Preferred Regulator/rectifier combo

[Tomb]

If you want reliable performance go for an AGM type. They give you mounting options but unfortunately they are no smaller than a standard wet type lead/acid battery.

I've been won over by the AGM (Absorbed Glass Mat) batteries, I'm using a Motobatt on an old Yamaha and a different make on my CB500, and as said they can be mounted differently to lead acid, which is a good option on café bikes, being able to lie them flat.

Another point worth knowing is if you have the spec of the battery you need you can get the Motobatts cheaper than buying one specifically for your bike, same thing in the end. I saved £20.

[philward]

Big problems for me know! I have modified the frame to mount the (£650!) alloy CR Rep oil tank so that there are now no standard oil tank mounts/etc and new brackets/braces. So watering down the authenticity of the rep a bit by returning to standard oil tank/battery box isn't an option. There isn't enough space that I can see for even a laid down std size battery under the racing seat. As it was my intention to fit a CR fairing, there won't be a kickstart only option. I might have to re-hack the back frame - the CR seat I've got fits on the rear 2 original mudguard mounts and the seat mountings setem I've fabricated to suit.
I think I've got a Christmas break of re-designing.
Thanks for feedback

[Tomb]

As long as the cranking rate of the battery is sufficient, the same as the original, you can fit any AGM battery, so a flatter style may fit somewhere else, I've known them be fitted under the engine and inside fairings.

[philward]

I am no electrician so I will bow to any sparks knowledge - what do you think of the info on the bottom of this link
http://electronics.stackexchange.com/questions/229026/using-li-po-or-lifepo4-for-diy-motorcycle-battery

Extract:
If you keep the cells at low voltage you keep them mostly discharged.

When charging the cells, you could use a Buck–boost converter that would keep the voltage at the right level no matter what the alternator is producing. You also have to make sure that the convertor has a current limiting option, like this one.

Advantages and disadvantages:

LiFePo4 cells are safer than LiPo cells.
The life of LiFePo4 cells is much better. You can realistically expect twice the number of cycles or years if you don't do so many cycles.
LiPo cells are much lighter and are more compact for the same capacity.
LiPo cells have higher C ratings so for just starting the bike this could be a big plus.
In both cases it's recommended you have a BMS with balance capabilities and a current limiting charger. When the batteries get full, the BMS disconnects the pack from the alternator automatically.

I would probably do it with a 4S LiPo pack because it would be cheaper and more compact. I would expect the pack to last for ~4 years and then I would reconsider it.

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Particularly ref the Buck Boost Converter

Your thoughts Sparks?