Using an inverter to charge from a car

[VultureChow]

Just started riding a Prodeco bike I got cheap. First of all, why the hell did nobody tell me how awesome electric bikes are? It's a perfect vehicle for my errands around town and frankly I could probably commute with it. I have a distinct feeling that when this one dies, I will be upgrading.

I wish to take it on a camping trip. I will not have access to electricity beyond what I bring myself and possibly begging some generator time off of a neighbor. Is it at all feasible to charge the battery off an inverter from my car battery. I can run the car a bit to make sure I don't drain the battery, I'm more concerned over how much longer it would take vs a wall charger and damaging the battery or the charger or the car.

 

[Drunkskunk]

You can run your Bike charger off the inverter. It needs to be a big enough inverter to handle the charger's demand. The charge time will be exactly the same as from a wall plug.

 

[VultureChow]

You can run your Bike charger off the inverter. It needs to be a big enough inverter to handle the charger's demand. The charge time will be exactly the same as from a wall plug.

How do I figure out the demand from the charger?

Edit: Watts = Amps*Voltage. My charger says input is 1.8A, output 2.0A. This gets me in a 200-300 Watt range, correct?

 

[Drunkskunk]

You got it. But my experiance with most automotive inverters has been less great. I've found they often are optimistic in their claims. my 500 watt inverter melted down when trying to run a 200 watt charger, and my 1100 watt inverter can just bearly manage to run 600 watts. I think they claim peak output, but not sustained load.

I'd advise getting at least a 500 watt unit to run your charger. But on a few rare occasions, that 1100 has been a life saver. it will run a small fridge, or a computer in a power outage

 

[VultureChow]

You got it. But my experiance with most automotive inverters has been less great. I've found they often are optimistic in their claims. my 500 watt inverter melted down when trying to run a 200 watt charger, and my 1100 watt inverter can just bearly manage to run 600 watts. I think they claim peak output, but not sustained load.

I'd advise getting at least a 500 watt unit to run your charger. But on a few rare occasions, that 1100 has been a life saver. it will run a small fridge, or a computer in a power outage

Thanks so much for your help. Do I need to bother with a pure sine wave inverter?

 

[el_walto]

You might want to keep your car running the entire time your bike is charging. You need a 216Watt+(constant) inverter.

After 3 Hours of charging your ebike, with your car off, your car battery will be flat.

I can't find numbers but I'm guessing your alternator will charge your car battery at 350Watts when your car is idle. Maybe you can find out these numbers. Just remember that a 60amp 15V alternator will only charge 60amps at a higher rpm than Idle.

Guessing your bike takes about 5 hours to fully charge from empty.

 

[Hwy89]

What type of battery chemistry are you using? You might be better served to get one of the rc chargers that use a 12V DC input. There is a lot of efficiency lost in converting from DC to AC then back to DC to charge a battery and since you will be idling a gasoline engine for hours that could mean Dollars wasted.
I have Quatro balance charger that is programable to any type of battery and clips directly to the car battery terminals. On our camping trip I took a 185 watt solar panel and a charge controller to keep the 12 V battery topped off while charging two e-bike batteries.
I fully agree with your statement and wish I had known about e-bikes a long time ago too.

 

[el_walto]

What type of battery chemistry are you using? You might be better served to get one of the rc chargers that use a 12V DC input. There is a lot of efficiency lost in converting from DC to AC then back to DC to charge a battery and since you will be idling a gasoline engine for hours that could mean Dollars wasted.
I have Quatro balance charger that is programable to any type of battery and clips directly to the car battery terminals. On our camping trip I took a 185 watt solar panel and a charge controller to keep the 12 V battery topped off while charging two e-bike batteries.
I fully agree with your statement and wish I had known about e-bikes a long time ago too.

She has a Prodeco bike. I don't think an RC charger will work though a BMS.

 

[el_walto]

Does anyone know how much power a standard car alternator outputs, when the car is at idle?

 

[wineboyrider]

This would be a great use for an rc charger as it can charge using 12v dc direct current???

