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Old 17-12-2017, 14:25   #1
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Trojan T105 Charging Efficiency

For various reasons Iíve come to believe I have the battery charge efficiency set too low on my battery monitor. What are others using for T105 charging efficacy?
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Old 17-12-2017, 15:13   #2
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Re: Trojan T105 Charging Efficiency

I've found that charging efficiency varies depending on where you are on the SOC. I've found that between 85 to 100% SOC the CE is pretty high, above 90%. As you go down the SOC the CE drops. at around the 50-60% SOC the CE is about 60%.

It's tough to get it exact but knowing where you cycle your batteries in their SOC range can help. I initially had my CE set at 90 and that was too high. Set it to 75 and that was too low. I'm now at 80 and I think that's too low still, but getting closer.
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Old 17-12-2017, 15:59   #3
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Re: Trojan T105 Charging Efficiency

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Originally Posted by sailorboy1 View Post
For various reasons Iíve come to believe I have the battery charge efficiency set too low on my battery monitor. What are others using for T105 charging efficacy?
I asked Trojan when I couldn't find it online or on their data sheet for the T105s.

Their response was:

Charge Efficiency Factor = 89%

I have kept the Charge Efficiency Factor set at 89% on my Magnum monitor/controller for the last 3.5 years [since this bank was new...] and I haven't noticed any adverse affects.

On a somewhat related note, I also learned the T105 Peukert Exponent = 1.24 [I don't recall if this was from Trojan or another credible source...]

I am unaware of any way to apply the Peukert exponent value using the Magnum controller.

In case this is useful.

Cheers! Bill
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Old 17-12-2017, 16:09   #4
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Re: Trojan T105 Charging Efficiency

I’ve seen that 89% thing before and think that’s what currently have programmed. But I think it may be too low for how I’m overall operating my system. I came across something from Trojan that said new batteries may be 96%.

I don’t what a debate, just wonder what others are using.
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Old 17-12-2017, 16:25   #5
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Re: Trojan T105 Charging Efficiency

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Originally Posted by kenbo View Post
I've found that charging efficiency varies depending on where you are on the SOC. I've found that between 85 to 100% SOC the CE is pretty high, above 90%. As you go down the SOC the CE drops. at around the 50-60% SOC the CE is about 60%.

It's tough to get it exact but knowing where you cycle your batteries in their SOC range can help. I initially had my CE set at 90 and that was too high. Set it to 75 and that was too low. I'm now at 80 and I think that's too low still, but getting closer.
I would have thought the opposite. It really takes a long time to get from 80% SOC to 100% SOC. The acceptance drops way off. Maybe Maine Sail will let us know for sure. He's the guru on that sort of stuff--------and just about anything else boat related. His web site: https://marinehowto.com/
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Old 17-12-2017, 16:41   #6
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Re: Trojan T105 Charging Efficiency

Charge efficiency is a number that can be measured two ways:

By the Ampere-hr, this number is quite high, 95 to 98 is not an unusual average.
---or---
By the Watt-hr, this number is lower, 90% or a little lower is typical.

What's the difference? If you measure Ampere-hrs going in and Ampere-hrs coming out you are ignoring the fact that the charging voltage is higher than the discharging voltage. So 1 Amp-hr at 14.4 volts (14.4 Watt-hrs) during charging has more energy in it than 1 Amp-hr at 12.8 volts (12.8 Watt-hrs) during discharge even though your amp meter counts them the same.

This is likely one significant reason you get such very different numbers for this value when you talk to different people. Whenever someone quotes a battery charge efficiency, be sure they specify which measurement they are talking about, and if they don't know the difference, you will want to talk to someone else.

For programming your Amp-hour meter, the Amp-hour efficiency is the one to use. For really evaluating the energy efficiency of the batteries the Watt-hr number is more important.
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Old 17-12-2017, 17:51   #7
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Re: Trojan T105 Charging Efficiency

Just interested what value others are using.
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Old 17-12-2017, 18:01   #8
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Trojan T105 Charging Efficiency

Quote:
Originally Posted by billknny View Post
Charge efficiency is a number that can be measured two ways:

By the Ampere-hr, this number is quite high, 95 to 98 is not an unusual average.
---or---
By the Watt-hr, this number is lower, 90% or a little lower is typical.

