E-Mountainbike Project

[BL_RV0]

I don't have a 24v PS though. Mine's 13.8v and 8.5a. Works fine for me, so I have no plans to upgrade it.

[J57ltr]

That was just in case you wanted to charge both batteries at the same time or if you wanted to use the 18V battery.

Jeff

[BL_RV0]

I was thinking of charging them as a 12v 24ah setup. Would that work with my current PS?

[J57ltr]

With what you have yes, the only thing you have to worry about is that the lower the voltage on the batteries the more current they are going to draw, so it might trip the PS when you first start to charge them. The only other thing you have to worry about is charging them too fast. I think a 12 Ah battery is recommended to be charge at about 2.5 amps max, but with them in parallel that would be 5 amps. If you have an adjustable power supply (most are) you can lower the voltage and watch the current drop and then slowly increase it until you are at the 14.4V value. I have been using a regular car charger the maintance free kind with a couple of resistors in series with the + output.

Or I will use my 60 amp power supply and just watch the gauges set it for about 1 amp charge and when the current drops I increase the voltage till I am back to 1 amp then repeat until I am at 14.4.

The maintance free charger is the easiest way since it will only go to 14.4V

You could get a 24V power supply and charge them in series and not have to remove the batteries and reconnect them.

Cheaper ones:

http://www.mpja.com/prodinfo.asp?number=16854+PS

http://www.mpja.com/prodinfo.asp?number=16855+PS

Jeff

[Metallover]

I use a car battery charger to charge my pbs.

[J57ltr]

What kind, brand or model?

Jeff

[riverat1540]

i have a mrc super brain 989 i use to charge all my stuff including pbs. i even used it to charge my real car battery when i was on a camping trip and left my lights on, and i was the only one there. im just lucky my cabin has an outlet. it will charge up to 5cells in lead acid mode, i believe each cell is 6v if i remeber right i dont use that setting much at all

[J57ltr]

2V per cell on Pb batteries.

Jeff

[BL_RV0]

Ok guys, there's been a slight change in plans. Well, first off- I got my batteries! Woot! They're from my old e-scooter, 3 12v 12ah, but they work great. So here's the plan: It's gonna be the same motor and ESC, and still 24v even though I have 36v worth of batteries. I'm gonna ditch the sprocket I bought and the idea of running a chain down to the rear gear cluster. When I grabbed the packs, I also got the rear sprocket and freewheel. It's a 80t #25 sprocket, and a crappy but working freewheel. So what I'm going to do is mount the sprocket/freewheel on my crank, a much better plan IMO. All I need to make is essentially a large washer, a spacer to adapt the crank OD to the freewheel ID- not hard at all. I'm going to order another primary sprocket from mcmaster, as well as some chain. The sprocket is a 1/2" bore #25 14t sprocket. With the gearbox and that reduction, it will match my highest pedaling speed- about 25-30mph. With the planned gearing, and my ratio from my "foot-powered" sprockets, I'm looking at exactly 25.7mph. Perfect. The ratios are 16:1 (GB), 80:14 (primary to secondary sprocket) and 16:40 (pedaling sprockets, gear up)... Some pics for you to clear it up incase my explanation is fuzzy...

Here's the layout (old sprocket not being used still installed)



80t #25 sprocket



Where that sprocket is going

[Metallover]

Are you going to support the end of the shaft of that gearbox?

[BL_RV0]

Nope, but the pics make it look longer than it is, I'll probably just cut off the excess.

[BL_RV0]

Mini update: 14t 1/2" bore #25 sprocket and 5ft of #25 chain ordered, scheduled to arrive monday.

[J57ltr]

Originally Posted by BL_RV0

Ok guys, there's been a slight change in plans. Well, first off- I got my batteries! Woot! They're from my old e-scooter, 3 12v 12ah, but they work great. So here's the plan: It's gonna be the same motor and ESC, and still 24v even though I have 36v worth of batteries.

Have you tried the 36volts worth of batteries with the 24v controller?

Jeff

[BL_RV0]

I can't fit them on the bike frame or get the reduction I need to go anything less than 40mph with 36v.

[J57ltr]

Oh, Ok I thought you were going to use all 3 batteries.

Jeff