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Charging in your car


Steef Klonoa

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The main thing you'll have to consider is how much power the outlet can serve. You should be able to find that in the user manual in your car. Compare that to your charger which has an output power of 120W if you're still using the Z10. You'll have to add some headroom to account for the efficiency of the charger. I wouldn't expect it to be much worse than 150W input power. (Whew that's small, compare that to my 84 volt charging at 5 amps for nearly 500W or a fellow Bostonian that charges with an insane 13 amps on his 100V wheel for an excess of 1300W.)

If your charge port can handle it, don't try using it unless the engine is running. You'll rip though your car battery very quickly.

Edited by Ghukek
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Yeah, your charger is outputting 120W but that's typically after some amount of loss. Any charger will have some amount of inefficiency. So the input wattage would be higher.

I assumed you were talking about an SUV that has a 110V AC circuit, but it sounds like you're talking about the standard 12V DC cigarette lighter port. In this case, no this will not work. You're taking a DC circuit, converting it to 110V AC and then plugging your charger in that to get DC out. This will work just fine for a cell phone or computer. The cell phone would probably be taking 10W if you're using a standard 5V 2A charger. There's a lot of headroom there for the inefficiencies that come with the chained DC to AC to DC converters. 

You could try to obtain an aftermarket charger for your Z10 that will only try to serve 1A for about 60W. That should give you enough headroom. Maybe 1.5A would work. (Your stock charger is serving 2A) I don't think you'll find one easily though; sorry about that.

(DC is Direct Current, AC is Alternating Current. With direct current you just have some amount of amps going in one direction, alternating current is just that; it oscillates like a wave, sometimes current is going one way, other times it's going the other way. Amps are a measure of current, Volts are a measure of potential difference, and Watts are a unit of power equal to Volts times Amps.)

It's theoretically possible to get your car to serve a Z10 charger; just not from the 12V cigarette lighter circuit.

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5 hours ago, Steef Klonoa said:

Ahh. Ok. Well thanks for the insight! I will definitely be taking this into consideration when I buy my next car haha.

I took a moment to look at the specs for an SUV with an AC outlet. The Toyota 4Runner has a 120V AC circuit that can serve up to 100W while the car is moving and 400W while it isn't. So to charge your wheel with your car, you'd really need to have the car stationary. This makes sense as it would be unwise to have such large amounts of power taken up while the car is driving. Various emergency systems need to be able to use power if needed and if you're using 400W for some appliance when that happens it may overload the system. Of course, if you're planning road trips, I'm assuming you're going to be wanting to charge it while driving and ride the wheel at your destination, so this won't be sufficient. The Nissan Titan has a 150W/400W circuit, so that actually may work. (You can buy a cheap power monitor to figure out how much power your charger draws.) If you ever go to buy a car with an AC outlet, make sure to check the power specifications of that outlet since it varies from model to model.

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I wonder if there's something you could put in between the charger and the vehicle to limit its power draw to acceptable levels for the car's limitations--even if it just took longer this could be a fair tradeoff.

Edited by AtlasP
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2 hours ago, AtlasP said:

I wonder if there's something you could put in between the charger and the vehicle to limit its power draw to acceptable levels for the car's limitations--even if it just took longer this could be a fair tradeoff.

I believe something like this converter from aliexpress should do it, it offers current limiting and the appropriate voltage ranges. It's a little overspec'd but that's good for something like this, and the input current would still be up to 10 amps. I've been messing around with the idea of using old packs as power banks for a unicycle, and converting them directly rather than going through the charger. 

 

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If you want to charge from a car properly you'll need a sine wave inverter that is rated at least 20% higher than the draw from whatever charger you want to use and it very likely would need to be wired directly to your car battery unless your charger is pretty small and only be used when the cars engine is running. 

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  • 3 weeks later...

Tudordewolf had a great idea ! Not only the converter will has higher efficiency than DC->AC->DC circle, it can set the limit Amperage. So it should be safe to set it to 67v/1A and plug it into the cigarette lighter socket. Man ! Why I have never thought of this ?

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TL;DR: Charge with the engine running, it takes a lot longer than you'd like and is only practical/efficient if you're driving the car for other reasons.

Those DC to DC converters can, in theory, work well.  The primary issue is one of confidence in the circuit.  LiIon batteries must not be overcharged and therefore the charge voltage MUST be limited to 4.2v/cell (67.2v for 16s, 84v for 20s).  This limit should be observed strictly and you should use a power supply which you're confident will never exceed this voltage.

