MoTeC Global Forum

my M800 wont allow the engine to start once the battery supply voltage drops below about 11V

with my installation, if it happens to need extended cranking because its really cold or whatever, and the battery volts drop to under 11V and it wont start , despite still cranking just fine. as soon as i add a jump pack, it fires immediately

battery passes all sort of load tests and the voltage supplied to the motec plug is within 0.2V of the battery post at crank

the specs indicate the Motec should be able to handle 6-20V

i cant find any reference to this issue on this forum or on a general Motec Google search "m800 minimum voltage"

any clues appreciated

thanks

Hi Terryo,
There are a couple of things that i would be checking.
Firstly, is the M800 actually powering down (if you are connected with a laptop, does it disconnect you).
Secondly, if it is not powering down, there are some other things you should check in the tune:
- Your dwell times. (Generally these are mapped against battery voltage)
- Fuel battery comp table. (Setup>Fuel>Battery Comp)

These could have been overlooked and will cause issues starting in low voltage scenarios.

i eventually got an answer from Motec that the dash will power down sub 8.5 volts. it only takes a fraction of second . apparently they worked out this was a problem and upgraded the c125 to handle lower transients, but they are unable to retro fit the upgrade to my dash.