Extending Battery life

Masterjoe · August 2015

I am wondering if the setup I have right now is going to be good for the 6-8 year life of my flooded 390ah deep cycle Trojan batteries. I have the recharge volts on both the XW 4024 inverter/charger and the MPPT 80 600 CC at 25v. We have 12 batteries in 3 strings and voltage of 28.8 when fully charged. Typically the CC exits bulk charge at 28.8 voltage drops to 26.9 after a bit in absorption and then floats for anywhere from 6-9 hours. The inverter sells to grid al the way up to nightfall then goes inot AC pass thru and we enter the evening at 25.6-25.9 depending on the loads until morning. LBCO is set to 22v. Thank you for any advice.

BB. · September 2015

28.8 (14.4 at 12 volt bank) volts may be a bit low of charging voltage for a room temperature battery bank. Check the Trojan manual and watch your water usage (if you have to refill the cells every month or less, too much charging. If you have to refill only every 6 months, may be under charging).

Also, LBCO may be better at 23.0 volts (11.5 vdc @ 12 volt bank) for normal operation (closer to 50% state of discharge--longer battery life).

Do yo have a hydrometer yet to measure the specific gravity of your batteries?

-Bill

Masterjoe · September 2015

Still need to get the hydrometer. I will be ordering it from here tonight. Supposed to have my installer come out tomorrow (cross my fingers), I will be going over the batteries with him making sure they are connected correctly, voltage is correct etc. What my installer says about the fact that the inverter is showing 0.00 is that the solar array breaker is tripping. So 18 250w panels in series going to 24v battery bank in 3 strings is what he said is an oversized system for our needs. I am wondering if maybe it is a bit too oversized for on MPPT 80 600 charge controller to handle? With our normal usage of around 730-800 watts we have enough power left over to power the house 4 more times.

Vic · September 2015

Speaking only of the batteries, their lifespan, and charging setpoints;

What is the exact Trojan battery model number? The exact model number affects the charge setpoints, target SG, as read on your Hydromter, and the design life of the battery.

If you can find the time to write a Signature, that describes the hardware aspects of your system, this will help others understand the overall nature of your system, and affect in a positive way, the replies that you will get. [I do hope that you have more than one MPPT 80 600 CC, or at least another CC!].
Thanks, Vic

Vic · September 2015

Vic wrote: »

Speaking only of the batteries, their lifespan, and charging setpoints;

What is the exact Trojan battery model number? The exact model number affects the charge setpoints, target SG, as read on your Hydromter, and the design life of the battery.

If you can find the time to write a Signature, that describes the hardware aspects of your system, this will help others understand the overall nature of your system, and affect in a positive way, the replies that you will get. [I do hope that you have more than one MPPT 80 600 CC, or at least another CC!].
Thanks, Vic

Hi Masterjoe,

Know that it is not good form to Quote oneself, but ...

OK, regarding your Trojan batteries, and prospective life;

Trojan makes nine different L-16 Flooded batteries, as I count them, on the following Product Selector Guide:
http://www.trojanbattery.com/pdf/TRJ...dSpecGuide.pdf

One has a Rated 20-Hour Capacity of 390 AH. It is the L16G-AC are THESE the batteries that are being used in your system?? OR, are they a different model? If different, what model number are they?

The details do matter, as the recommend charge parameters can be different, as can be the Target SG for one battery verses another seemingly identical from the same manufacturer, but having a different model number.

Historically, believe that the L16G-AC batteries were in the Floor Machine category, which may well be fine for a Hybrid system.

Here is the Selector for Floor Machine (FM) batteries:
http://www.trojanbattery.com/pdf/Tro...M_brochure.pdf

If your batteries are the L16R EA or R EBs, one might expect them to last somewhat longer, at least in cyclic daily use. Your Hybrid system is not exactly that kind of use.

In general for longest life from the kinds of batteries that we use;

Keep batteries COOL.
Do not cycle them too deeply -- less that 50% DOD maximum for most types of batteries.
Use a Battery Temperature Sensor (BTS), on all charge sources.

For flooded batteries;
Check electrolyte levels often - on a schedule is a good idea.
Buy several good Hydrometers. Test them all to see how well their readings compare, reserve one or two as backups.
Measure SGs fairly often, at least on your Pilot Cells.
Measure SGs of EVERY CELL once a month minimum, and record these values in the Battery Logbook
After the batteries are cycled a number of times (this is good for most Deep Cycle batts), you man not to mesure SGs monthly.
Add water during Absorption stage, or if not possible to do that, run a manual Absorb, at an elevated Absorb voltage, to mix the electrolyte, but can be 30 - 45 minutes (IMO).
Use only REAL Distilled Water.
Completely RINSE the Hydrometer after each measuring session -- three or four times should do the job -- reduces the sticky buildup that can cause erroneous readings.

Bottom line, treat Renewable Energy (RE) batteries like a well-liked member of the family. Treat them well, and they will return the favor.

FWIW, Vic

Masterjoe · September 2015

Vic,

Thank you for the reply, I would be treating the batteries better than my well liked family member lol J/K. The Batteries are in fact the Trojan L16G-AC 20 hour capacity 390AH. Fully charged from bulk-absorption is 28.9v before it goes into float for like 9 or so hours at 26.7v. So running into the lowest voltage I get at night before daylight and a recharge is 25.4 which is around 88% DOD. Recharge volts on both Inverter and CC is 25v. I will definitely take your suggestions into consideration. I am curious what the difference is between the recharge volts on the inverter and CC. Which does what? Suggested settings for both? Battery temperature sensor is installed and the max temp so far was 100 degrees but usually maintains from 76 - 84 degrees mostly. Checked electrolyte level yesterday and all cells are still full. My installer is happy I am taking a proactive approach to learn about the system and not switching off breakers and the like when I get faults. he was telling me the other day he is mostly running around right now fixing a system for a customer who freaks out when a fault comes on and she has flipped all the breakers and the system off and wondered why she did not have any power.

Vic · September 2015

Hi Masterjoe,

Thanks for the added information.

Your batteries may have a fairly high SG electrolyte, which would normally mean that the Absorption and Float voltages would need to be a bit higher than for batteries with lower SGs. Your Hydrometer will tell how well your batteries are being charged ... am not a Hybrid system kind of person, and there are several battery management strategies for systems connected to the Grid.

IMO, your batteries are running on the warm side of things. 100 F, to me is HOT for batteries.

Every 10 degrees C increase in battery temperature decreases battery life by HALF. This is not trivial, to me.

As an aside, one more question which was asked in another Thread that you started;
How many of the XW MPPT 80 600 CCs are you running on this system? I assume that you are running two of them ...

More Later, Thanks, Vic

Extending Battery life

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