For $20 that DC-DC converter looks like it might be worth a punt, however there is a practical consideration here regarding charge rates.

Let's take two scenarios for two wheels (V10F and MSX): 1) What's the maximum charge rate/minimum charge time you could expect from a 12v accessory outlet?  2) What's the current you'd need to draw to fast charge an EUC?

Note that you should only ever do this with the engine running so that the engine can recharge the car battery, otherwise all you're doing is flattening the battery you need to start your car :D I would expect that most modern vehicle alternators would be able to provide enough power to recharge the car battery providing that the engine is running.

Scenario 1: Maximum charge rate/minimum charge time from a 12v accessory outlet.

Typical maximum current from an accessory outlet is 10A.  Some vehicles are higher, perhaps 15-20A, but these are rare because the actual cigarette lighter connector is a terrible current conductor.  Typical battery voltage while the engine is running is 13.8v.

Therefore a typical cigarette lighter outlet can put out 138W while the engine is running.

The Inmotion V10F has a battery capacity of 960Wh so in a perfect charge scenario would take approximately seven hours to charge.  Due to inefficiencies in the conversion circuit and the need for the charger/BMS to slow down as it approaches a full battery I think it's reasonable to round this up to eight hours.

The Gotway MSX has a battery capacity of 1600Wh, perfect charge conditions that equates to 11.6h, probably closer to 13h in practice.

Scenario 2: Fast charging your EUC from a car battery.

Let's assume that the V10F can fast charge at 3A.  At 84v this equates to 252W.  A full charge cycle would therefore take (960Wh/252W) 3.8h, I'll round that up to four hours.  To draw 252W from your car you would need to draw (252W/13.8v) 18.3A.

Let's assume that the MSX can fast charge at 5A.  At 84v this equates to 420W.  A full charge cycle would therefore take (1600Wh/420W) 3.8h (weird coincidence), again rounded up to four hours.  To draw 420W from your car you would need to draw (420W/13.8v) ~30A.

Other thoughts...

I have considered buying a couple of large car batteries (leisure batteries) and sticking them in the boot (trunk) of my car with an inverter.  It wouldn't be a very efficient charging system but it would give me a way of charging an EUC overnight while camping.  Alternatively you could use a generator or just stay in a cheap hotel overnight :D

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I'm quite interested in something like this:

https://www.aliexpress.com/item/4000820345884.html

4 pieces of LiFePo4 together forms a secondary 12v battery. I can put it in the trunk. It will be charged during the driving and it can be disconnected and fast charge my EUC when I need it.

It's more expensive than lead-acid, but still quite cheap to have 1000wh charging power ready anytime I want. What do you think?

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2 minutes ago, Philip W said:

I'm quite interested in something like this:

https://www.aliexpress.com/item/4000820345884.html

4 pieces of LiFePo4 together forms a secondary 12v battery. I can put it in the trunk. It will be charged during the driving and it can be disconnected and fast charge my EUC when I need it.

It's more expensive than lead-acid, but still quite cheap to have 1000wh charging power ready anytime I want. What do you think?

You'll still need a BMS and LiFePo4 car charger so it's gonna get a lot more expensive. You can't just hook them up to the charging system of the car and not expect bad things to happen from the ebb and surge of the alternator.  A properly sized sine wave inverter directly connect to the cars charging system will give you the most flexibility and ease of charging on the go. 

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37 minutes ago, Willy510 said:

You'll still need a BMS and LiFePo4 car charger so it's gonna get a lot more expensive.

The BMS for LiFePo is cheap, $2 to $4 a piece.

https://www.aliexpress.com/item/1000005371392.html

I am just not sure how to limit the charging current. I want only max 5A of current to charge it while the car is moving. Maybe something like this?

https://www.aliexpress.com/item/4000343226131.html

 

37 minutes ago, Willy510 said:

A properly sized sine wave inverter directly connect to the cars charging system will give you the most flexibility and ease of charging on the go. 

Sine wave inverter will turn DC to AC then I will have a charger to turn AC to DC again. It's a good and safe idea, but I still want to go directly from DC to DC.

Edited by Philip W
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24 minutes ago, Philip W said:

The BMS for LiFePo is cheap, $2 to $4 a piece.

https://www.aliexpress.com/item/32860236720.html

I am just not sure how to limit the charging current. I want only max 5A of current to charge it while the car is moving. Maybe something like this?

https://www.aliexpress.com/item/4000343226131.html

 

Sine wave inverter will turn DC to AC then I will have a charger to turn AC to DC again. It's a good and safe idea, but I still want to go directly from DC to DC.

