E-Bike

[solarnewbee]

Purchased an E-Bike last year in the Philippines at the behest of the wifey (boss). 3 wheels with 1 seat up front for the driver and 2 benches in back for 4. 48 volts with 4 100ah 12v gel batteries. The electric motor is 1kw hits a whopping 38kph and claims 120km range. Fully loaded up it barely makes the hill out of our neighborhood at 11kph but it gets us where we need to go. We charge it at 6am to 11am on solar and forbid afternoon and night charging as doing that it sucks the lfp’s (800ah worth) down quite a bit.

So, the boss shows me a solar kit available to install on the roof of this E-Bike. It’s only 100w and probably 12v and comes with a charge controller (pwm most likely). Not seeing how that’s going to charge a 48v system, those numbers don’t work. Seems more of a gimmick really. Then I thought, I finally got the 2 panels that arrived broken from China replaced and just 1 would be just a little bigger than the E-Bike roof. 300w 72cells 36v.

Any ideas guys how to make that work? Multiple charge controllers, 1 for each batt? I’ve got some microinverters maybe drive the charger that came with the bike? Hmmm.  2 panels sideways at 72v with flashing warning lights and a a helmet for my big head?

Looking forward for your input.

[MadScientist267]

Sounds nice SN...

Only input I got other than that is that I've been messing with hoverboards and all I can say is however they calculate range, someone didn't have their equipment calibrated lol... But bikes may have much better results...

That said I have been messing with ways of increasing range without making major mods to the board itself, and one of the methods I've messed with involved one of those little 120W microinverter jobbies... All I can say there is I'm not impressed with all the conversion losses involved... And they add up quickly.

In a nutshell, go as "direct" as you possibly can and equally, avoid "repeating" conversions (like "one per" concepts). Both will eat your source alive, particularly small scale.

Look forward to seeing what you come up with tho... And a pic? 

Far as the behest... Lol... All I got

Steve

[solarnewbee]

Here it is in all its glory 😝 as well as the old trike.

A look at the panels on the front. 10 more on the backside.

Shooting for next year for permanent move there so I can get out of the rat race.

[Pete]

Hi Newbee, not sure how it would go but maybe you could use a buck converter to boost the panel voltage then use an MPPT controller to charge the batteries that way.
Or maybe try charging the batteries as two 24 volt banks using diodes as blockers from the regulators so that the two banks aren't connected together.
Buck converter probably easiest.
The machine looks pretty big, I am guessing that the 38klm it is rated at is downhill with a tailwind.
Maybe you could change the gearing if it has a gearbox to get up hills better, or put  a hub motor on the front wheel to act as a hill assist.
Have fun, the Phillipines sounds hot to me, but some like it that way
Cheerio
Pete

[MadScientist267]

Pete -

I'm assuming you mean "use a boost converter to boost", not buck...?

Either way this would have "negative gains", as MPPT isn't compatible with that type of scheme.

SN -

There may be some boosting type MPPT converters out there commercially available, I haven't used or seen one personally. That isn't to say they don't exist.

That said, years ago I was messing with what I was calling "pseudo-MPPT" in combination with a home brew buck converter. Boost would be very similar, just rearrange a few parts.

In a nutshell, MPPT relies on conversion topologies to work by allowing the input (PV) voltage to be different from the output (battery and load) voltage, so that the PV can operate at it's ideal voltage to extract as much power as possible from the panels. A simple standard converter in front of the MPPT will negate it's purpose because to do it's job, it needs to regulate the voltage at it's input. Normal converters aren't concerned with this, only the output.

True MPPT is relatively complex because it has to regulate input voltage, output voltage, in some cases output current, and have a means to find the peak availability (typically done with a computer controlled "sweep" or other algorithm that lets/makes it periodically seek the sweet spot).

The pseudo version isn't as efficient at it's job as the real thing, but is better than direct connection or buck alone, and boost alone would just try to drive the input into the ground, giving you "less than useless" results when it comes to trying to charge a battery with it (this side of it is a little more difficult to explain).

