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Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 08:07am 23 Sep 2006

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Hiya guy's
I recently got another 24 batteries for connecting up to my house array they are 2 volt 275 amp/hour and I'll hook them up in 2 arrays of 24 volts to suit my sa32 selectronic sinewave inverter. Now my house array is already setup with 14 kaneka thin film panels going thru an Aerl-900b mppt into 12 600amp/hour sonnenschein batteries. I'll also be buying 4 175 watt solar panels to add to my solar array but I won't be able to put the extra panels thru the mppt as it will be more than the rated spec's. Now I'm thinking of setting the new array up as a seperate unit and just connect the new battery array at the inverter input and install a throw switch so I can charge either battery array via my 80 amp staff& stanbury battery charger.

Now by hooking up the batteries at the inverter input a good solution or a bad one guy's as I don't want to stuff anything up.

Cheers Bryan

RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 09:12am 23 Sep 2006

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Hi Bryan. A little unsure of exactly what you've got there. It's bad form to hook new and old cells together, and even worse to hook dissimilar cell types (eg, flooded cells and VRLA) together. Different chemistry and/or characteristics, you end up with some drawing all the current and others getting nothing.

If you plan to hook them all together at the inverter, how can you tell which ones will get charged? They will back-feed at the interconnect point at the inverter.

(I have a similar problem - my old bank of 220 AH flooded cells, and my new VRLA 500AH cells - not only different capacity and different ages, but different chemistry).

Currently, I'm keeping the old 48V/220AH bank for backup. As flooded cells, its easy to check the SG with my trusty hydrometer. (Not so easy with glassmat/VRLA!). I've got the big bank hardwired to the 10KW inverter, and use a large DPDT switch to use RE to charge either bank, depending on need. Usually, that's the VRLAs, and just maintenance/topup charge for the others. I haven't worked out yet a good way to switch banks, as the inverter has a quite different setup for flooded cells.

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 09:56am 23 Sep 2006

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Hiya Ross,
Well mate both the sonnenscheins and the new batteries are both agm ones and about the same age or within 6 months. The new batteries were on a ups telstra system that never went into backup mode so their in asnew condition. The idea is to hook up a seperate array with the 175 watt panels in parrallel and I will have a spare plasmatronics solar charge controller rated at 24 volts. Now my idea of hooking the batteries at the inverter each bank should share the current used from the inverter and thinking when I run the charger as the batteries are connected at the inverter I wont need a throw switch

Cheers Bryan

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