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Topic: How do you know when it's time to replace your Trojan T105 house batteries? (Read 743 times) previous topic - next topic
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Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #25 –
Thanks. I still do not really understand the Volt & Ampere game, but your post makes it a little  clearer. That’s great.

 Yes, the third symbol is for the loads - and I have right now two Fantastic fans running, and the inverter is turned on (I basically leave it always on when I’m on the road and the rig is not connected to shore power).
 
Klaus
2001 26.5 Mid-Bath
 
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #26 –
Quote from: Klaus  - 

Can you (or someone else) tell me what this means in regards to my batteries? Are they good, kind of ok, or getting weak? Thanks!

This display is showing how your solar panels are charging your batteries. It is not showing you the state of charge or condition of your batteries. A battery monitor would help you do that. But load-testing is really the only way to know.

Charles
Harvest Hosts + Boondockers Welcome #23975
Escapees SKP #138195
2007 23.5' Twin King
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #27 –
With your 12V system, it is pretty simple:

Volts X Amps = Watts

Your Maximum Power Point Tracking solar charge controller will keep the output power very close to the input power.

Steve
2004 FL
2013 Honda Fit
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #28 –
Quote from: Charles and Donna  - 
This display is showing how your solar panels are charging your batteries. It is not showing you the state of charge or condition of your batteries.
Thanks. Why is the charge controller monitor showing 12.9 or 12.6 Volts below the battery symbol at night when it is supposedly only showing the charging but not the charge?  Since there is no charging happening at that time it shows 0 (zero) below the solar panel symbol. That I understand. But I don’t understand the Volt number below the battery symbol - what could that be if not the state of charge? I really would like to understand this, if possible.

Klaus
2001 26.5 Mid-Bath
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #29 –
That is the battery voltage, which IS an indicator of state of charge, assuming you know the battery temperature and have a chart to correspond those data points to the state of charge for a lead-acid battery. A true battery monitor will monitor the current to and from the battery and integrate to get charge in and out of the battery. It will also compensate for the inefficiencies of the battery chemistry, and temperature effects, to give an accurate assessment of state of charge. Battery charge is measured in Amp-hrs, so knowing the charge condition relative to full charge (~225 A-hrs) will give you a better idea of where you stand than trying to roughly infer it from battery voltage.

Steve
2004 FL
2013 Honda Fit
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #30 –
Quote from: Klaus  - 
Thanks. Why is the charge controller monitor showing 12.9 or 12.6 Volts below the battery symbol at night when it is supposedly only showing the charging but not the charge?  Since there is no charging happening at that time it shows 0 (zero) below the solar panel symbol. That I understand. But I don’t understand the Volt number below the battery symbol - what could that be if not the state of charge? I really would like to understand this, if possible.

Klaus
OK. You're making me do some homework. ;) First, I've never encountered this unit. I see it is a remote display for a series of MPPT charge controllers. I found the user manual online. The battery icon is variable and shows a crude estimated state of charge. The Volt and Amp numbers below the battery icon are the charge voltage and amperage being delivered to the battery. When there is no charging occurring the voltage displayed is the battery voltage from which you may determine its state of charge as Steve pointed out. None of these numbers tell you the condition or capacity of your batteries.

Charles
Harvest Hosts + Boondockers Welcome #23975
Escapees SKP #138195
2007 23.5' Twin King
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #31 –
Quote from: Klaus  - 
at 9 pm it will show between 12.9 and 12.6 Volt (using some lights, keeping my laptop and my mobile hotspot charged, having the 1500 Watt inverter on), and tomorrow morning - before using anything, just having had the inverter on over night - it will show 12.3 or 12.2 Volt (I had once only 12.1 Volt).

Can you (or someone else) tell me what this means in regards to my batteries? Are they good, kind of ok, or getting weak?

Good chance your batteries are on the downhill slide. That much voltage drop, overnight is a bad sign unless your inverter is drawing an excessive amount of power for some reason, you don't have the refrigerator on 120-VAC power, do you?

Is there some reason why you leave the inverter on at night? It uses some power just idling.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #32 –
"Is there some reason why you leave the inverter on at night? It uses some power just idling."

