Solar directly to batteries to equalize them

[Sail IC]

My boat is always on the hook. Neither the engine or my solar panels through the regulators will generate more than 14.4V, so I cannot equalize my battery bank.

My old battery bank died to what I think was due to sulfation. At 14.4 V they only took a low (sub 10A) current, but with only 10% charge taken out, the voltage dropped to below 12V.

New battery bank purchased (Trojan &-105s), but as I never stay at the dock, I cannot equalize them to prevent sulfation.

I have 500W of solar panels. They deliver around 17-18V (I think), and it gets regulated down to lower voltages.

Idea: To equalize the batteries. For a short time connect some of the solar panels (200W maybe) directly to the battery bank. Monitor the voltage and battery temperature, and if voltage goes much above 16V or too hot, disconnect the panels.

Is this a good idea or will I likely destroy something.

I read a statement from Trojan that most batteries which prematurely died was due to undercharging and hardly ever by overcharging.

[svmariane]

Just my 2 pence worth, but...

500 W seems enough solar to do the job so I'm suspicious of your solar regulator. Is it an MPPT type?

If not..... Maybe check into the likes of this: TS-MPPT-60
TriStar MPPT » Morningstar Corporation

I've about 350 W solar and have no problems using our TS-MPPT-60 to equalize our 600 A/H house bank.

Better results if the (free) software is utilized from a laptop (or similar).

Note: We run our boat with solar & wind power - no genset, no shore power, and not using motor except to maneuver.

{Our TS-60 allows for future solar expansion vice being limited by a TS-30.
No affiliation with the company except as happy customer. }

[pcmm]

What regulator are you using? most modern MPPT controllers have the ability to run an equalization program. some can even do it on a monthly equalization cycle.

[svmariane]

Originally Posted by Sail IC

Idea: For a short time connect some of the solar panels (200W maybe) directly to the battery bank. Monitor the voltage and battery temperature, and if voltage goes much above 16V or too hot, disconnect the panels. Is this a good idea or will I likely destroy something.

Did exactly that when our old non-TriStar solar controller died enroute Tonga / New Zealand. We lived. The batteries lived another two years. Why they died is another story.....

[rabbi]

Our regulators do that automatically once month. Maybe yours too?

[svlamorocha]

Originally Posted by rabbi

Our regulators do that automatically once month. Maybe yours too?

IMHK automatic "equalization" is one of the dumbest ideas that seduce buyers of boat equipment. I have seen enough examples of equipment fried by unattended equalization at about 15.5V.

Sent from my GT-I9192 using Cruisers Sailing Forum mobile app

[Salty Mike]

There is a discussion on here about battery orientation IIRC the plates should run side to side not front to back. if one side is allowed to stay dry too long as in when you are running heeled over on a long tack it is bad on them.

Sent from my RCT6077W22 using Tapatalk

[zboss]

I am going to be (shortly) selling 4 Genasun solar controllers that have been custom programmed by the factory specifically for charging Trojan batteries. They have a built in equalization mode... they automatically equalize every 30 days.

So far so good on our batteries. We are selling them because we are moving to carbon foam batteries and they have different charging voltages than the trojans. Let me know if you are interested.

[rabbi]

Originally Posted by svlamorocha

IMHK automatic "equalization" is one of the dumbest ideas that seduce buyers of boat equipment. I have seen enough examples of equipment fried by unattended equalization at about 15.5V.

Sent from my GT-I9192 using Cruisers Sailing Forum mobile app

We can set the voltage for equation just like for the normal charging stages so no problem

[svlamorocha]

Originally Posted by rabbi

We can set the voltage for equation just like for the normal charging stages so no problem

The problem is that the voltage required to "equalize" most batteries ( say 15.5 volts) is more than enough to make it likely that you will fry certain devices. If the equalization is "attended" you can disconnect all loads, but that will not happen if the equalization happens once a month on a timer.

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[btrayfors]

I've found through research and through personal experience that you don't need to equalize FLAs all that often -- maybe only once or twice a year -- provided that you frequently kick the voltage up to absorption level (14.6-14.8VDC) for a short time. This level avoids possible damage to onboard electronics and makes a measurable difference in battery capacity, electrolyte stratification and, presumably, in anti-sulfation.

My Victron is set to kick up to 14.8VDC for 30 minutes every other day before dropping back to resting voltages of 13.8VDC then 13.2VDC.

Given my druthers, I wish I could maintain 13.6-13.8VDC all the time, but my Victron automatically drops back to 13.2VDC after awhile and curiously that level is not programmable on my Multiplus.

Bill

[colemj]

Bill, are you sure about that float value?. We have a multi plus 3000 and the float value is certainly programmable on it.

Trojan recommends that batteries be equalized ONLY if the cell specific gravities are imbalanced, and to then equalize only until they rebalance. They don't think regular equalization is a good thing at all.

Mark

[btrayfors]

Hi, Mark...

Yes, I'm sure. On my Victron (Phoenix Multi Inverter/Charger 2500W/120A) the float value is also programmable. However, the so-called "storage value" is not. It's set at 13.2VDC and you can't change it. So the charger goes first to 13.8VDC (or whatever value you've programmed), then after a time of no activity it automatically drops down to 13.2VDC.

You're right about equalization (15.5VDC and above). I don't think it's required very often. And, I'd be leery about "automatic equalization", AKA uncontrolled equalization. With battery charging voltages that high, I'd wanna be right there to monitor/control what's going on.

Bill

[colemj]

I see that now. Ours is never operated such that we ever meet the conditions for switching to "storage" mode.

The "re-absorption" mode is programmable. You could set it to bump up every day for a few minutes, and that would probably have the same effect as sitting at 13.8V.

Mark

[btrayfors]

Mark,

Yes, that's what I've done since Feb 2012. The Victron is set to kick up to absorption voltage 14.8VDC every other day for 30 minutes.

Look at the yellow to green bars. That's the six-month period after I started using the every-other-day re-absorption voltage thing. A clear increase in measured capacity is seen in all batteries.

However, these batteries were already seven years old, and about 13 months later they all began to lose capacity (blue bars).

Battery #3 had clearly reached the end of it's lifetime. I removed it from the bank and went with the remaining house batteries for a few months until I replaced them all.



Bill