XR4Ti rally car, huge Odyssey battery. 3ma draw when off, lives on a battery tender constantly, charges at 13.5v or better when running. Battery tender has been green for days... but this is the voltage as soon as the ignition is turned on:
and upon switching it off again:
What could be going on here? This is a pretty fresh battery, and I don't know what else to test. Is the battery just bad? Tell me where else to look. Killswitch? Other wiring?
Voltage should be higher then from the alternator running no? My car on a standalone I have to throw a rev to excite the alternator into juicing. My 80s BMW bike did the same thing. That voltage when off is concerning though.
In reply to fatallightning :
Sorry- that is ignition on, not running, directly after the battery tender (green light, 12.5v or more) was removed. When running it is 13.5-15v.
In reply to fatallightning :
charging voltage is low. should be 14.3
Too much draw for just ignition. 10+- is normal when cranking.
I'm not sure what you're getting at- you think an ignition component or something that comes on with it is drawing the battery down from 12.5 to 10v immediately?
I think you must have some kind of ground to chassis someplace in the wiring for it to be draining so rapidly. That's the only thing I can think of other than the actual battery being bad incidentally that's exactly the problem Shawn was having in the turbo Miata last weekend.
In reply to irish44j :
Again though, fine when running, and only a 3ma draw when off- so how can it be draining? The amount of draw to pull it down from 12.5v to 10.something immediately upon switching on should generate some heat or something right?
You know that Odyessy batteries do not like excessive heat? If it is anywhere near the exhaust, you may have toasted it
Either the battery or the tender is berkeleyed.
OK, so we already established with everything off it draws very little.
Here's what happens with the killswitch on- each of these circuits has its' own switch or fuse so I could check them individually:
Fuel pump: 5a
Dashboard lights/sensors: 2a
Ignition coil/ECU/other stuff: 1a
That's 9 amps of stuff measured at the battery terminal, shouldn't be enough to draw the battery down in 10 seconds I think?
Also, after letting it get topped up by the tender again- tender plugged:
Unplugged:
Ignition on for 10-15sec:
I'd call that battery junk.
Have you done the obvious thing of testing it with a different battery to see if the result is the same?
IDK, if it drains 2v after 10-15 seconds ignition on, still seems like a short to ground in the ignition circuit side of things. Have you checked your connections at the kill switch to make sure they're not contacting anything? Mine are pretty close to metal stuff so they're heavily wrapped/protected from incidental contact. Could just be contacting something you're not touching, hence why not feeling heat (or its in the engine bay).
But I'd check a different battery first.
You got a battery with a dead cell. That's my gut instinct. You can't check each cell like we did on the submarine though......
Yeah it looks like a bad battery to me, even modern cars that put a huge load on the battery don't pull their batteries below 12v so quickly, and the amount of load your car is putting on the battery looks about right for a '90s car.
Switched it on after all night on the tender and it dropped right back to under 11v.
So I swapped in a spare battery and got this- much better:
Seems pretty definitive so I guess it's time to try to exchange the current battery. Still unsure how it could have died in under a year, but at least I still have the receipt and the box.
I called in for an exchange and Odyssey doesn't make this particular battery any more, so that seems like some sort of sign. They're giving me a slightly lower capacity replacement and a credit for the difference.
Well, at least they're doing something!
This was a classic bad battery scenario. What's funny to me is in my particular case as a highly trained and experienced auto tech, I can use what i know to determine a battery is bad without any real special tools. But, I ended up buying one of these cheap fixed-load battery testers for some planned hybrid battery cell testing that i still haven't done. What's been surprising to me is that i find it useful despite everything i already know. It's WAY faster to condemn a battery with this thing than it is to condemn a battery just by observing it's behavior under various circumstances like what you did with the bike. So even though i didn't think i wanted one for the longest time, now i'm happy i own one.
In reply to Vigo :
Agree. I have an old load tester that I haven't used in a long time.
Quick and easy.
Each cell is nominally 2v. Your battery keeps dropping right at 2V as soon as its unhooked from the charger = bad cell.
It'll eat another cell soon. It's junk, see if you get a prorated replacement.
AnthonyGS said:Each cell is nominally 2v. Your battery keeps dropping right at 2V as soon as its unhooked from the charger = bad cell.
It'll eat another cell soon. It's junk, see if you get a prorated replacement.
Sounds like he's already taken care of that...
¯\_(ツ)_/¯ said:I called in for an exchange and Odyssey doesn't make this particular battery any more, so that seems like some sort of sign. They're giving me a slightly lower capacity replacement and a credit for the difference.
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