What's the difference? If you measure Ampere-hrs going in and Ampere-hrs coming out you are ignoring the fact that the charging voltage is higher than the discharging voltage.


That is interesting, I learned something. Never thought about it.
Another reason why I hate amps, and wished we used Watts.

My Magnum ME-MBK that I just installed this week, has an Auto setting where is supposedly computes it every time you get to 100% SOC. I believe it determines 100% SOC based on charge voltage and trailing amps.
It has turned out to be more useful than I had hoped cause you can set constant current / constant voltage charging to terminate at a set number of amps in to the bank, for my 660 AH bank I have it set to terminate absorption and go to float at 3 amps. Iíll se tomorrow if it works like it should.

So far based on last two days, it takes 7 hours in absorption to get to 3 amps in when bank is discharged only to about 80% SOC.
Iím curious to see how well the Smart Gauge tracks with the Magnum, especially if it actually auto resets itself every time 100% SOC is achieved, although I can see if a full 100% is not obtained how that could compound errors.
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Old 17-12-2017, 18:16   #9
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Re: Trojan T105 Charging Efficiency

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Originally Posted by a64pilot View Post
That is interesting, I learned something. Never thought about it.
Another reason why I hate amps, and wished we used Watts.

My Magnum ME-MBK that I just installed this week, has an Auto setting where is supposedly computes it every time you get to 100% SOC. I believe it determines 100% SOC based on charge voltage and trailing amps.
It has turned out to be more useful than I had hoped cause you can set constant current / constant voltage charging to terminate at a set number of amps in to the bank, for my 660 AH bank I have it set to terminate absorption and go to float at 3 amps. Iíll se tomorrow if it works like it should.

So far based on last two days, it takes 7 hours in absorption to get to 3 amps in when bank is discharged only to about 80% SOC.
Iím curious to see how well the Smart Gauge tracks with the Magnum, especially if it actually auto resets itself every time 100% SOC is achieved, although I can see if a full 100% is not obtained how that could compound errors.
That looks real useful. Much better than going to float too soon.
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Old 17-12-2017, 20:21   #10
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Re: Trojan T105 Charging Efficiency

I am using 87% for Energizer GC2s as recommended by the manual and I also believe it is too low. I have been thinking to measure the actual SOC change with a hydrometer and get a specific value for my setup.

By the way, keep in mind that aging batteries appear to "charge" faster, so the charging efficiency changes with age. If you are really concerned about the accuracy, you need to calibrate for your own battery.
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Old 18-12-2017, 07:01   #11
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Re: Trojan T105 Charging Efficiency

So, I changed mine from 90% to 94%.
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Old 18-12-2017, 07:04   #12
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Re: Trojan T105 Charging Efficiency

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So, I changed mine from 90% to 94%.


Which is likely to cause you to undercharge.
I assume you have decided that you were overcharging based on water consumption, or specific gravity?
Donít shoot the messenger, just wondering the train of thought that got you to believing your actual SOC is higher than displayed?
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Old 18-12-2017, 07:22   #13
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Re: Trojan T105 Charging Efficiency

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Originally Posted by sailorboy1 View Post
Iíve seen that 89% thing before and think thatís what currently have programmed. But I think it may be too low for how Iím overall operating my system. I came across something from Trojan that said new batteries may be 96%.

I donít what a debate, just wonder what others are using.
Focus on the part that begins at Coulombic Efficiency.

Making Your Battery Monitor More Accurate
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Old 18-12-2017, 07:29   #14
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Re: Trojan T105 Charging Efficiency

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Which is likely to cause you to undercharge.
I assume you have decided that you were overcharging based on water consumption, or specific gravity?
Donít shoot the messenger, just wondering the train of thought that got you to believing your actual SOC is higher than displayed?
Maybe, but of course you are just making up your assumption. It was a simple crowd sourced question that had no right answer, just a simple "what are you using".
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Old 18-12-2017, 07:35   #15
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Re: Trojan T105 Charging Efficiency

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Originally Posted by Maine Sail View Post
Focus on the part that begins at Coulombic Efficiency.

Making Your Battery Monitor More Accurate
Thanks, but that was just a discussion on the topic and that wasn't the question.

So Maine Sail, what do YOU have (had) your CEF set to?
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