BionX 250PL Battery Issues

[GCinDC]

Bought the kit in December 08, got the battery replaced my mftr (via Canadian ebay retailer), in November '09, but wife didn't ride it much then. Now that it's spring and she's using it, she noticed the battery gauge doesn't show full. I've made this video to show the retailer:
[youtube]MsMyMzaL-xY[/youtube]
Before returning the old battery, the retailer asked me to check the voltage of the pack and the charger, to make sure they were up around 29V, for the 24V pack. But this time, I see the voltage up around, what 35V! This is odd, no?

I have to wonder if the replacement was sitting on a shelf for a couple years...

I'll see what the retailer says, but I'm getting really tempted to try to put 24V worth of lipo in there! Anyone have any suggestions?

 

[GCinDC]

Useful Links for my troubleshooting:

Everything you ever wanted to know about BionX... which apparently came from here.

Bionx LiMn battery post from VisforVoltage

 

[GCinDC]

moving this from another thread:

Sorry for threadjack! I'll post elsewhere when i get to work on this, but basically:

I've been talking to Ken at itselectric and have learned some interesting things:
- no bms on old batt
- the easiest thing to do would be to plug a new battery in to the charger port, leave the old one in there, so the new batt current goes through old batt!
- regen might prove problematic. but i could disable it in console or by using putting a magnet on brake lines, so it never knows when the brakes are used! tricky!

For my 24V LiMn system, the charger goes up to 29.4V. i'd love to use the same charger, but for 7s lipo, the charger will bring them up to 4.2/cell, so IF regen is used on steep hill at start of ride, i could overcharge it. w/ LFP's lipo vids, it's hard to imagine them blowing. and i have to think they could handle high voltage for a bit...

But for the battery life, it'd probably be better to charge them only to 4V/cell, so to use a 28V charger, if 7s. I'm really curious what the existing LiMn config is, 7s? I was reading somewhere that LiMn cells are 4V? I have no experience with them... Seems like a good idea anyway to understand the existing properties... I ramble.

 

[GCinDC]

And this is the first step!:

 

[slayer]

Hi GcinDc,

Are you saying that 3772 code will allow you to adjust regen strenght 0-64 and the voltage regen, can you change the value of the voltage?

is your question about using lipo with the regen?

 

[GCinDC]

Are you saying that 3772 code will allow you to adjust regen strength 0-64 and the voltage regen, can you change the value of the voltage?

is your question about using lipo with the regen?

No! This is just the diagnostic mode! It's my first step because I want to understand the existing (and supposedly new) battery performance (which has been unsatisfactory).

Since getting the new battery, it's been suggested to me to reset the console when the battery is fully charged. I've not done that yet, but will do so after the next charge. That might solve the one problem of the battery guage displaying ONLY 2/3 full after a full charge.

That will not explain why the dang thing dies after 5 miles and my wife spends more time using regen on it than zipping along!

Admittedly, my testing of this has been delayed because I don't have the time or patience to ride it much. It's too slow for me to bother riding it to work! (But I'm glad that it's not fast for her..)

My goal here is to improve the battery performance so she's got full power for hilly 10 mile commute hauling kids in a trailer - a big job for the 250PL, but she LIKES to pedal and doesn't want a heavy bike. And FWIW, I wouldn't trust her to do anything complicated with the electronics - i charge it for her half the time cause she forgets!

Anyway, as far as diagnostics this morning:

It had been hooked up to the charger:


I unplugged it, set the mode to diagnostic. The voltage displayed on the console was 28.7V. (It had been sitting on the charger, unridden for 2 days.)
I rode it around the alley and noticed the voltage sag to 27V but not much lower.
I hooked it back up to the charger and watched it rise to 29V.
I poked my multimeter into the charger ports and read: 35V! WTF?

 

[slayer]

check the battery in your multimeter , cause that just happened to me after forgetting the multimeter on for a few days i noticed the voltage reading was higher than it used to be and i changed the battery and now it is reading correctly

 

[GCinDC]

To respond to this:

GCinDC- I would do a pair of the Turnigy 8S 5.8Ah packs.... Charge LiPo to only 4.1v rather than 4.2 and it lasts a ton longer. That would make about 33v at full charge. If it's controller can't handle 33v, then toss the whole thing out. lol

The system is great, albeit slow, but that's perfect for my wife. 15mph up the hill is all she needs. (By the way, how'd your parents bikes turn out? Got a link? I think I read your phase wire upgrade post...)

