01 CAt Man Do

Judging from the size of my new charger for my ebike I'm thinking the charger must pull some juice. Thinking ahead, if I take my ebike on a road trip ( with my car ) is there an option to charge the battery from my car. I can do this with my bike light batteries but those are much smaller. Is there an inverter that can handle the current load or is this just undoable with a normal car electrical system?

unterhausen

doesn't it say what the current draw is? I expect you can use an inverter. Maybe not with a Prius though

Doc_Wui

The weak point is probably going to be your car's accessory (cigar lighter) port. They can handle 120-150W, but if the contacts are corroded on either the socket or your plug that number goes down and the connector heats up.

I charged my battery in the car last winter with a 36V2A charger. That's about 80W max. I had a 500W inverter. It handled it fine, but the connector did get fairly warm. I've had that inverter for many years The label says to not go over 150W with an accessory plug. I would have to connect it direct to battery to get 500W out of it.


.

01 CAt Man Do

Yep, exactly what I was thinking. I have a small inverter I picked up at Radio Shack ( many years ago ) when Radio Shack was still in business. Can't find it at the moment but I'm thinking it might be rated somewhere around 100 -120 watts. The charger for the ebike battery is outputting 42 volts @3.1 amps. That's about 130 watts. That's a lot of power to be drawing from your cigarette lighter outlet. My basic worry would be that it might blow the fuse on the cig. lighter outlet or even worse that the plug in the lighter outlet would get hot enough to actually melt the plastic on the plug ( or even the socket itself ).

Going forward it I do decide to take a camping trip somewhere and have no access to line power I might decide to buy a better inverter, one at least rated to 500 watts. I'll also make sure it has the clamp connectors that will allow direct connecting to the car battery. A good inverter should have it's own circuit breaker or fuse setup. Of course if I use something like this I'd have to let the car run while the e-battery is charging or I'm sure it would likely kill the car battery in no time flat. Certainly not the ideal situation as gas is not exactly cheap.

Nope, not going to mess with the cigarette lighter socket. I can safely use that for charging my phone and my 8.4 volt bike batteries so I'll not take chances with the e-bike battery.

pierce

the charger that came with my 48V 18AH battery says 55V at 2.0 amps output, 100-240VAC max 2.5A input. it takes about 9-10 hours to fully charge the battery pack when its run down to 0-1 bar. 55V at 2.0A is 110 watts, so allowing for conversion efficiency, I'd peg it at 120-150 watts input, the 2.5A max input is probably inrush current when its first plugged in, and then only at the 100VAC minimum input, at our 120VAC US power, I'd expect less..

I probably should plug it into one of my mFi Power plugs that will graph the power used, next time I charge the batt.

edit: ok, ran the bike at full throttle for a couple miles including up a steep hill, and the charger is pulling 122 watts. thats just barely in range of a cigar plug based inverter (IMHO, cigar plugs are 10A max).

after 20 minutes, the power started dropping fairly quickly, and 15 minutes later is under 70W

01 CAt Man Do

On second thought I don't think I'll try to charge an ebike battery using the car. I'm just not willing to let my car run for 6 hours while the battery charges. Of course there is option #2 ; a portable generator. I could get one for about $160 but I'm not willing to haul something like that around if I'm on a camping trip. Now if I were to rent or own a pop-up Camper or Trailer then maybe I'd go with it.

pierce

on camping trips, I'm planning on using my trailers dual golf cart batteries to run a 200W inverter.... and the trailer has a 160W solar panel on its roof. unless of course, I'm at a campground with power hookups, then its a just a simple plug-in...

01 CAt Man Do

I was musing over the idea of just bringing along an extra truck battery but pretty much the same inconvenience as a generator. Not to mention those have to be recharged as well.

Right now I'm just looking ahead as I'm starting to eye-up the FS e-mtb's. Mountain biking has always been my passion but at my age and with my health limitations, I can't see me pedaling up any more mountainous 6 mile climbs.

There is of course an option #3 ; just buy several replacement ebike batteries. That won't work for me though. A replacement Shimano Steps battery cost about $587! Nope, the $250 generator is starting to look like the better option. I'd hate having to use one ( noise, carrying a smelly gas can ) but at this point it seems the cheapest way to go. ( Most generators will run 6-7 hrs on a gal. of gas ....not to mention the more expensive ones will also run on propane )

Damn! why do the really nice FS e-mountain bikes have to cost >$5K! I'd hate having to retro-fit my current FS mountain bike with an E-kit but sadly that might be the cheapest way to go.

pierce

fwiw, 8 hours at 10 amps would *flatten* a truck battery.

pierce

k, I ran the 48V 18AH pack down to 2 bars today, and plugged it in. this is the charge curve, in watts. Divide watts by 12V to get amps on a DC system. I note that the light on the charger went from red to green about when that 'tick' is at about 8:10pm, about 3.5 hours after plugging it in, but it still seems to be charging a little. it will eventually shut off.

pierce

here is the cumulative charge over the same time frame, in KWH. .37 KWH is 370 watt*hours, so I guess I didn't even use half the charge of my battery. darn it, if I didn't live up a steep hill, I'd run this thing til it is nearly flat, and see how much power it takes to fully recharge..