[PSUBS-MAILIST] Battery Question

Mon Jun 20 08:57:19 EDT 2016

I suspect your correct Alec.  Means i'll have to take my batteries out
again now, and modify the connections......which is a real pain.  Hopefully
Sean will chip in.

On 20 June 2016 at 13:45, Alec Smyth via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Just to clarify, the drawing shows the contents of ONE battery pod. There
> are two such pods, connected with a battery switch so I can use one, the
> other, or both.
>
> On Mon, Jun 20, 2016 at 8:43 AM, Alec Smyth <alecsmyth at gmail.com> wrote:
>
>> I was planning to do your #2. Hopefully this is "cross string"?
>>
>> [image: Inline image 1]
>>
>> Thanks,
>>
>> Alec
>>
>> On Mon, Jun 20, 2016 at 7:19 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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>>>>>>> Personal_Submersibles at psubs.org
>>>>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>>>>>
>>>>>>>
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>>>>>>
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