Lightweight Battery with Megasquirt

[vindi49]

I've got a light weight battery, a Varley Red Top 25. It seems like it can't power my Megasquirt... which surprised me as my old Adaptronic was fine, but apparently they do drain a lot of power. So what other options do I have for a light weight battery that will provide enough power to run the Megasquirt but ideally be lighter than the standard one?

According to MX5Parts, the standard MX5 battery is about 31amp hours and cranking amp rate of 475.
Varley Red Top is 16 Amp Hours but not sure what the cranking amp rate is... what numbers are the important ones here, or what "spec" do I need?

The Varley is 7kg, not sure what the standard one is, but probably double that.

Russell.

[jnshk]

Something seems amiss here. I can't imagine that the MS would have enough current draw to kill the battery, unless you're leaving it turned on for extended periods before attempting to start the car or unless there's a short inside (in which case you'd probably be blowing fuses). Once the car is started, it should be essentially running off the alternator. Is it possible that something else with the MS is not configured properly?

[WestfieldMX5]

I'm using a Odyssey PC680 and I have no problems with it. It's rated at 680 cranking amp and 17 Amp hours. It's just under 7kg as well. It does crank a bit slower than a full size battery (180 rpm cranking), but the MS doesn't mind at all.