Is it dangerous or bad to increase the absorption voltage?

Re: Is it dangerous or bad to increase the absorption voltage?

Rngr275 wrote: »

Here are my controller settings (2-Classic 200’s, “Follow Me” enabled): Absorb Voltage=59.2, Absorb Time= 4hrs, End Amps=7, Float Voltage= 52.8.
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could I bump up the absorption Voltage kind of like a Lite EQ, or lower the End amps or should I increase the absorption time to even more to push up the SG.

How did you determine an end amps value of 7? --vtMaps

Re: Is it dangerous or bad to increase the absorption voltage?

Rngr..

You really MUST use the Temp Sensors on each charge source (although, in some configurations, the OB products CAN share a single RTS in some situations), and all of these sensors should be on the same battery near the center of the pack, about half way down the side of the battery. Ideally, the batteries should be in an insulated box that allows the batteries to be at/near the same temps as the rest of the bank. Have been using insulated boxes here, but with the box cover open, to allow heat from the bank to escape the box (yea, this is a bit of an issue with Hydorgen gas control).

As Marc noted, the output current from the CC toward the batteries includes the inverters and any loads on them. If those loads are fairly constant toward the end of an Absorption stage, all should ve very well in trying to use CC EA as a termninator of Abs. Since you have the FNDC BM, you can see the actual battery charge current. For the banks here that I monitor, the actual battery charge currents for termination of Abs are very close to 1.1% of actual battery bank capacity. Your batteries are somewhat different, and you should be able to find the value that your bank wants, once you can do 100% recharge on a given day.

Would not hurt to try to run the genset early in the morning, and perhaps the sun will be able to allow a full battery charge.

YES, raising the EA to a higher value will quite possibly shorten the Abs stage, it depends on weather you can reach that value. For now a bit below 1% of 20 hr capacity might be best until the bank gets fully recharged. Believe that you work on week days, so it may be difficult for you to monitor in real-time the charge progress, but those MN Classics DO have very good logging capability, as you know.

Regarding EQ, if it is possible, you might want to limit the Inverter's charge current, manually, as the battery approachs the EQ voltage. It is often recommended (although not necessarily by Trojan), that EQ current be limited to 5% of 20 hour Capacity. I forget what the max Charge Current limit is for the OB 3648, but it is probably 60 amps or so, which exceeds 5% by a reasonable amount. And, for doing a solar EQ from PV, you might also want to limit the CC's output current as well on the those sunny cold days. High charge currents in Bulk are often good for a battery (at least some times), so you might want to reset the CC limit at 60.5 or 61 volts (temp comped) manually, and reset to the normal level after EQ.

Furthermore, IMHO, EQ voltage should be Temperature Compensated. Do not know the environment that your batteries experience, but your location gets COLD, am sure ... believe that you may be one of the wise OG folks with a basement/Root Cellar battery room ... forget. Above are just My Opinions, YMMV. Enough for now, Have fun, Vic

Re: Is it dangerous or bad to increase the absorption voltage?

Hi Rngr275,

Fine on the battery cellar and box, that sounds fine, better than my situations ...

The EQ seems fine to me. The batteries are probably cool, so, the CC BTS(es) would increase the charge voltage by perhaps one volt or a bit more on your 48 V system, so your 59.2-ish CC V setting is not really that high, and your could increase the CC Absrb V setting to a bit above 60 V without much concern IMHO.

YES, the Classics should have come with an approx 10-foot bright blue phone style cable with phone type connector. The sensor is a rectangle about 3/4" X 1.5" or so ... you might look around for them, perhaps in the original Classic box. I do not know about Follow Me FW, so it would be safe to use both BTSes. You might ask about this on the MN Forum. Do not recall seeing that mentioned there RE Follow Me.

And, yes, it is normal that the current drops when the EQ voltage is met, and should continue to diminish as the EQ continues to some point where it may well stabilize, similar to the Absorption stage.

Your batteries should serve you well, as you are paying attention to them when they are youngsters, and they should grow up well-balanced. Good Luck, Vic

Re: Is it dangerous or bad to increase the absorption voltage?

Rngr275 wrote: »

I was disappointed that the classics did not have a temp sensor connected to them. I have read that the classic controllers come with the temp sensor. I will check with the installer to see what the deal is and either get them from him or I will order a couple... do I need one on each controller? Did I mention I will order immediately!

For what its worth, the battery sensors of outback and midnite are interchangeable.

Rngr275 wrote:

Day one ran out of sun, day2 had 4 hr Abs then went to Float... EA was in the 7-8A range so I think the Charge time dominated EA.

Are you saying that you did not achieve an end amps of 7?

Cariboocoot wrote:

7 Amps on 740 Amp hours is quite low indeed.
End Amps is typically 2% of battery bank capacity plus an allowance for any current going out of the batteries while charging.

For what its worth, my Interstate batteries have an end amps of 1% of their 20 hr capacity. That is at an absorb voltage of 29.6. If I use the higher absorb voltage (30 volts) that Interstate recommends, the end amps will be a bit higher.

--vtMaps