New Battery Bank Questions

Maine Sail · Feb 23, 2018

firehoser75 said:
Looking for some opinions/advice, just what these forums are great for!
I am installing a new battery bank of 6 golf cart flooded lead acid batteries. Should these batteries be "conditioned" in any way other than ensuring they are fully charged after the install and cycling them partially down a few times before putting them to their full task?
As one of my charging sources, I have a 570 watt solar array with a Morningstar MPPT controller. When I equalize the batteries (using the shore charger), should I disconnect the solar array during the process? I know I need to shut down all DC devices to avoid damaging them with the high voltage, but do I need to do anything to the solar?
I am trying to treat the new batteries as well as I can.
Thanks,
Tom

Before installing I wire every 6V bank in parallel first then charged it to 7.4V (14.8V at 12V) until current tapers to near nothing (less than 1% of Ah capacity). I then boost the voltage to 15.5V for an additional hour. This puts the batteries in "balance" with one another so when they are put in series we don't have batteries out of SOC balance.

Batteries in series won't naturally balance for SOC unless you frequently equalize the bank and even then this is longer and tougher than just wiring them in parallel at 6V.

Out of balance series batteries are one of the most common problems I see with series wiring.... Also make sure your first few cycles, 8-10, are deep-cycles that are fully returned to 100% SOC after each cycle. This helps define the pathways used through the lead during discharge. By deep cycle I mean to at least 50% DOD but there is no problem during break in with going to 70% to 80% DOD so long as they are followed up with a 100% SOC recharge.

There should be very few items on-board that can be damaged by 15.5V but it is still a best practice to turn these items off when EQing. Solar does not need to be turned off, it will do this on it own once bus voltage exceeds the controllers regulation limit.

Hello Below · Feb 23, 2018

Maine Sail said:
I then boost the voltage to 15.5V for an additional hour.

Really good information and something I would have thought would be carried out by the battery distributors prior to handing off to the end user. Given that most of us do not have access to the equipment to do this, I assume that it could be done at your local marine/RV battery store? And just for clarification that additional hour voltage boost would be to 7.75V for a 6V?

Xanthus · Feb 27, 2018

Maine Sail said:
Before installing I wire every 6V bank in parallel first then charged it to 7.4V (14.8V at 12V) until current tapers to near nothing (less than 1% of Ah capacity). I then boost the voltage to 15.5V for an additional hour. This puts the batteries in "balance" with one another so when they are put in series we don't have batteries out of SOC balance.
Batteries in series won't naturally balance for SOC unless you frequently equalize the bank and even then this is longer and tougher than just wiring them in parallel at 6V.

Why do you do this with six volt batteries? You don't do it with 12 volt batteries, do you?
12 volt batteries are two 6 volt batteries in one case.

Maine Sail · Feb 27, 2018

Xanthus said:
Why do you do this with six volt batteries? You don't do it with 12 volt batteries, do you?
12 volt batteries are two 6 volt batteries in one case.

I do commission charge 12V batteries too and I also do that in parallel, speeds the process..

Because batteries ship, then sit in various trucks, warehouses and temps, and can self-discharge at varying rates I commission charge any battery before it is installed..

The three cells in a 6V battery are usually well balanced, within that unit/shell, like a new 12V battery, but the next battery you may be wiring it in series with may not be in balance with the first. Placing batteries in series, that are out of balance, results in a continuation of intra-bank imbalances.

The easiest way to initially put batteries into SOC balance, that will later be in series or series / parallel, is to charge them in parallel to commission them. Because most boat-owners don't equalize regularly the imbalances can remain for quite some time and cause issues down the road. The issues of series-string imbalance is not a new one, just one that is often ignored in the marine market. Only recently have companies started to address the issue, in the marine space, with series battery balancing devices.

Maine Sail · Feb 27, 2018

Hello Below said:
Really good information and something I would have thought would be carried out by the battery distributors prior to handing off to the end user. Given that most of us do not have access to the equipment to do this, I assume that it could be done at your local marine/RV battery store? And just for clarification that additional hour voltage boost would be to 7.75V for a 6V?

Battery distributors hardly ever touch a battery other than to pull it from the shelf and sell it. Some batteries may sit for a year or more before being sold. They are supposed to "top" them every 3 months or so but it rarely happens even with the best distributors. I know of one battery distributor who's warehouse is routinely hoovering in the 100F range for 4-5 months per year. This means much more rapid self discharge. Yes 7.75V X 2 = 15.5V @ 12V

For a certain test I was running for one of the publications I purchased a brand new very expensive battery on-line (no local distribution). When it arrived it could not deliver anywhere close to the rated capacity (about 20% of the capacity not there) even after break-in cycling. When I gave the manufacturer the actual numbers engraved into the case this battery was 16 months old and had been sitting in a California warehouse for most of it. Funny enough it had a small round date code sticker that suggested the battery was 1 month old. That sticker had been applied by the distributor, not the manufacturer.

Maine Sail · Feb 27, 2018

Bill Roosa said:
Most battery charges have a 30 day equalize mode. If you leave the charger on all the time it will equalize the bank once every 30 days. Can boil some water during this automatic process so makes it all that more important to check the batteries monthly at least

Most battery chargers require a manual EQ activation due to risk and the litigious society we live in..

Ward H · Feb 28, 2018

Maine Sail said:
Before installing I wire every 6V bank in parallel first then charged it to 7.4V (14.8V at 12V) until current tapers to near nothing (less than 1% of Ah capacity). I then boost the voltage to 15.5V for an additional hour. This puts the batteries in "balance" with one another so when they are put in series we don't have batteries out of SOC balance.

Maine, can this be done in the boat and will the Sterling Pro Ultra 30A charger do this?
The charger is only listed for 12V. For two GC2 batteries, do you still wire in parallel and use a custom setting to balance the two 6V batteries?

I assume not balancing the batteries results in possible lower available Ah?
How important is this step for the daysailer/occasional over night sailer or spends most of his nights in the slip with shore power?

Maine Sail · Feb 28, 2018

It's a 12V charger.. Wire them as a 12V bank, fully charge, then EQ the bank and check SG of each cell.

Bob S · May 14, 2018

Maine Sail said:
Before installing I wire every 6V bank in parallel first then charged it to 7.4V

RC,
One last question
Should this be wired in parallel as one bank or can it be done in pairs (6 battery bank 3x).
My local US Battery distributor has switched to Superior Batteries because US is quoting him a 7 month lead time.

Maine Sail · May 14, 2018

Bob S said:
RC,
One last question
Should this be wired in parallel as one bank or can it be done in pairs (6 battery bank 3x).
My local US Battery distributor has switched to Superior Batteries because US is quoting him a 7 month lead time.

It can be done as one bank it just takes longer.