Wiring In Series (pro vs con)

[OceanPlanet]

Originally Posted by missourisailor

I sent the following to Firefly Peoria a few days ago.

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Dear Sirs,
When will the L-16 4v Carbon Foam batteries be available?

Second Question, Are these made in the Peoria plant?
If not, how will warranty issues be resolved?

Thanks for your time.

-----------

Here is their responce:

Thanks for your email. The L-16 4V batteries are readily available in India. To answer your second question, I would like to inform you that these batteries are manufactured in India and not Peoria. Be rest assured for the warranty concerns, as it will be resolved from Peoria.

Please feel free to contact us should you have any questions.

Regards,
Team Firefly

Yes, they say they can make all we want...here we are waiting for them....some orders over 4 months old. However we do think they will eventually catch up with their claims...;-)

I sure hope so, anyhow.

[john61ct]

Originally Posted by OceanPlanet

It's no problem to discharge 100% with the Firefly; probably not 100 times just for fun, however the full charge/discharge cycles actually improves their capacity for subsequent use.

So you define that zero SoC as 10.5V, as standard?

And do you think the "commission charging" protocol outlined here http://www.cruisersforum.com/forums/....php?p=2468543

is generally applicable to all lead batts, anything different for Firefly?

My plan is to do an accurate "initial benchmark" 20-hour load test when commissioning, and let that also fulfill that part of the breaking in process.

[OceanPlanet]

Originally Posted by john61ct

So you define that zero SoC as 10.5V, as standard?

And do you think the "commission charging" protocol outlined here Breaking in new batteries? - Cruisers & Sailing Forums

is generally applicable to all lead batts, anything different for Firefly?

My plan is to do an accurate "initial benchmark" 20-hour load test when commissioning, and let that also fulfill that part of the breaking in process.

yes, 10.5v is considered 0% SOC. I can't speak to "all lead batts", as every type/brand may have different characteristics. However, I agree with Maine Sail (as I always do) that all Pb batts need some cycling to get them up to capacity.

And certainly for FF the full charge/discharge/recharge cycles, especially with a higher charging rate (.3 to .5C) apparently helps develop the chemical pathways for faster charging. When new they may gas off a bit on the first few charge cycles, however the FF engineers (and also the original inventor, who now lives here in Maine) say that is part of the conditioning process and nothing to worry about.

So yes, don't be afraid of a few full charge/discharge cycles. However...with any Pb other than FF, be sure to not leave them at low SOC (certainly not at 10.5v) for any length of time! They won't like that...

[john61ct]

I won't do that even with FF, really want to maximize longevity, for me their unique properties are for exigencies "just in case".

Since the "lower than usual currents" part of the breaking in process is so widely recommended, I'd probably stick to .2C for the first few months, unless I don't see capacity rising over the first few deep-test cycles.

Later will use a charger sized at .4-.6C. . .

Thanks!

[OceanPlanet]

Originally Posted by john61ct

I won't do that even with FF, really want to maximize longevity, for me their unique properties are for exigencies "just in case".

Since the "lower than usual currents" part of the breaking in process is so widely recommended, I'd probably stick to .2C for the first few months, unless I don't see capacity rising over the first few deep-test cycles.

Later will use a charger sized at .4-.6C. . .

Thanks!

FWIW, the original inventor (Kurtis Kelley) has told us about tests they did where they discharged the batts to 0V, and let them sit for a month with a resister across the terminals. This would be death to any other Pb batt. Then they did several (IIRC, four) charge/discharge cycles and would up with 5% increase in capacity vs. before the 0V abuse.

I would imagine that such treatment would shorten the cycle life. However also note that in Maine Sail's PSOC testing, after 30 PSOC cycles (then a couple full charge/discharge cycles) he got a .5% increase in capacity.

Weird, yes. And don't really understand how it works. However, according to Kurtis the heavy sulfation somehow conditions the carbon foam to actually perform better. He's explained a some of the tech to me, but much goes over my head.

[john61ct]

That is very cool.

I like the thought of you, he and Rod working together up in Maine conspiring to make the world of marine electrics a better place.

I'll make it up there with the kids for a visit one spring. . .

[john61ct]

Originally Posted by missourisailor

On my current system of 8ea 6v batt's, one set of series wired 6v batts are around 0.5v lower than the other 3 sets. The odd thing is that this set, is the set nearest to the positive power cable.
So having the pos. cable on one end of the bank and the neg. cable on the other end, seemed to have no effect on bank balance.

