Ubley Drove Oct Meet-up

[stretchy]

Nice to meet you all and although I didn't have a ride round it looked very interesting and when I have a new tyre for 'Thugsley' my XR400 I hope to join in!

OK the most interesting thing for me is the range of machines everyone had and it's good to see bikes in the flesh so you can see what they're really like. The Scorpa T ride was interesting and the owner was especially honest about it's shorcomings.

I'm a technical chap (Electronics) and am particularly interested in new battery technology as ALL my bikes are/will be electric start and am looking to save weight wherever I can.

If anyone has and thoughts/questions on electrical/bike related subjects I'd be very interested to hear from them.

Thanks again Shaun for the Monoshock for my XLR, it has transformed it!

See you all in November.

[hondaxrnut]

hi stretchy,
glad the shock worked out ok,
yes it was a brill day, cant wait until the nov one, just have to fix edds gearbox again!

[jarl]

Hiya. Was yours the electric start XR?

We should meet sometime, I'm also quite interested in the electrics/technical side of things. One thing I think you'll find interesting- heard of LiMN (Lithium Manganese) batteries? They can burst for 20C max for up to 30 seconds and continuously discharge at 8 to 10C. This means that 4 18650 size cells in series can put out about 30A at ~12V for a few seconds whilst you start your bike. Total runtime would be theoretically be about 3 minutes (assuming regular breaks and a 30A starter motor), which should be enough to get you through a days off-roading; at 10 seconds per start thats about 18 starts, and if your motor has kick and electric then you can save the electric boot for when you're tired/dropped it. Not sure about charging whilst on the bike, but I've no doubt it's possible, though it'd probably be easier with a dedicated charger at home due to the nature of charging li-ion (constant current then constant voltage). Another great thing about LiMN is that it's 100% safe, and won't vent with flame no matter what you do to them. Since they're capable of releasing so much current, care must be taken to ensure they won't short circuit in a bad crash, however. Also, they should be mounted away from the engine as their operating temp. is stated at -10'C to 60'C. Details can be found here, they are described as IMR cells

Should be able to save a few lb's on lead acid? Not to mention these are affordable and readily available, unlike A123's

[stretchy]

Ok Jarl, Yes, well I got these;

LiFePO4 26650 Cell: 3.2V 2600 mAh, 42A Rate, 8.32Wh

I'm still waiting for my LM2679 from RS so I can charge the things from the bike. I have a current clamp, 'Scope etc so can't wait to get stuck in.

I'm hoping to fit this lot under the seat of my XLR200.
Still not sure on the regulator tho' as I haven't measured the o/p from the 3 phase generator; I need nearly 15v to charge the batteries efficiently so I made need 'Boost' rather than 'Buck'.

You tried LTSpiceIV? very impressive.

I'm not fully registered on here, but suppose I should now that I've met up with some like minds!

You can mail me tho'; on-one(atttt)jstretch.fsnet.co.uk.

Other things to consider are; A solid state solenoid (big fet), programmable timing (slightly more complex!) or anything else you can think of?

Stretchy.

Oh and Yes That was my 'leccy XR400. Rather chuffed when I found that one on E-Blag. The bloke who sold it lived across the road from Mr XR-Stuff who'd done all the work sold it too him but he never road it!?. Its fitted with the engine from the TRX quad, essentially the same but without the kickstart (shame!) a milder cam (pulls like a train). Looks like a simple enough swap but guess you need the CDi too. I have another TRX engine (another cheapy from E-B) so wanting another XR to put it in, ANYONE?!

I'm over in Brisol, you're, (anyone) is free to pop over anytime. I have a decent lab with equipment up to 6GHz as do like my RF and did have 6 bikes in the garage but now a more managable 3.

