Honda Prelude battery drain question.

[Bobthebeard]

Am loving my recently acquired Prelude, but a quick question if I may? If left unused for more than a couple of days the battery goes flat. As in totally flat. Have checked out the cause and the drain is caused by the 'clock' circuit. Removing the 10 amp fuse stops the drain. The digital clock still powers up with the fuse removed but forgets the time after switching off the ignition, a relay can be heard clicking in if the fuse is replaced with ignition off and the clock remembers the time, although the display goes off as normal with the ignition. What else could be powered up by the circuit? 10 amp fuse seems a lot for a digital clock....The stereo also forgets everything with fuse removed, but a 10 amp fuse still suggests something else is involved....

Anyone?

[hauserplenty]

That means they probably put all the continuous memory wires on the same circuit. Chances are the PCM and any other modules you have are on there too.  Hence the 10AMP fuse.

 

1. Charge the battery overnight with at least a 6 AMP/10 AMP charger. A trickle-charger will not work.

2. Measure the voltage with a meter about 15 minutes or so later. Or, turn the headlights on for three minutes to bleed off the surface charge. If the result is less than 12.66V, have the battery load tested. A "toaster" (looks like a meter box with springs inside) is not an accurate test.

If the result is less than 12.5, replace the battery.

3. Clean the contacts with baking soda & water, then file 'em till they shine.

 

Or check the date code on the battery. if it's getting close to 5 years old it could be the battery.

It's likely you have more than one keep-alive memory on that circuit, and if the battery's going duff that explains it nicely. Honda batteries are quite small so they tend to fail quicker than most.

[Bobthebeard]

That means they probably put all the continuous memory wires on the same circuit. Chances are the PCM and any other modules you have are on there too.  Hence the 10AMP fuse.

 

1. Charge the battery overnight with at least a 6 AMP/10 AMP charger. A trickle-charger will not work.

2. Measure the voltage with a meter about 15 minutes or so later. Or, turn the headlights on for three minutes to bleed off the surface charge. If the result is less than 12.66V, have the battery load tested. A "toaster" (looks like a meter box with springs inside) is not an accurate test.

If the result is less than 12.5, replace the battery.

3. Clean the contacts with baking soda & water, then file 'em till they shine.

 

Or check the date code on the battery. if it's getting close to 5 years old it could be the battery.

It's likely you have more than one keep-alive memory on that circuit, and if the battery's going duff that explains it nicely. Honda batteries are quite small so they tend to fail quicker than most.

Thanks for that! Will try the above.

[castros_bro]

Do you have a CD multichanger lurking somewhere connected to the stereo?

 

Take out the 10A fuse and stick an ammeter in it's place which will tell you if the battery is draining externally and by how much.   For further VIS like fun disconnect items to find how much each is consuming. 

[twosmoke300]

Does the car have a Cat 1 alarm ?

 

Seperate plip buttons with a rubbery feel?

 

These are a honda supplied aftermarket alarm that many of the faster hondas had fitted on the dockside so they could be insured in the uk.

 

Sometimes these can cause battery drain problems.

[Bobthebeard]

Does the car have a Cat 1 alarm ?

Seperate plip buttons with a rubbery feel?

These are a honda supplied aftermarket alarm that many of the faster hondas had fitted on the dockside so they could be insured in the uk.

Sometimes these can cause battery drain problems.

Indeed it does have an alarm. A Laserline unit that looks professionaly fitted, although came to me without plips or any means of activating it. Having pulled out the two multiplugs and fuses at the rear of the alarm the drain does appear to have gone! Now 13 milliamps, was 247 milliamps with alarm still connected.

Many thanks!

[twosmoke300]

If it's laserline it won't be a Honda fit. They were made by Hamilton and Palmer . Glad you traced the fault. Always happy to help with Hondas and I still have a man on the inside for newer stuff.