Giant Lite Voltage Rating

[Bike_on]

Hello All,

My name is Dan, new to the forum. I own a 2004 Lite, and live in the US. I bought the bike almost new in 2006, and have been commuting to work on the bike. It has been a great ride. I have over 4000 miles on the bike.

My battery is starting to wear. I think one of the NiMH cells may be reversed. My question is: WHat is the max voltage the controller can handle?

I could restock with fresh NiMh. But I am also tempted to add a switch and use the A123, LiFEPO4 batteries, at 33V. Can it handle it?

Back to my Lite. Here are my performance/improvements I have done:
1. The 4 speed allowed me to average about 16.5mph max.
2. I changed the rear cog from a 20T to a 16T. My max average for a 25 mile ride was 20.5mph.
3. I added pedals with SP2 clips for efficiency.
4. I added aero bars, Forte2 for multi position and wind resistance.
5. On a warm, mild day, I would easily ave at 18-19mph when the battery was fresh. On cold days, lots of cloths, 16-17mph.
6. I changed the rear hub to a SRAM 7 speed, 16T cog. My average dropped 1mph accross all conditions.
7. I typically pedal vigourously, and my input has a big impact on range, as expected. If I dog it, I get 15 miles at 15mph now. The light blink early. I have yet to turn off, but my speed and power decrease is noticeable.

Ideas?

Dan Rowell
Laurel, MD

[flecc]

The unit handles 26 volts with Li-ion ok, but I think 33 volts will be going too far and could blow the mainboard. The "controller" is like no other, being more like a computer motherboard with a CPU managing a whole variety of functions.

Here's a pic of the mainboard.

Obviously new NiMh cells will improve the performance, but having a greater range of gears often impairs the range on these bikes. The original 3 speed Lite which gave around 20 miles in a typical set of conditions would drop to about 17 mile range with a 5 speed hub, though this difference varies according to how hilly an area is.
.

[jac]

hi on the giant twist battery what should the voltage reading be when fully charged

jim

[sparky5]

Originally Posted by jac

hi on the giant twist battery what should the voltage reading be when fully charged

jim

Hi Jim
Ive just checked my "best" battery it was fully charged a couple of days ago and is holding 27.03 Volts.

Funny thing though I also have a sick battery that reads 26.67 Volts !
And shows a full bank of indicator lights.
Just goes to prove you cant tell a good 'un by voltage alone !
HTH

Cheers, Mark.

[Bike_on]

I seems to remember measuring 29V on a fully charged, resting battery a couple years ago.

Dan

[Bike_on]

Flecc,

Thanks for the pic. The controller will likely have a regulator to step down the variable voltage input, and at high voltage will dissipate more power. The other limiting parts are the capacitors ratings, and the MOSFET ratings.

Have you ever had any hard numbers for these?

Dan

[flecc]

You are right with that 29 volts on a healthy 24 volt NiMh Dan, but that's not under load of course. My concern on the LiFePO4 is that the voltage will hold up under load quite well. There's been some motherboard failures on the Lafree's Panasonic units and that's the main cause of them being scrapped in fact.

The other concern is that the unit does cut out on excess temperature according to the makers, though it's never happened to me in the past.

I have no hard numbers on the components, though the electrolytics look like the marked types, and you might be able to see the coding on the mosfets.
.

[Bike_on]

Flecc,

You seem to be the go to guy for Giants on the right side of the pond. I guess if you do not know the voltage limit, then who will.

I prefer to not do a smoke test.

The power from the motor, via the gears is adequate when the battery is fully charged. I personnaly would like to ride longer with the voltage holding up.

The thermal shutdown would be a plus/protection if Lipoys were used.

So I see the real issue being the voltage rating.

Thanks for your help.

Dan

[Bike_on]

Flecc,

Do you have any leads for a schematic on the Giant Lite controller? Do you know anyone else who might know the voltage limits? I am not sure who to ask.

Thanks,
Dan

[flecc]

Nothing at all on this Dan, Panasonic seem to keep this sort of information to themselves and bike manufacturers. I've tried communicating with BikeTech who have used these units for years on their bikes, but they just don't respond, possible due to language difficulties, since they are a German speaking Swiss company.

One problem is that the electronics on these are far more than just a controller, the complex mainboard being more in the style of a computer motherboard complete with a central processor performing a wide range of functions.

Mainboard
.