Hi Deepbass

I've recently got some stuff through the post office and its gotten a lot better and quicker. Also got stuff from Banggood, these were couriered to my house without me even paying for shipping. It seems like the companies from China have sorted out the customs and distribution issues over here. A company called Buffalo did the customs clearance and even had a payment gateway for the customs payments. Was very surprised since I was expecting the normal 3-6 months lead time via the post office. Instead I had the parts within 2 weeks.

Here is some motivation: https://hackaday.com/2019/07/28/russian-ebike-goes-everywhere-possibly-legal/

There are a few other ebike/cart and buggy projects on Hackaday. I don't want to derail this thread but there is also a EV forum with lots of info...

Thanks, I have ordered from PClink, they claim 10 to 15 days. Also with a name like pclink I can use it as a business expense!

The next item on the list is the quad.

I have possibly sourced a donar quad. A Bombardier 200 Rally, 2002 model with a missing engine top end. The problem is, it is in Cape Town. Transport costs may be prohibitive, otherwise I'll have to continue hunting.

Once you go down the EV rabbit hole you come across some amazing projects. How about a Tesla drivetrain in a Rolls Royce? https://www.teslarr.com/

Edited October 24, 20196 yr by DeepBass9

I have had a look at quite a few different electric quad projects that people have done, and I am definitely, as a first pass, going to use lead acid car batteries. There is a place I have found that supplies reconditioned car batteries for R500, guaranteed for 6 months. I will get 4 x 40Ah batteries and connect in series, which will give 1kWh storage to 50% DOD, or enough to run the 2kW motor flat out for half an hour. The weight will probably be about 45kg, probably similar to the engine and gearbox.

Lithium batteries are just too expensive to use in this application. Also the electric motor pulls a lot of amps as it starts up, and I don't think your readily available solar type lithiums are up to the job. Lithium Batteries designed for EVs are helluva expensive. I have come across a few DIY projects where people use batteries from scrapped Nissan Leaf's (leaves?) or similar EVs, but I don't think that scrap battery market exists yet in SA. 

For charging I am going to use a normal 12V battery charger and try and design a circuit with switches or contactors so I can switch the batteries from series 48V to parallel 12V. If anyone has a smart way to do this I would appreciate some tips.

Edited October 24, 20196 yr by DeepBass9

1 hour ago, DeepBass9 said:

or enough to run the 2kW motor flat out for half an hour.

There is not a chance that those lead acids will do it either.

4x 40Ah = 48V 40Ah = 1.92kWh

So a 2KW motor will be discharging them at 1C, I think the absolute best you can expect from lead acids will be 0.5C (Even then they won't last very long)

Golden motors have a LFP battery with BMS already sealed in a stainless stell case with a charger:

https://www.goldenmotor.com/

Its a 48V 30Ah pack, for 890 USD, so quite a bit more expensive, but it can handle 60A continuous discharge so around 2.8KW

Pair that with the 3KW motor they have and you will have a pretty nifty quad that will be good to run for ages.

Sadly the problem with converting things to EV's as I have learnt is, that it is very expensive, even for a small project, but you should look past the upfront cost and into the running and maintenance costs as well.

Edit:

They also have a 20Ah version, which should give you the 2KW continuous discharge you need for 655USD, perhaps you should give that a go? 

Edited October 24, 20196 yr by PJJ

It's not the intention to run it flat out, if you run it at half power you will get an hour etc, just a comparison. Cold cranking amps on a car battery is in the region of 300A to turn an engine against compression. I'm sure that will  be quite sufficient to get you moving. Most of the quad conversions I have seen use lead acid.

R2000 vs $890 is eight times the cost. Uneconomic for sure. For that price I could buy a quad and 200 litres of fuel.

Edited October 24, 20196 yr by DeepBass9

18 minutes ago, PJJ said:

So a 2KW motor will be discharging them at 1C

 

7 minutes ago, DeepBass9 said:

if you run it at half power

That's still C/2 discharge. I've always been told that C/5 is about as high as you can go, but obviously that's continuous discharge. Of course lead acid batteries routinely do short bursts of high power: It's called starting an engine! 🙂

One point of comparison might be to look at what golf carts use: the old 6V 225Ah Trojan battery. What I don't know is the size of the motor, or the average distance traveled during a game of golf 🙂

2 hours ago, DeepBass9 said:

I don't think your readily available solar type lithiums are up to the job

Readily available solar LFPs can do C/2 continuously, 1C for several minutes, and 2C for a few seconds. It should be at least as capable as a starter battery, but with a much longer life.

I agree that going to a higher energy EV chemistry is a step too far.

Cost is the problem there  R15k vs R2k.

59 minutes ago, DeepBass9 said:

R2000 vs $890 is eight times the cost. Uneconomic for sure.

I don't think so at all, those lead acids will last for what? 150 cycles?

The LFP will do 1000+

And also, your R2K lead acids will also need a charger (Add R1K? and perhaps a battery balancer  HA02 R650?) which that LFP pack comes with.

And you would also need to design your own enclosure to house everything.

So its probably going to end up being R3-R4K even with the refurbished lead acids.

Lets split it down the middle R3.5K vs R13K: So 3.7 times the price for 6+ times better cycle life?

And also charging the LFP pack will only take ~1 hour where your lead acid pack will easily require 4+ hours.

You are trying to solve a problem that I don't have! A R30k quad bike defeats the purpose of the exercise, which is to have cheaper transportation that what I currently use. (Which is admittedly either a 4.2 landcruiser, 3.0 Colt bakkie or 4.0 tractor, so not too much of a challenge!)

Edited October 24, 20196 yr by DeepBass9

I'm going to get it up and running on cheap LA, if it works really well then I'll consider lithium when the cheap LA's expire. There is also a bit a weight required to replace the weight of the engine, otherwise the shocks will be way too hard.

