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What brand of charger do you use to equalize batteries

Oct 29, 2012
289
Catalina 30 TRBS MkII Milwaukee
Maine Sail mentions using a DC power supply to equalize batteries in this article:

Maine Sail also has a tutorial regarding leaving the batteries in the boat all winter. Which you may find helpful.
 
Sep 26, 2008
335
Hunter 340 Wickford, RI
I completely agree with you Richard, captcoho, shemandr. It's all about giving back. Even through Rod's recovery he's still helping others. That MaineSails article outlines the equalization process completely. Straight forward easy to read. I hope it helps others in doing an equalization on their batteries as well. I'm equalizing an old battery I have as I'm writing this response to test the equipment I have. After about 2 hours now, the specific gravity is almost equal in all cells. I'll keep checking.
 

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dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
I completely agree with you Richard, captcoho, shemandr. It's all about giving back. Even through Rod's recovery he's still helping others. That MaineSails article outlines the equalization process completely. Straight forward easy to read. I hope it helps others in doing an equalization on their batteries as well. I'm equalizing an old battery I have as I'm writing this response to test the equipment I have. After about 2 hours now, the specific gravity is almost equal in all cells. I'll keep checking.
What's your open circuit voltage on that set-up?

dj
 
Sep 26, 2008
335
Hunter 340 Wickford, RI
Just sitting in my garage (1 year) with no loads on it at all. Voltage was 12.38 v. So, approximately at 70 % of capacity.
 

dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
Just sitting in my garage (1 year) with no loads on it at all. Voltage was 12.38 v. So, approximately at 70 % of capacity.
Sorry, I meant what's the open voltage on your charger before hooking to the battery.

dj
 
Sep 26, 2008
335
Hunter 340 Wickford, RI
The DC voltage is +\- 18 V The DC Amp is 0.5 Amp
Prior to starting I had Specific Gravity readings of 1.250 (2 cells) to 1.270 (4 cells)
I'm about 3 hours into the process and have Specific Gravity readings now of 1.275 in all but one cell (which is 1.265)
This was a much older, unused battery so I figured it was a good test subject.
 
Nov 30, 2020
67
Macgregor 22 Dania, FL
A modern charger that has automatic equalization is a very good idea. If you REALLY want to do it by hand, here is the info you need: Leave the battery in its box or put it in an old cooler. Cover it loosely with a thick rag or old towel. The objective here is to contain flying acid in case the battery decides this would be a good time to explode. Raise the voltage to 15.6 volts for 15 minutes, no more. Your old Eico may not be "man enough" to charge a Group 24 battery that hard. It was really intended as a bench accessory for auto radio repairmen. Remember that you are deliberately abusing the battery plates to expose fresh lead / lead dioxide. It is better to underdo this treatment than overdo it.
 

dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
Raise the voltage to 15.6 volts for 15 minutes, no more.
I strongly disagree.
For flooded lead acid batteries, I find that it will often take many hours to properly equalize the battery, depending upon state of sulfation.

Lifeline specifically states for their AGM's to perform this for a 4 hour cycle.

Remember that you are deliberately abusing the battery plates to expose fresh lead / lead dioxide. It is better to underdo this treatment than overdo it.
This is not correct, as long as you have excellent control of voltage and current. With proper controls, you are primarily breaking down lead sulfate back into it's respective lead and sulfur.

dj
 

dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
The DC voltage is +\- 18 V The DC Amp is 0.5 Amp
Prior to starting I had Specific Gravity readings of 1.250 (2 cells) to 1.270 (4 cells)
I'm about 3 hours into the process and have Specific Gravity readings now of 1.275 in all but one cell (which is 1.265)
This was a much older, unused battery so I figured it was a good test subject.
Your open voltage is too high. Can you turn it down to not exceed 16.2 volts?

dj
 
Sep 26, 2008
335
Hunter 340 Wickford, RI
I did dial back the voltage to 16V. I've been in and out checking this battery for the past 4 hours as it progressed.
I now have an equal Specific Gravity in all cells of 1.275. And an ending voltage of 13.68 - 13.74 V. That's leaving out right now at 13.68V.
So this battery is done and I will be checking it as the days go on.
I'll start my 3 others in the next few days.
 

