Total loss electrics

[Edbear]

If you are running a total loss system on your race bike, I had a query from a customer about the Shorai batteries in this situation. I emailed Shorai Tech and asked the question. I thought their reply would be of interest to everyone doing so regardless of the battery you are using. Here is the email I received...

Before we can advise you, we MUST know what the current draw is on your system. A Digital voltmeter which has an inline ammeter can be used to determine that. Typically max current draw happens somewhere around torque peak of the motor.

Once you know the draw, you can calculate usable minutes like:

(LFX Pb Eq Rating/3) * 0.65 = Usable Ahr (This takes the battery down to 35% charge)

For example with an LFX 18:

(18/3) * .65 = 3.9 Ah usable

(this leaves 35% capacity, roughly, to be SURE no over discharge)

The divide the result by the max current draw of your system. So if your draw is 3.9A:

3.9Ahr/3.9A = 1 hour run time

Or if your draw is 7.8A, you would get ½ hour, etc.

Seems a good general calculation. Has anyone done this for their own use? How do you find the endurance for a race?

[Mental Trousers]

I'd love to know what the max draw on my bike is. Main problem is getting to full load (load as opposed to revs) is extremely difficult in the shed. Pretty much has to be done either

• on the road
• on the track
• on a dyno

Of course, if the bike is moving it kinda makes it difficult to look at a voltmeter under the seat.

[White trash]

I'm glad you mentioned this Ed as I'd planned to ask you. I intend to run my bucket total loss and will need one of your fine products to help it keep running. No idea what the draw will be yet as the motor's still in China.

Also PMing you regarding trade enquiry.

[Edbear]

I'd love to know what the max draw on my bike is. Main problem is getting to full load (load as opposed to revs) is extremely difficult in the shed. Pretty much has to be done either

• on the road
• on the track
• on a dyno

Of course, if the bike is moving it kinda makes it difficult to look at a voltmeter under the seat.

Wassa matta? Can't you bend yourself like a pretzel at 200km/h and check the voltage..? Getting under the seat would help with wind resistance too...

I'm glad you mentioned this Ed as I'd planned to ask you. I intend to run my bucket total loss and will need one of your fine products to help it keep running. No idea what the draw will be yet as the motor's still in China.

Also PMing you regarding trade enquiry.

And China's a long way away... Got your PM mate!

[nadroj]

I'd love to know what the max draw on my bike is. Main problem is getting to full load (load as opposed to revs) is extremely difficult in the shed. Pretty much has to be done either

• on the road
• on the track
• on a dyno

Of course, if the bike is moving it kinda makes it difficult to look at a voltmeter under the seat.

Jaycar have a panel mount (could be velcro mounted) digital volt meter (8-30Vdc) that could be wired directly across the battery - $29-90. Not sure about a digital ampmeter thou.

[Grumph]

Never checked an injected bike but carbed motors powering only the ignition usually max out at 1.6 amps draw - often less.

[bogan]

The sneaky /3 on their ahr (equiv) is a bit dodgy I reckon, shoulda just listed the actual ahr rating imo. Still, at least I can figure out how long an alarm/whatever on standby will last properly now.

[Edbear]

The sneaky /3 on their ahr (equiv) is a bit dodgy I reckon, shoulda just listed the actual ahr rating imo. Still, at least I can figure out how long an alarm/whatever on standby will last properly now.

I think it basically means it will last a third longer to dead flat, but Shorai recommend recharging at 30% minimum.

[Edbear]

This chart is also a help.

[k14]

Never checked an injected bike but carbed motors powering only the ignition usually max out at 1.6 amps draw - often less.

Yeah a standard carb'd bike will run all day on pretty much any SLA or A123 12v cell. However an injected bike is very thirsty, iirc the fuel pumps usually draw around 10A. I ran total loss on my 450 Gixxer 600 at nationals earlier this year. I had three 4 cell A123 packs in parallel and I never had any problems running them for up to 25 mins. I read a guy on another forum getting around 40 mins of run time on a GSXR600 with the same configuration. For total loss on an injected 600 or 1000 you need to be very careful cause if your battery isn't fully charged you could easily run out of juice 3/4 of a way through a race. To be honest it is most likely not worth the hassle and risk of a dnf, for a very very small increase in performance.

