Urbanmover UM70 - Comes stock with a 24v 15amp battery pack (12v x 2 lead acid batteries) = Can I upgrade to 36v LiFeP04???

4 posts / 0 new
Last post
aboveliquidice
Offline
Last seen: 8 years 3 months ago
Joined: Tuesday, April 28, 2009 - 00:33
Points: 19
Urbanmover UM70 - Comes stock with a 24v 15amp battery pack (12v x 2 lead acid batteries) = Can I upgrade to 36v LiFeP04???

By providing more voltage - I have heard that this can lead to more motor output, at the cost of motor longevity... what is the principle behind this.

I understand the need to maintain the same amperage - ie not frying anything - but what are the effects of overvolting?

Please enlighten the V-noob :-)

dogman
dogman's picture
Offline
Last seen: 11 years 10 months ago
Joined: Tuesday, April 29, 2008 - 15:41
Points: 830
Re: Urbanmover UM70 - Comes stock with a 24v 15amp battery ...

It could fry something anyway. First off, lifepo4 36v batteries start out at around 44 volts when fully charged. Unlike sla's that will quickly drop to a lower voltage the lifepo4 will stay pretty high for a lot longer. Your 24v system that has 28v or so at the start might have components in the controller that just can't handle 36v, let alone 44. Look inside and see if the capacitors have lablels on them that say 40v. A 36v controller will usually have caps labeled at least 60v.

As for the rest of the thing, the motor, the wires to the motor etc, it won't care too much what that voltage is, or amperage is, but it will care what the watts is. Watts is amps x volts. Watts means speed, and also the heating that comes with it. Everything that gets hot will get hot faster with more watts. So if you increase the volts, then keeping the amps from increasing is a good idea. I increased the amps and the volts on a heinzmann motor once and got to ride it for about one hour. Apparently that motor didn't like doubling the wattage since the smoke soon poured out of it.

The other issue that could lead to melting stuff is simply the ride time. A lot of this stuff is designed to be ridden for about 30 minuites at full speed, and by then it has to go on the charger. Switch to lifepo4 and suddenly your ride time doubles or triples, and it is possible to melt stuff that way too, without increasing the wattage at all. Yeah, you guessed it, I've done in a motor that way too.

Anyway, you might want to test 36v with a third sla battery before shelling out for a 36v lifepo4 that might cook everything. Or just stick with 24v, and get lifepo4 in 36v when you have a ride designed for 36v. If you like to tinker with stuff, then go for it, and figure a new 36v motor and controller into the budget.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

myocardia
Offline
Last seen: 11 years 7 months ago
Joined: Friday, November 7, 2008 - 04:07
Points: 104
Re: Urbanmover UM70 - Comes stock with a 24v 15amp battery ...

By providing more voltage - I have heard that this can lead to more motor output, at the cost of motor longevity...

You heard right. Higher voltage= more watts.

what is the principle behind this.

Well, power= watts, and 1 watt= 1 volt x 1 ampere, which is the same as saying that watts= volts x amps. If you have more of either, you have more power/watts. This page goes slightly more in-depth, if you're interested: http://en.wikipedia.org/wiki/Watt

I understand the need to maintain the same amperage - ie not frying anything - but what are the effects of overvolting?

That's true, but note that amperes does NOT equal ampere-hours, which is what batteries are rated at. Amperes is the amount of current that you're supplying to your electronics & motor at any given moment. Ampere-hours is amperes x hours. For instance, your two 15Ah batteries can actually supply a few hundred amperes, for a second or two. Their rating, though, means that they can supply 15A for 60 minutes, or roughly 1A for 15 hours.<--Those two don't translate exactly, but close enough for government work, at least.

Cliffs notes:
1) Power= volts x amperes.
2) To make your skateboard move faster, raise your battery voltage.
3) To make it travel farther, add more ampere hours of battery storage capacity.

aboveliquidice
Offline
Last seen: 8 years 3 months ago
Joined: Tuesday, April 28, 2009 - 00:33
Points: 19
Re: Urbanmover UM70 - Comes stock with a 24v 15amp battery ...

Gents - thank you for taking the time to reply. I was unaware of the much higher voltage coming from the battery packs after they are removed from the charger... Would it be easier to simply get a 24v 15ah LiFeP04 pack instead? My battery pack was purchased originally in 2006 - and has sat without use for about 7 months or so. When charged - they show 25v. However, I am seeing a marked decrease in power after an hour's use.

I should note that I have also had an issue with blowing fuses... Which makes me think that the controller was not designed for heavy loads - and the fuse design is tailored to match. Currently, I have a 15 ah 250v fuse running between the batteries (that are in series) - A 15 ah 250v fuse from the battery pack prior to the logic board / controller (It is a closed box with a heatsink and a bunch of wires) - finally there is a 5 ah 250v fuse that runs in between the key socket and the logic board (to prevent surge of somekind). I have experienced blowing the external fuses (the one in the battery pack and the inline fuse from the battery to the logic board) under heavy load.

Blowing the internal 5 ah fuse was the main reason (I believe) that the board was down and sat for 7 months. I only recently (through some motivation from fellow members) tore the motor assembly open and found the problems.

I think adding another SLA would be a better option if the current pack wasn't at such an aged state. I would also like to get more speed from the board (the current 12 estimated is a bit on the slow side)...

Perhaps gutting the internal components makes sense. The board currently has a wired controller - and a wireless module would be a nice addition.

Final question. To run the board - I would need a battery, controller, motor - and the wiring to connect them. Is that correct? I think my board has really great bones - but could definitely use some upgraded components.

Log in or register to post comments


Who's online

There are currently 0 users online.

Who's new

  • wildbeas
  • lkonings
  • Kenechukwuezegbulem
  • Paguilar
  • simplyeric

Support V is for Voltage