12V or 24V advice

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Howdy Everyone:

Allow me to introduce myself. I'm Colonel Monk, and I've been lurking here a little bit for a year or more.

I'm doing my own EV based on a chinese bike rickshaw. It's 3 wheeled, and weighs about 150 lbs unladen. It need's only to travel 5-10mph, nothing faster, as it's domain will be the dry lake bed at Burning Man festival in Nevada.

I've decided on an etek-style brush motor (one of the cheapies - Manta I believe) and so I'm now moving on to figuring out what controller to use, etc...

24V systems seems to be the most common - but I don't need speed, I need range. I'd like to do 12V and here's why:

-I have 4 - 12v 85Ah Deep Cycle Batteries in my Motor Home for a total capacity of 340ah. These will be located in a wagon being pulled by the rickshaw.

-I already have 12V smart chargers - one is a 2000W Magnum Energy inverter for RV - it doubles as a 4 stage battery bank charger with an output of up to 100amps for fast charging. I already have 600 invested in that.

Are there motor controllers out there for 12V that could do say up to 50 amps? Preferably programmable as I'd like to set it for economy and be able to set the top speed.

Am I missing something? If I use 24v controller can I get the same range from the batteries or will I definately get more from using 12v?

Is there any way of running in 24V and throwing a switch to charge in 12V?

I'm also wondering how to figure what sort of range I can expect, given a total weight (rickshaw, wagon, batteries, people) of around 1500 lbs. All wheels will be 26" Bicycle wheels (but with super thick 1/8" spokes...)

Any help to get me started would be appreciated.

Thanks,

Colonel Monk

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Re: 12V or 24V advice

Colonel, If all you need a 5 or 6 MPH and maybe up to 10 MPH why not use a contactor and save the expense? Pedal up to 5 MPH and kick in contactor via the 12 volts. This way you limit start up current. That is how the Zappy scooter was powered. Kick"n"go via a relay.

If I use 24v controller can I get the same range from the batteries or will I definitely get more from using 12v?

12 volt x 170 AH = 24 volts x 85 AH so range is about the same minus resistive losses on lower voltage and Peukert stuff but not much difference really. A controller with give more range because of flyback diodes in unit. A lot of Curtis controllers do both 12 and 24 volts.

Is there any way of running in 24V and throwing a switch to charge in 12V?

use a DPDT switch. It might be a good idea to use a switch rated at a fair amount of amperes just in case batteries do get a bit out of balance. But running on 12 volts will assure lower speed and current draw. If you use a controller you can control current via PWM and fine tune your pusher. I guess that is your rickshaw thing is right?

I'm also wondering how to figure what sort of range I can expect, given a total weight (rickshaw, wagon, batteries, people) of around 1500 lbs. All wheels will be 26" Bicycle wheels (but with super thick 1/8" spokes...)

I would guesstimate a real range of ten miles but I need and you need to know actual current draw under normal driving conditions. I based it upon my driving my Palmer Trike. It said 20 to 25 miles range and did a real 8 to maybe 12 miles before volt meter went down fast.
BTW do use a safety circuit in case of jack knifing and break away.

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Re: 12V or 24V advice

Thanks alot for the reply!

Sure I'd love to skip the expense of the controller but definitely need speed control and with the potential weight of the vehicle I'd rather be "pedal-assisting" than the other way around. The vehicle is designed to be a people-mover and as such will be frequently stopping to pick people up. It'll be alot more enjoyable to let the motor do the work...

The controller (if programmable) will also allow me to smoothly accelerate for best battery economy, right?

The alltrax controllers seem to be popular for programming - any others I should look at?

OK, so the size of my fuel tank (12 vs 24 volts) is really a wash. I get that. I just needed to hear someone with experience note it. What do you think about using lead acid batteries? That's what I have in my RV currently, if I can use the same batts it'll save me alot of money, especially considering I will only be using the vehicle occasionally. One thing is that the batteries are not totally new - they seem to hold at about 12.5V. Will that significantly shorten my range? I have used a desulphator on them extensively but in the months before I owned the RV the previous owner did not care for them properly.

Regarding the switching from 24v on the run to 12v for charging: a friend and I this weekend talked about doing this by switching, but wouldn't it require more that 2 poles? Currently I have a wiring diagram in which 5 poles seem necessary. Of course, it's no picnic finding a 5PDT switch rated for 100A or more - We are looking at double throw knife switches. Any other ideas? I uploaded a pic of the diagram...

