Thanks Bill, sorry I'll try and give you more information.

I'm using a Zivan NG3 charger and don't have a BMS at the moment, just a
bunch of QNBBM cell balancers.

Previously I stopped the charge manually when the Curtis was saying 100%.
The Zivan also displays a charging progress and it would also be at 100%.
But lately the Curtis is saying 30% when the Zivan is showing 80% complete
and some of the cells are starting to jump up to 4V during that phase of
the charge. Whenever a cell goes over 4V I've been stopping the charge and
allowing the cell balancers to even out the pack again.

Is there anything other information I should be providing?

Thanks for your help.

Matthew



It all came out of a working car and has been fine until recently when the
pack

07966 806 727


On 7 August 2017 at 15:13, Bill Dube via EV <ev@lists.evdl.org> wrote:

> You have not given quite enough information about your system to fully
> understand your issue.
>
> However, to fully charge your 25 LFP cells to 100% SOC, your charger
> should shut off at a voltage of a minimum of ~3.45 volts on all cells.
> The full-charged pack voltage should be 87.5 volts, or a bit more.
>
> 3.6 to 3.8 volts on the highest cells is where your BMS should be set to
> reduce the output of your charger. You should not be going over ~3.8 volts
> on any cell.
>
> Your charger should be controlled by your BMS somehow, hopefully.
>
> Like I said, we need a bit more information on your system to understand
> exactly what your problem really is.
>
> Bill D.
>
>
> On 8/7/2017 12:53 AM, Matthew Quitter wrote:
>
>> Thanks guys... but if the charger is turning off at a fixed voltage how
>> do I get more power into the pack?
>>
>>
>> On 7 Aug 2017, at 05:02, Bill Dube via EV <ev@lists.evdl.org> wrote:
>>>
>>> I agree. Voltage on LFP cells is useless for determining the SOC.
>>> The voltage is very constant except at near 100% SOC and at 0% SOC.
>>> You really need information about the middle, and voltage doesn't give
>>> any clue about that.
>>>
>>> You need to count the amp-hours, like with an E-meter or a Cycle-Analyst.
>>>
>>> Bill D.
>>>
>>> On 8/6/2017 7:00 PM, Willie via EV wrote:
>>>>
>>>>
>>>> On 08/06/2017 07:38 PM, Matthew Quitter via EV wrote:
>>>>> Hi Guys,
>>>>>
>>>>> My 1238-6501 Curtis controller gives very different SOC % for similar
>>>>> voltages.
>>>>>
>>>>> For example I've recorded a pack voltage of 82.2 and had the Curtis
>>>>> show
>>>>> 22%, 31%, 43%.
>>>>>
>>>>> The pack is made up of 25 Thundersky 160Ah batteries.
>>>>>
>>>> With LFP cells, you can't accurately infer SOC from voltages in the
>>>> middle of the range.  The voltage/SOC curve is too flat.
>>>> _______________________________________________
>>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>>> Read EVAngel's EV News at http://evdl.org/evln/
>>>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group
>>>> /NEDRA)
>>>>
>>>>
>>>> _______________________________________________
>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>> Read EVAngel's EV News at http://evdl.org/evln/
>>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group
>>> /NEDRA)
>>>
>>>
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> Read EVAngel's EV News at http://evdl.org/evln/
> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group
> /NEDRA)
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: 
<http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20170807/a719ea64/attachment.htm>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)

Reply via email to