So my new inverter shuts off when the sun comes out....

Re: So my new inverter shuts off when the sun comes out....

Blackcherry04 wrote: »

Well, .1 -.2 could be a +/- error. 14.8 - 14.9 is a little high for t-105's, they just don't need that much on a daily basis unless the SG's are coming out low, I'd drop them to more like 14.6 or so especially in the summer, they'll last longer.

This is another question I had. Trojan's page on charging lists 14.8V as the "daily charge" (absorption) for flooded batteries. But their data sheet on T-105s says 2.35-2.45V per cell, which is 14.1-14.7V for a 12V system.

So data sheet doesn't match their other information on battery charging. Not to mention that 14.1 to 14.7V is a rather wide spread. Maybe I'm being too precise in my thinking about charging voltage and that it doesn't matter all that much as long as it's within a specified range?

I might try dialing down the absorption voltage and see if I can't find a happy medium. My new inverter still won't work during equalization (>15V), but that's infrequent enough that it won't really matter. It sure would be nice to get this inverter to work, I have an inverter on 24/7, the reduced no-load draw would be helpful, especially in winter.

Re: So my new inverter shuts off when the sun comes out....

It's been about a month since I dialed the voltage down on my charge controller, from 14.8V to 14.6V in absorption stage. The inverter has been working fine since I did this, it's been in near 24/7 use with no problem.

However, my batteries don't appear to like the lower voltage. I added two more panels to my system a couple days ago. I was hoping that might solve the problem, but I kind of figured it wouldn't since absorption amps are usually in the 1.5-2.5 range even when the panels are getting full sun.

My four 158W panels were charging my two Trojan T-105s all day today with almost no load (couple amp-hours at most). I checked my batteries at 5:30 pm, specific gravity was 1.270 and 1.260 (testing middle cell in each battery). That's only 95% and 90% charged based on Trojan's chart. That's about average for what I've seen since I reduced the absorption voltage.

When I saw this I equalized the batteries for about 2 hours. At the end the SG was 1.275 and 1.265. 100% and 95% charged based on Trojan's chart, about as good as I've seen with these two batteries. I'm measuring SG with a Hydro-Volt, which has automatic temp compensation. It was hot today, 90 outside, maybe a bit hotter in the trailer in which I keep my batts.

I'm thinking if I hike the absorption voltage back up to 14.8V, I'll see my charge controller actually achieve float, which I almost never see. I haven't seen it in float mode for more than a month or two. That seems like a problem.

Re: So my new inverter shuts off when the sun comes out....

BB. wrote: »

SG readings sound good. You are usually aiming for >90% SOC once to several times a week (when actively cycling the lead acid batteries).

Are the SG readings good before or after equalization? Before they were 1.27/1.26, after they were 1.275/1.265.

I can usually achieve >90% SOC, but not >95% since I dialed down the absorption voltage. The highest I've seen since late June was ~1.28 after a couple hours of equalization and when I had absorption set at 14.8V.

One battery has always been weaker than the other since I got them in April. Thread here.

How much water are you using? If these are the Trojan RE batteries--They have been reported as using less water than their traditional batteries. So, in 1 month, you may not see much water usage.

-Bill

I recently watered the batts, but I don't have a good sense for how much I'm using. They were lower than expected, I'd only watered them a couple times since I got them in the spring. Still learning that side of battery maintenance, I was using an AGM batt previously.

Re: So my new inverter shuts off when the sun comes out....

Cariboocoot wrote: »

Well Trojan batteries do want higher Voltage than a 12 Volt system likes to run at. That's one problem.
Most 12 Volt inverters do not like these high Voltages and especially do not like equalization Voltages; they scream and shut down. That's another problem.
Raising the Absorb Voltage will not increase Float time. More likely the opposite as it takes longer to reach a higher level which means there is less daylight time for completing that cycle and entering Float (it has nothing to do with the actual SOC). This is yet another problem and it sounds like one of lacking insolation.

My panels get full sun all day, no shade at all. It's been hot and sunny lately, very few clouds. So insolation isn't a problem. I'm wondering if the Tristar charge controller has an absorb time that's set too long, as you suggested. I don't know what that time is or how to change it. How low should the amps go before it should switch from absorb to float?

Run the gen & Iota first thing in the morning before the panels start to produce. Then let them take over and see if Float is achieved. Measure the time for Absorb (the TriStar may be set for too long) and watch the current.

I'll try this, hopefully will have time this weekend.

BTW getting around the problem of inverters shutting down due to 'high Voltage' on 12 Volt systems is a recurring discussion. If the inverter is small enough you can put a diode (must be able to handle the maximum current) or two in-line with it to drop the Voltage to less-than-warning levels. This also has the advantage of effectively raising the LVD which keeps the batteries from being drained too low.

I switched back to my little Sima 150W inverter, which has no problem with 14.8V, or even equalization voltage (15.3V).

Might try the diode trick. I know nothing about them and have no idea how to wire one into my inverter circuit, but always good to learn new things. What size?