# Question Re: Chrging Batts in Winter



## Rick (May 10, 2002)

I have 500 watts of panels keeping 4 Trojan L 16 REB (wired as 12 volts) charged. The batts are in fair condition.

I run a Sundanzer 12 volt freezer and draw between 100 and 300 watts for computer use daily.

The system cycles 5 to 7 times a week until the winter solstiice.

When the system doesn't cycle / won't the next day I use my laptop batteries until I need to fire up the 2000 watt genny to charge everything DC including the trojans.

My question is: in cold weather, when the system won't cycle (at night) should I use the extra voltage pin that raises the Iota - 55 amp charging volts from 14.8 to 15.4.

There is already temperature compensation invalved.

Even with the 15.4 volts it generally will not give me more than 3 out of 5 blinks (xantrex 35) towards a full cycle, but I don't want to tax the trojans with to many volts just because it is cold (not their fault).

My inexperienced, gut feeling is go ahead and use the pin if the system is still trying to cycle.


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## Gray Wolf (Jan 25, 2013)

It's hard to respond to this without more info. Could you repost telling us what "blinks" and "cycles" mean with your system? Does your charger automatically switch from bulk to absorb to float to equalize to ___? What settings do you have for these charge rates? How low, in volts, do you discharge your bank? How did you determine that 55 amps was the proper charge rate? What is your fully charged voltage? What temperature are your batteries?

All in all, a charge should start at the maximum amperage for the bank and then taper off to float at the end.


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## Jim-mi (May 15, 2002)

What he means is that he has an Iota 55-12 ......The 55 is the max amps at start up.
The Iota will taper down the current as the batt bank charge comes up.
There should be monitoring hardware in the circuit to read current and voltage.

That is not good if you are trying to determine state of charge just from the stupid blinking LED's on a C35..........

In the very least put in a Tri-Metric and let it give you data.


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## Rick (May 10, 2002)

Gray Wolf said:


> It's hard to respond to this without more info. Could you repost telling us what "blinks" and "cycles" mean with your system? Does your charger automatically switch from bulk to absorb to float to equalize to ___? What settings do you have for these charge rates? How low, in volts, do you discharge your bank? How did you determine that 55 amps was the proper charge rate? What is your fully charged voltage? What temperature are your batteries?
> 
> All in all, a charge should start at the maximum amperage for the bank and then taper off to float at the end.


GW - thanks for your input.

The blinks correspond with Bulk/ Float / Discharging or Charging.

When the light stays a solid green it has cycled from Bulk to Float. 

The Charger does not switch as far as i know, just the controller. 

I think our Bulk is 14.2 but might be 14.8...I'm pretty sure our Float is 13.2

I can check and report this after mornings light. I have it set where BW solar suggested when they sold me my panels and hardware, and they suggested the 55 amp charger. 

Bank has never been below 12.4 - it is outside in a half insulated shed, and I have never tested the temp on a 30 deg F outside air temp day. 

It was 65 deg F today and I drained the bank down to around 12.4 knowing I would resort to the generator for light, computer and DSL for my job and could charge the Trojans.

The batteries were in bulk when I started the charger, I raised it's voltage to 15.4 for an instant, and the LED indicator immediately started blinking 3 out of a possible 5 times before bulk is attained.

I unplugged it because I am still trying to determine if using the plug (15.4 volts) to get my system to reach bulk and then Float settings, might be harmful to my batteries.

BW solar told me to use the charger if the system did not "cycle" at least one time in a 7 day period.


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## Rick (May 10, 2002)

Jim-mi said:


> What he means is that he has an Iota 55-12 ......The 55 is the max amps at start up.
> The Iota will taper down the current as the batt bank charge comes up.
> There should be monitoring hardware in the circuit to read current and voltage.
> 
> ...


Jim-mi

I guess sometimes not good is better than terrible :shrug:

What if I am too stupid of a blinking light to figure out how to install a Tri-Metric?

I have one in the box. I opened it, took one look at it and said "no way can I do this"! Now I work 45 hours a week, and haven't the time. 

All the kings horses, and all the kings men could not find someone within 100 miles, as learned and capable as yourself in these matters that could help me.

I appreciate your contributing to my puzzle.

Now ,,, let us say this is a true / false question, if you don't caer...

Based on my vague information re: my system, taking battery health :

On a dozen 30 degree days in the winter, temperature in the battery shed maybe 38 degrees, I should charge a battery bank whose panels have not seen good sun in 3 days with a 55 amp charger at 15.4 volts, instead of 14.8 volts for 4 hours.

True or False?

I will go back into my cave, and light a candle :whistlin:


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## Rick (May 10, 2002)

Our bulk setting is 14.8

Float is 13.2


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## Jim-mi (May 15, 2002)

Those are pretty standard voltage settings 13.2 and 14.8 . . . . .
The 15..4 is used for an "equalizing" charge . . . . which you should only need to do maybe once a month..
Other equipment has compensation for ambient temperature . . you do not have that with the Iota.
Don't take that plug in or out while charging.....

