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Charging ebike in the boonies


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#1 muttmaster

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Posted 07 March 2021 - 05:10 PM

Well, just spent my stimulus money on a Rad ebike. I am sure I will be much stimulated. Maybe even more so if congress approves ebike 30% tax credit. Before the ebike arrives, I am trying to figure out best ways to charge up battery while in the boonies for multiple days.

I have read RC Jim’s post on ebike, watched Utube on charging while camping. Seems like many options exist for me while out there in my FWC, and I like options and I like to explore what seasoned ebike and FWC owners have done.

I do have a Honda eu2200i, and some have posted that they charge the bike just fine, but I am not sure if the inverter on the eu2200i is a pure sine wave type specified by Radbike for charging the lithium 48 v. I do carry a 350 watts pure sine wave inverter on trips that I can use off the camper battery or the generator if needed.

I have 160 watts stock ZAmp plus 100 watts Renogy on top, which is more than I need as the AGM gets topped up by 10 or 11 in the morning. I can get more or bigger panels if needed to charge up to two 750 watts, 48 v batteries. I plan on getting extra ebike battery or built my own to extend range of the ebike. The battery are pretty expensive and I don’t want to ruin them while charging it. The Ideal set up for me is to be able to have two fully charged ebike battery for the days ride, while charging a spare battery during the day with solar and after getting back to camp, be able to top off the two used up battery with either generator or via inverter off camper battery. Double my needs if I bring a friend with Rad ebike too.

Some have used separate batteries and inverter to charge the ebike battery, and I may explore that option too if I DIY a 48v Lithium power center. But that maybe the most expensive option and it will have to wait.

I also saw on Utube ebike owners solar charging directly from panel to Victron mppt controller and plug into ebike battery directly without using the Radbike charger, which lead me think maybe I like a separate charging setup from FWC. So, I hope all the solar and electrical and ebike gurus on the forum can give me some advise on what is the best way to keep on riding.
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#2 astropuppy

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Posted 08 March 2021 - 12:49 AM

Very interested.


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#3 Vic Harder

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Posted 08 March 2021 - 01:00 AM

How many AH are the bike batteries?


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#4 muttmaster

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Posted 08 March 2021 - 02:52 PM

I was hoping a guru would chime in. Vic, Rad bike battery is 14 ah for the RadRunner Plus. They also offer a slimmer profile one that is 10.5 ah.

There are aftermarket batteries that is 52 v but I have not looked into them yet. Below is info on the Lunacycle site.

www.electricbike.com/52v-battery-3077-fet/

Edited by muttmaster, 08 March 2021 - 03:15 PM.

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#5 Vic Harder

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Posted 08 March 2021 - 09:04 PM

That web site you linked to sets off my computer's warnings.... I dug up this site RadRover 5 - Fat Tire Electric Bike | Rad Power Bikes

 

Looks like the battery is 48V, 15AH.   The included charger is 48V, 2Amps = roughly 100Watts. 

 

The thing that might be confusing (it got me, thanks to rando for pointing it out in a kindly way!) is that a 15AH battery is not just a 15AH battery.  What do I mean?  The amount of energy stored is 48V x 15AH = 720 WATT hours.  A 12v x 15AH battery only stores 12*15 = 180WH.  

 

So what?  (sorry about that pun).  In your camper you will need 4x as much power being generated to fill a 48V 15AH battery as you would to fill a 12V 48AH battery. 

 

So using the factory charger that came with your bike, a fully depleted battery should take 7 hours to charge (7Hrs x 2A = 14AH). You want to do that 2-3 a day for your multiple batteries, right? So call it 14*3 = 42AH... at 48V.  The 12V AH needed to make that happen is actually 4x that (plus a bit more because of electrical losses), so 42AH *4 = 168AH.  If your AGM batteries are fully charged before dark and you are going to bed with the intent to charge all three batteries overnight, you will need 2x that to avoid depleting your AGM's below 50% (never mind running the fan/fridge etc).  That's a 2* 168 = 336AH 12V battery!  Huge and heavy.... 

 

If all that looks right, I would use your existing 350W pure sine wave inverter and plug the factory charger into it and charge during the day after your solar panels have already finished charging your camper batteries. 

