What would happen if I used my old 8D's with my new 8D's?

softdown · July 2017

Marc Kurth said:

@softdown:

I do a LOT of 24/48/72, 2v cell strings for 48v AGM battery banks. When I speak with the Chief Engineer at a particular battery manufacturer about variations in individual cell voltages, he invariably responds with: "Marc, what are the individual cell voltages in a 48v bank with 8D's?" He goes on to explina that the same thing happens internally with a 6v, 8v or 12v battery. Please note that this applies to batteries of the same type and vintage.

After a lot of years doing this, I have become a huge believer in long float time to let batteries reach the same level.

Marc

Yes.....well I wanted a long float and got rain instead. Thinking it may take about a week to "break in" the "new" batteries. Something like that?

Marc Kurth · July 2017

"Break in" involves draining some energy and putting it back. Roughly a dozen partial cycles will bring your batteries up to full capacity. Don't focus on precise standing voltages until then.

I meant allowing a good long (8-12 hours) float time every week or two (or more often!) in normal operation. This is an opinion coming only from field time with a whole lot of battery banks over the last 9-10 years - and hearing the same thing from folks way smarter than I.

Marc

softdown · July 2017

Marc Kurth said:

"Break in" involves draining some energy and putting it back. Roughly a dozen partial cycles will bring your batteries up to full capacity. Don't focus on precise standing voltages until then.

I meant allowing a good long (8-12 hours) float time every week or two (or more often!) in normal operation. This is an opinion coming only from field time with a whole lot of battery banks over the last 9-10 years - and hearing the same thing from folks way smarter than I.

Marc

I am keeping some of the FullRiver AGM's for use on a liveaboard sailboat in ~2-3 years. Would they store significantly better if I hooked them up and let them do normal cycling for two weeks? Thanks in advance.

FWIW....this mornings voltage started at 49.2 volts. Not good and not bad. Hard to judge when the rain robs one of several hours of float. Plus the batteries are not broken in yet.

Solray · July 2017

> @softdown said:
> Now the old 8D readings have become interesting:
> The battery with the positive charging cable is reading 14.3. Mfd in late 2011 and placed in service in early 2015.
> The battery with the negative charging cable is reading 13.02. Mfd in 2016, my newest battery.
> The other two old batteries are reading 13.7.
>
> I have always found very strong correlations between SG and voltage. Willing to bet the old battery now has higher SG readings. Also wondering if a weaker battery accepts a higher charging voltage more readily. Perhaps this high "float voltage" will disappear after the sun hands the duty baton over to the moon? I will probably report on findings.
>
> Running the RJ5 temperature sensor through foot thick walls was absolutely 2 1/2 bi**hes. Impossible without a wire puller, tape, and vaseline. Even removing vaseline impregnated tape was tricky.

I use a drill bit with a hole in it to pull wires through walls. Just drill, leave the bit in the wall, go thread a wire through the hole in the bit and use that to connect to the wire you are pulling. Then go back around again and pull it right through.
It makes life very easy.
https://www.amazon.com/gp/aw/d/B00004YO6E/ref=mp_s_a_1_3?ie=UTF8&qid=1501172558&sr=8-3&pi=AC_SX236_SY340_FMwebp_QL65&keywords=18+inch+drill+bit&dpPl=1&dpID=31MN+Qdi-kL&ref=plSrch

Marc Kurth · July 2017

softdown said:

Marc Kurth said:

"Break in" involves draining some energy and putting it back. Roughly a dozen partial cycles will bring your batteries up to full capacity. Don't focus on precise standing voltages until then.

I meant allowing a good long (8-12 hours) float time every week or two (or more often!) in normal operation. This is an opinion coming only from field time with a whole lot of battery banks over the last 9-10 years - and hearing the same thing from folks way smarter than I.

Marc

I am keeping some of the FullRiver AGM's for use on a liveaboard sailboat in ~2-3 years. Would they store significantly better if I hooked them up and let them do normal cycling for two weeks? Thanks in advance.

FWIW....this mornings voltage started at 49.2 volts. Not good and not bad. Hard to judge when the rain robs one of several hours of float. Plus the batteries are not broken in yet.

