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diy solar

Is my new battery charger defective?

The battery will be above 99% at 13.7V. Based on the comments above, this is quite adequate and 14.4V is too high.

The battery maker listed 13.8V, I am afraid to go higher.

Yeah, there's very little extra kW/h to gain once you arrive to the upper knee in the charge (SoC) curve, many people only charge into the 90-ish percentile range to extend cell life. I've heard several here on the forums who even only cycle 20%-80% to get more years out of their banks...
 
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Don’t know why you want to hang on to a defective charger.

Your battery won’t get a full charge at 13.8V.
14.4V bulk is perfect for your battery.
… if you want to squeeze the last 3% into it.
 
… if you want to squeeze the last 3% into it.
The point is that the charger is defective.

How long will it take to charge to 13.7V? The last section will be a trickle charge. It would be insane to do that with a generator.
 
The point is that the charger is defective.

How long will it take to charge to 13.7V? The last section will be a trickle charge. It would be insane to do that with a generator.

Wouldn't that depend on what stage the charger is on in the charge cycle?

Before I would suspect a faulty charger, I would maybe put on an oscilloscope, a voltmeter that can read across time, or even just a normal voltmeter (if I could stay there and monitor it through a complete charge cycle), bring the battery down, and start charging, watch the voltages as it comes back up, and confirm if it behaves properly (charges bulk CC, and flips to float CV).

Because isn't it possible that when he is observing the 13.67v that the charger has already flipped over to float stage, at the done with the bulk charging phase? Then can pull off the charger and see where the voltage settles at.

Some of these chargers even have trim pots inside them on the boards that can be tweaked by advanced users to fine tune float or whatever. I know on my IOTA charger there is such trim pot, I can tweak final CV stage voltage. But if it's already within a good spec where I want it to settle then I wouldn't worry about it. Doesn't mean a faulty charger though, just means I can tweak it if desired (if it wasn't set consistently with other units on the line, from the factory).
 
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Because isn't it possible that when he is observing the 13.67v that the charger has already flipped over to float stage, at the done with the bulk charging phase? Then can pull off the charger and see where the voltage settles at.
No, not possible. The OP stated voltage reached 13.67V and stayed there. The charger NEVER got into bulk. And... 13.67 is not a specified float voltage. He also tried AGM mode with no change in output voltage. The charger is defective. I would not trust it.

It's highly improbable you'll see anything abnormal with an oscilloscope. Another voltmeter could confirm initial readings.
 
No, not possible. The OP stated voltage reached 13.67V and stayed there. The charger NEVER got into bulk. And... 13.67 is not a specified float voltage. He also tried AGM mode with no change in output voltage. The charger is defective. I would not trust it.

It's highly improbable you'll see anything abnormal with an oscilloscope. Another voltmeter could confirm initial readings.

One wouldn't know unless they had watched the entire charge cycle with amps and volts monitoring. Bulk is CC, so it would hold the amps constant, volts may come up after some time to specified number, and when it arrives at xx volts, it signals switch to float CV (holds voltage), and lets the amps balance in until no more current flows at that voltage.

So without watching an entire charge cycle while monitoring, then it can only be implied that it didn't do its job if we're only going off of a couple sample-points given by the OP. A scope reading both amps and volts could capture a larger sample of the charging cycle behavior in order to arrive to a more specific conclusion.

I'm not saying you're not correct, but we don't know if that is what is occurring here without collecting more data.

If he really thought the charger was not right, then could exchange it for a replacement of same model, and observe the behavior of that one. I agree that if it is only floating the whole time, it could take a long time to charge a battery (if it isn't able to do bulk CC for the first majority of the charge cycle), but we don't have enough data to know if that is what is happening here.

If he has an amp-clamp he could measure current as well as voltage and watch it on charging, to help decide if bulk is working right.
 
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Very good comments, thank you.
The LEDs on the charger indicate the status: the Bulk and the Float stage. The batteries settled at about 13.5V a few hours after the float stage disconnect and I am watching the self discharge, the drop was about 0.03V for two units and 0.05V for the third, in 22 hours.

I plan to discharge and the charge using the charger while monitoring the voltage closely. I have a scope (not a fancy one) but I do not see how it can be of use here. I also have a DAQ but the task or re-loading software and configuring it is not something I want to do at this time.

While I do not intend to float the batteries with this charger the drop of 0.17V upon the disconnect from the charger bothers me. One's battery slightly faster self discharge - likewise. I will be testing further.

Thank you again.
 
And here is how my story ends: I spent all morning configuring the DAQ device to log the battery voltage and the charging current (as a voltage drop across a calibrated shunt, on the negative terminal of the battery). When all was ready a loose wire from the "+" terminal accidentally touched the DAQ and fried it. Stupid me. Thus I started charging from the SOC 40% and watched the battery voltage on the shunt-connected battery monitor (That shunt drops about 40mV at 50A charging current. The presence of the drop explains why the battery reached the excessive voltage of 14.56V).

The battery voltage reached 14.56V and at this point the charger went into the floating stage.

The voltage started dropping, the monitor was showing 0.20A going back into the charger. When the voltage reached 13.68V the current dropped to zero. This must be the true floating voltage of the charger. I disconnected the charger, V stayed at 13.67V. The self-discharge started.

I think, I'd rather have this float at 13.7V, not 14.4V as promised in the charger's manual. As I have seen, the voltage eventually drops to 13.5V and stabilizes there. Indicating the 99% capacity. I am OK with loosing 1%.

Thank you for your helpful comments.
 
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