[PSUBS-MAILIST] Battery Question

Mon Jun 20 08:42:26 EDT 2016

Hank.  I have 2 banks like this.  so 8 batteries in total.  The pic was
only showing the possible configuration of 1 single set.

On 20 June 2016 at 13:26, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> James,
> I like option two for the reason you mention. My first thought is to have
> a battery bank switch but this eliminates the need for that, unless you
> want to isolate one bank for get home safety.
> Hank
>
>
> On Monday, June 20, 2016 5:20 AM, James Frankland via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Thanks Guys.  I need to absorb this information.  A lot to read here.
>
> I don't really understand the "cross string" thing either.  I will attach
> this picture of the 2 possible ways of doing it (for my application) and
> maybe Sean or someone can comment?
>
> I currently have the batteries rigged in Config 1, but have been advised
> (possibly incorrectly) to use config 2.  Apparently this is how most high
> power UPS systems are configured and allows redundancy if 1 pair fails.
>
> Any ideas?
>
> Thanks
> James
>
>
> 
>
> On 19 June 2016 at 23:56, Sean T. Stevenson via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> If you wire two or more batteries together in parallel by connecting all
> of the + terminals together and all of the - terminals together (hopefully
> using bus bars or large and short cables), instead of making your power
> draw or charging connections to the + and - terminals at one end of the
> battery string (i.e. at a single battery), you should instead, for example,
> connect to the + terminal of the first battery in the string, and the -
> terminal of the last one.
> Sean
>
>
> On June 19, 2016 3:53:58 PM MDT, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Sean,
>
> I'm afraid I didn't get the meaning of "cross string." The other
> mitigating measures I'm in compliance with, but could you maybe share a
> little diagram of what you meant by "cross-string"?
>
>
> Many thanks,
>
> Alec
>
> On Fri, Jun 17, 2016 at 2:03 PM, Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> As far as battery interconnections are concerned, in the absence of a
> battery / cell management module, it is next to impossible to ensure that
> individual battery voltages stay balanced. That said, you can minimize the
> potential for un! balance by making sure that your parallel batteries are
> connected cross-string, instead of to the terminals of one battery in the
> parallel bank. By this, I mean make the positive connection to the first
> battery in the parallel string, and the negative connection to the last
> battery in the string.  As far as the series connections go, there is only
> one way to hook it up, but you can minimize the unbalance by ensuring that
> every battery is of the same type and capacity, and of the same age (I.e.
> replace all batteries simultaneously). Also, try not to tap off of a lesser
> number of batteries if you need a lower voltage for some purpose - instead,
> use a DC-DC converter powered by the entire string.
> As for charging, see if a recommended charge curve is provided by your
> battery manufacturer, and source an appropriate charger. The specs you
> listed are straightforward: maximum 2.4 Volts per cell (Implying 14.4 Volts
> max for a 12V battery) during charge, with nominal charge voltage 2.35 V
> per cell (14.1 V on a 12V battery. Once charged, the float voltage must
> drop to 2.25 - 2.3 Volts per cell (13.5V - 13.8V on a 12V battery).  For a
> 24V system, you would double these values.
> The maximum ripple spec has to do with the quality of the rectifier
> output. A good quality charger will have circuitry to create more pulses
> per AC cycle and smoothing capacitors on the output side to better
> approximate a DC output. The ripple is the distance between minimum and
> maximum peak amplitudes on the "DC" output side.
> Sean
>
>
> On June 17, 2016 4:53:35 AM MDT, James Frankland via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
>  Hi All
>
> Could anyone give me a hand with a battery charging question.  It sounds
> simple enough but I seem to be getting conflicting advice all over the
> place.
>
> How do I charge my battery banks correctly?
>
> I have just spent a lot of money on a brand new set of batteries and I
> don't want to charge them incorrectly.
>
> The batteries are WING ESL 55-12.  AGM
> 12v
> 55ah
>
> On the sheet it gives charging instruction.
>
> Float 2.25 - 2.30 VPC @ 25deg C
> Cycling 2.35 @ 25deg C
> Max 2.4 VPC Max Ripple 0.05C (A)
>
> This seems straight forward enough for a single battery, but I have them
> configured as a bank which seems to be where the issue lies.
>
> 2 pairs in parallel, then the 2 pairs joined in series to give 24v.
>
> I will have to ! charge them as a bank through the 24v output terminals.
>
> I will add the spec sheet of the batteries.  Hope it gets through.
>
> Any advice appreciated.
>
> Regards
> James
>
>
>
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