Anyway, you're talking about replacing the original batteries? Or for powering via the charger port? In any case, I really want to use the existing 29.4 Charger to charge only one pack... And for 8s, that would only get each cell up to 3.625... I'm kinda tempted to try 7S, and set a buzzer to go off at 4.1V lol...

Just curious, how do you think the lipo's would react, if they were hot off the charger at 4.1V and then got 50V @ 5A for 1 minute? Would it be much different than how LiMn would react?

One of the tests I'm going to want to do is opening up the pack and hooking up a multimeter to the pack and testing regen voltage. (The V didn't change much during similar test under diagnostic mode.)

 

[GCinDC]

So it is 7S!

What I can't figure out is how the pack leads measure 37.6V and the charger only goes up to 29.4V???

 

[GCinDC]

Tested the battery out. It's dog doo. Hot off a charge, it was peppy the first time up the block long hill 3 block from my house but completely gagged the second time. Mind you, I was pulling a trailer, but still... The voltage, in diagnostic mode seemed fine, dropping to 26.5V at lowest - 25.2 is nominal. Do dying batteries still hold their voltage like that?

I'm still in discussions about another replacement from the dealer.

In the meantime, what would be the best way to tie in a new pack? If I keep the old battery, rather than plug the new one in via the charger port, as suggested, I'd rather drill a hole in the back, run a wire through and splice it to the charge wires.

That's not going to work because the new one will need a higher charge... Hmmm.

What I really need to do is TEST to see if this will work first before worrying about how to charge it/them. In that case, I'm thinking about cutting the charge wire, attaching andersons so it can be connected to EITHER charge the old batt (29V) OR be attached to new batt, test lipo (33V).

In the meantime, does anyone know what the WHITE wire going to the charge port is???

And the yellow coming from the pack?

If I were to remove that batt and wire in a lipo, what should I do with the yellow? My ping pack had a separate charge wire (blue), but supposedly, this pack doesn't have a BMS...

And can anyone suggest a reason why the charge port/battery leads read 35V if the charger only goes up to 29V?

 

[GCinDC]

Okay, gearing up to replace the battery (or parallel an 8s lipo to it). Took a closer look:

The thing that continues to boggle my mind is that the battery measures ~36V. How can this be if the charger (and the diagnostic console) read only 29.4V?????

Does this make sense to anyone?? (hello, hello, hello)

In any case, sure seems like a better plan would be to replace it with a 9S....

(too bad I just bought 6 x 4s 2200mAh from hobby partz, their last lipos in stock! - to make 8s3p 6.6Ah)

 

[GCinDC]

closeup of board, by the way, for the record:

 

[GCinDC]

Please, LiMn experts chime in: How can a 7s LiMn battery read 36V?

Do LiMn cells charge to 5.14V?

 

[GCinDC]

How can a 7s LiMn battery read 36V?

answer: 7s can read 36v when multimeter also displays BATT...

I changed the multimeter battery and measure 28.5v.

 

[GCinDC]

My order of 4S 40C lipos have arrived, but instead of building an 8s 3p 6600mah pack, I'm thinking it would be better to go 7S after all.

PROS:
bulk charge in parallel with bionx battery
able to fully charge lipos 4.2V, won't have to worry about out of balance w/ bionx pack

CONS:
full charge 4.2 shorten lifespan
danger of regen overcharging the pack
gotta buy more batts

But I'm thinking it'd be better to get as close to 9.6Ah on the second pack as well. Thinking for some reason I should have more lipo range than bionx (LiMn), 10+Ah. Not sure why...

 

[GCinDC]

These are tiny! 2200 mah Blue Lipo: 5x 3s & 5x 4s.

Decided to arrange them in two rows, should I want to use each 3s or 4s pack elsewhere, as a 'booster'.

Barely had enough wire on each lead for the ends to meet! Running out to andersons.

Still waiting for the balance taps...