[jarl]

Of course, forgot about LiFEPO4, most of my electrics knowledge comes from the lighting area of things, and since LED's need ~3.7V and a standard li-ion battery is ~3.7V, this just works. Use LiFEPO4 and suddenly you need all sorts of odd configurations of batteries and driver circuits and chargers. For a bike it should be pretty sorted though, and IIRC LiFEPO4 actually discharges harder than LiMN; win win. Suprised you went for 26650, was it a case of that being the smallest you could get? Also, how much do the LiFEPO cells sag? I know you're looking at 4 LiMN to stay above 12V under starter motor load, even though 4 well charged LiMN would sit at 16V at no load. Since 4 LiFEPO sit at just over 12V well charged with no load anyway, you may have to use a fifth cell? (but since they're bigger cells they should sag less...?)

Never gone near a computer program to help me with my circuits, piece of paper and a brain is all I need. Might explain why I never got beyond the dead simple stuff?

The fact that you're charging LiFEPO4 means I have no idea for chips or configurations to use. That said, I don't know a whole lot about high current charging of conventional 3.7V cells.

Do LiFEPO have advantages to under-charging? Taking a 3.7V cell to 90% (4.1V) will greatly increase cycle life, for example.

[stretchy]

'Suprised you went for 26650, was it a case of that being the smallest you could get?'

These were the only ones at a fair price/size/capacity, I guess all they have to do is start the bike, bit worried they'll only charge at 5A max, 10A would be better.

'Never gone near a computer program to help me with my circuits, piece of paper and a brain is all I need. Might explain why I never got beyond the dead simple stuff?'

I'd Have a good look at LTSpice as it's pretty much drag and drop and you have a virtual probe to poke around with! Especially for DC power circuits as ALL of Linear's chips are in there(and there's a Yahoo Forum). I recently cobbled together a 50W class E amp @ 2 MHz and then built it, it was fairly close to sim. You can just piddle around too, changing components to see what effect it has on the ciruit, a good 'backwards' way of learning ! (my prefered method!). Was recommended it by a self taught friend of mine who's now 'Chief Design Engineer' (He likes that!) for a Telecomms manufacturer.


Are there any precautions I need to take with my regulator running from the 3 phase genni o/p?

JohnB

[jarl]

Are there any precautions I need to take with my regulator running from the 3 phase genni o/p?

Why are you using 3 phase output from your gen? Surely you should stick a few diodes in to get fairly smooth DC output before doing anything else, not to mention controlling rotor current to keep output voltage at a sensible level?

Or have I got completely the wrong end of the stick?

[stretchy]

There's only 3 wires coming out of the genni (all the same colour) and normally go into a regulator with just Plus and Minus coming out. I'm assuming this is 3 phase and has no field winding? (fairly common?).

http://media.photobucket.com/image/m...d_03/CB/rr.jpg

OK I wired up a 3 phase rectifier to it last night, the voltage varies a tad from 30V at idle to over 120V at 6000 rpm, holy crap how do I regulate that!

I did find this;

Voltage Regulator for Permanent-Magnet Alternators

Mind you I haven't measured the o/c o/p from my reg yet as I need 14V9.

There aren't many circuits around and even modern stuff (LM5116) tops out at 100V. Looks like that will need a 2 stage circuit which makes it rather over complex.

Any ideas?

Oh I still think we should possibly discuss this via normal mail as it's a tad off topic??

And........Who were you at the Ubley meet up?

All the best

Stretchy.

[jarl]

"Any ideas?"

Not really! The first thing that springs to mind is wiring one of the poles out of phase, but that'd give pretty lumpy output. Would it be possible to use a reg/rec for any random bike?

"Oh I still think we should possibly discuss this via normal mail as it's a tad off topic??"

What was the topic to start with?

"And........Who were you at the Ubley meet up?"

The mad one on a transalp

[stretchy]

Have measured the o/p of the XLR's reg an is about 14V and is higher the less RPM which is a shame as I don't intend to do much time idling!

See you're over in Hants, I was in Alton/St MaryBourne for a couple of years but wasn't riding then; how are the lanes round there?

I have some boost/buck samples on way from Linear so will have a tinker with those when they arrive.

I think the SCR circuit is the way to go but with switcher rather than the pass tranny.

Str.