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/diy/ - Do It Yourself

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1124965 No.1124965 [Reply] [Original]

I'm about to become a van dweller and want to prepare the interior for living by myself.

Now i didn't do electronics for a long time but i know how to hold a soldering iron, and i'm trying to high-level plan out how to 220v power the van. My current idea is to:

1. Add second (multiple ?) batteries. (do i have to upgrate the alternator ?)
2. Get a generic 1kW 12/220V inverter.
3. Monitor the batteries voltage and turn the engine on if needed to charge.

Now this plan has a shitload of unknown variables so i wanted to throw the ball around with you.

How do i calculate the parameters so i wont drain the batteries in
1 hour if i know i'm using X watts, maybe i can make some kind of "time left at current power usage".

How do I protect from over powering (using too much ampers, not a native speaker).

I imagine i would be using a mac charger once every couple hours (60W), some led lightning (20W ?), and once in a while some high power utility like a microwave or a heater (1kW).

I would be grateful for any tips and thoughts.

>> No.1124966

>>1124965
>once in a while some high power utility like a microwave or a heater (1kW).
at least triple the inverter (3+kW)

>> No.1124975

>>112496
This is good advice.
Most electric tools draw way more power to start the motor than they do to run.

So a 800w drill may infact need up to 3.5kw to "start".

>> No.1124977

>>1124965
>heater (1kW).
Heater is Bad Idea. Will such your batteries empty in no time and this will kill them. 12V*100Ah=1200Wh. You want to discharge your lead-acid batteries by just 50% to keep them alive. This gives 600Wh or 30min of 1kW. Plus losses. "It's cold, I'll heat for just a moment more" and the battery goes kaputt.

>> No.1124979
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1124979

>>1124977
That is good to know.

The heater was just an example, but anyhow - how would i go about checking the charge of my batteries? Is there an easy tool for that or does it requre the acid test (with the pipete)

>> No.1124986

You maybe confusing units of power(watts) with units of energy(watt/hours). To calculate how many watt-hours your battery will last you'd have to know the amp/hour rating of the battery then convert it to watt-hours. The batteries age and condition would also have to be factored in. How fast you draw power from a battery effects how much totally energy you'll get too.

My advice is to setup an arduino/pi/whatever dev platform you use to monitor current both in and out of the batteries. Then run the batteries down and charge the system with the ardiuno logging everything. You'll end up with the usable amount of current the batteries actually have stored with no real math involved. As long as the arduino is watching all current flow in and out the number should stay accurate.

>> No.1124991

Normal car batteries are made to give out short, heavy bursts. You need a "deep cycle" or "marine" battery for leisure use.

>> No.1125069

>>1124979

Humm. I thing a volt meter would work. Nah better do the acid test to be sure.

>> No.1125073

>>1124975
a induction motor yeah will need several times the rated current to start

but a drill no, because they generally aren't started under load and they're usually brushed universal motors (AC/DC).

>> No.1125079

I found this years ago on this thread. Has lots of good ideas on how to become a van dweller. Wonder what happened to this guy

>> No.1125084
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1125084

>>1125079
Image didn't post fuck me.

>> No.1125103

>>1124979
LM3914 with leds and / or beep when battery voltage drops to a certain level

>> No.1125109

you could use a dual battery isolator. your alternator will charge all the batteries connected to it. but it will isolate 1 battery which will be used to start the vehicle. the isolator would not drain the starting battery.

>> No.1125117

>>1124965

You can put a solar panel on the roof to charge the batteries when the engine isn't running, it's a common camping-van accessory.

>> No.1125196

>>1125069
a simple voltage reading is not sufficient to tell the charge of a battery. A battery can read nominal voltage and then drop suddenly under load if it's drained.