I have had a battery drain past few days, today I tested voltage from alternator, it spiked to 19 volts a couple of times and down to about 2 a couple of times, could this be the battery drain source

 

I forgot to post vehicle info, 2004 f150 xlt 5.4

 

It might not be the drain but it looks like a bad voltage regulator in the alternator. Were those readings taken with the engine running?

 

I would go to Autozone or other and have your battery/charging system tested - it's free and will likely answer your question. You might want a second opinion at O'Rielys or other. Likely a failed alternator. Are you battery connections clean?

 

Id start by having batt and alt tested at parts store (free). If you don’t have other issues, you likely have bad volt regulator on alt.

if batt passes and when it’s charged up, disconnect alternator and let sit overnight or a day (at least as long as you had noticed drain). If drain problem is gone it was likely your alt. If it’s not gone, more testing needed.

note: you can have an alt that will pass a test, but still be a open draw (I’ve had it happen to me).

post back with what you do and how it goes.

 

Will do, and thanks for replying

 

The alternator B+ (output) is directly connected to the battery via a couple fuse links on your application.

This means your 2 volt reading was either in error or a connection issue. If the alternator was not outputting voltage on the B+ circuit, you would have alteast seen battery voltage on the output line if the fuses and circuit was still good.

This also raises the question if the 19 volt reading was inaccurate as well.

 

You should put ALL your truck's details & history (as much as you know) into your signature so it shows with each post, as this page explains:

(click this text)


Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.

 

I think I have discovered the issue, when I got the air intake removed from the throttle body and was able to get to the plug on the back of the alternator, it was not secure

 

That's a start. The 19 volt reading is still a bad sign. Maybe it was actually 1.9?

You should check for proper voltages at the battery posts with the engine off and engine running to be sure of where you're at now. A 2004 probably has the simple internal regulator in the alternator. Should be about 14 volts at idle, if the battery was fully charged when you started.