage too?



Cheers

[Wy_White_Wolf]

*In regards to MPPT Controller?

1.) What was a 36 volt solar panel ever used for anyway?

Grid tied systems that don't use batteries. They are trying to reach string voltages in the 300-450 volt range.

2.) When you said 40-60 amp MPPT Controller I take it that with the 2-36v panels in series will output 72v, so are you telling me the controller has adjustable voltage too?

Close. Not adjustable but it works as a DC-DC converter where it converts the excess voltage to amperage. This allows for higher array voltages to keep losses and wire size down and when converted increases the usable watts that can be put into charging the batteries.

WWW

[patrickp708616]

When you get your current set-up working well for your cooler, study the "math" of it, and then you'll be able to know what more equipment will do for you.

However, it is better to build for a particular need than it is to just build.

What was the 36 volt panel ever used or built for?

[patrickp708616]

1.) What was a 36 volt solar panel ever used for anyway?

Grid tied systems that don't use batteries. They are trying to reach string voltages in the 300-450 volt range.

2.) When you said 40-60 amp MPPT Controller I take it that with the 2-36v panels in series will output 72v, so are you telling me the controller has adjustable voltage too?

Close. Not adjustable but it works as a DC-DC converter where it converts the excess voltage to amperage. This allows for higher array voltages to keep losses and wire size down and when converted increases the usable watts that can be put into charging the batteries.

WWW

Life is GOOD!!! Thanks for all the answers. I did find a matching Renesola Panel here in Ft Myers for $200 so I'll be picking that up as well as a MPPT Controller.

**What should I expect to pay for the controller? The prices range from $200 to $900. I dont care about the cost but would rather over-rate it a little. Did you see anything in particular on Ebay or somewhere else that I should buy?