Pseudo basically gets set up so that it's approximately in the middle of the PV's typical sweet spot (using a simple pot), and tries to hold it there. To do this, the feedback of a standard converter is basically just moved to the input "instead of" the output.

There's a catch however, hence the quotes above... You'll still want it to respond to the output voltage of course, to limit the maximum voltage the battery and load sees... But it's not too incredibly tricky to make a simple "mixer" that allows you to set both, if the chip controlling the conversion doesn't have 2 inputs (MC34063 vs TL494 comes to mind, for example).

It's still not a "super simple" solution, but is far more simple than a full blown MPPT to do from the DIY perspective.

Just a thought.

Steve

[BenandAmber]

EBay has a boost MPPt charge controller and it's probably just the right size for that it's a little green Square I have seen good reviews on it

[solarnewbee]

Howdy!

Recently made a battery changeout. The VSLR 12v 70ah were swollen and had been reduced to about 4 kilometers range. Purchased 16 100ah lfp’s $45 each. Haven’t been able to run test yet because of typhoon season and quarantine. My daughter did all the work with me-on FaceTime, really impressed me. The bms was too small since the inrush current exceeded 45a and probably uphill too. Ordered a Daly 100a bms with lcd screen and Bluetooth.

Now to find a way to clamp it all down with the existing clamps. Much smaller footprint and exposed  buss bars. There’s the limit of my daughters skills, maybe. Could lay a restaurant size cutting board across it then layers of plywood. I have seen people use plywood on the buss bars but plywood is not a dielectric. Will check restaurant supply and see what falls out.

Pics of new battery pack, old battery pack, small bms it was only thing available quickly. With all the delays I should have just shipped a Daly bms from AliExpress before. DHL free shipping and it was there in 10 days, pretty impressive for China.

See ya!

[solarnewbee]

Howdy All!

So the latest change is a new Daly 150A BMS that can handle the current of the tricycle current.

Unfortunately we found 2 cells were bloated and not a clue why except maybe just poor quality. The voltages were within 10mv of the others. They’re at 3.23v now so I may find the difference spread as they charge. 2 more are one order now anyway. These are 100ah, 30ah more than the old ones and according to the kids it goes uphill without effort now. If those cells overcharged then the cheap bms didn’t stop charging when necessary.

The new bms has Bluetooth so it will be easier to monitor. At $45 each I can’t afford to keep swapping them out. I purchased locally so I hope they didn’t sell me B grade batteries.

Best Regards

[solarnewbee]

Long story short, these lfp batteries shown above $#!+ the bed. I had ordered a new charger custom from china and was assured it was designed for lfp’s. Seems the charge absorb stop point was 62v and bloated half the batteries. We now have 4 100ah sla agm. I have a Huwuei server power set at 60 volts going into an old mppt charger. Not quite enough to excite the charger so I added a boost converter and set it at 87v (random) goes up to 120v but wasn’t going to push it. The output caps didn’t look especially healthy. Someday soon they may pop but I have plenty. This charges the larger e-bike. The other charger is a cheap Chinese mppt maybe charger with a 72v charger driving it. This charges the small trike. I encourage the family to plug them in when return from a run. This way they won’t run it below 80% charge often. Those batteries were $500 and I do t want to do that again soon.

[Pete]

Hi Solar, I left you a message over on the Back Shed forum about your inverter.
will get back to you on this project later
Pete

[solarnewbee]

Quick question because I’m not familiar with charging sealed lead acid batteries. I’ve been letting the mppt charge controllers internal program do the job. It is user selectable up to a point then you get a fault warning. I have heard on the is forum talk of numbers for wet cell or 60v. Any thoughts?

[lighthunter]

For sealed AGM batteries
Bulk: 57.6- 58.4
Float: 54 - 55.2


Somehow thought you had FLA
Here that is....
Lead Antimony Flood lead acid.
Bulk/absorb 58.8V daily
Float 54V. Daily
Equalize 64V never, -Ha, yes its necessary but only while watching whats happening with SG meter etc.

Lead Acid batteries come in several flavors and they are ALL different. So starting there, you said wet cell or FLA, assuming Lead antimony type since most deep cycle like Trojan are this type.

