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Does size matter (batteries)
jrrsparky - 19/8/11 at 09:08 AM

What size battery have you guys used for a BEC (R1 engine) with electric reverse, to stop the engine cutting out and the reversing light dimming.

[Edited on 20/8/11 by jrrsparky]

britishtrident - 19/8/11 at 09:43 AM

Have you considered using a separate battery and a split charge relay ?

tomgregory2000 - 19/8/11 at 10:01 AM

Why fit a second battery?? I see no point as you will be adding more weight and have to find a place to put it and then the wires etc etc Just fit a bigger main battery.

What capacity(sp) battery have you fitted at the moment?

Mr Whippy - 19/8/11 at 11:10 AM

engines don't need much current to keep running, neglable compared to a starter motor and if you fit some super bright LED's as reverse lights that could help too

britishtrident - 19/8/11 at 11:13 AM

If you put a heavy load on a battery the voltage across the battery terminals drops due to the internal resistance. When a starter is doing the job it was designed to do ie starting an engine iIn typical cold conditions even with a good fully charged battery the terminal voltage will drop to between 9 and 10.5 volts. If the battery has a dodgy cell or undersized or is low on charge the available voltage will be anything down to 6 volts.

mark chandler - 19/8/11 at 01:32 PM

If you stick a car battery on a bike engine you risk frying the alternator !

britishtrident - 19/8/11 at 03:02 PM

Burglar alarm battery should be enough to keep the engine running, small (ie the little japanese) car battery for reverse and starting.

britishtrident - 19/8/11 at 03:08 PM

quote:
Originally posted by mark chandler
If you stick a car battery on a bike engine you risk frying the alternator !


A lot less than the aternator trying to pump less than 9 v up to 13.4-14.7v when the reverse motor is running.

The alternator dosen't really know what size battery it is charging all it sees is the battery voltage the alternator output current should be regulated by the alternator.

jrrsparky - 19/8/11 at 03:33 PM

Thanks for the replies,
I have a Odyssey Battery PC625: Dry Cell, 12 V, Deep Cycle, 265 Cold Cranking Amps, on at the moment, when i first tried it with the reverse the engine didn't cut out, the only thing different that I can think of is the reversing light, I'll take the bulb out and try it but I doubt the small amount of current it takes will make much difference.

JoelP - 19/8/11 at 05:04 PM

quote:
Originally posted by mark chandler
If you stick a car battery on a bike engine you risk frying the alternator !


I think you are thinking of the issues of jumping a bike engine off a running car engine. Not sure how a normal car battery would have any effect on the bike engine - my bec had no probs.

40inches - 19/8/11 at 05:07 PM

quote:
Originally posted by britishtrident
Have you considered using a separate battery and a split charge relay ?


That's what I have done, with an intelligent split charge relay.