 

[el_walto]

This would be a great use for an rc charger as it can charge using 12v dc direct current???

RC Chargers take 12V input, BUT i don't know what ones would possible convert 12v up to 36v. You probably need at least a 10s charger, and even then I'm not sure how you would charge. I'd suggest you stick with your inverter idea, unless someone knows a 12v charger that will work.

 

[VultureChow]

What type of battery chemistry are you using? You might be better served to get one of the rc chargers that use a 12V DC input. There is a lot of efficiency lost in converting from DC to AC then back to DC to charge a battery and since you will be idling a gasoline engine for hours that could mean Dollars wasted.
I have Quatro balance charger that is programable to any type of battery and clips directly to the car battery terminals. On our camping trip I took a 185 watt solar panel and a charge controller to keep the 12 V battery topped off while charging two e-bike batteries.
I fully agree with your statement and wish I had known about e-bikes a long time ago too.

He has a Prodeco bike. I don't think an RC charger will work though a BMS.

She, and it's a LiFEPO4 38.4V

also, thanks for the help everyone.

 

[Ykick]

This would be a great use for an rc charger as it can charge using 12v dc direct current???

RC Chargers take 12V input, BUT i don't know what ones would possible convert 12v up to 36v. You probably need at least a 10s charger, and even then I'm not sure how you would charge. I'd suggest you stick with your inverter idea, unless someone knows a 12v charger that will work.

I've been playing around with one of these and seems to be able to handle 12v up to 36v....

http://www.ebay.com/itm/1pcs-Boost-DC-DC-Converter-Power-Supply-Step-up-Module-10-60V-to-12-80V-600W-mah-/300896310668?ssPageName=ADME:L:OU:US:3160

 

[dnmun]

you can use a balance charger on a pack with a BMS installed. the BMS doesn't interfere with using the balance charger since the charging current does not go through the BMS. you hook the JST plugs to the charger and connect the two charger leads to the plus and minus terminals of the battery, not to the negative C- terminal on the BMS.

 

[VultureChow]

you can use a balance charger on a pack with a BMS installed. the BMS doesn't interfere with using the balance charger since the charging current does not go through the BMS. you hook the JST plugs to the charger and connect the two charger leads to the plus and minus terminals of the battery, not to the negative C- terminal on the BMS.

And now we are straining my understanding of batteries and electronics. The most I've ever done is tinkered with some addressable LED's and an arduino.

 

[fechter]

If the battery is 38v and the charger output is 2A, then you need about 76 Watts off an inverter. Most cheap 150W or 200W inverters should be able to handle this. No need for sine wave, as the charger is going to rectify the AC anyway.

Car at idle should have enough to run that.

Using an inverter to run the charger is inefficient, but it does work and is relatively cheap. Several people have done it before.

Try it out at home first to be sure it works.

 

[VultureChow]

If the battery is 38v and the charger output is 2A, then you need about 76 Watts off an inverter. Most cheap 150W or 200W inverters should be able to handle this. No need for sine wave, as the charger is going to rectify the AC anyway.

Car at idle should have enough to run that.

Using an inverter to run the charger is inefficient, but it does work and is relatively cheap. Several people have done it before.

Try it out at home first to be sure it works.

Will do. I just wanted to get some advice on it first. I'm still hoping I can borrow some generator time off my neighbors when they are already running theirs. But this will give me at least some piece of mind that I can charge it on my own.

 

[dogman dan]

You just said the magic word. Generator is the thing you need, unless you have some huge 12v batteries to carry around.

Running a 2000 cc engine to get 75 watts is pathetic, even if it does work. Keeping an eye on the car battery voltage, you might be able to figure out some more reasonable procedure than running the car for 3 hours. 5 min engine on, 15 min engine off, something like that. But hard on the car battery then. Charging while driving someplace else makes some sense.

Though likely a piece of pretty cheap junk, you might consider the 90 buck generator from harbor freight. Sure to last at least as long as a cheap inverter.

But if there is a generator around in the camp spot, just trade beer or gasoline for juice.

