# SKY Battery-pack with 20700 Li-Ion (?max. Voltage & connector-shape?) **URL:** \ **Category:** Tempest Owners\ **Created:** [April 30, 2019, 2:04pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450 "2019-04-30T14:04:56Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![matthiasginster](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@matthiasginster](https://community.tempest.earth/u/matthiasginster)\ **Post date:** [April 30, 2019, 2:04pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/1 "2019-04-30T14:04:56Z")
Hi volks, hey @WFmarketing While this overall topic was discussed over pages of threads, there are two things I could not find after hours of reading: 1. What is the max. acceptable voltage? I’m planning to use 4-6pcs of 20700 batteries in parallel. This will give me 19-28Ah with a nominal voltage of 3.7V (max. 106Wh). After charging, these Li-Ion batteries peak at about 4.1-4.2V. I’d like to use them connected directly to the SKY, so I can see how the voltage drops and at which time a recharge is required. Can the SKY accept this voltage without problems? Any voltage-regulator would output a rather constant voltage which makes it impossible to see how the battery empties. 1. In order to bring the power into the SKY, I’d like to use the bottom-connectors with some 3D-printed adapter. I could start to measure and with some trial & error, but - is there a chance to get a 3D model / shape from WF? A drawing would be good too, whatever 🙂 I can use Autodesk-Inventor files (IPT) as well as STEP, SAT, IGES, DXF, DWG etc. Once I finish my pack (which is not even started yet due to the information above is missing), I’ll publish a manual for you guys. Regards, Matthias ---
**Author:** ![vinceskahan](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/vinceskahan/32/2785_2.png) [@vinceskahan](https://community.tempest.earth/u/vinceskahan)\ **Post date:** [April 30, 2019, 3:15pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/2 "2019-04-30T15:15:33Z")
or you could wait for the Solar panel for the sky, which is coming real soon (and it’s GREAT) ---
**Author:** ![WFmarketing](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/wfmarketing/32/62_2.png) [@WFmarketing](https://community.tempest.earth/u/WFmarketing)\ **Post date:** [April 30, 2019, 3:38pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/3 "2019-04-30T15:38:38Z")
Hi @matthiasginster . We would strongly recommend opting for the new Solar Power Accessory for SKY which has a built in charge controller and a 1000mAh LiFePo4 battery. We just received a batch of 1000+ units this week and will be emailing all existing smart weather stations owners with a %off coupon to purchase via [shop.weatherflow.com](http://shop.weatherflow.com) in the next few days. To answer your question, the max operating voltage for SKY is 3.8. Anything above that will probably break the unit. We would recommend using a buck converter or a LiFePo4 battery if you really want to supply external power. ---
**Author:** ![vreihen](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/vreihen/32/13217_2.png) [@vreihen](https://community.tempest.earth/u/vreihen)\ **Post date:** [April 30, 2019, 4:02pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/4 "2019-04-30T16:02:26Z")
> [@WFmarketing](#): > > We would recommend using a buck converter How is a buck converter going to perform with the tiny power draw that the Sky needs? Maybe I’m going crazy, but I am under the impression that DC-DC buck converters like to be run under a harder load or bad things happen… ---
**Author:** ![rderr](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/rderr/32/114_2.png) [@rderr](https://community.tempest.earth/u/rderr)\ **Post date:** [April 30, 2019, 8:57pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/5 "2019-04-30T20:57:56Z")
There are very good low power buck converters on the market now. TI makes the TPS62808 which is around 90% efficient at 1mA. Unfortunately, it’s a chip BGA package, so it’s very difficult to hand solder. -Rob ---
**Author:** ![matthiasginster](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@matthiasginster](https://community.tempest.earth/u/matthiasginster)\ **Post date:** [May 2, 2019, 10:00am UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/6 "2019-05-02T10:00:01Z")
Allright guys, so what is @WFmarketing 's expectation of te availabillity for the solar-panel? FYI: I’m living in Germany. Regards! ---
**Author:** ![dsfg](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/dsfg/32/9736_2.png) [@dsfg](https://community.tempest.earth/u/dsfg)\ **Post date:** [May 2, 2019, 10:16am UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/7 "2019-05-02T10:16:19Z")
Hey Matthias, It is allready available : > [@Solar Panel Power for SKY - Now Shipping](https://community.tempest.earth/t/solar-power-for-sky/37/100): > > Click below for 40% Off discount code. Valid for all existing WF customer until May 31, 2019. The discount code ( SOLAR40OFF ) is applied at the checkout step when buying from [shop.weatherflow.com](http://shop.weatherflow.com). This link should have the code embedded and take you directly to the Solar Power accessory page: [https://shop.weatherflow.com/discount/SOLAR40OFF?redirect=%2Fproducts%2Fsolar-power-accessory](https://shop.weatherflow.com/discount/SOLAR40OFF?redirect=%2Fproducts%2Fsolar-power-accessory) Shipping will be ˜ 25$ to Germany… + Tax… maybe a combined order would at least reduce shipping fee… Stay tuned I’m checking with “Zoll” ---
**Author:** ![matthiasginster](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@matthiasginster](https://community.tempest.earth/u/matthiasginster)\ **Post date:** [May 2, 2019, 12:20pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/8 "2019-05-02T12:20:37Z")
Awesome, I already finished the ordering-process 😃 Thank you! ---
**Author:** ![dsfg](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/dsfg/32/9736_2.png) [@dsfg](https://community.tempest.earth/u/dsfg)\ **Post date:** [May 2, 2019, 12:32pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/9 "2019-05-02T12:32:54Z")
So you are not interested in a group order ? Actually, it would be no big issue with the taxes. The import rate for the EU is either for Luxemburg (17%) or Gemany(19%) the lowest. In both cases for an order of more then 3 SOL an additional fee of 2,7% would be applied. One has to calculate and discuss with WF-Team if a group order of Gernany located or even EU located customers would be possible. ---
**Author:** ![radex13](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/radex13/32/3963_2.png) [@radex13](https://community.tempest.earth/u/radex13)\ **Post date:** [May 2, 2019, 12:58pm UTC](https://community.tempest.earth/t/sky-battery-pack-with-20700-li-ion-max-voltage-connector-shape/3450/10 "2019-05-02T12:58:43Z")
Intéressé aussi ! J’habite en France 🙂