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Charging your E-bike via an inverter and a 12v battery


MadKon

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I've connected an Inverter to the car battery (Car Running) and Ran a Kettle to Boil on It.

I wasn't comfortable doing It. Is it OK to do this or not ?

 

Ouch .... the typical kettle is about 1 800 W, or roughly 150 amps ....

 

PS - if you are talking of the very small camp type kettles, the wattage should be more inline with what a 12V system can manage ....

 

 

 

 

The rule of thumb is to go for a 24V system when you consistently exceed 500W, to keep reduce the amps drawn.  Also the reason why most off the grid systems run at 48V, to keep the current flow through the batteries lower.

 

This is at the core of why I went for a very small 12V system for my house lights.  Easy, cheap installation, works perfectly, BUT, I knew that I wont ever power the microwave from this.

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completely misread your post ..  :oops:    thought you mean charge direct from panel to battery (something I would do)

No worries I thought as much. 

 

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Gooi a small generator on the roof and burn some dinosaurs to charge the battery?

You probably already carry some Jerries and/or an extended fuel tank full of them.

 

My bikes run on braaivleis and beer and those are abundant in off grid habitats. So i don't have these first-world problems.

 

I’m a peasant, I know.????????

Edited by morneS555
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Gooi a small generator on the roof and burn some dinosaurs to charge the battery?

You probably already carry some Jerries and/or an extended fuel tank full of them.

 

My bikes run on braaivleis and beer and those are abundant in off grid habitats. So i don't have these first-world problems.

 

I’m a peasant, I know.????????

 

NOU gaan ons braai ...

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Madkon thanks for prompting me to finally do the experiment ....  :whistling:

 

This battery box has a 120A.h Gel battery.  It handles higher currents and lower discharges better than traditional batteries.  Paired with a quality inverter it is very handy "anti-eskom-load-shedding" device ....

 

I connected the ebike-battery charger to this, and monitored the charge.

 

attachicon.gif1.jpg

 

 

The initial high charge rate explained why my previous attempt with a smaller inverter did not work.  It starts charging at 22,9A with a battery voltage of 12,4V, thus about 284W.

 

attachicon.gif2.jpg

attachicon.gif3.jpg

 

 

At about 50% state of charge for the ebike battery the charge rate started lowering.  It is now drawing about 15,5A from the gel battery, at about 12,6V. 

 

NOTE - the "50%" of the ebike battery is a best guess ..... I would have to do more tests, and log more data to accurately show the decline in charge rate as the ebike battery reaches a higher state of charge.

 

 

EDIT - staying steady on the 15,5A charge rate for some time now ..... 

 

 

 

 

So yes it can be done.  BUT, these are high currents.  Make sure to use the correct equipment, properly sized cables, etc.

 

And be SURE to use a very good quality pure sine wave inverter.

 

 

 

How many times can you charge an ebike battery from a "car battery" ? .... uhm ja .... this will put a very good load on a deep cycle battery, not sure I would subject a car battery to this.

 

As others have suggested .... THICK cables, decent inverter, and charge it while you are driving, ie while the alternator can supply the juice.  And then I will make sure to only do so while the headlights, wipers etc are NOT being used.  

 

 

 

 

As for me doing this via my little solar system ....  :thumbup:   Certainly a possibility !!  I would wait until the PV system battery is fully charged, then start charging the ebike battery.  During the high charge stage the battery will supply 60%, and my small PV panel 40% (good sun conditions), then as the ebike battery charges and the charge rate drops the PV would supply more and more of the charge rate.  So maybe 20A.h load on the PV battery, which can be topped up later in the day.  But this is based on a little 100W panel, with a 150W panel the system will be balanced better.... but now I am deviating from the core principle of the small systems for the lights .... 

Edited by MadKon
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Madkon thanks for prompting me to finally do the experiment ....  :whistling:

 

This battery box has a 120A.h Gel battery.  It handles higher currents and lower discharges better than traditional batteries.  Paired with a quality inverter it is very handy "anti-eskom-load-shedding" device ....

 

I connected the ebike-battery charger to this, and monitored the charge.

 

attachicon.gif1.jpg

 

 

The initial high charge rate explained why my previous attempt with a smaller inverter did not work.  It starts charging at 22,9A with a battery voltage of 12,4V, thus about 284W.

 

attachicon.gif2.jpg

attachicon.gif3.jpg

 

 

At about 50% state of charge for the ebike battery the charge rate started lowering.  It is now drawing about 15,5A from the gel battery, at about 12,6V. 

 

NOTE - the "50%" of the ebike battery is a best guess ..... I would have to do more tests, and log more data to accurately show the decline in charge rate as the ebike battery reaches a higher state of charge.

 

 

EDIT - staying steady on the 15,5A charge rate for some time now ..... 

 

 

 

 

So yes it can be done.  BUT, these are high currents.  Make sure to use the correct equipment, properly sized cables, etc.

 

And be SURE to use a very good quality pure sine wave inverter.

 

 

 

How many times can you charge an ebike battery from a "car battery" ? .... uhm ja .... this will put a very good load on a deep cycle battery, not sure I would subject a car battery to this.

 

As others have suggested .... THICK cables, decent inverter, and charge it while you are driving, ie while the alternator can supply the juice.  And then I will make sure to only do so while the headlights, wipers etc are NOT being used.  

 

 

Thanks Chris for doing the experiment. I cant believe that the initial current drawn is about 30A. What size inverter did you use for the test and was it a pure sine wave inverter?

