temp control and hookup question

wmd239 · November 2010

Hi yall
i am in the process of hooking up my first solar system on my rv.

i started with 1 135 watt panel and bluesky solar boost 2000e, and 2 group 29 interstates.

My question is about hooking this all together.

the bluesky has a temp controller but i dont know where to hook this up from. (which terminal?)

Which wire should i use for this ?

Also am i right in hooking the wire from the bluesky into the first positve pole and last negative pole on my series wired batteries?

BB. · November 2010

Re: temp control and hookup question

Lots of open ended questions...

Here is a nice thread with video from Keven in Calgary Canada that shows designing and installing solar PV in a small RV trailer.

And here is a web page on how to wire up a battery bank with multiple batteries in parallel:

Smart Gauge battery wiring page

The temperature sensor may be connected to the battery post (if designed for this) or on the side of the case (wherever it can accurately measure the battery temperature).

-Bill

wmd239 · November 2010

Re: temp control and hookup question

Ok thanks for those links.

I guess i just need to figure out if my batteries have a temp control and where it is?

i have 2 interstate srm 29's

does anybody have any idea about this?

also which type of wire is best for a temp sensor?

waynefromnscanada · November 2010

Re: temp control and hookup question

Your batteries won't have a "temp control". Your charge controller may come with, or have available as an option, an external temperature sensor/probe which is designed to be located at, or on the battery, or one of the batteries in the pack, to send battery temp info back to the charge controller, which it (the controller) can use to compute the proper charging voltages, which vary depending on the temperature of your batteries. These sensors usually come with a good length of proper wire, with one end properly attached and molded into the sensor package, thus protecting the connections from the corrosive environment that tends to surround batteries.
Best of luck man. You've entered on a great journey of learning.

wmd239 · November 2010

Re: temp control and hookup question

ok cool, thanks for that clarification.

now where abouts should i attach this sensor (wire) to the battery?
should i just attach to a random pole?
is it ok to use regular wire for this or should i have a specific type of sensor wire?

BB. · November 2010

Re: temp control and hookup question

Wire your batteries just like the Smart Gauge Link above...

Connect your voltage sense leads (if that is what you are talking about) to the same point at which you take power from the battery bank (the common bus point).

Use a small cable with twisted pair. Ideally, place a small fuse (rated no larger than the wire can carry) in the + lead at the battery to the wire to prevent short circuit fun.

If this is a battery temperature sensor--how is the sensor terminated... It there a piece of metal you can bolt to the battery bank (I think I remember positive post preferred). Otherwise glue to the side of the battery in a space free from drafts (you want the temperature of the battery, not the air around it).

Read the instructions that come with the RBTS. They should tell you how long of wire run you can add (if any) for their sensor. Again small gauge twisted pair should be fine.

There are thermal couples which use two different types of metal bonded together. Lengthening with the wrong type of wire can cause temperature reading errors. But, I think the popular charge controllers use some form of PTC (postive temperature coefficient resistor) which is not sensitive to the type of metal in the wiring.

-Bill

wmd239 · November 2010

Re: temp control and hookup question

Thank you for that. im still a little foggy on this battery temperature sensor.

i have a drafty battery box for some reason, there is lots of vent holes. so im not sure if i will get a accurate temperature reading.

i attached the instructions from my manual. it shows 2 leads going into 1 termination. isnt this gonna cause problems if i attach it to the positive pole?

BB. · November 2010

Re: temp control and hookup question

The temperature sensor should be insulated from the metal lug itself--So the lug can be attached to either battery pole without problem.

Lead is very good at transferring heat, so the lug will be very close to the internal battery temperature--even in a drafty box.

-Bill

wmd239 · November 2010

Re: temp control and hookup question

ok new issue.

i just finished hooking up everything, for some reason i am not getting any charge to the charge controller.

the charge controller on pv input shows a negative charge. .025

i checked the panel directly and its reading 21 DCV, and it is showing no DCA

is there something wrong with the panel? or am i not reading it right?

shouldnt the panel show some sort of DCA its getting full sun.

BB. · November 2010

Re: temp control and hookup question

Do you have the controller attached to the battery bank? Many will not work at all without a battery connection or if the batteries are seriously dead.

