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Forum Index : Electronics : need bacis help want to build a 48VDC/54VCD to 120VAC inverter
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Quazee137 Guru  Joined: 07/08/2016 Location: United StatesPosts: 571 |
I have two E-Trikes using 48Volt 20AH LiFePO4 batteries and two backup batteries. I looked into USP backups but most took 12Vdc. I would like to use one the two extra 48Volt LiFePO4's to run my refrigerator during power outages. The 2nd extra battery to keep my modem/computer/display, cameras and alarm system. The batteries have built-in BMS. Unloaded they are at 54VDC. Chargers 58.4 3A What got me thinking about this is the truck/car commercials showing running house. So far power outages here have been between 2 hours and 10 hours. Any guidance would be appreciated. Thanks Quazee137 |
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poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418 |
Hi 48V and 20AH This is about 1kW.hr energy storage The power needed to keep a fridge running is quite low when the motor is not running, maybe less than 50 Watts For a short time (1-2 seconds) the power level for my mid sized fridge when starting up is about 1,500 W, which then settles down to about 200W to run the motor for a few minutes. So this gives some guide to the power levels that need to be supported. I would aim for something that can do 2000W Energy needs: My home has one fridge and one freezer. During the period form 2am to 7am last night there were 12 motor starts and total energy used was about 1kW.hr This also includes all the phantom loads such as computers/modem/TV/etc. which are all on standby or sleep I expect you might consume a bit less than 1kW.hr / 7hrs but probably not 1/2 of this. No load power of an inverter can be as little as 12W but probably a bit more, maybe 20W is more likely for your first build. If I was you, I would obtain more battery storage. Maybe find a used e-trike battery that is still OK... I would want about 2kW.hr to be sure to have enough. Parts list: A 1 to 2kW toroid transformer, with a 120V AC winding. You will be making the primary winding yourself. A suitable sized inductor (something like 50uH which does not saturate below about 75 Amps) An inverter board such as this and choose the 48V 110V version. A box to put it in 250V mains rated capacitor of some value (from 1uF to 4.7uf) which will be part of the LC filter on the inverter board's output. Value to be determined later. The inverter board linked to above is the best option in my view because it has the totem pole FET Gate drive and this gives side effect benefits that protect the very easy to damage Gate drive ICs present on the inverter control board. A torid transformer will be more efficient than an IE type and be needed if you want to have a low no-load power draw. That's what I would do. wronger than a phone book full of wrong phone numbers |
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