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SOC / DOD


Jaco De Jongh

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Hi Everyone

Next question. I think that I understand the Charging side of things. I will write it out as I understand it. Please correct me if I am wrong.

I use the Trojan T105. 2 Banks of 8.

According to the data sheet from Trojan.com I should

1: Bulk Charge at 59.3Volt (My Infini can only handle 58.4V)

2: Float charge at 54Volt (Infini set to 54V)

As for charge rate, I gathered from some other discussions on the forum that the best charge rate is between 10% and 13% of 20H rating of battery. With 2 banks in parallel I am sitting at 450ah so my Max charge rate is limited at 50A. Is this correct and acceptable?

As for SOC , I can figure out what is suppose to happen here and how to measure it, but being a open voltage measurement, I guess that is where a battery monitor comes in. Either that or disconnecting the battery's to measure it accurately. Do i need a monitor  per bank, or only one?

Now where I miss the bus completely. DOD, how do I go about determining my Low limits and different cut off points. I understand that load plays a role. My normal load at night is between 200 and 5oowatts. Please I need some assistance in understanding DOD better?  I've never gone below 49.2volt before the PV starts producing power again in the morning. But what is my DOD to go from basically 54V to 49.2V?

 

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Hi Jaco do you have a bmv battery monitor. The infini SOC is not correct. It is also base on voltage

Sent from my SM-G920F using Tapatalk

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6 minutes ago, Jaco de Jongh said:

Thanks Manie & Viper, I have just send him a PM, hope he will have some good news in his reply.

No problem, next to look at is the battery balancers just as important especially on parallel banks. 

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7 hours ago, Jaco de Jongh said:

1: Bulk Charge at 59.3Volt (My Infini can only handle 58.4V)

Note the difference between the T105 and the T105RE. The RE has lower absorption voltages. It's a common topic of discussion around here about how the Voltronics cannot deal with Trojan batteries (can't go high enough to do an equalisation charge).

When you quoted a price of under 15k for 8, I knew it was probably the non-RE model :-)

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@plonkster Sorry sir, I am looking at this data sheet http://www.trojanbattery.com/pdf/datasheets/T105RE_TrojanRE_Data_Sheets.pdf 

The T105 RE datasheet shows a 0.02V lower requirement than the T105's requirement for bulk charge and the float charge is the same at 54V. Even with RE's my unit can still not reach that value.

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Mmmmh it appears I made a mistake. I had a bank of T125 batteries at some point, and I remember I had to charge them at 29.6V (on my 24V bank). So through a lot of back and forth over time, always because people with Chinese inverters have voltage troubles, I came under the impression that it is specifically the golf-cart battery (the non-RE model) that was affected. Seems I was wrong.

If the spec indicating 2.35-2.45V per cell is correct, then any voltage between 56.4V and 58.8V will do. So just set it as high as it will go.

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Seems I also missed that sheet you got with the same charging spec as the T105 RE.
I don't charge mine at maximum I use that basically as a range to set it according to temp.
So in summer I set mine to the lowest and in Winter at the higher end of the range.
What I have found is at the lower settings you use way less water as less gassing occurs.

Jaco the difference between the two is that the RE batteries use another 2kg of lead for thicker plates.
The RE also gives you about 1000 more cycles at the same SOC 80% and 70% and around 500 down at 50% SOC.
Also these changes

The Premium Line features:

  • Alpha Plus® Paste with T2 Technology™ which optimizes porosity development in the active material enabling the active material to be used more effectively. This results in sustained battery performance over a longer period of time.
  • DuraGrid™ Design provides a thick grid structure that resists corrosion, and when combined with the Alpha Plus Paste with T2 technology, increases overall battery life.
  • Maxguard® XL Separator is exclusively available in Trojan’s Premium and Industrial lines. It features a wide-channel design which increases acid flow for optimum battery performance, and provides even greater resistance to stratification, a typical mode of failure in batteries used in renewable energy systems.
  • The Polyon™ container is Trojan’s ultra-rugged case design which protects against damage caused by harsh environmental conditions, such as moisture and dirt buildup, and safeguards against potential acid leaks.
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31 minutes ago, Jaco de Jongh said:

Viper_za, that part I could figure, estimated 5 years compare to estimated 8 years. My concern was regarding the so called difference in charging current requirements.

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Yeah they seem to be the same on the charging side. Only thing is the RE can take a bit more abuse with the thicker plates and other add-on's like smart carbon etc 

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By way of clarity. I also have 2 spec sheets for the T-105RE. The one is clearly stating a 54V float for a 48V bank and the other states 2.20V. Which is right? The former is a recent download.

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  • 2 months later...
On 7/29/2016 at 4:02 PM, Gerald_db said:

 

By way of clarity. I also have 2 spec sheets for the T-105RE. The one is clearly stating a 54V float for a 48V bank and the other states 2.20V. Which is right? The former is a recent download.

 

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That's a good question. Can you share the documents  or links to the spec sheets?

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The T-105RE had its SG increased a few years ago with a corresponding increase in the various voltages. 54V is the correct float voltage. The lical agents were still issuing the old spec sheet. The one on the trojan.com website is correct.

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Here is the latest T105RE doc I have. 

Absorption charge: 2.35-2.45 = 7.05-7.35v per batt: 48v = 56.4-58.8v
Float charge: 2.20 = 6.6v per batt: 48v = 52.8v
Equalize charge: 2.58 x 3 = 7.74v per batt: 48v = 61.92v

If you have temperature compensation even better: Subtract 0.005 volt per cell (VPC) for every 1°C above 25°C or add 0.005 volt per cell for every 1°C below 25°C.

T105RE_TrojanRE_Data_Sheets.pdf

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