The actual current draw measurement is a ways off I suppose..... Any hints on doing a paper model to estimate it? I'm working on doing this for my vehicle and have found a formula for estimating rolling resistance. I suppose that and a free-body diagram of the vehicle and weight I should be able to figure a theoretical torque value required to come up to speed and then how much it takes to maintain. Of course, nothing is a substitute for actual measurements.

Thanks for the help!

CM

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Re: 12V or 24V advice

Lets start off with Alltrax. The programming is ONLY for input. Not for speed programming. My Alltrax is programmed for Inductor input and I use it on resistive of an unusual ohmic value. You can program inductor , resistive 0 to 5K, 5k to 0, 10 volt input or lots of other choice but either way it will go from zero MPH to full speed. It might have other features like HPD but I didn't need any of that stuff in my tractor or bug.
If you have Deep Discharge battery pack 12.5 is probably OK but really you need to load test the batteries in question. Like using an Inverter with a nice load for 1 , 2, or 3 hours. EV batteries are usually rated in minutes of use at 25 or 75 amperes. Marine uses 25 amp load and EV cars use 75 amp load for 100 or so minutes. Inverters have 10.0 volt cut off so using a 1000 watt load will need 100 amp at 12 volts And 750 Watt load will need 75 Amperes.

Regarding the switching from 24v on the run to 12v for charging: a friend and I this weekend talked about doing this by switching, but wouldn't it require more that 2 poles? Currently I have a wiring diagram in which 5 poles seem necessary. Of course, it's no picnic finding a 5PDT switch rated for 100A or more - We are looking at double throw knife switches. Any other ideas? I uploaded a pic of the diagram...

I can't figure out how you can use 5PDT. I know of only one way to wire up for 12/24 and that is DPDT with top and bottom battery going to center posts. top terminals shorted, and bottom going to opposite polarity. Contactors come in reversing type already. See Curtis wiring instructions.
I guess if you want to go controller Alltrax is best bang for the buck. As far a battery capacity you need to load it down and capacity is measured in AH and to be specific 20 hours but you can also do 10 or 5 or three hours. If sulphated then you have to have that type of desulphator.
I have to figure out a way to make a schematic to send you I guess. I only have OrCad and an all in one copy machine to SD disk to insert in email I guess. Give me a call if you need help. I am listed in V and my home page signature.
On second thought I think you might be right. Just needs a little butter on it.
Toast!
Most RVs use a regular flooded battery and not a marine like should be in there. I worked in an RV place fixing chargers and hardly ever saw proper battery back there. Where did you upload Pictures?

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Rusty

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Re: 12V or 24V advice

Guys:

Let me try again with the schematic:

Wiring Diagram.jpg

I think what you were missing is that there are 4 batteries in my bank, not two. Therefore, there are 4 terminals needing an alternate connection for the battery. The 5th pole sends the positive terminal to either the 12V charger OR the 24V controller. This leaves the circuit open when not in use which seemed like a good idea.

Let me know what you think.

CM

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Re: 12V or 24V advice

Spaceangel and others:

Hey thanks alot so far for your help.

I hope my wiring diagram helps with understanding why the 5PDT switch. I'm not an electrical engineer so forgive the simplicity of the switch wiring - I don't know how to do it schematically but can draw it out for myself.... The blocks indicate the poles on the switch and what will be connected to them.

Again the function there is to allow the series/parallel switching of two banks of two 12v batts - so there are 4 batteries total. The 5th pole allows the motor circuit to be open when in 12V mode, and the charger circuit to be open in 24V mode.

We're waiting on some quotes for the knife switches - I fear being made of stout copper that the cost will be ridiculous.....

However, it seems all this switching might not be necessary. Upon some additional searching I have found that INDEED Alltrax does have 12V-24V controllers - so if I can get the model AXE2434 or AXE2444 I can remain at 12V and that will really simplify my setup. They seem more expensive than the 24-48 controllers for some reason but I have located one at a "reasonable" cost.

I have looked at the programmability for this controller, and unless I'm missing something it appears that you can set the maximum current along with:

Adjustments via Controller Pro software:
Throttle acceleration / deceleration rate and map profile
Armature current limit
Brake current limit
Under / Over voltage shutdown
Half Speed Reverse
High Pedal Disable
Plug Brake

What else....

Oh, I saw in an earlier post about a pusher? This rig will be a puller, I just can't put a sizeable battery bank and all the electronics on the rickshaw - there's no room for all that. So the wagon will support the weight of the batteries (4-6) and all the electronics, and some passengers / cargo.

