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Forum Index : Solar : Odd Battery question trojan battries.

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Old Seagull Man
Newbie

Joined: 21/12/2019
Location: Australia
Posts: 29
Posted: 11:22am 15 Oct 2020
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my neighbor has a small battery bank on hobby farm.

Its consists 8 trojan t105 batteries. all new.
But he finds that when he charges them up, the first and the last battery, as he put it dont have any go.

So i dropped in on the weekend and checked all the wiring and the settings on the charge controller. all as the manual says they should be.

So checked the specific gravity of all the batteries and shore enough, battery 1 and battery 8 were around 1.12 and  6.12 volts all the other batteries around,   1.26 and 6.5 volts. i have suggested he swap  the order of the battery's, and try again. and see what happens.

Any ideas?
 
Solar Mike
Guru

Joined: 08/02/2015
Location: New Zealand
Posts: 685
Posted: 11:39am 15 Oct 2020
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Sometimes the end batteries run slightly cooler and this will affect their charging, relative to the others. If the 8 batteries are bumping up against each other the inner ones have less surface area to dissipate heat.

Try placing them in a rack off the ground with an air gap between them, so they all get good air flow for equal cooling. Also make sure your charger has a battery temperature sensor, so they get the correct charge rate.


Cheers
Mike
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 3402
Posted: 07:28pm 15 Oct 2020
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Excellent advice Mike.
If an off the ground rack is just not possible, at least sit each battery on a thick piece of wood so its not in direct thermal contact with soil or concrete.
Cheers,  Tony.
 
Old Seagull Man
Newbie

Joined: 21/12/2019
Location: Australia
Posts: 29
Posted: 02:04pm 16 Oct 2020
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Thanks for the thoughts guys.

The battery's sit on steel shelving inside a large shed.
And have the controllers temp probe connected to the case of the third battery in the set.

All the joining cables are the same length and same cable.

Next time i visit i will take a 12v charger and see if i can get the odd two to charge.
As i don't have a 6 volt charge to do them one at a time.

So no luck so far
 
Revlac

Guru

Joined: 31/12/2016
Location: Australia
Posts: 367
Posted: 02:30am 17 Oct 2020
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I had a similar situation once, 4 12v batteries on a 48v system and 2 of them were low.
An easy fix, was to connect a car head light on each of those that were high, just to knock the voltage down a little, the charge controller would then push the other 2 up, did this for a day and its been good ever since.

It was easy me to do that than lug the Heavy charger up to the shed.
Cheers Aaron
Off The Grid
 
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