Ebike trailer 200ah

[Flybyebike]

I will attempt to build my own trailer with 200ah of lead acid to charge on the go through a dc to dc converter
My bike is 63v 15a currently around a 30 mile range on throttle only at 25mph.
I hope to get atleast 150 miles out of 8 car battery's wired together in 2s 4p configuration to give me a trailer battery of 24v 200ah.
I will use a dc to dc boost converter to step up the voltage to 63v to constantly provide power to the charging side of my battery already on my bike
I'm using around 8-900w on the flat at 25mph so if I put 300w from trailer I should triple my range to 90 miles continuous riding.
Then I'd have to stop and wait a few hours for my battery to charge back from the trailer side.

I could just run at 15mph (around 300w then I could potentially run till my bike and trailer are empty together giving a mega range of over 400 miles but at 15mph
Also I haven't taken weight into account on the range.

If not hilly terrain I wouldn't think it would matter when riding for long times with minimal stopping
(I travel the full 30 miles of my bike and only stop and start once or twice as I'm riding in country lanes with no junctions)
In city I would think that there's no point with battery trailer as power points are everywhere or just have spare battery at home charging.

Please give thoughts

 

[boudin]

What car batteries are you planning to use that are 50AH apiece? That sounds more like lawnmower or UPS size cells to me, the car/truck batteries I'm familiar with are more in the 75AH range.

I'm curious what actual effect the additional 250lb and boost-circuit inefficiency will have. Going to depend a lot on how fast (and how often) you accelerate. Taking 25mph turns with that heavy of a bike trailer...

 

[Flybyebike]

Sorry I didn't explain fully the purpose of my build
I want to go on weekend long rides with camping at night.
The main routes I will take will consist of flat long roads (hardly any sharp turns)

My partner will be coming on her ebike that I've Built to the same voltage and spec.
so I will Like to charge her bike also from the trailer during stops/breaks

I have some car battery's at 48ah they are from small cars here in the UK 1.0L petrol I think.. although I doubt I'll get 48ah from them being lead acid

Speed will not be an issue as I will be cornering slowly haha.
my motor is a 9c 2808 so can handle the torque needed to pull away I get around 25mph from 63v at full throttle. I will also help with my legs

Finally Im thinking of getting a 24v USB circuit to charge phones and laptop while camping from the trailer

In my mind this makes it worth while building it with more ah than I need as I Could stay out having adventures on my bike rather than worry about my power remaining

 

[LewTwo]

Hmmmm .... 400 miles at 15 MPH.
According to my calculations that is a bit over 26 hours on the saddle (without any rest periods). You might want to invest in a very, very comfortable bike saddle, some gel padding, real coffee (with caffeine) and some saddle sore salve.

I also suspect the E-Bike's efficiency (miles per watt hour at xx MPH) will drop significantly towing all that lead.

 

[amberwolf]

I will attempt to build my own trailer with 200ah of lead acid to charge on the go through a dc to dc converter
My bike is 63v 15a currently around a 30 mile range on throttle only at 25mph.
I hope to get atleast 150 miles out of 8 car battery's wired together in 2s 4p configuration to give me a trailer battery of 24v 200ah.
I will use a dc to dc boost converter to step up the voltage to 63v to constantly provide power to the charging side of my battery already on my bike

Make sure the DC-DC has (an adjustable) constant-current limit on there, that is set to limit current to the max charging current of the battery, or less.

If you just put a voltage source on the charging input, with no limiting, then if the battery draws more current than the DC-DC can handle, it may damage or destroy the DC-DC. If hte DC-DC can output more current than the battery can handle and the battery is in a state that causes it to draw that much, it may damage the battery or it's BMS. So the DC-DC needs current limiting in a CC or constant-current method.

LED PSUs like those from Meanwell (HLG, ELG, etc. series) can do this, if you find one that will run on the voltage range the lead pack will have.

Also note that the DC-DC will not be 100% efficient (probably 75-85% or thereabouts), so you can't get the full capacity out of the trailer pack.

Additionally, lead-acid itself is not 100% efficient, and won't give you the full rated capacity when new unless you are using it at less than it's "20 hour rating", or 1/20th C. For a 50Ah battery, that's 50 / 20 = 2.5A maximum. For 4p of those, that's 10A maximum.

As the lead ages (which can happen over 100-150 cycles or less if they are discharged from full to empty, and worse if they are left empty for any length of time, especially repeatedly).

I'm using around 8-900w on the flat at 25mph so if I put 300w from trailer I should triple my range to 90 miles continuous riding.
Then I'd have to stop and wait a few hours for my battery to charge back from the trailer side.

The trailer's air resistance is likely to increase power usage noticeably at 20-25mph (less so below that). You can test this even without the lead pack by putting a box on there that simulates it, and then do some riding to see what your wh/mile is at various speeds.

I could just run at 15mph (around 300w then I could potentially run till my bike and trailer are empty together giving a mega range of over 400 miles but at 15mph
Also I haven't taken weight into account on the range.

The weight is likely to increase rolling resistance of the trailer significantly, and increase the wh/mile usage of your system, decreasing the range.

Every stop/start you make, and every even slight incline, is going to do the same.

As a note, if you are using 8x 50Ah-ish lead acid batteries, at something like 30-40lbs each (or more), plus a trailer, it's probably going to be 300lbs+, possibly as much as 400lbs. That is a LOT of weight, most bike trailers don't carry more than around 100lbs. (I've built trailers that carry that much or more (upright piano, hundreds of pounds of dog food, etc), so they can do it, but it took some experimentation and failures to reach that point. I have threads for a few of the trailers here on ES if you want to look for them to build your own based on one.)


If you want to you can also go to http://ebikes.ca/tools/simulator.html and setup your conditions and approximate equipment, to see what kind of power usage you might have depending on the actual setup you end up using for the trailer (wheels, weight, etc).

 

[Chalo]

This is a very bad idea. You will waste most of that energy just hauling the trailer that will ruin your ride and cause you all kinds of grief and inconvenience from various failures and breakdowns. Assuming 50 percent depth of discharge (which is what lead acid batteries can actually deliver), you're looking at about 250 pounds of batteries for 2.4kWh, not including the power electronics or the cargo trailer you need to tote them.

We live in a time when there are lots of underexploited lithium batteries salvaged from EVs. (None of which use lead cells anymore. Take the hint.) Not all of these cells have top notch energy density, but all of them make lead look like a chump's game.

Lead batteries are only useful in stationary applications anymore, and they can barely be justified for that unless they're both free and still functional.