Trojan T105 4 x 6v what voltage reading would you expect (1 Viewer)

PeterCarole29

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Jul 23, 2013
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Hi ,I bought last year new from Tanya Batteries 4 x T105 6 v batteries and have had them in the camper with solar panel and a sterling power 2.5kw pure signwave charger inverter charger is 45amp inteligent.

I have never been happy as they have only read 12.6v sometimes 12.7 when fully charged the charger is set on the correct setting.

What do other people read there Trojan batteries at fully charged.
Many thanks Peter
 

Pugsy

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Hi i have 2x t105s 6v. (2 years old now)
During daily charging(i see this most days as i am just finishing a 5 month trip in portugal) mine charge upto 14.6 then after about 2 hours float charge at 13.5 and when the sun goes down they normaly sit at 2.8 or 2.7.i do have to check the acid levels about every month whilst here as they need a little top up each time.
Cheers cris.
 

pappajohn

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12.6v/12.7v a couple of hours after charging and charger/solar disconnected/switched off sounds OK to me.
If you're reading on the control panel etc try connecting a multimeter direct to the battery bank.
You may be surprised how crap and inaccurate some panel meters are.
 
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12.6v/12.7v a couple of hours after charging and charger/solar disconnected/switched off sounds OK to me.
If you're reading on the control panel etc try connecting a multimeter direct to the battery bank.
You may be surprised how crap and inaccurate some panel meters are.
I have 4 almost new T105 when isolated from charge as above read
12.7 which equates to fully charged I believe .
 

pappajohn

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I have 4 almost new T105 when isolated from charge as above read
12.7 which equates to fully charged I believe .
Yep, that was my point but many control panel meters are, shall we say, slightly optomistic to say the least.
No substitute for a good multimeter which should state its accuracy, unlike the panel meters

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PeterCarole29

PeterCarole29

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Thanks for the replies my other concern that i have,nt tried to address till now is when we first got them they would appear to go down to 11.9 v on a multimeter at batteries when using a 1200w hair drier after only a short time.
I have just looked up and if i am correct my batteries when fully charged are 185ah. Having tested the connection of van meter it reads only .1 difference than the multimeter at batteries.

I want to test them as they are fully charged now.

What is a good test for me to do
 
Jan 19, 2014
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Not too high a drain, like a 10 amp load over a timed period. Maybe if you have an inverter you could plug something appropriate in to get 10a?
A dc clamp meter or battery monitor would be handy.
 
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PeterCarole29

PeterCarole29

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Not too high a drain, like a 10 amp load over a timed period. Maybe if you have an inverter you could plug something appropriate in to get 10a?
A dc clamp meter or battery monitor would be handy.
Hi thanks for the reply. as you have guessed not to technical.
Yes i have the inverter connected and if i am only able to moniter it with the display volt meter would i be looking to plug it in and then see how long it takes for the voltage to drop to bellow 12v
 
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Using the battery voltage to estimate the state of charge can be misleading. The voltage only indicates the state of charge with no amps going either in or out. Even then you need to leave it with no load/charge for an hour or two to let the voltage settle.

Connecting a 1200 watt inverter is exactly the kind of thing to give you a misleading voltage. If the battery is 100% charged, and you connect a 1200 watt load (= 100 amps) the voltage will drop instantly. maybe to less than 12 volts. When the load is removed, the voltage will slowly recover, to indicate maybe 90% charged. So the voltage while the load is running is not a good indicator of the state of charge.
when we first got them they would appear to go down to 11.9 v on a multimeter at batteries when using a 1200w hair drier after only a short time.
See what I mean?
I have just looked up and if i am correct my batteries when fully charged are 185ah. Having tested the connection of van meter it reads only .1 difference than the multimeter at batteries.

I want to test them as they are fully charged now.

What is a good test for me to do
In theory they will give 185/20 = 9.25 amps for 20 hours. So 9.25 amps for 2 hours will take them from 100% to 90%. Check the voltage before and after, allowing time for it to settle.
 

Misterg

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Dec 8, 2017
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4 x T105 6 v batteries

I have just looked up and if i am correct my batteries when fully charged are 185ah

It should be a lot more than 185AH - a pair of Trojan 105s is 225 Ah at 12v, so if you have four of them (2 pairs) your battery bank is 450 Ah at 12V.

P.S. My pair of Trojan T105s , purchased from Tayna last year (May 2018 manufacture) read about 12.65 volts when fully charged and allowed to settle for ~24 hours.

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pappajohn

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To give you an idea what effect a high load can have on instantaneous voltage reading....
A charged starter battery at 12.7v can show as low as 9v while cranking a large engine for a few seconds.
Once you stop cranking the voltage will return to 12.7v or very close within seconds.
A large inverter will do the same but the longer it's running the lower the voltage when it is turned off.
 
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PeterCarole29

PeterCarole29

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Sorry had missed the last few replies. Thanks everyone i feel at lot better now and understand it better and yes i have more amp available than i first said.
 

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