They would be happier on float for that extended period. Do keep in mind the overall age since manufacture when you get 2-3 years down the road from today. There is a finite life, so saving batteries for future is often a losing proposition - or at least expensive anchors.

You bought them for a great price - use them now and save up to buy more later. Who knows, Elon seems to think that Lithium might be almost free by then

Marc

softdown · July 2017

Solray said:

> @softdown said:
> Now the old 8D readings have become interesting:
> The battery with the positive charging cable is reading 14.3. Mfd in late 2011 and placed in service in early 2015.
> The battery with the negative charging cable is reading 13.02. Mfd in 2016, my newest battery.
> The other two old batteries are reading 13.7.
>
> I have always found very strong correlations between SG and voltage. Willing to bet the old battery now has higher SG readings. Also wondering if a weaker battery accepts a higher charging voltage more readily. Perhaps this high "float voltage" will disappear after the sun hands the duty baton over to the moon? I will probably report on findings.
>
> Running the RJ5 temperature sensor through foot thick walls was absolutely 2 1/2 bi**hes. Impossible without a wire puller, tape, and vaseline. Even removing vaseline impregnated tape was tricky.

I use a drill bit with a hole in it to pull wires through walls. Just drill, leave the bit in the wall, go thread a wire through the hole in the bit and use that to connect to the wire you are pulling. Then go back around again and pull it right through.
It makes life very easy.
https://www.amazon.com/gp/aw/d/B00004YO6E/ref=mp_s_a_1_3?ie=UTF8&qid=1501172558&sr=8-3&pi=AC_SX236_SY340_FMwebp_QL65&keywords=18+inch+drill+bit&dpPl=1&dpID=31MN+Qdi-kL&ref=plSrch

I'm sure that operating drill bits inside of tight multi-layered 12" walls with 3/4" thick power cables snaking through is exceptionally brilliant.

Lest someone fail to notice the sarcasm, I did that once. Imagine my shock to find the insulation had been drilled away and the copper wiring exposed and shorting out.

softdown · July 2017

Marc Kurth said:

softdown said:

Marc Kurth said:

"Break in" involves draining some energy and putting it back. Roughly a dozen partial cycles will bring your batteries up to full capacity. Don't focus on precise standing voltages until then.

I meant allowing a good long (8-12 hours) float time every week or two (or more often!) in normal operation. This is an opinion coming only from field time with a whole lot of battery banks over the last 9-10 years - and hearing the same thing from folks way smarter than I.

Marc

I am keeping some of the FullRiver AGM's for use on a liveaboard sailboat in ~2-3 years. Would they store significantly better if I hooked them up and let them do normal cycling for two weeks? Thanks in advance.

FWIW....this mornings voltage started at 49.2 volts. Not good and not bad. Hard to judge when the rain robs one of several hours of float. Plus the batteries are not broken in yet.

They would be happier on float for that extended period. Do keep in mind the overall age since manufacture when you get 2-3 years down the road from today. There is a finite life, so saving batteries for future is often a losing proposition - or at least expensive anchors.

You bought them for a great price - use them now and save up to buy more later. Who knows, Elon seems to think that Lithium might be almost free by then

Marc

Finite life...yes. Given the remarkably low self discharge life, cool storage conditions, and quality of manufacture and components, I suspect the life is not as finite as others may be.

Call me bull headed, but I enjoy getting more life out of seven old 8D FLA's with very little resale value at all. They do fine... until a cell "shorts out". Curiously my old battery with two bad cells took a full charge. I will test the voltage tomorrow.

So the 1am power outage remains a major curiosity. What happened that day? I was gone for half of it, perhaps my security systems have become huge power consumers.

Solray · July 2017

softdown said:

Solray said:

> @softdown said:
> Now the old 8D readings have become interesting:
> The battery with the positive charging cable is reading 14.3. Mfd in late 2011 and placed in service in early 2015.
> The battery with the negative charging cable is reading 13.02. Mfd in 2016, my newest battery.
> The other two old batteries are reading 13.7.
>
> I have always found very strong correlations between SG and voltage. Willing to bet the old battery now has higher SG readings. Also wondering if a weaker battery accepts a higher charging voltage more readily. Perhaps this high "float voltage" will disappear after the sun hands the duty baton over to the moon? I will probably report on findings.
>
> Running the RJ5 temperature sensor through foot thick walls was absolutely 2 1/2 bi**hes. Impossible without a wire puller, tape, and vaseline. Even removing vaseline impregnated tape was tricky.