[bogan]

I think it basically means it will last a third longer to dead flat, but Shorai recommend recharging at 30% minimum.

Nah that is the *.65 bit, the divide by 3 is because lead acid ahr ratings overstate their useable ahr by a large margin (a factor of 3 I would guess!), something to do with the fact you can't deep cycle them. ie, you can only pull 6ahr out of an LFX18, and you can only repeatedly pull 6ahr out of a Yuasa 18ahr batt or similar. Some fucker is having a laugh with these sort of ratings, the electric revolution will sort em out though

[Edbear]

Yeah a standard carb'd bike will run all day on pretty much any SLA or A123 12v cell. However an injected bike is very thirsty, iirc the fuel pumps usually draw around 10A. I ran total loss on my 450 Gixxer 600 at nationals earlier this year. I had three 4 cell A123 packs in parallel and I never had any problems running them for up to 25 mins. I read a guy on another forum getting around 40 mins of run time on a GSXR600 with the same configuration. For total loss on an injected 600 or 1000 you need to be very careful cause if your battery isn't fully charged you could easily run out of juice 3/4 of a way through a race. To be honest it is most likely not worth the hassle and risk of a dnf, for a very very small increase in performance.

That's another question, is it a move that is not really noticeable in practise due to too many other, more signifcant variables?

Nah that is the *.65 bit, the divide by 3 is because lead acid ahr ratings overstate their useable ahr by a large margin (a factor of 3 I would guess!), something to do with the fact you can't deep cycle them. ie, you can only pull 6ahr out of an LFX18, and you can only repeatedly pull 6ahr out of a Yuasa 18ahr batt or similar. Some fucker is having a laugh with these sort of ratings, the electric revolution will sort em out though

Ah, my lack of technical knowledge again...

[bogan]

That's another question, is it a move that is not really noticeable in practise due to too many other, more signifcant variables?

I can't understand why nobody seems to offer efficient reg-rects to combat this problem, not running total loss at the track probably means you might use 100W on the bike, and burn at least another 100 through the reg/rect. Surely an efficient reg-rect could drop this wastage down to 10W, and probly remove the need for a battery entirely, thus saving weight.

Ah, my lack of technical knowledge again...

yeh that's what I'm here for, free knowledge for free batteries right okey:

[k14]

That's another question, is it a move that is not really noticeable in practise due to too many other, more signifcant variables

It is certainly a real gain (maybe 1hp on a dyno) but that is ~0.8-0.2% gain on a 600 or 1000. On a 125 with 38-40 hp it is a big advantage but as the bike gets bigger the advantages dwindle and the benefit vs risk equation becomes lop sided. Also in NZ the supersport and superbike races are longer than the other classes so that increases the risk of something going wrong. Every lap is a lap closer to a dead battery. If I was to go back racing I probably wouldn't bother with it, half the reason I did it was an experiment, plus I did save 1.5kg by ditching the stator and some of the starter hardware.

[Mental Trousers]

That's another question, is it a move that is not really noticeable in practise due to too many other, more signifcant variables?

It is certainly a real gain (maybe 1hp on a dyno) but that is ~0.8-0.2% gain on a 600 or 1000. On a 125 with 38-40 hp it is a big advantage but as the bike gets bigger the advantages dwindle and the benefit vs risk equation becomes lop sided. Also in NZ the supersport and superbike races are longer than the other classes so that increases the risk of something going wrong. Every lap is a lap closer to a dead battery. If I was to go back racing I probably wouldn't bother with it, half the reason I did it was an experiment, plus I did save 1.5kg by ditching the stator and some of the starter hardware.

It can make a very noticeable difference on some bikes. A VFR400 goes from being a nice 400 to a bit of an animal if you ditch the stator. Throttle response is much crisper and the engine feels a hell of a lot more lively in general.

Of course total loss is a total loss for endurance racing