How many Ah for my 1974 Commando?

What is the problem we are trying to solve here?
LA cells have a century of performance history. If the issue is weight savings I think going on a diet is more beneficial.

You are right, of course. For me it was simply less fuss and fiddling PLUS the size difference. I didn't care anything about the weight but it was especially helpful when I installed the Alton E-start - plenty of space to mount the solenoid in the battery box instead of trying to find some other location.

The Li batteries do punch above their weight for e starting as long as the bike is a reasonably easy starter.
That's where the Pbeq rating comes from, a one time short blast from fully charged.

Glen

worntorn said:

Search the forum to get history on Sparx stator, rotor and ignition problems.

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And, again as a sample of one, I've been running the Sparx charging system for 10 years with no problems. Until this last summer when the R/R shit the bed. Did NOT replace it with another one. But that high output 3 phase is really nice. I'll probably put my Lucas rotor back on for next season, just because.

ludwig said:

That's because your alternator couldn't keep up.
Type or size of battery is irrelevant here.

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I know this very clearly... Why do you think I am telling it...
If MM wants to run around on a Mack Truck or moto guzzi or (55 gallon drum) battery that's fine...If the alternator won't charge it then eventually the electrical load will run it dry........cure is increase charge or decrease load. If you are not aware of and control the charging VS battery relationship then you don't know when you will be calling a flatbed for a ride home.

maylar said:

Shorai Batteries require a charging system output of 13.1 Volts or higher at idle

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Somewhat cryptic statement? if you can make 13.1 at IDLE you don't need a battery....
Yep I'm done.

There are so many options for self-designed systems that its hard to take any kind of sample from a Commando population.

For that reason its seems reasonable to allow some wiggle room in the design!

dynodave said:

Somewhat cryptic statement? if you can make 13.1 at IDLE you don't need a battery....
Yep I'm done.

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Hard to use an electric start without one... and if it wasn't for that, I wouldn't have a lithium.

Someone please enlighten me. Roughly, what does the charging system produce at idle? If I'm reading this thread correctly, the lithium ion needs more charge at idle than the stock system can give it? That's not really a huge problem unless you idle a lot.

@KNorton with your engine switched off, and no consumers like coil or lights drawing any power you will see the rest voltage of your battery it’s value varies depending on the type of battery you have.

• Lead acid (including gel, AGM, flooded and drycell) are 2.1 volts per cell, so you should see 12.6 volts at rest

• Lithium based (including lithium-ion, lithium polymer, LiCoO2, lithium cobalt oxide and LiFePO4) are 3.6 volts per cell, so you should see 14.4 volts at rest
  

At engine idle you should see the voltage at the battery drop to around 11 to 12 volts

This shows that you are drawing more out than you are putting in - absolutely normal and by design for the charging system of this era.


Holding your revs at between three and four thousand RPM you should see the voltage reading go up to around 14 to 15 volts.
For reference, the factory zener dumps to ground at 14.3 volts.

gtiller said:

Lithium based (including lithium-ion, lithium polymer, LiCoO2, lithium cobalt oxide and LiFePO4) are 3.6 volts per cell, so you should see 14.4 volts at rest

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Lithium iron phosphate (LiFePO4) is about 3.2 volts per cell. Freshly charged at rest my Shorai reads about 13.4 volts.

@maylar I have always gone by peak voltage as the description for cell voltage. To my knowledge, this is the same as all the battery manufacturers do.

When I take both my Shorai batteries off the Shorai charger, I see them at 14.4 volts (as measured on my AVO and my Fluke)

https://shoraipower.com/charging



Not that it really matters - I just wanted you to be aware of where i get my numbers from.


There is a nice little article on Rex's Speedshop for those that are not familiar with Lithium-based batteries:

https://www.rexs-speedshop.com/wp-content/uploads/2018/10/LiFePO4-Need-to-Know-Facts.pdf



Unless I had the belt and braces I described in my previous post, I wouldn't entertain the idea of any kind of Lithium-based battery under my butt and a couple of gallons of petrol between my legs!!!

