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Battery replacement ???


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Hi Guys,


So currently I am running a 3kw solar system at home.

It is off-line and not connected to the grid.

It is only running during the day. At night, it switches to normal power.


I have some 2nd hand battries I got from a friend some time back. Their work chucked them due to age.

Currently it is 2 banks of 48V each at 100AH per bank.


I was planning on going grid-tied later this year, but now CPT have made me re-think this.


Should I go with 2 strings of 100AH or rather go single string at 200AH?


Max I have seen on my system is 58Amps at 48V, so around 2,8kw.

Also been leaning towards Lead Crystal battries.



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Bosch have a new system using lithium batteries. If I were going this route ( which might be soon ) I would go with a hybrid controller with a gel battery bank - no export to grid only use for charging batteries and when in need importing energy from the grid - I would go with a single string tho.

I think CT Municipality has made a big mistake with it's protectionism of its profit margin over promoting green energy and attempting to get at least 10% of its consumers to go green.

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I've got a small lead crystal battery  (7.2 ah 12 v ) that i use to run an outside light and it worked perfectly so far.

I would like someone to do a proper test on them,maybe Wetkit can be our lab rat.

Wetkit excuse my ignorance but how many and what batteries do you have?


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Clint, I'm currently running a 48V system.

2 strings of 48V, each string 4 x 100AH battries.


When running full load, I can run up to 60Amps @ 48V.


For me it is a question of battery life vs cost.


P.S. This just popped into my brain......

What about capacitors? Guess their storage time is way too sort for solar?

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  • 2 weeks later...

Wetkit - The batteries you currently have is Fiamm- mono lite 100 Amp, if I look at the picture displayed. They are really good batteries as their cycle life is good. I've had 4 x 180 Amp of the same brand and 6 x 100 amp also of the same brand for the last 4 years. They just  don't like cold weather. The cost is not bad and you will get good cycle life out of it, you will just need more than what you have, as you know. 


I have 12 x 110 amps AGM's of a different brand , but the price is not worth the hype and they are not that forgiving.

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Hi Regie,


Thanks for the feedback.


I am still looking at all my available options, but for now it looks like Hybrid grid tied invertor, with feedback blocking, meaning no feedback onto the grid.

This way I can keep my pre-paid meter.

If i buy 600 units every month and only use say 400 units in summer months, the "spare" units will help me in winter again.

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