The charging current for that Iota will look like a bell curve . . really tapering off near the end of a "charge" . . .down to just an amp or two holding the batt's in "float"

This is why having (for instance) the Tri-Metric in the system you can read the voltage and current and know that the batteries are charged and you there for can shut the generator off.

I have several and use several Iota's . . . .Very good stuff.

Come on Rick . .don't belittle your self . . . . .you can do it .
You put the shunt in the negative battery cable,. . . . .two little wires go on one side of the shunt and one little wire goes on the other side of the shunt . . . .and these little wires go to the head of the Tri-Metric...............


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## 12vman (Feb 17, 2004)

I have a Trimetric and a C-40. I run my float at 13.6 and bulk at 14.2. A couple of hours after a charge period, the battery settles down to 12.4. (Full Charge)

The LED in the C-40 lets me know where I'm at in a glance. I watch the Trimetric for the voltage level. The LED is a quick reference and it follows the situation with accuracy. It took me a week to get the settings in the C-40 exactly where I wanted them but they are right on the money.

Running the bulk voltage much over 14.2 will just boil the crap out of the battery for no reason. If you see them bubble like half flat soda pop while in bulk, that's good enough. An occasional bubble now and then during float is fine. 

This is the logic that I used with a set of golf cart batteries and I got 8 yrs. of service from them. I could have maybe squeezed another year from them but I had my Surrette S-600's setting there waiting. I didn't change my settings on the controller and figure that all will be fine.

I monitor my voltage more than anything. If they get near 12 and I have a cloudy period, I consider firing up the back-up. The lowest I ever let them go is 11.9.

Quote..
*"Even with the 15.4 volts it generally will not give me more than 3 out of 5 blinks (xantrex 35) towards a full cycle, but I don't want to tax the trojans with to many volts just because it is cold (not their fault)."*

Your controller monitors voltage, according to the settings. Have you ever seen a solid green LED? Is the Iota connected directly to the battery?

The Trimetric is nice. It tells me how many amps I'm getting from the panels or the back-up. That's handy to let me know how things are. I rarely use the other functions. I just monitor the voltage and that tells me everything that I need to know. I have a ventilation fan on my bathroom fixture and I can tell by the speed (pitch) of the sound it makes if my battery needs a charge or not without looking at anything.

Cold batteries are bad Ju-Ju. Mine are inside with me near the foot of my bed. If I'm cold, I know they are..


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## Jim-mi (May 15, 2002)

. . ."Cold batteries are bad Ju-Ju" . . . . .absolutely.......

Giggle around and find the data how batts loose capacity with low and high temps....it is startling......

Voltage compensation for cold batts follows a semi complicated formula .....

Don't ask me . . ask the battery manu's why all battery performance data is based on an ambient temp of 77 F . . . . . .


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## Rick (May 10, 2002)

Don't take that plug in or out while charging.....

OOPS

I don't have the greatest set up and have had Distilled water freeze before my eyes when poured into a quart jar. I guess heating it up would be good.

It was the instructions that looked so intimidating.

The Tri-Metric cable is routed from the Building the freezer lives in through the conduit and the sits coiled waiting in the battery shed.

Thanks for the encouragement.


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## Rick (May 10, 2002)

I reset the Bulk at 14.3 Maybe I should notch the Float up to 13.4 or more?

These girls turn 5 in May. They have had hot Summers and mad cold Winters. I will have to watch them. The meter will help establish a set point for them, so I will try to get that done in Spring.

The Iota is connected directly to the Batteries. I see the solid green indicator most days by Noon, Winter solstice of course - maybe 3, 4 times a week and closer to 1:30

12vman - is that a typo that you consider 12.4 fullyu charged - is that for the Surrettes?


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## 12vman (Feb 17, 2004)

*12vman - is that a typo that you consider 12.4 fullyu charged - is that for the Surrettes?*

Yep.. They ramp to 14.2, hold for an hour, and drop to 13.6 during a charge period. After they sit for an hour or so, they level out to 12.4 and can sit there for hours, possibly into the next day, depending on how much of a load that I put on them. Normally they may drop to 12.3 over night if I'm online and jammin' on the stereo..  If I conserve, it can be a week or more before I need to use the back-up..

I'll use things until I see the voltage getting near 12 volts and then I start thinking about starting up the genny. That could be 2-3 days because I do get a little bit of charge every day from the panels with just daylight during the winter. (2-4 amps)

8-Unisolar 64's, C-40 Controller, 8-Surrettes @ 12 v.d.c., 2800 Watt genny, and a Schumacher SE-4020. That's all, folks..


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