Regarding the batteries: Yes there are flooded-cell type, run-of-the-mill interstate marine/rv deep-cycle/starting type. Yes, there is a classification where they blur the lines between the two batteries, believe it or not. They are not true deep cycle type and my guess is that they would not perform nearly as well in my vehicle as a new real set of deep cycle batteries.

I will take your advice and do some controlled load-testing of my bank to get an idea of how well they are doing. I've been looking for a reason to get a "real" set of batteries in my RV, and I'm leaning toward a shiny new set of trojan cells. Pricey, but I've heard that they sport thick plates and can handle sustained crashes that would ruin other batteries. Not that I plan to crash them, but when you live on battery power it does happen occasionally.

thanks,

CM

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Re: 12V or 24V advice

Col. It is apparent you have knowledge of how a reversing relay / contactor works. I have been using a 12 / 24 volt system for three years using cheap Walmart nEver-Start "MAXX" 29 series batteries so you caught me off guard using a 5PDT relay system. A battery is defined as a group of cells but paralleling them still is a battery and in series as a bigger battery. It is old but safe practice to parallel them if they are the same chemistry and leave them as 2 each - 12 volt batteries. Mine have been like that for a long time and still thirteen point something sitting for a while. Just keep it simple and use the two batteries to make one "BATTERY" and do the same with the other set of two.
Use a DPDT and wire it for reversing like you drawn out but use DPDT.
B+ and B- to controller battery pack
B+ and M- to Motor
Pin 1 to KSI
Pin 2 and 3 to 0-5K throttle
Hook 100 Amp charger to battery pack with fuse or fuses
and you are on the way to Rick Shaw? Who know if you use Alltrax 12 / 24 it might work well on 12 volt without going into low voltage shut down. Once you get the controller and if you decide on 5K to 0 then you can order a RS-232 cable to USB and download information into unit to change controller throttle assembly. If your battery pack is DEAD then there are battery additives like VX-6 and EDTA and others for flooded type of batteries. Let us know your range on dead battery pack. It will get better with a few charge discharge cycles.

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Re: 12V or 24V advice

http://www.toontracker.com/realaudio/spaceang.ram

I'm not sure I'm getting how this charging the 24v system with the 12v charger works. You COULD just have a plug in for each one to get it one at a time, and that's probably safest. In Hollywood there's a popular 12v/24v switched unit battery format that people want to build their own and rent to the production company rather than having them rented from the camera supplier. Then they have one wired wrong and then there's a repair bill. . . .

I always like to say, the problems you spare yourself with the cheap insurance policy make the trip worthwhile. What a shame to let 'Burning Man' be ruined for you because you didn't want to spend $50 for your pusher to work right. And better to see it than be it, at that event. http://www.curriestore.com/731-ezip-controller.html Maybe someone around you wrecked one, around me Craigslist will have someone who maybe broke the front wheel and forks and used the batteries on something else, and now you can have what's left for $15. Or maybe it's just the plastic broken up and LOOKING bad so they don't ride it. . . . (Say, you noticing a bunch of these readers are drooling at this?)

http://www.packratworkshop.com/trailer2menu.htm Hours of fun seeing everything this guy has built.

http://rqriley.com/b-pusher.htm

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Re: 12V or 24V advice

Howdy Dauntless:

Thanks for your suggestions.

I think maybe you misunderstand my vehicle project a little bit. It's not just a bicycle, it's a heavy steel rickshaw (200lbs?) pulling a trailer full of heavy batteries and people. So more like an EV, in terms of the hardware/battery pack it's gonna take to move it. It does have pedals, but in an "off-road" environment it's a joke to try and pedal it and 3 people around in the desert sun.

I don't think a hubmotor or e-bike controller could reliably move it, and anyways this is real chinese gear - the wheels look like bike wheels but the spokes are 1/8" in diameter - thicker than motorcycle spokes! So a traditional hubmotor couldn't fit.

I'm leaning toward an etek-type motor - it's overkill and I won't be using but just enough of it's power to move the rig at low speed, but it won't let me down out there.

About the charger - I'm not cheaping out. I have a very sophisticated charger for 12V that can charge a 300Ah pack in a few hours. A charger like this costs several hundred dollars, so this is my motivation for trying to work with what I have. To find a comparable charger in 24V will cost a pretty penny indeed - in the $1000's.

