12vdc battery reading 16v..?

cizzi

Over the past year I've been monitoring my outdoor deep cycle battery I use in a standalone solar installation, the battery is always at 100% full because there is no current currently drawn on a regular basis, when I check the voltage reading directly on the battery it goes as high as 16.x volts sometimes.. i'm using a morningstar sunguard 4.5A charge controller because of the small size of the installation and I know that in colder temperatures the sunguard allows more current to flow to the battery (i live up north) however shouldn't it stop it at 12.7 volts? or 13,14,15 .. my concern is that when it shows 16 volts I may be damaging my battery? let me know what is happening thanks.

icarus

Re: 12vdc battery reading 16v..?

How cold?

-40 might get that high depending on the configuration of the CC,, but it should be lower now.

T

niel

Re: 12vdc battery reading 16v..?

well, assuming it to be a standard lead acid battery, you should check the water levels to see if too much electrolyte has escaped. if you see the plates above the water level then you are frying the battery. if it needs water use distilled and if the plates were exposed then sulphation has started. the problem is the temp compensation built into the controller is nice to a point, but it's the battery temp that's important and not the controller temp and is why the sensor is usually recommended to be remote as you can't mount the controller on the battery itself. the battery may have warmed from charging, but it may not be reflected by the ambient air temp so the voltage is held high and could boil out your battery. raised charge voltage levels in cold weather are normal for controllers that have temp compensation. also note that the controller while in operation will also raise the temp on the built-in sensor making it a game of russian roulette.
my advice to you seeing it isn't being pressed for use is to bring the battery and controller inside. some provision to trickle charge the battery either from solar or some other regulated supply is recommended as you don't want the battery to lose its capacity sitting in storage.

cizzi

Re: 12vdc battery reading 16v..?

its a GEL battery from deka 31AH .. does that make any difference? i'm trying to justify the 16v readings still

icarus

Re: 12vdc battery reading 16v..?

Check the batteries in your volt meter. Low dvm batteries can cause erratic readings,

Tony

cizzi

Re: 12vdc battery reading 16v..?

batteries are fine, i just went out there with 2 different multimeters, same reading.. although it shows 13v right now because i used a LED light to see my readings (its night here right now) and the led is a load from the battery

niel

Re: 12vdc battery reading 16v..?

that might be a worse situation as a gel is a vrla type. the vents on vrla types are more or less safety devices in the event of too much internal pressure. looking at this pdf, http://www.eastpenn-deka.com/assets/base/0139.pdf on page 11 it shows max voltages at different temperatures. i cannot justify a 16+ v reading from your battery.

icarus

Re: 12vdc battery reading 16v..?

According to the Deka spec sheet: "Charge voltage must be limited
(14.4 to 14.6 volts maximum at 68°F)"

http://www.eastpenn-deka.com/assets/base/0919.pdf says that absorb charge should be 2.35-2.4 volts per cell, making 14.4 max.

Float voltage should be 2.25 to 2.3 volts,, making 13.8

Sounds like you have your controller set improperly,

Tony

cizzi

Re: 12vdc battery reading 16v..?

Controller cannot be set first of all. Its a sunguard 4.5A from morningstar.. and its a homemade project so I'm really not too picky about all the little specy details. Its been fine for a whole year in a harsh canadian winter and can still maintain its charge at 100%.

niel

Re: 12vdc battery reading 16v..?

look at what this says on the gels from page 11;

Temp. Charge Float Temp.
°F Optimum Maximum Optimum Maximum °C
≥ 120 13.00 13.30 12.80 13.00 ≥ 49
110 – 120 13.20 13.50 12.90 13.20 44 – 48
100 – 109 13.30 13.60 13.00 13.30 38 – 43
90 – 99 13.40 13.70 13.10 13.40 32 – 37
80 – 89 13.50 13.80 13.20 13.50 27 – 31
70 – 79 13.70 14.00 13.40 13.70 21 – 26
60 – 69 13.85 14.15 13.55 13.85 16 – 20
50 – 59 14.00 14.30 13.70 14.00 10 – 15
40 – 49 14.20 14.50 13.90 14.20 5 – 9
≤ 39 14.50 14.80 14.20 14.50 ≤ 4

kind of a conflict wouldn't you say tony? also of note is this statement;

The open circuit voltage of
a fully charged 12-volt battery is 12.8V at 68°F (20°C).

cizzi

Re: 12vdc battery reading 16v..?

When the temperature gets warmer here I will see if the voltage regulates to the chart. Thanks for your help guys! Think positive!

niel

Re: 12vdc battery reading 16v..?

i'll say a prayer to the great sun goddess in addition to crossing my fingers if that helps you?;):D

icarus

Re: 12vdc battery reading 16v..?

Neil, Cizzi,,

In the citation I note,,, the float and absorb voltages are at 25c/77f with a voltage differential of .005v/degree C. So your chart gives a float voltage of 13.7.

Now,, I don't know exactly which Deka battery series you have,, so I assume the Valve regulated gel cells. I didn't dig any deeper with other models.

Tony