You need a real BMS and not one of those passive balancers, that pack is capable of a 270A discharge . If you don't have proper regulation really bad things can happen all around. 

 

You can use a hobby charger for 12V dc input but you'd want to regulate the input so the pulsing of the alternator wouldn't fry the charger and or battery.  Most of them will say to use while idling and not while driving unless the 12v is regulated.  

 

To go Dc to DC you'll need a buck booster or a solar charge controller to boost the 12V to your charging voltage is the most popular route.  These are popular ones in the DIY crowd. https://www.amazon.com/Numerical-Regulator-10V-120V-Converter-Adjustable/dp/B01GFVI6R6/ref=sr_1_2?dchild=1&keywords=drok+booster&qid=1598205751&sr=8-2

https://www.amazon.com/Fuhuihe-MPT-7210A-Controller-Battery-Display/dp/B07PVDY1V7/ref=sr_1_47?crid=3NC79G0QD3RV3&dchild=1&keywords=solar+mppt+charge+controller&qid=1598205885&sprefix=solar+mppt%2Caps%2C217&sr=8-47

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On 8/23/2020 at 2:06 PM, Willy510 said:

You need a real BMS and not one of those passive balancers, that pack is capable of a 270A discharge . If you don't have proper regulation really bad things can happen all around. 

Thank you so much for the warning ! I will always keep that in mind.

On 8/23/2020 at 2:06 PM, Willy510 said:

You can use a hobby charger for 12V dc input but you'd want to regulate the input so the pulsing of the alternator wouldn't fry the charger and or battery.

Hm... that indeed will be a big problem. Yeah, I definitely need a better charger for this.

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On 8/17/2020 at 8:22 PM, Philip W said:

Tudordewolf had a great idea ! Not only the converter will has higher efficiency than DC->AC->DC circle, it can set the limit Amperage. So it should be safe to set it to 67v/1A and plug it into the cigarette lighter socket. Man ! Why I have never thought of this ?

 

You could even set it as high at 1.5A within the cigarette lighter's 120W spec and 10% inefficiency. As others have mentioned, not exceed 4.2V per cell is crucial, though I suspect most BMS's will enforce this standard - that's how the balancing works, they begin bleeding off any voltage above 4.2V, allowing the cells that haven't caught up yet to do so.  It's not a good idea to count on that, though, so you could set it to something like 4.15V per cell, 66.4V - practically a whole volt of safety margin. The flipside to that is that you'd still need to use the regular charger to make sure the cells get balanced every once in a while. 

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12 hours ago, tudordewolf said:

so you could set it to something like 4.15V per cell, 66.4V - practically a whole volt of safety margin.

For this setup I just need to set the output to 66.6v (being evil). The per cell thing will be done by the EUC itself.

12 hours ago, tudordewolf said:

You could even set it as high at 1.5A within the cigarette lighter's 120W spec and 10% inefficiency.

I don't really want to push the socket. I want slow and steady. For most of the park ridings I will only use 200 to 300 wh power. So 66w/h is good enough for me.

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  • 1 year later...

I have connected a Bestek 300W pure sine inverter directly to the 12V battery of a Bolt EV, with a 30A inline fuse. (Too much draw for the actual cig lighter.) So far works well w/ regular charger, am expecting I could probably safely charge up to 2A. Not rapid, but enough to charge while driving on road trips. 

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Get a dc-dc converter with high efficiency and a wattage rating that it can sustain over a longer time. High efficiency will help to keep it run cool.

If it can do 500w max then you'll charge your 100V wheel with 5A, etc. Make sure the input cables are thick enough because to pull that kind of current over 12V is going to be a lot.

If it's 300W on the input but only achieves 70% efficiency when stepping up from 12V to 100V then you're just going to get 2A and a lot of heat produced by the DC-DC converter = bad. 

Find out the efficiency for the step in voltage that you need.

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  • 1 year later...

Yes, all you need is a Goal Zero 6000X power station, put it in your car trunk and you can charge anything you want! One fully charged 6000X power station can charge a wheel 3 to 4 times. Recharge the power station at home or charge it while driving your car. 

Edited by Scubadragonsan
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On 5/3/2023 at 11:15 AM, Scubadragonsan said:

Yes, all you need is a Goal Zero 6000X power station, put it in your car trunk and you can charge anything you want! One fully charged 6000X power station can charge a wheel 3 to 4 times. Recharge the power station at home or charge it while driving your car. 

very pricy and humongous solution....

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