Trojan L16RE-B batteries poor performance/defective???

90cummins · December 2014

I have a new Xantrex XW4024 inverter for backup purposes with 4 Trojan L16RE-B batteries with a 20 hour rate of 370amps.
I’ve performed a couple load tests and the low voltage warning comes on after 5 to 30 minutes depending on load. The last test was with a 600 watt load and it went 2 hours.
They should support 600 watts for 6 hours at 50% DOD.
What voltage is allowable at 50% DOD when under a 0.6kw load?
I’m trying to design a test scenario so I can get some good data to confirm or deny poor performance.
The batteries are new and currently at 42 degrees.
When In set up the inverter charger I installed the battery data so it would charge at the correct rate but perhaps it is wrong.
What should the bulk, absorb and float voltage and amperage be and how long?
I’ve looked thru Trojans literature and set the charge voltages per their recommendations but the batteries being 42 degrees may require a different setting.
Suggestions for a controlled load test welcome.
Thanks
90cummins

Cariboocoot · December 2014

Re: Trojan L16RE-B batteries poor performance/defective???

Couple of things:

1). They are new batteries and will need to be cycled a few times before they actually achieve full capacity.

2). As load increases real capacity decreases at the moment. Id est the heavier the load draw the lower the actual capacity so the less time it will be able to support that load compared to the rated capacity.

The 20 hour capacity rating would be determined at a load around about 450 Watts, so you are loading them a bit heavy. The 42 degree temperature is definitely working against you (assuming that's Fahrenheit) because cold batteries have less capacity. RTS is your friend there, and the current flow should warm them up a treat.

The most important thing is to get out the hydrometer and check how low the SG is going and how far back up it comes under charging. Absorb Voltage for these on a 24 Volt system should be around 29.6, possibly higher.

I'd reduce the load (even use an irregular load that averages out to 450 Watts over the time span of 20 hours) and cycle them for a month making sure that they are not drawn too low and are as fully recharged as possible on each cycle (check with hydrometer). Adjust Absorb Voltage and time if needed to achieve full recharge.

BB. · December 2014

Re: Trojan L16RE-B batteries poor performance/defective???

I know I sound like a broken record... Specific Gravity and cell voltage measurements? Did the batteries start at 100% SOC?

If you have a single bad battery or cell, generally you should see it via SG differences and/or voltage per battery measurements (under load or charging current).

At 42F, the battery bank should still be at ~90%+ of capacity.

-Bill

Vic · December 2014

Re: Trojan L16RE-B batteries poor performance/defective???

Cariboocoot wrote: »

Couple of things:

1). They are new batteries and will need to be cycled a few times before they actually achieve full capacity ...

...I'd reduce the load (even use an irregular load that averages out to 450 Watts over the time span of 20 hours) and cycle them for a month making sure that they are not drawn too low and are as fully recharged as possible on each cycle (check with hydrometer). Adjust Absorb Voltage and time if needed to achieve full recharge.

Agree about cycling a new battery bank to build Capacity.

Believe that Coot is mentioning that the TOTAL theoretical Capacity of your single string of RE-b batteries is equivalent to a load of about 450 watts for 20 hours, BUT, of course that battery would be completely DEAD at the end of that run. So the most that anyone would want to discharge the bank would be to 50% of that Capacity.

Since the batteries are cool, and young, would suggest trying to discharge them to about 75% SOC for the first cycle, or so. AND watch the total battery voltage carefully, as BB Bill noted. Also noted by Bill, note the voltage of each battery during the discharge process. If the bank voltage or battery voltage begins to fall fairly rapidly, compared to the previous interval of ten minutes or so, TERMINATE the discharge, and begin recharge immediately.

A load of about 450 watts for about four hours might be a good beginning discharge test. But the battery voltage should be monitored every five or ten minutes -- at least the bank voltage. Discharge tests are a bit risky, if not carefully monitored for rate of change of bank/battery voltage, as it is possible to completely discharge one cell, which is very bad. And, worse yet, is the risk of reversing the terminal voltage of the fully discharged cell, by continuing a discharge further, and ruining it beyond any possibility of its recovery.

It is not possible to say just what the terminal voltage should be for a given load and SOC of the bank. Just watch for the rate of change of bank voltage, when the rate of voltage decrease begins to accelerate, this means that at least one cell is starting to near full discharge. The first few cycles should not be too deep. The bank should fall into line with more cycles, perhaps to a deeper DOD, and you will gain experience with the nature of the bank and your system. Be a bit gentle at first, perhaps more like breaking-in a new engine.

Some battery manufacturers recommend a Commissioning EQ after a full initial charge ... believe that Trojan has had such a recommendation.

Opinions, YMMV. Good Luck, Vic

westbranch · December 2014

Re: Trojan L16RE-B batteries poor performance/defective???

It helps you stay organized if you make your self a small spreadsheet on which to record, manually, and then fill it in on your computer for long term records.. I made mine cell #, etc on the vertical axis and time on the horizontal as it was a 5 hr discharge ,measured every 1/2 hr for 3 hrs and then 15 minutes till failure to maintain the voltage.

your results may be different. As Vic said, every 15 min. to start ad see just what is happening...

hh

Trojan L16RE-B batteries poor performance/defective???

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