Then there is the "character of the battery" through the life of these batteries their needs can change so you need to watch behavior and adjust accordingly. Some dont like higher voltages and boil water instead which can shorten life. So good care of FLA is not "one size fits all"

If they are new and true "deep cycle" bulk/absorb starting point is 58.8V.
Meaning charge with available amps staying below max battery charge current until voltage rises to 58.8V then maintain that voltage for absorb time until current drops significantly. Then terminate charge.
Record specific gravity, and ending current.

If your batteries are taking a fair amt of current and the voltage never builds to 58.8 then maybe 57.5 is the right number.

Try to hit the sweet spot, dont push them too hard too high voltage nor too soft and monitor capacity and SG. Equalize can bring capacity and SG back up a bit but you also corrode the positive electrodes by the harsh treatment and so loose life that way.  Sometimes you cant win no matter how good you treat em then other times.... true story, the auto charger on a golf cart failed to terminate. Ran all weekend, there was literally no water left in them. I grabbed a new 3Gal jug of drinking water, almost  all the water fitnin the 6 batteries. That was over a year ago and the batteries still act like new, nearly 4yrs old now. I dont expect them to last 10 years but they see the worst abuse imaginable and no signs of weakness yet. By the way those perform i would say daily hard work is better than sitting idle. Seems like deep FLA batteries that get treated soft become weak. I will look at brand name and update.

Everyone has different ideas about how to treat lead acids. Many on this forum know more about it than me so consider the sources and the environment. Cold is higher hot is lower for example.

By tbe way, wheres Doc Hubert? havent heard from him in a while. hope he didnt bolt the hatch down yet . Those politicians gettin on everybody's nerves lately. Least our supreme court shot down their latest scams so we dont hav to wear diapers on our faces at work anymore.

All the best, have fun!

[lighthunter]

Heres a good visual of charge voltage profile of the lead acid types i ran across today. The numbers are slightly different from info in previous post but as mentioned, its best to watch behavior of lead acid and adjust setpoints on behavior. A bad connection can also raise havoc with auto chargers and leave your battery uncharged or other malfunctions in charger can overcharge and ruin batterys. This is why with lithium you always need a secondary circuit to verify and monitor to prevent damage. Many a ruined FLA or AGM couldve been saved by using Battery monitor systems as well. It just didnt get popular since lead acid isnt as expensive and usually wont burn up your property

[Pete]

Hi LH, I have BAE Valve regulated Lead acid batteries, they say to have the float set at 2.3 to 2.4 volts per cell.
It seems that each type of battery is different slightly.
So on a 12 volt system mine would be 13.8 to 14,4 volts.
I guess that gel batteries aren't open so cannot be charged as high as the others.
My regulators are adjustable, so far they are doing a good job.
I try to never let my batteries go under 80% charge if possible, they have been down to 70% once of twice in winter, but now with more panels they don't get down much at all.
I reckon a 20% discharge is enough, I want them to last as long as possible.
Cheers
Pete

[lighthunter]

Hi Pete , i know nothing about BAE, i looked up a pdf about them and it agrees with your 2.4vpc finishing/absorb voltage 14.4 for 12v or 28.8v daily finish for 24v.  The float they refer too is after charging is done and just to prevent or balance self discharge i think. That voltage appears to be 2.23 vpc or 13.38V, 26.76V.
With daily use solar, float doesnt happen too much. Those really look like nice batteries, they should last a long time.


I have a lithium bank but also still have the 510Ah 48v fork lift battery. I just cant seem to kill it. I was gonna get rid of a month ago because it always acted full but wouldnt supply much before voltage fell. A couple weeks ago i decided to deep discharge it and bump the charge voltage up from 57 to 59, what a difference. Its now back doing useful work. Very wierd because this battery used to resist high charge voltage and boil like a pan of water on high heat. For some reason it seems to act more normal now. Its previous life ended with more than a year in storage at about 1.6vpc.
I know they say FLA last longest with only mild disharge 20% like you say but it seems like this one acts a bit like a horse. If you go out and run once in a while they stay in better shape. In other words an occasional  deep discharge somehow improves performance.