I highly recommend _against_ the 2v L16s.  You are not going to a better battery, or fewer cells; just the cells are wired internally, making it very difficult to assess each cell independently.  I trouble shot a system of Trojan 2 v L16s, that was only 2 years old, but was trying to run a large compound.  I had to use my infared camera to ID the dead cells, and there were plenty of them, but each individual"2v" battery had correct voltage.

A system anywhere in this size range needs to go to real 2 v cells, like the HUP or other large format battery that is designed for what you are trying to do.  L16s are the equivalent of buying 4 VW bugs, when you really need one 3/4 ton Dodge.

Do yourself and your customers a favor, and save the L16s for systems that require less than 800 AH.   Batteries are the number one source of failure and dissatisfaction off grid.  Don't cheap out.

Ray Walters
Remote Solar

On 4/4/2023 5:42 PM, Dave Angelini Offgrid Solar via RE-wrenches wrote:
Hurts my head !  Agree that you will have more trips to this house after the next one. This is most likely not going to get you 2 more years. All of the wiring is good, clean, and tight?  Who really knows how long it could last? Probably fine thru summer and fall. Much better with the next L16 size up and 24 (2V) cells. Lot's of capacity choices there from Rolls and others.
Almost Cheers time !
*Dave Angelini Offgrid Solar "we go where powerlines don't" http://members.sti.net/offgridsolar/ e-mail offgridso...@sti.net text 209 813 0060*


On 2023-04-04 4:21 pm, Ray Walters via RE-wrenches wrote:

So the 24 batteries are actually 72 individual cells that are trying to charge equally, with essentially no BMS. Its not just max strings, but max # of cells, and that's double my maximum.

You mentioned they use it pretty hard, so that's the other big part of how long L16s will last.  If the customer is barely using the available capacity, I've seen batteries last closer to 10 years, but in this case, I think the remaining cells are close to finished. I'm into using batteries for as long as possible as well, but customer and installer suffering come into play, as well as the fact they'll use much more water at the end of life, and cause a lot more corrosion damage.

Not to be a turd at the pool party, but its not reasonable to plan on another 2 years of service.  My guess is that you will probably have more cells fail by the time you return with the prorated warranty replacements.  Certainly rolling into the summer months, more cells are going to start failing like pop corn. (Pop, pop, pop)

Fortress is a good battery, but some of the programming, (especially LVD) can be tricky with older inverters.  I had to use the aux out on the CC to switch off the inverters.  IF the inverters are Outback, they have a remote switch, if its something else, you might have to actually switch off a relay on the AC output.

Ray

On 4/4/2023 2:45 PM, Daniel Young via RE-wrenches wrote:

Thanks all for the advice. I figured it was not worth trying on a different battery brand. I honestly needed to be able to tell them I researched it and asked my peers.

The client really uses the 3 x strings they have and did not really want to go down to 3. They are currently choosing to get the two Rolls under the prorated warranty, and hopes to get another 2 useful years out of the bank before planning to replace.

Already prepared him on the cost of the equivalent Li+ at todays prices. So he knows roughly where he is heading.

Side note: I am in the camp of trying for 2 x strings when possible (agree that 3 x strings is the absolute limit, and not the best option), simply because if a single cell goes bad, I don't want a client with essentially nothing available until we can get a replacement and get on site. With 2 strings, they can make due at least. That'll go out the window with Lithium though. Looking at Fortress Power for the next battery bank for this client. But we will see what changes in the market by the time it's needed.

With Regards,

--

Danny Young

NABCEP PV Installation Professional #031508-90

Engineering Team Lead
Solar Energy Solutions

Lexington | Louisville | Bloomington | Cincinnati | Evansville | Indianapolis

513-448-5176 (mobile)

877-312-7456 (Main Office)

da...@sesre.com <mailto:da...@sesre.com>

*From:* RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> <mailto:re-wrenches-boun...@lists.re-wrenches.org> *On Behalf Of *Dave Angelini Offgrid Solar via RE-wrenches
*Sent:* Monday, April 3, 2023 4:34 PM
*To:* RE-wrenches <re-wrenches@lists.re-wrenches.org> <mailto:re-wrenches@lists.re-wrenches.org> *Cc:* Dave Angelini Offgrid Solar <offgridso...@sti.net> <mailto:offgridso...@sti.net>
*Subject:* Re: [RE-wrenches] replace part of rolls battery bank

5 years old on 3 strings, it might not matter to mix, better get ready for a new bank.

I have never used more than 1 string for my clients and get closer to 10 years life, so maybe there is better advice out there.

Good Luck!

*Dave Angelini Offgrid Solar*
*"we go where powerlines don't"*
*http://members.sti.net/offgridsolar/ <http://members.sti.net/offgridsolar/>*
*e-mail offgridso...@sti.net <mailto:offgridso...@sti.net>*
*text 209 813 0060*

On 2023-04-03 11:03 am, Daniel Young via RE-wrenches wrote:

    Hello Wrenches,

    Have a client with 24 x Rolls S550's. 2 of the batteries have
    given up the ghost. Rolls will replace them under the pro rated
    warranty.

    The issue us, the client is wanting to replace them with non
    Rolls batteries to save $. They can get 400AH 6V L-16 form
    factor FLA batteries from a local battery house for the same
    price I am going to get the new Rolls for. And that also means
    they don't need to pay for freight. The net result is that they
    could save $4-500 by getting the batteries locally. No freight,
    and no markup on the batteries we provide (I can technically add
    the lost markup back in as labor, we do need to make something
    off of the 3hr one way drive to swap the batteries)

    Question is, has anyone got experience mixing battery brands
    like this?

    3 x strings of 8 c S550's (L-16HC would be the replacements)
    both dead batteries are on the same string.

    Whole battery bank is near the 5yr old mark.

    The last rolls battery bank the client had lasted them 10 years.
    (they baby the battery bank to be sure, and take maintenance
    seriously)

    I understand where the client is coming from, but do not want to
    let them shoot themselves in the foot, and I simply do not know
    what the chances are of swapping in batteries from a different
    brand. In my head, I don't see a big issue, even if they are sub
    par, they will likely just get older faster, and fail around the
    same time as the rest of the 4-5yr old battery bank. But I'm
    unsure if there are any more subtle issue that these other
    batteries would cause.

    Client has been loyal for more than a decade, so I want to give
    them a fair shake at saving some $ now, as they plan to move to
    lithium when the whole battery bank finally gives out.

    With Regards,

    --

    Danny Young

    NABCEP PV Installation Professional #031508-90

    Engineering Team Lead
    Solar Energy Solutions

    Lexington | Louisville | Bloomington | Cincinnati | Evansville |
    Indianapolis

    513-448-5176 (mobile)

    877-312-7456 (Main Office)

    da...@sesre.com <mailto:da...@sesre.com>

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