I use a drill bit with a hole in it to pull wires through walls. Just drill, leave the bit in the wall, go thread a wire through the hole in the bit and use that to connect to the wire you are pulling. Then go back around again and pull it right through.
It makes life very easy.
https://www.amazon.com/gp/aw/d/B00004YO6E/ref=mp_s_a_1_3?ie=UTF8&qid=1501172558&sr=8-3&pi=AC_SX236_SY340_FMwebp_QL65&keywords=18+inch+drill+bit&dpPl=1&dpID=31MN+Qdi-kL&ref=plSrch

I'm sure that operating drill bits inside of tight multi-layered 12" walls with 3/4" thick power cables snaking through is exceptionally brilliant.

Lest someone fail to notice the sarcasm, I did that once. Imagine my shock to find the insulation had been drilled away and the copper wiring exposed and shorting out.

They are installer bits, made for the purpose, you need to use some caution with any drill bits, are you saying you made holes in your wall without drilling? That is dangerous too.

softdown · July 2017

This mornings voltage shows 50.1 volts. That is what I had hoped to achieve. It is now quite possible that the old 8D's will quit developing bad cells every ~1/2 year. In celebration I turned the fridge/freezer down a couple degrees yesterday.

Having a powerful battery bank is awesome. Highly recommended.

Though my Outback MATE SOC meter crapped out while I was in the vicinity. It now seems to think that I have a 51% SOC and have not had fully charged batteries in 2.7 days. All that in spite of showing 50.1 volts at 5:30am. Electronics and I simply don't get along that great.

softdown · July 2017

1am power outage no longer a mystery. In spite of "taking a charge" yesterday, the questionable battery is now showing 8.5 volts....two bad cells indeed. Why did the charger still "charge it"? It almost always revolts against charging batteries with a bad cell.

softdown · July 2017

FWIW, my Johnson Controls 8D's built in 2011 have provided much better service than later years. My weakest battery is the second newest. Have several 2011 vintage still going strong.

Solray · July 2017

> @softdown said:
> 1am power outage no longer a mystery. In spite of "taking a charge" yesterday, the questionable battery is now showing 8.5 volts....two bad cells indeed. Why did the charger still "charge it"? It almost always revolts against charging batteries with a bad cell.

Bad charger too maybe.

Marc Kurth · July 2017

softdown said:

1am power outage no longer a mystery. In spite of "taking a charge" yesterday, the questionable battery is now showing 8.5 volts....two bad cells indeed. Why did the charger still "charge it"? It almost always revolts against charging batteries with a bad cell.

In the world of modern chargers, 8.4v to 8.6v is a common threshold for 12v chargers to declare "bad" battery instead of simply an over discharged battery. There are also many chargers that will charge a dead battery.

I do not recall what you have.

softdown · July 2017

Marc Kurth said:

softdown said:

1am power outage no longer a mystery. In spite of "taking a charge" yesterday, the questionable battery is now showing 8.5 volts....two bad cells indeed. Why did the charger still "charge it"? It almost always revolts against charging batteries with a bad cell.

In the world of modern chargers, 8.4v to 8.6v is a common threshold for 12v chargers to declare "bad" battery instead of simply an over discharged battery. There are also many chargers that will charge a dead battery.

I do not recall what you have.

Usually use the Battery Minder 12248 for the 8Ds. It has 8amp charging capability and seems like a good charger.

I have no idea if the "desulfator" function works or not. I used to think it helped. Now I just try to keep batteries at 12.6 volts or better. After the battery is fully charged, it goes into a flashing "desulfate" mode.

Two of the cells in the bad 8D showed "water". I often double check stuff. Intermittent problems are everybody's delight?

softdown · August 2017

FWIW and hardly worth mentioning, Sam's Club has switched from Johnson Controls in Mexico to East Penn which is made of "imported and domestic" materials. The rep felt that Johnson quality had deteriorated significantly. That was also my experience though I can not offer a scientific sample.

What would happen if I used my old 8D's with my new 8D's?

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