Switching the voltage of the pack isn't rocket science, though it could be costly

I'm pretty sure the Alltrax 2434 controller will work for me and my desired voltage, though I have some more research to do. Certainly, it will handle it at 24V but I need to verify that 12V is with Alltrax.

thanks

CM

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Re: 12V or 24V advice

Col, I just went to a web site and saw the prices. $388.00 FOR AXE2444 Input voltage: 12-24 volt battery system
Max. Current: 400 amps,Input voltage: 12-24 volt battery system, Undervoltage: Cuts back @ 16 VDC, Voltage Drop: <0.10 VDC @ 100 amps , Switching Frequency:18 kHz, Programmable: yes/RS-232, Plug Braking:no, 2-min. Rating: 400 amps
5-min. Rating: 350 amps, 1-hr. Rating: 200 amps, Undervoltage: Cuts back @ 16 VDC, Voltage Drop:<0.10 VDC @ 100 amps
Switching Frequency: 18 kHz, Programmable: yes/RS-232, Plug Braking: no
Alltrax AXE-2434 Controller
Price: $435.00
WHY? Did I miss something. http://store.kta-ev.com/DC-Motor-ControllersandProgrammers/Alltrax_Axe-2444.aspx
Also Are you going to make one 12 volt battery out of two and use the 12 / 24 volt system using a DPDT? Let us here from you on performance / range when project is under way.
If you want to sell the pieces in months or years to come you can get better monies for better parts.

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Re: 12V or 24V advice

Howdy SpaceAngel

Why? What are you asking? About the controller?

The controller (ALLTRAX AXE2434 or 2444) is designed for 12V or 24V operation. I spoke to ALLTRAX this morning and they told me that it will operate from 8-30V.

I asked alltrax, if speed is not important, what is the benefit of running 24V vs 12V - and basically they agreed that all else being the same (number and capacity of batteries) then it really doesn't make a difference whether I run at 12V or 24V. The higher current associated with using 12v might necessitate me using a higher gauge wire but that's no big deal. I'm going to be charging at high current anyway, so I'll need the heavier gauge for that anyway.

So, using that controller will give me a shot at trying 12V, and if for some reason I find that won't work I can rewire for 24v later which is the other option. So it seems like a good plan to me.

I have found a slightly better deal, though for some reason these controllers are a bit more expensive than the 24/36/48 volt models....

Does that make it a bit clearer?

CM

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Re: 12V or 24V advice

BTW, can you post a link to the reverse relay/switch that you were referring to?

Thanks for the help guys, seriously. Nobody I know really knows about this stuff so it's all new to me. I'm a machine designer so it's not that foreign either, but you know what I mean...

CM

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Re: 12V or 24V advice

I just mentioned about the 2444 model. I just can't figure out why the 400 amp model is cheaper~er than the 200 amp model.
reversing relay= http://cgi.ebay.com/CURTIS-ALBRIGHT-DC88-358-CONTACTOR-1-105-220-24V-NEW-/190382337492?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=i...
or
http://fs.bookpawnshop.com/C/Curtis-24-volt-DC88-271E-forward-reverse-contactor/
If you want you can call me anytime.
There are a lot of reversing DC-88 on eBay right now. Just use a switch that has a detent in it so you can't go from forward to reverse like instantly like I did once. Massive arcs and sparks and totaled armature and brush holder.

Why? What are you asking? About the controller?

The controller (ALLTRAX AXE2434 or 2444) is designed for 12V or 24V operation. I spoke to ALLTRAX this morning and they told me that it will operate from 8-30V.

I just want to reiterate about the stupid pricing why is the better~er model of Damon's play toy cheaper~er?

No I am sorry it is not clearer? I think I see the over all picture and I feel it is good enough but maybe not. Use a 12/24 volt relay? yes/no?
And or use a reversing contactor like DC-88? A nice AXE2344? not bad choice as a matter of fact a great choice. Use existing charger? Not a bad idea, Use old battery pack in 12 / 24 volt format great also. My typing skills and placement has a lot to be desired for I can go from one subject to another quick time. I am wondering about low voltage cutoff on AXE-2344 of 16 volts but it is for 12 volt too?
My controller is some 600 amp jobby from Damon himself. Some sort of inside business deal I guess. I do a lot of making things out of stuff I have around here and to do what you are trying to do. Use existing stuff to make things. And I save old Contactors and controllers too for other projects.
Another change of subject~ make sure coil is CO
CONTINUOUS OPERATION
magnetic blows out are nice in any case but one does not really need it till you hit 36 volts or more.
Rusty

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