FWIW, at approx 1000 RPM idle, my Commando (Alton 150W alternator/Podtronics) will produce 13-13.1 VDC at idle with the TriSpark ignition. The voltage may be higher or lower with other ignitions depending on their power draw. As I've said, the Shorai 18 AH has been working fine for nearly 10 years in that configuration!

maylar said:

Lithium iron phosphate (LiFePO4) is about 3.2 volts per cell. Freshly charged at rest my Shorai reads about 13.4 volts.

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Likewise, I run a 3 phase alternator, Podtronics, Triumph-Spark and a 21aH Shorai lithium iron battery. Whether charged with a battery tender or
a vigorous ride (lights off) at 3500-4000 rpm, the battery at rest reads about 13.4 volts. And that battery spins the cNw electric starter like
nobody's business.

maylar said:

And, again as a sample of one, I've been running the Sparx charging system for 10 years with no problems. Until this last summer when the R/R shit the bed. Did NOT replace it with another one. But that high output 3 phase is really nice. I'll probably put my Lucas rotor back on for next season, just because.

Click to expand...

What was the R/R that caused you this problem ?
Paul

Thank you gtiller.

FWIW, the voltage regulator should dump excess voltage not being used as heat. So even though you are using a state of the art charging system, if the bike doesn't use the "extra" power, it gets dissipated in the air stream as waste heat.

Forgive me if I'm incorrect. I'm still learning all I can about this bike and I'm certainly open to any and all useful ideas!

For those that have not tried yet, the Tri Spark Mosfet R/R will produce 14.39V at tickover and holds it there nicely as the revs rise, this is using a BSM and single phase stator. I am thinking about a Lithium battery but not happy with the way the cell balancing works. I am not sure, but would like each cell control system fused so in the event of failure it fails open and battery dies, and not overcharges and ignites. Nearly convinced on this Lithium technology, but not quite.

@KNorton that's certainly the case in the original zener diode that our bikes were supplied with.

And the output of the alternator was kinda 'matched' to the power consumption of the consumers on the bike (coils, bulbs etc) so that the zener didn't have to dump too much power and get too hot.

Upping to a high output alternator and not using more power gives you potential to introduce more issues as your zener will spend more time dumping out more excess power that is produced.
This is compounded when you start to introduce LED lights, which consume less power.


A "state of the art charging system" like a Podtronics, Tympanium, Boyer Power Box etc... puts the rectifier and regulator all under one roof. They are potted up in resin and loaded into the back of an aluminum heat sink which is painted black.
However, in order to keep the heat out of these and prevent them from failing prematurely, they are designed to short out the AC input side when your DC battery is charged and doesn't require a charge.

It is my opinion that this shortens the life of the alternator stator (others may disagree with that, but it's my opinion)
I personally feel that a short-type reg/rec is a step back from the original zener on the bike in this respect.

MOSFET reg/recs (like @Madnorton refers to) have much better and accurate control on charging and series-type reg/recs (my own personal preference) work by opening the AC circuit when the battery doesn't require charge, so both are much better options.
I am keenly waiting to test a series-type MOSFET regulator rectifier, but no-one has produced one yet.


Of course there are those that will stick a lithium-based battery in and have ten years of trouble-free service, and those that will buy a reg/rec from ebay for $5 and wear it like a badge proudly for all to see, but we as people just like our bikes are all wired differently!

Madnorton said:

For those that have not tried yet, the Tri Spark Mosfet R/R will produce 14.39V at tickover and holds it there nicely as the revs rise, this is using a BSM and single phase stator. I am thinking about a Lithium battery but not happy with the way the cell balancing works. I am not sure, but would like each cell control system fused so in the event of failure it fails open and battery dies, and not overcharges and ignites. Nearly convinced on this Lithium technology, but not quite.

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Might I please ask...What is BSM?
6 years of college and 40+ years mostly in high power electronics and have not run across this BSM. Motorcycle term??
Also I suspect a trispark mosfet R&R makes nothing...it controls, limits
I am keenly aware of series opening(very high impedance) vs shunting to ground regulators vs designed in load balancing Gtiller refers to... like on my 2+4 coil early atlas alternator.

Battery status monitor

Madnorton said:

Battery status monitor

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Thank God for that, my two brain cells came up with British School of Motoring!
I guess I've still got my L plates on when it comes to 'lectricity