Overloading the Alternator

[mrrc]

I've had problems in the past where when you have two power sources in parallel, one can end up drawing so much current that it overloads, even though both power supplies together should be able to supply the current needed.

We are using a Honda CBR600R engine and it's suppose to put out 333w/5000rpm. That's about 27A for everyone 5000 rpm. We're not sure what our rpm will be as it's our first car!

What I'm wondering is how much current can safely be drawn from a 12A-A motorcycle battery in parallel with the alternator rectifier? Is it possible to overload and burn out the rectifier or alternator with these motorcycle engines?

How much current is usually able to be drawn from the battery and alternator in
a) cars where alternators keep up to the battery and
b) cars where the battery eventually goes dead and has to be recharged?

Please answer any questions i have or provide any insight you have, thanks!

[mrrc]

I've had problems in the past where when you have two power sources in parallel, one can end up drawing so much current that it overloads, even though both power supplies together should be able to supply the current needed.

We are using a Honda CBR600R engine and it's suppose to put out 333w/5000rpm. That's about 27A for everyone 5000 rpm. We're not sure what our rpm will be as it's our first car!

What I'm wondering is how much current can safely be drawn from a 12A-A motorcycle battery in parallel with the alternator rectifier? Is it possible to overload and burn out the rectifier or alternator with these motorcycle engines?

How much current is usually able to be drawn from the battery and alternator in
a) cars where alternators keep up to the battery and
b) cars where the battery eventually goes dead and has to be recharged?

Please answer any questions i have or provide any insight you have, thanks!

[Erich Ohlde]

What kind of high current devices are you planning on putting on your car? We have run 2 fans and a fuel pump off of the F4i with no problems.

I would find it very hard to overload the alternator on an FSAE car.

A way to test is to see if you are overloading the alternator is to watch battery voltage with the engine running. above idle you should have above 13V (should get to about 14-14.5 at 5krpm i think). if it is below that you are pulling too much power.

I doubt you would burn out the alternator very quickly since it is somewhat in an oil bath. You might fry the diodes in your rectifier tho.

[mrrc]

Thank you, so if the battery needs recharging after running for a while, the alternator is likely at its peak power output limit and this should be avoided, right?

How much current might we be able to draw from the alternator while our car is idle?

[jrickert]

You have everything the bike had minus lights and horn. The bike is designed to idle with lights. Unless you are running a fusion reactor, I have never seen an FSAE car with a power deficit.

[Trevor]

We had some charging problems last year. We were running an electric fuel pump, water pump and a fan. Most importantly we had one or two less than perfect alternators. I think that a car running significant electronics could have issues if the battery were drained from starting, and unusual current draw or alternator problems.

[Erich Ohlde]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mrrc:
Thank you, so if the battery needs recharging after running for a while, the alternator is likely at its peak power output limit and this should be avoided, right?

How much current might we be able to draw from the alternator while our car is idle? </div></BLOCKQUOTE>

Exactly. Although I have seen 'wiring harnesses' (if you really can call them that) which were so bad they kept the charging system from working correctly (poor connections, bad grounds, improper methods, etc).

Our cars have been able to idle with fuel pump, and a 10 amp electric fan.