First time planning for emergency power using 72V EV battery pack

Started by MJSfoto1956, February 21, 2019, 02:16:31 PM

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MJSfoto1956

Newbie here.

I have an electric motorcycle with a 72V 5kWh lithium battery pack that I want to use as emergency backup power.

The plan is to install 1000W of solar panels and have them tied to the grid only during "normal use". The idea is that the panels are primarily for emergency only, but might as well tie them to the grid and get a small reduction in our electricity during the interim.

When an emergency hits, I would manually plug the eMotorcycle (from outside the house of course) into the MPPT charge controller which would then power a subpanel for select 115V circuits. The goal being the panels + battery would last 7 days or more of limited power to the house.

In a later phase, I would retire the eMotorcycle battery once it gets worn out, using it in the house as a power bank, eventually adding more 72V packs in parallel as I use them up for my EV projects.

Attached is a high-level concept drawing. Not sure what parts might be involved here. Any help appreciated.

Michael


ClassicCrazy

Your concept does not look right .
A grid tie inverter has the PV go directly into it and then it syncs with the grid and pushes power into it. If the power goes off then the grid tie inverter shuts off.

You second picture shows an mppt controller going to your motorcycle battery then to an inverter . Were you thinking this would be the same inverter as the first picture ?  That  wouldn't work. You may not find an inverter that would run off your motorcycle battery because of the battery voltage, the grid tie inverter would not turn on because there was no grid power - you would have to have a battery based inverter . You also need a charge controller that would handle your  motorcycle battery and its BMS circuitry would have to functioni properly too . Assuming your motorcycle has a 110v charger - it is probably properly designed and matched to take care of your motorcycle battery so using that is the best option to charge the motorcycle batteries . Of course you cant do that without 110v ac.


There are some hybrid  systems that  can stay on and power some house circuits even if the grid power goes down. But I think they have their own dedicated batteries . 

1000w of PV isn't probably enough to mess around connecting it to the grid -  unless maybe you get some enphase type panel mount grid tie inverters for each panel.  Depending on which power company you have there could be enough extra stuff they want  you to install to send power into the grid that just wouldnt make it worth it . Unless you just do it stealth and don't care about getting paid from power company and want to offset  your power so you don't tell the power company you have them .

If you want emergency backup power for a day or two now and then  a gas powered generator is probably the easier option .

Or you could build a battery based PV system and it's own battery powered inverter .

Larry



system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

tecnodave

MJS......

Larry pretty much said it!

A grid tie inverter does not operate without the grid and the off grid inverter cannot synchronize to the grid........

You would need two separate systems to do this

My opinion.....You are way over your head on this one.......read lots more!

David

I don't mean to be insulting......just pointing at reality
#1 Classic 150 12 x Sharp NE-170, 2S6P, 24volt L-16 Rolls-Surette S-530, MS4024 & Cotek ,  C-40 dirv.cont. for hot water
#2 Classic 150 12 x Sharp NE-170, 2S6P, 24 volt L-16 Interstate,Brutus Inv.
#3 Kid/WBjr 4/6 Sanyo 200 watt multilayer 4/6 P
#4 Kid/WBjr 4/6 Sanyo 200 watt multilayer 2S 2/3 P