 

 

 

As for me doing this via my little solar system ....  :thumbup:   Certainly a possibility !!  I would wait until the PV system battery is fully charged, then start charging the ebike battery.  During the high charge stage the battery will supply 60%, and my small PV panel 40% (good sun conditions), then as the ebike battery charges and the charge rate drops the PV would supply more and more of the charge rate.  So maybe 20A.h load on the PV battery, which can be topped up later in the day.  But this is based on a little 100W panel, with a 150W panel the system will be balanced better.... but now I am deviating from the core principle of the small systems for the lights .... 

 

 

Madkon thanks for prompting me to finally do the experiment ....  :whistling:

 

This battery box has a 120A.h Gel battery.  It handles higher currents and lower discharges better than traditional batteries.  Paired with a quality inverter it is very handy "anti-eskom-load-shedding" device ....

 

I connected the ebike-battery charger to this, and monitored the charge.

 

attachicon.gif1.jpg

 

 

The initial high charge rate explained why my previous attempt with a smaller inverter did not work.  It starts charging at 22,9A with a battery voltage of 12,4V, thus about 284W.

 

attachicon.gif2.jpg

attachicon.gif3.jpg

 

 

At about 50% state of charge for the ebike battery the charge rate started lowering.  It is now drawing about 15,5A from the gel battery, at about 12,6V. 

 

NOTE - the "50%" of the ebike battery is a best guess ..... I would have to do more tests, and log more data to accurately show the decline in charge rate as the ebike battery reaches a higher state of charge.

 

 

EDIT - staying steady on the 15,5A charge rate for some time now ..... 

 

 

 

 

So yes it can be done.  BUT, these are high currents.  Make sure to use the correct equipment, properly sized cables, etc.

 

And be SURE to use a very good quality pure sine wave inverter.

 

 

 

How many times can you charge an ebike battery from a "car battery" ? .... uhm ja .... this will put a very good load on a deep cycle battery, not sure I would subject a car battery to this.

 

As others have suggested .... THICK cables, decent inverter, and charge it while you are driving, ie while the alternator can supply the juice.  And then I will make sure to only do so while the headlights, wipers etc are NOT being used.  

 

 

 

 

As for me doing this via my little solar system ....  :thumbup:   Certainly a possibility !!  I would wait until the PV system battery is fully charged, then start charging the ebike battery.  During the high charge stage the battery will supply 60%, and my small PV panel 40% (good sun conditions), then as the ebike battery charges and the charge rate drops the PV would supply more and more of the charge rate.  So maybe 20A.h load on the PV battery, which can be topped up later in the day.  But this is based on a little 100W panel, with a 150W panel the system will be balanced better.... but now I am deviating from the core principle of the small systems for the lights .... 

 

Thanks Chris for doing the experiment. I cant believe that the initial current drawn is about 30A. What size inverter did you use for the test and was it a pure sine wave inverter?

 

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I used a Meanwell 500W pure sine wave inverter.

 

 

I was advised to stay with Victron or Meanwell.

 

 

During lockdown I used this setup to power my dual screen pc as well as the tv during loadshedding. With a gas stove, 12V lights and radio, and this box we carry on as normal during loadshedding ....

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I used a Meanwell 500W pure sine wave inverter.

 

 

I was advised to stay with Victron or Meanwell.

 

 

During lockdown I used this setup to power my dual screen pc as well as the tv during loadshedding. With a gas stove, 12V lights and radio, and this box we carry on as normal during loadshedding ....

If I may ask, who sells Meanwell inverters and what is the after sales service like?
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I've connected an Inverter to the car battery (Car Running) and Ran a Kettle to Boil on It.

I wasn't comfortable doing It. Is it OK to do this or not ?

No!

Resistive loads are a nightmare on inverters, car batteries can deliver high amps for the startup load of a car but arent designed to produce continuous power, it will kill that battery really quickly.

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No!

Resistive loads are a nightmare on inverters, car batteries can deliver high amps for the startup load of a car but arent designed to produce continuous power, it will kill that battery really quickly.

 

ok, need to jump in here .... restive loads is actually best thing for inverters .. its constant, no spikes. (of course if its in the limits of the true inverter capacity (not the china rating))

 

I run kettle/geyser/stove/microwave/aircons (inverter type)  all of our inverters without any issues as long as its below max ratings.  

 

Agree with the fact that the car battery might have taken a knock, but if its a modern car with >100A alternator and car was running it probably would have not done any damage.

Edited by Karman de Lange
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And then you real sine wave inverters and not so real sine wave inverters  (which are cheaper) - they are okay for electronics, but not magnetic loads like motors,  something to do with harmonics

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I've connected an Inverter to the car battery (Car Running) and Ran a Kettle to Boil on It.

I wasn't comfortable doing It. Is it OK to do this or not ?

The rating of the inverter will give the size of the load it can sustain and possibly also a burst rating for a short time, that will generally be in Watts.

 

There is also a VA rating, applicable to 'active' loads where current does not flow in sync to voltage, that will be higher that the Watts.  This is Apparent Power not Real Power. This rating is needed if you want to run something with a magnetic coil like a motor (ie pump) BUT there is also inrush current to deal with, which is just when the motor gets power in the initial current is very high for a like  a few milliseconds, but this is where most inverters will come short.

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I've connected an Inverter to the car battery (Car Running) and Ran a Kettle to Boil on It.

I wasn't comfortable doing It. Is it OK to do this or not ?

With your car running it is ok as long as your inverter are strong enough give the kettle power. It is better to use a gas stove thou.

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