Wonder if physical rotating the order? Or periodically swapping the neg/pos ends?

[missourisailor]

Originally Posted by john61ct

Wonder if physical rotating the order? Or periodically swapping the neg/pos ends?

I can't answer with anything other than speculation. As the only way to do this is to physically move the batteries around. Something that is PITA to do!!!

All of my electrical/electronic teaching and experience tell me that the ideal way to parallel batteries is to have the pos lead at one end and the neg at the other. Which is how it is currently set up.

So in theory, all thing else being equal, they should have stayed closer in-balance. Which leads me to believe that I have a resistance issue going on. Internal or external is the million dollar question.

I can tell you that I have measured the resistance between the post's and the ring terminals using a Wheat-stone. And it is so low that just moving the meter leads around causes the deflection meter to go wild. This tells me that the external connections are good, leading to internal resistance.

So if I am pushed for a cause and effect....I'm going to have to say that at the very least, one or both of the suspect batteries, had some increased internal resistance built into it/them.

[john61ct]

Check out #4 here http://www.smartgauge.co.uk/batt_con.html

Yours is the usual, #2

[missourisailor]

Originally Posted by john61ct

Check out #4 here SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Yours is the usual, #2

Yes mine is liken to #2.

Method #4 is just #2 with the taps in the middle.
Just imagine how long some of those cables have to be with 8 batteries.
Then figure out the cost using 4-0 cable. Also you have three ring terminals stacked on two posts.

I've often seen #3 used in marine and land based banks. And if the batteries are side by side/head to foot, and the buss bars are directly overhead, the cable lengths can be quite short.
But... as in my setup, the bank is split into two locations (separated by the propulsion engine). Which means that all 8ea, 4-0 cables would have to be 6' each (Assuming the cell interconnects just go from pos to neg). Not only a lot of weight but a lot of cable.

One last thing to consider, number of connection.
The weak point of any installation are the connections themselves. No matter how well they are crimped there will always be resistance there. Either at the crimp itself or between the terminals. And the more terminals you use, the more resistance you build in.

On method #1, #2 and #4, for a four battery set up, 14 ring terminals are required.

Method #3 uses 18.

So IMHO. even #1 is better than #3.

[john61ct]

Originally Posted by missourisailor

even #1 is better than #3.

not in the results, I've seen wildly unbalanced batts in a very short time, there are proof youtubes out there as well

obviously when space and placement are not ideal there is a conflict between what's ideal and how far we're willing to go

at least basing our decisions on sound info helps

[missourisailor]

Originally Posted by john61ct

not in the results, I've seen wildly unbalanced batts in a very short time, there are proof youtubes out there as well

obviously when space and placement are not ideal there is a conflict between what's ideal and how far we're willing to go

at least basing our decisions on sound info helps

Generally I agree with you and I should have worded the last part, better.

What I meant/should have said is that even though method #3 is the best way to connect batteries in parallel, because there are more connection points, care must be taken to assure that good conductive crimps are made. And that there is also good conductivity between the ring terminals and either the buss bar and/or other ring terminals.

Without such assurances, method #3 is no better (and might be worse) than #1.

[john61ct]

Yes, for me quality supplies, solid terminations and oversized wires are a given.

As an example, I was happy to pay $300+ for crimpers on eBay, a major bargain since the cheapest new price is over $2,500.

I actually like the idea behind #4 best.

[Zil]

My 6 gc2 bank is wired as #3 with 18" 2/0 cables to the buss bar. Every thing has been good for three years now. I designed the wiring then built the box around that.

[OceanPlanet]

A note about series vs. parallel...


Batteries from the same mfg, same rating, etc. are rarely actually exactly the same capacity. Of course the consistency varies from brand to brand. For instance...when Maine Sail was doing battery testing, some of the suppliers had to send him three batteries before they would meet the claimed spec.


Batteries may sit on shelves for long periods, and/or have been treated differently, with permanent consequences. To assume they are perfectly match when connecting in series is a gamble. So if building a series-connected bank that you want to last, it's a good idea to capacity test each one and make sure they are at least reasonably matched. If you have a dud you can hopefully exchange it.


And...check the voltages often! If they drift off, at least you'll know and can do something about it (dismantle, put in parallel for a day, etc.).