Back to RC chargers, you'd simply need to add wires at the right spot to use an RC charger. You'd charge half the battery, then the other half. Typical cheaper RC chargers do 6 cells at a time.

 

[VultureChow]

dogman, this is more of a backup procedure if I can't get some generator access. I'm thinking you're correct that I don't need to full on idle the car for the full charging time, rather pulse it on and off. It's a rental car, so I'm not concerned about the wear and tear on the car battery.

 

[Hwy89]

I have always disliked generators in campgrounds. Some of the little Hondas aren't too bad, but an annoyance all the same. You could possibly find a coffee shop or cafe that would let you charge while you have a leisurely lunch. Camp grounds with camp hosts often provide power for the host's site. You won't use a Dollars worth of electricity but it might help if you offered to pay.

 

[VultureChow]

I have always disliked generators in campgrounds. Some of the little Hondas aren't too bad, but an annoyance all the same. You could possibly find a coffee shop or cafe that would let you charge while you have a leisurely lunch. Camp grounds with camp hosts often provide power for the host's site. You won't use a Dollars worth of electricity but it might help if you offered to pay.

It's ummm, not that type of camping. Burning Man. Dry lakebed with no services (or trees, rocks, bugs) for miles. Some camps bring generators. The noise from the genny's is possibly the least offensive noise out there. Unless you actually like dubstep.

 

[dogman dan]

Definitely barter for your power with genie owners then. For burning man, booze should do the trick.

But if you really want to ride when you want, go buy that 90 buck generator at harbor freight. The car will run out of gas out there after a week of this. The little generator will charge your bike multiple times on one gallon. Just bring a 5 gallon jug of premix.

With your own genie, then you can just plug in, walk off, and nap or go ogle some more weird people instead of sitting in the car turning it on and off.

At burning man, two batteries and a generator would be the thing to do. I'd want to be on that bike all damn day.

 

[panurge]

If the place has enough insolation, and you are able to carry a flat 0.6m x 1m x 0.03m poly solar panel plus regulator, then you could invest a bit more compared to a generator, and get something like this http://www.ebay.com/itm/ECO-100W-PV-Solar-Panel-solar-cell-module-100Watt-solar-kit-controller-Z-bracket-/261240635566?pt=LH_DefaultDomain_0&hash=item3cd327c0ae

This will save your car, your battery, the sphere and your funds and probably self-payed after the first 3 or four charge compared to a car engine running even for short periods

You are restricted to the day time for charging, that's the contra....

I run a similar array with 2 old Pb batteries from a landcruiser running 24v (2x 120 Amps) they no longer have enough Discharge capacity to reliably start the 12HT engine, but are not really dead so I found that they works great, as a buffer battery, inline with a solar charger or a grid charger, and my hyperion RC charger running 12v (single) or 24v 2s. If the charger has enough power you could get full power from it almost without discharging the Pb battery.

In your case you could easily use your car's battery for this...and/or try directly plug your charger with the inverter to the direct load output of the regulator (tipically is there for a direct device use like leds).

Anyway if you dont agree with the solar panel for some reasons, the cheaper and faster way (but need some work) is maybe to have a second car battery paralleled or eventually alternated with the stock one this could be made in many ways depends if your car suffers or not minor issues from a total battery unplug) from manual exchange to harnesses / switch.

I love free camp, I did it for years in greece, am waiting my kids will grow a little more 'to start again!!

 

[VultureChow]

Definitely barter for your power with genie owners then. For burning man, booze should do the trick.

But if you really want to ride when you want, go buy that 90 buck generator at harbor freight. The car will run out of gas out there after a week of this. The little generator will charge your bike multiple times on one gallon. Just bring a 5 gallon jug of premix.

With your own genie, then you can just plug in, walk off, and nap or go ogle some more weird people instead of sitting in the car turning it on and off.

At burning man, two batteries and a generator would be the thing to do. I'd want to be on that bike all damn day.

How loud is it? Do I need baffles?

 

[dnmun]

if you are driving a rental car to this campsite it may already have electrical power at the campsite.