Problems with new batteries

palausystem · July 2016

I recently replaced my aging Surettes with US Battery RE L16 XC's. I topped off the water when I got them 6 months ago.

Problem is I can't do an EQ. When I set the controller voltage as high as it will go, the batteries reach that voltage fairly quickly and the amps then drop of quickly. The batteries also don't seem to be getting charged up properly (according to SG's) I think for the same reason. And they haven't used up water.

I did a load test with a 1500w blow dryer to see if any of the batteries would drop voltage but they looked fine.

I'm wondering if this has something to do with the batteries not being cycled down. It's been sunny ever since the install and at night we are barely sipping at this oversized battery bank.

Any ideas appreciated

SunnyBoy, Sunny Island, 3.1kW panels, 800 Ah battery

vtmaps · July 2016

If those batteries were brand new, I would say that they need to be cycled a few dozen times before they settle down and behave properly. Try to discharge them at least 25% (down to 75% SOC) before recharging them.

Since the batteries are not brand new (6 months old), I'm not sure what to say... if you have never gotten the SG up to spec in 6 months, there may be some sulfation and the batteries may have diminished capacity.

--vtMaps

Vic · July 2016

palausystem,

What brand and model of Charge Controller are you using?
What are you using for Absorb voltage, Absorb time ( or End Amps setting), and EQ voltages?
What are the SG readings that you are seeing?

Thanks, Vic

palausystem · July 2016

Controller is Sunny Island 5048U.
Absorb time is 2 hrs. Absorb voltage is 2.52. Eq volatge is 2.6
SG's are around 1.250
Sunny Island goes into "boost" mode about every 3 days to do the charging. The rest of the time it's in float.

Vic · July 2016

Hi palausystem,

Your Absorb voltage looks to be in the right range. Veq may be a bit low, but depending on the Depth Of Discharge that the batteries experience, the Absorb time may be too short.

Believe that the target SG for full charge, is about 1.277 SG, IIRC.

What is the purpose of this system? Grid backup, ... or ?
Are you using a Battery Temperature Sensor (BTS)?
What is the Float voltage setting?

Since your batteries do not appear to be getting fully-charged, perhaps you should switch to trying to do a full charge every day, with your present settings, to see if that gets the batteries fully charged.

A reasonable amount of battery charging will occur at the Float voltage, on days where there is no Boost charging.

Thanks for the Signature line. Vic

Problems with new batteries

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