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Inverter size and recommendation for portable solar generator
#1
Hey my fellow diy'ers,

I'm currently in the process of Designing and building a portable solar generator. I'm going to be using brand new reclaimed 9s pouch cell packs.

Each pack is:

CAPACITY : 2890mah / 2.9Ah
NOMINAL VOLTAGE : 32.85V
FULLY CHARGED : 37.8V
FULLY DISCHARGED : 25.2V

Also each pack has its own BMS w/ balancing
*** not feasible to split packs up ***

My plan is you put 15 or 20 packs in parallel. Every 10 packs is just over 1kwh

So my question is:
* What type of inverter should I use? 36v or ???

* Should I use a large Buck or boost converter to change the voltage first?

* What size inverter do I realistically need in order to run a small flat screen TV, some fans, some low voltage LED lights etc... 600w, 1000w, 1500w etc...?

Initially I think I'm just going to use it without solar but want to implement solar charging in the near future. If that has to be taken into account when choosing an inverter. Most likely going to use 100w/150w solar panel...

Do they happen to make an AIO solar charge controller / inverter? Just curious...

I'm an electrician by trade and Electronic hobbiest / battery guy for 20+ years

FYI- doing this on a extreme budget!.!.! Looking to purchase a cheap / reliable inverter and eventually MPPT solar charge controller. My mother lives in Florida and doesn't have people to help her, and she doesn't like the idea of a generator so I figured this would be perfect for her.
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#2
It's an awkward voltage range there.... 7s would be a prefect match for a 24V system.
It's generally a bad idea to run a buck or boost device between battery & inverter due to the high currents & potential for instability.
If you had to, you could try a strong buck converter to drop voltage to 24V or 12V.
Otherwise maybe just run everything (loads) directly off 12V with a reasonable buck converter?
If the TV have an external power supply, maybe consider a suitable DC - DC converter for that.
Hopefully she's ok with swapping plugs & cords around when there's an outage :-)
OffGridInTheCity likes this post
Running off solar, DIY & electronics fan :-)
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#3
(01-24-2020, 04:11 PM)bigjoncoop Wrote: Hey my fellow diy'ers,

I'm currently in the process of Designing and building a portable solar generator. I'm going to be using brand new reclaimed 9s pouch cell packs.

Each pack is:

CAPACITY : 2890mah / 2.9Ah
NOMINAL VOLTAGE : 32.85V
FULLY CHARGED : 37.8V
FULLY DISCHARGED : 25.2V

Also each pack has its own BMS w/ balancing
*** not feasible to split packs up ***

My plan is you put 15 or 20 packs in parallel. Every 10 packs is just over 1kwh

So my question is:
* What type of inverter should I use? 36v or ???

* Should I use a large Buck or boost converter to change the voltage first?

* What size inverter do I realistically need in order to run a small flat screen TV, some fans, some low voltage LED lights etc... 600w, 1000w, 1500w etc...?

Initially I think I'm just going to use it without solar but want to implement solar charging in the near future. If that has to be taken into account when choosing an inverter. Most likely going to use 100w/150w solar panel...

Do they happen to make an AIO solar charge controller / inverter? Just curious...

I'm an electrician by trade and Electronic hobbiest / battery guy for 20+ years

FYI- doing this on a extreme budget!.!.!  Looking to purchase a cheap / reliable inverter and eventually MPPT solar charge controller. My mother lives in Florida and doesn't have people to help her, and she doesn't like the idea of a generator so I figured this would be perfect for her.

>What type of inverter should I use? 36v or ???
There's no magic - you have to find one that is in a compatible voltage range to draw power from your battery.  You also have to have a plan to avoid drawing your battery below minimum voltage limits by either making sure the Inverter shuts-off appropriately and/or make sure the BMS works.    There are 'cheap' 36v inverters such as Reliable....
https://www.ebay.com/itm/Solar-Power-Inv...SwvDNdpois
which lists a reasonable 36v range. 

>Should I use a large Buck or boost converter to change the voltage first?
Just do the math on amps - and be prepared for loss of efficiency.   Typically this is to be avoided.

>What size inverter do I realistically need in order to run a small flat screen TV, some fans, some low voltage LED lights etc... 600w, 1000w, 1500w etc...?
No magic -  you need an inverter that can produce the watts you need.   IF you plan surge usage (such as an air conditioner) then you'll for sure need a more expensive inverter as the cheap ones (such as Reliable above) typically don't do well.   When I tried running an 12,000BTU AC on a 3000watt Reliable it blew / melted inside causing a dead-short.   *Be sure to have proper fusing*

>Do they happen to make an AIO solar charge controller / inverter? Just curious...
Anything's possible in the wide/wonderful world...  but for lower end / cheap components for a DIY solar charger I've not seen any.     You can find inverter/charger combinations such as this: https://invertersrus.com/product/kisae-ic121040/   but not sure about 36v range.       As far as all 3 - inverter+charger+charge-controller...  I've not seen any in the 'cheaper' relm - and would be interested if you find one Smile
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