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Battery not staying at absorption

Posted: Tue Jan 21, 2020 12:14 pm
by jfedoutback
I am off the grid. I recently got new Trojan L16P-AC batteries for our solar system. These batteries get to the absorption setting and immediately drops to the float setting. I have the absorption setting time set at two hours. How do I get them to stay in absorption?

Re: Battery not staying at absorption

Posted: Tue Jan 21, 2020 12:21 pm
by Gwendoly Espe
Can you update your profile to include the equipment in your system and OpticsRE profile, if you have one? Where are you seeing this, on the inverter or charge controller?

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 9:58 am
by jfedoutback
We found the Absorb End Amps was set at 44 amps. the outback book setup says the default setting is 0 and we reset it to the default setting by using the Mate. We think when the battery went into absorb it was over the 44amps and went immediately into float. Today after being reset it is now in the absorption cycle. I am not sure why the Absorb End Amps was set at 44? The person who brought our new batteries I believe set it at that and I have no idea why? I am in Mexico and there is a language barrier between me and the technician.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 10:25 am
by raysun
That would impact the charge cycle certainly. Many other parameters will as well.

I'd strongly advise you follow Gwendoly's advice and update your forum profile with details of your equipment.
You will inevitably have other questions and having the details will help others give on-point answers.

For example, if you have three parallel strings of L16 battery blocks, 44A would be about right for Charged Return Amps used to derive 100% State of Charge.

You can click on other users' names to see their profiles.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 11:05 am
by jfedoutback
ok, I will fill out the information. I am new to this site. We have 24 volt and two parallel strings of 4 batteries.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 12:16 pm
by Gwendoly Espe
It sounds like this is resolved?

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 12:52 pm
by jfedoutback
No not really, we are reading other posts on this site. We set it to 30. Our system is quite old but with new batteries. Our original batteries lasted the projected lifespan of them at 11 years. We understand we won't get that out of these but would like to know we have the proper settings to charge them.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 1:52 pm
by Mike Curran
This site https://www.trojanbattery.com/product/l16p-ac/ lists your batteries' C20 rate at 420Ahr. With 2 parallel strings that gives you an 840Ahr C20. Basic rule of thumb for FLA battery end amps is 2-3% of the battery C20 rate, which puts your end amps at ~21 amps.

Your 2 hour absorb might be a little short, depending on how deeply you discharge your battery each day. You want the battery to be fully charged but no more by the end of the absorb cycle, and the only way to determine this is with a battery Hydrometer, at least until you get a feel for how your battery is doing.

The Rolls battery manual has advice on setting this up. I haven't looked at Trojan's site for similar info but Rolls' info should still be applicable.

https://www.google.com/url?sa=t&source= ... J_k9Y_34KX

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 2:04 pm
by raysun
Screenshot_20200122-114832_Drive.jpg
From the Trojan website.

Charging parameters:
Absorb Voltage: 29.6
Absorb Time: ?
Float Voltage: 27.0
Float Time: ?
Equalize Voltage: 32.4

There are two battery chargers listed for your system - FlexMax 80 and the inverter charger. Both can have the charging parameters set via the Mate.

Absorb time should likely be longer than 2 hrs., but I don't have a specific number to suggest. Absorb should continue until the charging current is roughly 2-3% of the Amp-Hour capacity of the battery at the 20 hour rate, so 840 x 0.03 = 18-25A. You may need to contact Trojan to get a concise number, or establish it experimentally by setting Absorb Time long (8 hours) and watch the charging current.

Float Time is usually set equal to Absorb Time.

There are a couple of additional parameters: Rebulk voltage and Refloat voltage, that also need to be set for the battery. They help the system decide when and how much to recharge the battery.

Is there a FlexNet DC battery monitor in the system?

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 2:07 pm
by jfedoutback
Thank you very much, I really appreciate your help and expertise.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 2:08 pm
by jfedoutback
No we have an old system.

Re: Battery not staying at absorption

Posted: Wed Jan 22, 2020 4:38 pm
by raysun
jfedoutback wrote:
Wed Jan 22, 2020 2:08 pm
No we have an old system.
Is there any sort of battery monitor on the system?
Getting 11 years from a battery is really very good in all but the most meticulously maintained systems. Its amazing if achieved without battery monitoring.

There's a Mate 3, inverter and FM80, all purchased at the same time?

Is there an internet connection at your location? Is your system on OpticsRE?

Re: Battery not staying at absorption

Posted: Thu Jan 23, 2020 5:29 am
by jfedoutback
I thought 11 years was really good for the old rolls we had and are hoping to get 5 out of these but may be dreaming. We are in Mexico on a beach where it is really hot and humid. I am going to check into a battery monitoring system. Yes our charge controller and inverter and mate are original.

Re: Battery not staying at absorption

Posted: Thu Jan 23, 2020 6:16 am
by raysun
Does the Mate3 have an ethernet port as well as the proprietary communication port? Both are side-by-side on the back of the unit. The ethernet port permits connection to a local area network and to the internet.

If connected to the internet, Outback's cloud application: OpticsRE, is quite useful. The Outback web site has a demo to learn about the app's functionality.

Outback's battery monitoring tool is the FlexNet DC. It works in conjunction with the Mate, and FM80 charge controller to manage and monitor battery charge and discharge.

Also, does the system have the Outback Remote Temperature Sensor (RTS) cable to support temperature compensated charging?

Re: Battery not staying at absorption

Posted: Thu Jan 23, 2020 8:09 am
by jfedoutback
we have an ethernet port that is from the mate to the inverter. The mate has another port on it for a HDMI cable that isn't being used. We don't have a temperature sensor. We have been using the history to check day to day. We use the house for about 6 months then leave for 6 and have someone keep an eye on the water levels. We run a couple fans on timers when we are gone but not the refrigerator. I guess we should be monitoring the more. I will check out the information you are sending me.

Re: Battery not staying at absorption

Posted: Thu Jan 23, 2020 8:34 am
by raysun
jfedoutback wrote:
Thu Jan 23, 2020 8:09 am
we have an ethernet port that is from the mate to the inverter. The mate has another port on it for a HDMI cable that isn't being used. We don't have a temperature sensor. We have been using the history to check day to day. We use the house for about 6 months then leave for 6 and have someone keep an eye on the water levels. We run a couple fans on timers when we are gone but not the refrigerator. I guess we should be monitoring the more. I will check out the information you are sending me.
The RJ45 port that connects a Mate directly to the inverter is not ethernet, rather an Outback proprietary network protocol. All the Outback devices have this communication port. That it uses an RJ45 (ethernet) cable is a bit of a confusing issue. Same cable type but two different network protocols.

The Mate can communicate with multiple devices (inverter, charge controller, battery monitor) by way of a special communication hub that Outback offers. A HUB4 would be used in your setup. With the Hub in place, and all devices connected, the RTS cable attaches to the inverter, which then shares temperature data with the charge controller for temperature compensated charging. If the HUB4 is not used, then an RTS is needed for both inverter and charge controller (two cables total), so each can do temperature compensated charging.

The complete equipment suite: inverter, FM80, Mate3, FNDC, and HUB4, can provide a great deal of control over battery charging. This would contribute materially to battery service life. 5 years, and more, would be reasonable for L16s, properly maintained.

I'm not sure what the HDMI is in reference to. I understand the early Mate3 did not have an ethernet port, but I'm not sure what other ports might have been included. The Ethernet port is vital for connecting the system to the internet. Once connected, OpticsRE app gives full control and monitoring of the system from anywhere in the world.