 

And keep monitoring your SOC on the camper batteries to ensure you are still good for the essentials overnight. 

 

Make sense?


Edited by Vic Harder, 09 March 2021 - 10:59 PM.

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#6 muttmaster

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Posted 08 March 2021 - 09:18 PM

Planning on getting Victron mppt 100/30 soon. Some Brit on Utube demoed using Victron 150/70 and 300 watts panel to charge the battery directly without the stock Rad charger. Possible without damaging the battery?

Rad bike told me my Honda eu2200i should be able to charge 14a via charger. But they only recommend ac wall charging. I am not sure if I want to use generator if I don’t have to. Guess I’ll have to experiment a bit to see how long it will take to charge up one battery, then maybe get another factor charger if the needs arise.

Thanks for looking into it, and the good advise.

Found a forum specifically on e bike charging. I will spent some time on it soon.

If I get a bigger inverter, say 1500 watts, will it charge faster?

Edited by muttmaster, 08 March 2021 - 09:55 PM.

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#7 Vic Harder

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Posted 08 March 2021 - 09:55 PM

The recommendations for charging Lithium batteries vary.  For some reason, Rad bikes included a 2A charger.  What do they say about your warranty if you charge faster?  

 

Can it be done?  Yes.  Should it?  Depends on how much battery life you want, I think.  Faster charging is harder on the batteries.


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#8 muttmaster

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Posted 08 March 2021 - 09:59 PM

It will be April delivery for my new toy. I don’t have any warranty info on the battery but will look into it.
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#9 rando

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Posted 09 March 2021 - 03:55 AM

Planning on getting Victron mppt 100/30 soon. Some Brit on Utube demoed using Victron 150/70 and 300 watts panel to charge the battery directly without the stock Rad charger. Possible without damaging the battery?

Rad bike told me my Honda eu2200i should be able to charge 14a via charger. But they only recommend ac wall charging. I am not sure if I want to use generator if I don’t have to. Guess I’ll have to experiment a bit to see how long it will take to charge up one battery, then maybe get another factor charger if the needs arise.

Thanks for looking into it, and the good advise.

Found a forum specifically on e bike charging. I will spent some time on it soon.

If I get a bigger inverter, say 1500 watts, will it charge faster?

 

 

A couple of points - you can only charge direct from your solar panels if they are wired such that their output voltage is above 50V or so.  For that you would likely need 3 panels in series, and I think you only have 2, so that is a no go. 

 

For charging from your camper battery, the limiting factor would be the 2A charger.  A bigger inverter won't help, so it will take 7-8 hours to charge a completely dead battery.   Is there a faster (higher current) charger available?  You should be able to fully charge these in 2 hours without damaging them. 

 

With the 2A charger, the generator option seems like the worst of all (for you and those around you).  You would still need to run the generator for 8 hours to charge one battery, and it would be incredibly inefficient.  At that point you may as well buy a dirt bike!


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#10 rando

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Posted 09 March 2021 - 03:59 AM

That web site you linked to sets off my computer's warnings.... I dug up this site RadRover 5 - Fat Tire Electric Bike | Rad Power Bikes

 

Looks like the battery is 48V, 15AH.   The included charger is 48V, 2Amps = roughly 100Watts. 

 

If all that looks right, I would use your existing 350W pure sine wave inverter and plug the factory charger into it.  Just keep monitoring your SOC on the camper batteries to ensure you are still good for the essentials overnight. 

 

Using the factory charger, a fully depleted battery should take 7 hours to charge (7Hrs x 2A = 14AH). You want to do that 2-3 a day for your multiple batteries, right? So call it 14*3 = 42AH

 

Your roughly 360W (actual is likely more like 300W) of solar can produce 360W/15V = 24A.  I doubt your stock ZAMP solar controller can actually put out that much (a Victron 100/30 could)... if you could get that full power into your batteries/charger in 8 hours of sunshine you could recharge 8Hr * 24A = 192AH.  

 

You should be good to go.

 

Make sense?

 

You may want to check these numbers, thinking in Watt-hours.   If the batteries are 15Ah at 48V, that is 720Wh or 2160Wh for 3 batteries.  That is a lot of Ah at 12V!


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