Trojan T105 Batteries – First real test

[centro]

About a month ago we bough 2 x 6v Trojan T105 deep cycle batteries to use as replacements for a 115ah Leisure battery.

We have just given them their first real test at Hop Farm Festival over the weekend. We left Portsmouth last Thursday at noon with the batteries at 100% charge and the the fridge cooled from mains hookup. The fridge — which is a Weaco 70w was left running until midnight on sunday at which point I switched it off as we were going to leave the site the next morning.

The drive home from Kent to home was about 2 and a half hours, so the batteries got a top-up from the split charge relay. I have taken a reading with a multimeter today (Wednesday) and the batteries are still 85% charged.

[pmoc_2001]

Nice! It's a good feeling is'nt it when you know your beer will remain cold and bbq meat fresh over a weekend. It's one less thing to worry about. Get a nicly sized solar pannel and you could last alot longer.

[California Dreamin]

And what was the state of charge before you set off back home?

This is the reading you really need as you have no idea how much charge was put back in from the drive home.

Martin

[ghost123uk]

I wonder what the time on v time off (thermostat) of a fridge like that is ?

70W = 5.83 amps @ 12 Volts and fridge was on for aprox 72 hours = 420 Ah so the fridge must only be "on" for perhaps ~20% of the time to be still running after 72 hours.

Mind you, it is a good result anyway, running a fridge off batteries for that long
MInd you, for £270 they should be good

Where have you fitted them ?

[California Dreamin]

I am always concerned about the work the alternator in doing trying to charge such high capacity batteries from a low charge state....I guess the brush pack and slip rings must get a bit of a hammering given that they would be at a higher level of charge for much longer periods than they were initially designed for.

Martin

[ghost123uk]

Yeh, I wonder what current is taken by a pair of Trojans like that which are fully discharged ? Most lead acid batteries are not happy charging with more than around 20% of their rated capacity. In this case that is 45 amps. I don't know what a fully discharged battery would draw but if the source (alternator in this case) is capable of more than 45 Amps it may be an issue. These batteries are primarily designed as traction batteries and as such would normally be charged from a current controlled external charger.

I use a 7Ah Gell Battery for firing up my model aeroplane engines. These must not be charged at more than ~10% of their rated capacity. To limit the charging current from the van (it is on permanent float charge in the van, ready for use), I put a 5 Watt bulb in series with it. This keeps the initial input below 1/2 Amp. I know "we" like to get our big leisure batteries up to charge quickly but I wonder if some sort of current limit might be called for to protect the investment.

[ringo]

I am always concerned about the work the alternator in doing trying to charge such high capacity batteries from a low charge state....I guess the brush pack and slip rings must get a bit of a hammering given that they would be at a higher level of charge for much longer periods than they were initially designed for.

Martin

Lets see if the guys that have installed stirling chargers suffer... They make the alternator work a hell of a lot harder.

Ringo

[centro]

And what was the state of charge before you set off back home?

This is the reading you really need as you have no idea how much charge was put back in from the drive home.

Martin

Good point. I didnt check that as I wanted to get home after 5 solid days on the pop

I wonder what the time on v time off (thermostat) of a fridge like that is ?

70W = 5.83 amps @ 12 Volts and fridge was on for aprox 72 hours = 420 Ah so the fridge must only be "on" for perhaps ~20% of the time to be still running after 72 hours.

Mind you, it is a good result anyway, running a fridge off batteries for that long
MInd you, for £270 they should be good

Where have you fitted them ?

Its a compressor fridge - Doesnt run constantly. Trojans are installed under the rear seat

[California Dreamin]

I am always concerned about the work the alternator in doing trying to charge such high capacity batteries from a low charge state....I guess the brush pack and slip rings must get a bit of a hammering given that they would be at a higher level of charge for much longer periods than they were initially designed for.

Martin

Lets see if the guys that have installed stirling chargers suffer... They make the alternator work a hell of a lot harder.

Ringo

From experience I know that the brush set and slip rings wear considerably faster on a vehicle with split charging or anything really that consistantly loads the alternator......I suppose that makes sense as there is increased spark/contact errosion with the higher and more sustained loads going through the rotor.
At £12 a pop, it certainly wouldn't be a bad idea to carry a spare regulator brush pack and I did notice on a recent link a 'heavy duty set' is available.

Martin

[lloydy]

I am always concerned about the work the alternator in doing trying to charge such high capacity batteries from a low charge state....I guess the brush pack and slip rings must get a bit of a hammering given that they would be at a higher level of charge for much longer periods than they were initially designed for.

Martin

Lets see if the guys that have installed stirling chargers suffer... They make the alternator work a hell of a lot harder.

Ringo

This could well be the case, but.... my sterling is 50amps and my alternator is 120amps, so my understanding is that it will cause no stress at all to the alternator. Some of the bigger sterlings may cause an issue long term, but they do have temp sensors to monitor battery and alternator temps which shut the sterling down if they get too hot.
As for the trojans, i thought the idea was not to charge them on the move as they don't like the small amount of power a alternator will put into them (shorten life) and that you didn't need to charge them for weeks/months? I have two 80AH leisure batteries, i've spent a whole weekend stationary, running a compressor fridge, stereo going most of the day and lights in the evening. My battery voltage dropped by .55volts, a two hour drive home fully recharged them.
I really like the idea of these trojans, but would like to see some data from not charging them, leaving your fridge plugged in, and just normal electrical use like charging phones ect. At the moment it doesnt seem to dissimilar to standard leisures? Shame if that is the case, as they show a lot of promise

[California Dreamin]

I can remember a similar thread to this some months back and the almost super human qualities of Trojan batteries. Good as they undoubtedly are, a rated output is a fixed specification, Trojan batteries aren't somehow sprinkled with pixie dust so the user can take their specification as merely heresay and add 500% as being somewhere close lol.
Quote about the legend that is Trojan that you didn't need to charge them for weeks/months?

They do have some very impressive features: extreme deep cycle recovery characteristics, high capacity combined with relatively small size..they are very good, as good as their quoted output infact.

Martin

[bigherb]

Well put Martin. I did start writing something similar but couldn't be arsed in the end.

[pmoc_2001]

Nice! It's a good feeling is'nt it when you know your beer will remain cold and bbq meat fresh over a weekend. It's one less thing to worry about. Get a nicly sized solar pannel and you could last alot longer.

Jinxed my fridge. Bloody thing would not start yesterday. Compressor is simply not starting (not even starting and stopping as is the case with low voltage or voltage drop). Checked voltage to wires and connected direct to known good battery and other fault finding still no luck. These things (Danfoss compressors) are pricey so well gutted.

[pmoc_2001]

Solved! Broken Thermostat

[centro]

Trojan batteries aren't somehow sprinkled with pixie dust so the user can take their specification as merely heresay and add 500% as being somewhere close lol.
Quote about the legend that is Trojan that you didn't need to charge them for weeks/months?

Im under no illusion that these batteries are made of magic. I did my research based on my needs and Trojans suit me.
Im sure someone who only uses a leisure battery for their 12v lights and other low power consuming items could go months without charging them, but im running a 70w compressor fridge and will no doubt have to charge them more often. I want to run my fridge for a good 4 or 5 days at festivals or when im wild camping, and from experience, no 115ah leisure battery can do that too often and recover from from such heavy drainage.