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dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
I did dial back the voltage to 16V. I've been in and out checking this battery for the past 4 hours as it progressed.
I now have an equal Specific Gravity in all cells of 1.275. And an ending voltage of 13.68 - 13.74 V. That's leaving out right now at 13.68V.
So this battery is done and I will be checking it as the days go on.
I'll start my 3 others in the next few days.
Do you know what the ambient temperature is right now where you are? It's really more for a data point. Specific gravity is the best way to check this. Nice!

dj
 
Sep 26, 2008
335
Hunter 340 Wickford, RI
It’s 42 F.
I will really know my end results over the next few days and going forward from here. But it’s a straight forward process and I do suggest a new modern DC Bench Top Power supply for accurate readings, if you’re are going to make this one of your maintenance projects.
For some of us, if you remember Sears and Roebuck automotive. They would take your battery and place it on a bench overnight for you, load test and balance them for free. And if it didn‘t hold a charge after that, you bought a new battery. They had rows of them on bench’s all connected everyday. That was then, this is now.
 
Jun 11, 2004
1,220
Oday 31 Redondo Beach
Glad it seems to be working out for you. Shows that old equipment isn't necessarily bad equipment just because it doesn't have a built in electronic brain. You just have to use your brain and be attentive.

I do miss the old Sears stores.
 
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dLj

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Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
It’s 42 F.
I will really know my end results over the next few days and going forward from here. But it’s a straight forward process and I do suggest a new modern DC Bench Top Power supply for accurate readings, if you’re are going to make this one of your maintenance projects.
For some of us, if you remember Sears and Roebuck automotive. They would take your battery and place it on a bench overnight for you, load test and balance them for free. And if it didn‘t hold a charge after that, you bought a new battery. They had rows of them on bench’s all connected everyday. That was then, this is now.
I've been using a very good DC power supply for decades at this point for doing equalization. I was taught about it years ago by a retired electrical engineer from Hoover Dam. He had told me a well maintained lead acid battery will last 12 to 15 years, sometimes longer, if properly maintained. Not too long ago, I finally found a reference that supported that faded memory as I was involved in a discussion with Mainesail about battery life and equalization...

I recently upgraded my power supply due to an accident destroying my original power supply. I've very pleased with my new power supply. Looking at your specific gravity numbers, I think you'll find that battery will work quite well for some time yet.

dj
 
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Jun 8, 2020
71
Hunter 34 White Portland, OR
I just replaced our undersized and aging charger work a Guest Charge-Pro Onboard Battery Charger 3 Bank 15amp 12v purchased at West Marine.

The unit is built by ProMariner with a lot of the same innards, just not the fancy name on the front.

Amoung it's features are:

Built-in safety: reverse polarity, over-current, over-voltage, over-temperature and ignition protection. In-line fuses for maximum DC wire protection.

- Battery Conditioning

100% Waterproof (IP67) and shock resistant for all fresh and saltwater applications

Dedicated battery charging, sensing and control per bank

For all 12 volt flooded and AGM lead acid batteries. 2 year warranty

-auto senses type of battery connected


how this helps, cheers!

Sam
 
Dec 28, 2015
1,357
Laser, Hunter H30 Cherubini Tacoma
Not to be judgmental, but with such a modern design boat it appears your battery charging system is from the pre digital era. A hard wired, dedicated on board "smart" charger is what you should be thinking. You might also want to upgrade to larger batteries. My 1977 27 footer, for instance, has 2 Costco wet cell, group 27 batteries that are maintained with a 20 amp Tru Charge 3 stage smart charger. It's literally plug and play. It is able to handle 2 separate banks, I have a house bank and a motor bank. I normally get 42 mos, or more from these basic batteries.
My system was installed by the previous owner, probably in the early 90's... I acquired the boat in 99, have never had a problem.
There's a lot of savvy electrical people on this forum that I'm sure can give you some awesome, specific advice.
But honestly, and I mean this in a very encouraging way, now is a good time to upgrade the whole system.. charger, larger batteries and a proper shore power system installation. Good luck.
If your looking to get through a he winter on them then don’t bother with equalizing
 
Oct 22, 2014
16,107
CAL 35 Cruiser moored EVERETT WA
Looks good Sam, if you have two 75 amp hr Grp24 batteries in decent shape. If not you’ll be sing that battery song, “Killing me softly” over time.