9 minutes ago, DeepBass9 said:

You are trying to solve a problem that I don't have! A R30k quad bike defeats the purpose of the exercise, which is to have cheaper transportation that what I currently use. (Which is admittedly either a 4.2 landcruiser, 3.0 Colt bakkie or 4.0 tractor, so not too much of a challenge!)

Yeah beating any of your current modes of transport will definitely not be hard.

My point is just, I think (and I could be wrong) that the upfront cost of lead acid vs LFP will eventually not at all matter since the cost per kWh of the LFP pack handily beat out the lead acids, so its simply a case of paying for your next 8 years of battery needs upfront, or have it deferred to every 2 years. 

1 hour ago, DeepBass9 said:

4.2 landcruiser,

I assume it's the 4.2 liter straight 6 naturally aspirated Diesel? Those are nice. Bit heavy on the juice... but nice!

Edited October 24, 20196 yr by plonkster

I expect 500 000 km from that engine, I've done 150 000 in 8 years, so it is due for an engine overhaul in 2038. 🙂

Edited October 24, 20196 yr by DeepBass9

Quad bike acquired : R2000 . Will collect later in the week and and see if any repairs are required. The current owner has all of the bodywork, seat etc. He is going to remove and keep the engine :

Edited October 28, 20196 yr by DeepBass9

The bits an pieces for this are coming together and by next week I should have the motor and controller and the quad frame. I'm trying to figure out the best way to charge the 48V battery bank on the quad. I've been trying to figure out a way to switch the battery bank to 12V parallel, but it is complicated and requires lots of switches. 48V battery chearged are either chep and crappy, or quite expensive. Connecting the quad battery bank in parallel with my existing battery bank will probably have unintended consequences, like frying the quad batteries.

Would it work to get a cheap 48V solar charge controller and connect it to the busbars on my main bank, and use that to charge the quad's bank? 

  Like this : https://www.communica.co.za/products/solar-reg-48v-60a-ecco?utm_source=www.communica.co.za&variant=17184887242825&sfdr_ptcid=31591_617_495141845&sfdr_hash=36ccacc97e3a79b2b463a3325de01008&gclid=Cj0KCQiAtf_tBRDtARIsAIbAKe2_6z2vJKLJlRxcjsZpsvKcNXI-wPnamsby5LwhLQGZKCwRI4PrzoYaAuGdEALw_wcB

Or this : https://www.weable.co.za/pwm-charge-controller/bluesolar-pwm-light-charge-controller-48v-10a.html?gclid=Cj0KCQiAtf_tBRDtARIsAIbAKe1hBHnuXGwE_3KM6UyCK9l4iZ2zenzup_weVUPzIIs5iNPolg13vyUaAkjUEALw_wcB

Edited November 4, 20196 yr by DeepBass9

1 hour ago, DeepBass9 said:

Would it work to get a cheap 48V solar charge controller and connect it to the busbars on my main bank, and use that to charge the quad's bank? 

Remember that you need around 5V above battery voltage before an MPPT will even start, so charging from one bank to another is unlikely to work.

BUT.... how about reconfiguring the 48V quad battery into 2 x 24V. That would take less switches and you'd be able to use a buck converter to charge DC-to-DC.

11 minutes ago, plonkster said:

Remember that you need around 5V above battery voltage before an MPPT will even start, so charging from one bank to another is unlikely to work.

BUT.... how about reconfiguring the 48V quad battery into 2 x 24V. That would take less switches and you'd be able to use a buck converter to charge DC-to-DC.

That's a good idea, actually 24V battery chargers are readily available, maybe that is the way to go: 24V charger and 2x24V batteries. Thanks!

2x24V you could do with 3 switches - one to isolate the two halves of the bank, and the other 2 to connect the two 24V pairs. So with a 3 pole switch it could be one action, correct?

Hmm, you need the one switch to open, and the other two to close. Maybe it can be done with a changeover switch.

Edited November 4, 20196 yr by DeepBass9

12 minutes ago, DeepBass9 said:

Hmm, you need the one switch to open, and the other two to close. Maybe it can be done with a changeover switch.

Easiest I can think of is a 2 pole changeover. Wired something like this:

Thanks, that should do the trick.

Edited November 4, 20196 yr by DeepBass9

You may just need to be careful. 48V may damage a 24V charger. Possibly put a red led or something that only lights up when it's configured for 48V to warn you not to connect the charger.

3 minutes ago, Stanley said:

You may just need to be careful. 48V may damage a 24V charger. Possibly put a red led or something that only lights up when it's configured for 48V to warn you not to connect the charger.

I'm trying to figure out a way where it is not possible to make that mistake. 

Just now, DeepBass9 said:

I'm trying to figure out a way where it is not possible to make that mistake. 

I think the easiest would be some indicator (possibly using an auxilliary switch on the changeover), or otherwise connect the charger positive to the positive of the left battery on the diagram. That way, if the switch is in the wrong position you only charge half the bank, but don't risk damaging the charger.

46 minutes ago, DeepBass9 said:

I'm trying to figure out a way where it is not possible to make that mistake. 

Wire the 24V charger to the left-hand bank (as in the picture). When the switch is in the 24V position, then both batteries are charged. When the switch is in the 48V position, then only the left side is charged... not ideal, but nothing blows up.

Edit: Of course that means there is a shorter path to the one than the other, will have to decide how much you worry about that. The other option is to use 2 x 24V chargers and not use a switch at all.

Edited November 4, 20196 yr by plonkster

19 hours ago, plonkster said:

The other option is to use 2 x 24V chargers and not use a switch at all.

A far better idea, IMHO. 24 V chargers are readily available.