[RE-wrenches] Low voltage lithiums

Bradley Bassett bbassett2 at gmail.com
Sat Nov 19 10:28:23 PST 2022


On some LFP batteries the cell balancing only happens at full charge, so
you do need to get to full every so often. Discover AES is one that needs
this.

Brad

On Sat, Nov 19, 2022 at 10:10 AM Dana Orzel via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Another issue is what charge controller are you using? I know for me with
> Outback products I’ve had to switch from an FM 80 to the OB - FM 100 in
> order to have a more accurate high-voltage cut out voltage.
> The FM 100 has a much more accurate micro processor in it then the FM 60
> or 80 per Brad Bassett with AEE.
>
> Dana Orzel
> C: 208.721.7003
> E- dana at solarwork.com
>
> On Nov 19, 2022, at 7:15 AM, Jeff Clearwater via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Hi Kris
>
> What voltage do you have your charge settings at?
>
> I recommend that bulk or absorb voltage for lithium iron phosphate not be
> set above 56 V  - there is no reason for it even though many manufactures
> suggest higher settings.      In cases where total storage is sized
> generously enough I  often use 55.6 or even 55.4 in order to target 95% as
> full instead of 100% in order to extend cycle life.   and for float there’s
> no reason to ever go over 54 V and better maybe even to be in the mid-53s.
>
> See if that helps assuming you had it higher.
>
> The other thought is you have one bms that is perhaps not protecting
> overcharge  and allowing a temporary spike when the others do limit.
>
> Hope that helps!
>
> Best Jeff C.
> Village Power Design
>
>
>
> Sent from my iPhone
>
> On Nov 19, 2022, at 6:32 AM, Kristopher Schmid via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> 
> Greetings all,
>
> I have seen an issue on two different systems that I am hoping someone can
> shed some light on for me.  One was a 48 volt pack of 12 volt Battle Bornes
> and the other was a 24 volt pack of SOKs.  What happens is when reaching
> the end of the bulk charging stage, the battery voltage spikes and sends
> the inverter into an overvoltage error.  Can anyone explain what is
> happening and a solution?
>
> Thanks,
> Kris
>
> Shine On!
>
> Kris Schmid
> Legacy Solar, LLC
> 137 West 1st Avenue
> Luck, WI 54853
> www.legacysolar.com
> 715-653-4295
> NABCEP Certified PV Installation Professional
> Licensed Wisconsin Master Electrician
> BSEE
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