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Conditioning new batteries.

Nov 6, 2020
13
Mariner 36 California
I posted this on another website but though it might be good to post here. Maybe get Mainesails thoughts if he happens to see it.

I just bought a couple of new Trojan T-105 batteries for my house bank. I will install them this weekend but wanted to get a little feedback on this before i do.

I have read before that they (new 12 volt batteries) should be conditioned (broken-in) when new.

I had a link to a good article on this but cant seem to find it anymore. I found a couple of resources on the net.

One golf cart company/manufacturer recommends that in the first 10-20 charge/discharge cycles the batteries be drained to 75% DOD and brought back to 100% SOC immediately after. I found another article that mentioned something similar.

I am curious what some of you think about this procedure and its affect on battery life/ability to hold a charge? Does this procedure fall into the 'battery myth' category or is there science behind it?

I'm a big fan of Mainesail's website but i couldn't find any reference to this procedure. Do any of you do this? If so, has it made a noticeable difference? If you do...what procedure do you use? I'm having a difficult time determining how i would actually get my batteries to 10.5 volts if i did this? I'm not sure what 12 volt equiptment i could use to draw them down that low.
 
Feb 6, 1998
11,317
Canadian Sailcraft 36T Casco Bay, ME
What is more critical is to make sure both batteries are at the same SoC before wiring them in series. We have a set in the scrap heap right now where one series battery was only hitting 7.0V (=14.0V at 12V) at a 14.8V absorption charge. The other was hitting 8.6V (= 15.6V at 12V). The battery that was hitting 8.6V at a 14.8V absorption was completely dried out and cooked while the other battery, only ever getting to about 7.0V, was totally sulfated. Why? Easy the batteries were wired in series at differing states of charge and he owner never caught it.. Unlike when wired in parallel, series batteries have a very tough time equalizing SoC.

By wiring your new batteries in parallel and charging them as a 6V bank @7.4V to 100% SoC they will start out balanced. You can then wire them in series and they should remain in balance for quite a while. They will take a while to break in and doing a few 80% DoD to 100% SoC cycles won't hurt and can help break them in faster. They key here is to follow up any 80% DoD cycle with a 100% SoC recharge.
 
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Nov 6, 2020
13
Mariner 36 California
Very interesting...thank you. One of the batteries is resting at 6.32 and the other at 6.37 volts right now.

I do have the Sterling Pro charger so luckily i can manually set the charge voltage for the parallel charge.
 
Feb 6, 1998
11,317
Canadian Sailcraft 36T Casco Bay, ME
ProCharge Ultra is a 12V charger not 6V... You'll need a 6V charger or a bench top power supply with variable current & voltage. You have one battery at 100% and the other closer to 90% best to balance them..
 
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Nov 6, 2020
13
Mariner 36 California
ProCharge Ultra is a 12V charger not 6V... You'll need a 6V charger or a bench top power supply with variable current & voltage. You have one battery at 100% and the other closer to 90% best to balance them..
Ah thanks for clarifying that. I thought i could just set the charge voltage going into the battery in the custom setting.

I am in no rush so i will pick up a 6 volt charger. I will definately use it again in the future. Im assuming once in a while they will go out of balance and they should be voltage equalized?
 
Apr 22, 2011
659
Hunter 27 Pecan Grove, Oriental, NC
Couldn't you parallel the two batteries for a few days and let them settle to the same voltages. Then series connect them and charge to 100% with the 12v charger. Let them rest and check their individual voltages. If the same you are good to go. If there is still a difference, parallel them again while they are fully charged.
 
Feb 26, 2004
21,365
Catalina 34 224 Maple Bay, BC, Canada
There are probably a gazillion boats with 6V banks in series/parallel.

I read a TON of boating websites.

I have never, ever heard of this issue re 6V batteries.

1. Thx to Maine Sail for commenting.

2. Wonder why I've never heard of it before.

Breaking in new batteries is NOT unusual, because the plates need to be etched. There are thousands of posts going: "I just bought new batteries but they don't seem to be doing well." The answer, the simple one, is to USE them. Others recommend a deliberate heavy discharge followed by a full charge. Relatively same effect.
 