Isn't it always on? In fact, I couldn't tell you how to shut it off. Guess I could open the panel and look.

Chris
Formerly: 2002 30' IB
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #33 –
All inverters I've seen have an on/off switch. The ones that are also converters and battery chargers still have a way to turn off the 110vAC outputs to the coach. As battery chargers they are expecting shore power or generator power input. As converters they act like other converters and apply a 12v DC to the coach either from the batteries or shore/gen power.  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #34 –
Thanks for all your answers.

Steve and Charles: I start to understand the general workings of this better.

Larry: One reason I left so far the inverter on at night is a 3 Watt LED lamp with a 110 Volt AC adapter. It's my bedtime reading light; it makes a very beautiful light. Another reason are my mobile hotspot charger and the hotspot booster; they are both connected to 110 Volt. Pure convenience. Last night I turned everything off (including the 1500 Watt Samlex inverter which has like the charge controller a remote control unit inside the RV) before turning in. After that I had 12.4 Volt on the charge controller display and 12.42 Volt at the converter board - and I had exactly the same values 9 hours later in the morning before using any lights or other devices. I will now always turn everything of at night and check the voltage then and in the morning for a while - and I guess my batteries will still make it for some time.

Klaus
2001 26.5 Mid-Bath
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #35 –
Hi Klaus. Your Samlex inverter's idle current with low or no load on it is listed at 1 amp.. That is it consumes for itself about 12 watts per hour that it is on. At 85% efficiency it takes 15% just to run itself.  This is typical really, and would be useful for running the microwave, and other power consumers for short amounts of time.
     The way to have small 110v AC items powered is to use small inverters. I bought two small 75 watt inverters for $20 awhile back.  I use them to power chargers, (cell phone and whatnot) and my AC TV. Running the TV takes about 20 watts depending on how bright the screen is and how loud the volume is set. Idle currents are low, in the 2 watt range or lower. I don't leave them on longer than necessary.   (2 watts is less than 200 ma.)   That is about the current of a small LED overhead light.     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #36 –
Klaus,

For reference, when a 6-volt battery is fully charged it has an open-circuit voltage of 6.37 volts after resting for at least 6 hours or more. For your two-battery arrangement the fully charged voltage would be 12.73 volts. However, unless you measure each battery separately, you won’t know if either battery is fully charged. Your voltage reading of ~12.4 volts in the morning means that your battery system is down to roughly a 70% state of charge. Just curious, does the MT50 battery icon show this approximate reduction?

Charles
Harvest Hosts + Boondockers Welcome #23975
Escapees SKP #138195
2007 23.5' Twin King
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #37 –
Quote from: Klaus  - 
Larry: One reason I left so far the inverter on at night is a 3 Watt LED lamp with a 110 Volt AC adapter. It's my bedtime reading light; it makes a very beautiful light. Another reason are my mobile hotspot charger and the hotspot booster; they are both connected to 110 Volt.

Check the LED's adapter, many LED bulbs run on 12-volts. You may be able to wire it directly to a 12-volt supply and eliminate the adapter.
Both our old hotspot and present cell booster use 12-volts, you may be able to find 12-volt adapters and eliminate having to use the inverter.
Most of the accessories used in RVs can be found in 12-volt versions, rather than 120-VAC.
We only use our small inverter to change our electric toothbrushes and bike batteries, neither of which have available 12-volt chargers. Everything else runs on 12-volt power.
12-volt power is our primarily energy supply for electronic and electrical appliances, every time power is converted from one form to another, a certain percentage is lost to inefficiency .

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: How do you know when it's time to replace your Trojan T105 house batteries?
Reply #38 –
Hello Everyone, Great discussion.  Original owner of our 2008 26 1/2 with no solar.  The Trojans are still doing the job but I think I might be pressing our luck.  Back and forth on replacement-Lithium, AGM, or stay with the 105s.  No real changes in our future as to our RV routine.  Not wanting to get into converter change and rework. This discussion has helped me decide that the best course of action is to stay with the 105s.  I have always used the Profill so upkeep has never been a problem.  Thanks again for your help and if you think I might have missed something just let me know.

Bill
Bill and Linda Hicks
2008 MB