-Bill

BB. · November 2010

Re: temp control and hookup question

Also check solar panel to controller polarities.

-Bill

wmd239 · November 2010

Re: temp control and hookup question

Yes i have it attached to batteries. i have 2 bats. i attached the positive to main positive terminal and ground to the second batteries ground.''its was showing bat voltage but pv charge was showing -.025

wmd239 · November 2010

Re: temp control and hookup question

Yep rookie mistake i had solar poles reversed.

thanks for sticking with me on that one Bill

one other thing after checking my pv current im only getting .008 while its charging.

doesnt this seem low?

niel · November 2010

Re: temp control and hookup question

by your pic in post #7 there is no connection for ground. the + and - of the pvs must go to their designated inputs shown on that pic. the same goes for your battery connections. do not tie the minus of the pvs to the minus of the battery as this should not be a common connection.
ok i answered as you found your error.

BB. · November 2010

Re: temp control and hookup question

Does not sound right. If the battery came right off a battery charger, perhaps it went direct to float.

Otherwise, set your amp meter to 10 amp full scale and measure the panel's short circuit current--assuming your meter can manage the panel maximum current.

And never short your batteries with a current meter.

-Bill

wmd239 · November 2010

Re: temp control and hookup question

yes somethings not right, by the status light it is in bulk charge but only produce 00.3 on the charge controller for input and output.

i hope i didnt short the battery when the wrench touched both poles, it still shows 12.5 v

BB. · November 2010

Re: temp control and hookup question

What is your battery voltage while charging?

Some controllers may be damaged if the panels or the battery is connected backwards.

Check the manual.

-Bill

wmd239 · November 2010

Re: temp control and hookup question

ill have to wait and check tommorow since the sun is setting right now.

it says in the manual it could be damaged if left hooked up for extended periods of time, so it is possible.

but it wasnt hooked up that long. and still has display

btw does it matter which ground pole from my 2 batteries i hook the ground from the charge controller?

BB. · November 2010

Re: temp control and hookup question

Functionally for the charge controller, no... For best battery operation, follow this website's recommendations:

Smart Gauge battery bank wiring

-Bill

wmd239 · November 2010

Re: temp control and hookup question

OK everythings seems to working properly, but doesnt seem to have a high output charge, it is a little cloudy today but the highest output current i have seen is 1.7.

Is this normal?

also i was told i shouldnt worry about the temp sensor, so i disconnected it since the battery bay is pretty close to the charger temperature, does this seem right?

BB. · November 2010

Re: temp control and hookup question

A good maximum power (very clear/cool day, battery less than 90% state of charge) would be:

135 watts * 0.77 derating * 1/14.5 volts = 7.2 amps

It is not unusual to see 50% of that with just some light overcast. Much less if thick cloud deck.

Check the battery voltage when charging... Assuming the charger is set for >14.2 volts, and the battery is less than 14.2 volts--the charger should be outputting its maximum available current (unless the charger has decided to enter "float mode" which would be around 13.7 volts).

-Bill

wmd239 · November 2010

Re: temp control and hookup question

its got a voltage of 13.1 while charging in bulk.

i dont know if its set for 14.2, i dont know how to check or change this.

it seems to stay in bulk charge also.

does this seem right?

BB. · November 2010

Re: temp control and hookup question

If the charge controller is in "Bulk"--Then the battery is setting the voltage right now (state of charge and amount of current)... As the battery chargers, its voltage will slowly rise to the "Absorb" voltage of around 14.2-14.5 volts or so).

If you want, you can use a 10 amp range amp meter to short the solar panels and measure its Isc--Which is only slightly larger than Imp for the panel will be.

Isc is pretty much proportional to the amount of sunlight hitting the panel. And you can use it to estimate the amount of power going into the charge controller.

As always, be very careful with an Amp Meter (or DMM set to read Amps). Never short out a battery with a current meter--it will damage/ruin the meter and its leads. Normally you "cut" a wire and insert the amp meter in series to measure the amperage.

Solar panels are one of the few power sources you can connect (short) directly with a current meter without any damage (as long as the current meter is set for Isc > meter maximum supported current).

At this point, if you have "full sun", then 1.7 amps does sound like a problem.

-Bill

temp control and hookup question

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