May 24, 2004
6,573
CC 30 South Florida
Batteries in series will discharge or charge at the same rate. If one battery has more charge than the other by the time the weaker battery reaches full charge the other one can be fried by the charger. On the other hand the weaker battery will hit a critical discharge level before the other one reaches a safer 50% level. It is advisable to have batteries at the same SOC before connecting them in series so that the SOC will go up an down in a synchronized or balanced manner. It will prevent overcharging or over discharging those out of balance. This is one reason why batteries should be of a similar age so that they can be balanced. Hope this is simple enough of an explanation. Learned this the hard way from a Golf Cart battery bank.
 
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Nov 6, 2020
13
Mariner 36 California
Batteries in series will discharge or charge at the same rate. If one battery has more charge than the other by the time the weaker battery reaches full charge the other one can be fried by the charger. On the other hand the weaker battery will hit a critical discharge level before the other one reaches a safer 50% level. It is advisable to have batteries at the same SOC before connecting them in series so that the SOC will go up an down in a synchronized or balanced manner. It will prevent overcharging or over discharging those out of balance. This is one reason why batteries should be of a similar age so that they can be balanced. Hope this is simple enough of an explanation. Learned this the hard way from a Golf Cart battery bank.
Much thanks. That explanation really helped me visualize what Mainesail described. That makes perfect sense now. I have a 6 volt charger coming tomorrow so will parallel them and charge here at work. I will let them rest and re-check/charge them if necessary a couple of times to make sure they balance before installing them.

I think Mainesail should be donating $$$ to his readers not his readers donating to his website. Before i started reading his website i had a nice savings account. Now i have sailboat wiring and charging systems that look like they belong on the space shuttle and no more savings account.
 
Nov 6, 2020
13
Mariner 36 California
There are probably a gazillion boats with 6V banks in series/parallel.

I read a TON of boating websites.

I have never, ever heard of this issue re 6V batteries.

1. Thx to Maine Sail for commenting.

2. Wonder why I've never heard of it before.

Breaking in new batteries is NOT unusual, because the plates need to be etched. There are thousands of posts going: "I just bought new batteries but they don't seem to be doing well." The answer, the simple one, is to USE them. Others recommend a deliberate heavy discharge followed by a full charge. Relatively same effect.
Thanks Stu. Yes i just murdered a fairly new "Dual use' West Marine battery thinking it was truly a deep cycle battery...UGH! Just when i think i'm really starting to learn a thing or two i manage to completely destroy something.
 
Jan 11, 2014
6,516
Sabre 362 113 Fair Haven, NY
Thanks Stu. Yes i just murdered a fairly new "Dual use' West Marine battery thinking it was truly a deep cycle battery...UGH! Just when i think i'm really starting to learn a thing or two i manage to completely destroy something.
Welcome to DIY boating. We learn from our failures not our successes. Don't be too hard on yourself. I have a basement full of learning experiences.
 
May 24, 2004
6,573
CC 30 South Florida
In parallel power from one battery will flow into the other and this balances them, but in series that does not naturally happen. If you have two batteries to balance just charge them fully and then connect them in parallel for a couple of hours and they should closely balance each other. Yes, it is possible to partially charge them in series at 12V for a couple of hours and then reconnect them in parallel and allow them to rest until they reach balance with a final reconnection in series for the final charge at 12V to 100% capacity. This could be done if there is no access to a 6V charger. Is the out of balance condition a critical factor? I would say it depends on cycling and the SOC differential. A couple of points will not likely make much difference especially in the short term but a 5 to 10 point difference would likely hurt a battery prematurely and the other one in short order.
 
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Nov 6, 2020
13
Mariner 36 California
Welcome to DIY boating. We learn from our failures not our successes. Don't be too hard on yourself. I have a basement full of learning experiences.
yes im finding this out. it is nice though when i do do something right and it works perfectly. im not sure i should say this out loud though.
 
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