cranking power

[Ed_RX7]

i\'ve Noticed problems when i\'m starting the car. I have loads of ICE and a bigger battery in the rear of the car. When driving the battery voltage is anywhere between 13.8 volts and 14.1 volts which is cool. When not driving its at about 11.5 to 12.5 volts but when cranking and looking at the PFC commander I sometimes notice battery voltage going down to 7-8 volts which is when it seems like it wants to die but then suddenly fires and starts:reallymad...really ticks me off.....compression is ok....no excess smoke...and coolant is ok.. etc...anybody got any ideas?


I have grounded the battery back to the front of the car so shouldn\'t be an earthing issue...what else could cuase a power drop when cranking?

Totally baffed!!!:confused:


Ed

[mraraju]

when starting make sure all unnecassary loads are turned off, ice lights etc.

while cranking ur battery should not drop below 10 volts.

Have you got a split charging system??

If all loads are turned off and it still drops that low then your battery is either knackered or you have got a wrong rated battery.

your cca (cold cranking amp) might be too low on the battery.

In either case you will require a new battery.

Raju

[Martiny]

Cant explain the massive voltage drop, though I would check the earthing to the engine, or even add some more.

[MikeLMR]

what size are the power cables running to starter from the battery ? if they are too long/too small you will get a large volt drop across them,

[Ed_RX7]

Thanks For the replies guys.

The cables are pretty Thick....really high guage. So that shouldn\'t be a problem...earthing has been routed back to the engine bay. Will put an additional one just in case but don\'t think thats the problem......The only think I can think it is is that I would need a battery with a better cold cranking ability....anybody have any suggestions?....what do others with ICE use?

Cheers again

Ed