I have a little 13 lb odyssey pc625 battery with no metal jacket. I relocated it to the trunk which is safe because it’s fully sealed. Also I put a fatty marine fuse on positive cable right next to the battery just-in-case. I have good ground to chassis back there, and a 4-gauge cable running positive up to the fuse block under the hood. The batt is about 3 yrs old.
I started having starter problems recently so I started troubleshooting… drove me nuts… I think running low voltage when the starter was struggling to turn over may have damaged the starter and maybe even other components in line. I replaced starter relay, had the starter overhauled, added extra ground directly to starter, and checked underdash wiring and switches, installed a cheap voltmeter to the stereo’s + and - leads to keep an eye on things.
Still, my battery seems to drain. Lately the behavior has gotten weird, no battery light comes on at the dash but I can see the voltmeter go as low as 10 volts :uhoh: and the engine almost dies. When this is happening if I turn the car off the starter struggles to turn over. Then all of the sudden voila! volts go back up to 12.5 for no reason. Never see em go above that tho. I have resorted to charging the battery w/ Odyssey’s special charger every few days.
I tested the “battery check” light and it seems good. Also w/o removing the alternator, I checked the voltage between ground and the main positive terminal at the alt while the engine was running and it was 14.3 at different RPMs. One mechanic told me the alternator could be on its way out so it fails every-now-and-then.
So,… does this sound like a battery problem or alternator? I don’t think kragen/auto-zone can test my odyssey batt anyone else have one of these? I am thinking of getting their pc680 metal-jacket I think it would be better but don’t want to dish out the $140+shipping for it yet if I have a bad alternator…
hmm, 14.3 seems a bit low right at the alternator?
Also found this: Battery Testing
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3. The battery needs to sit for 24 hours outside of the vehicle and the voltage tested again to see if the battery holds the charge.
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Load Testing:
PURPOSE: generally performed because the battery is not performing as expected or as specified. This test will determine the battery’s overall condition and its ability to deliver an engine’s starting current requirement while maintaining a specific battery terminal voltage.
NOTE: Most Load Testers can be adjusted for the temperature of the battery. It is important to best determine the temperature of the battery and adjust the tester accordingly.
TEST PROCEDURE:
Step 1: Battery terminal voltage must be 12.60V or greater to test. If the battery voltage is below 12.60V, charge battery before testing.
Step 2: Connect the Load Tester cables and the test leads of a separate Digital Voltmeter (±0.25% DC accuracy, if the Tester has no direct DC Voltage Meter) to the battery terminals.
Step 3: Adjust the Tester Current Load to achieve ½ the Cold Cranking Amperage (CCA) rating of the battery and apply it for 15 seconds.
Step 4: At the end of 15 seconds, note the battery voltage on the Tester Voltmeter or the Digital Voltmeter and discontinue the test.
TEST EVALUATION:
This test is a pass or fail. Compare the recorded test voltage to the chart below. If the battery test voltage is above the appropriate voltage at the determined battery temperature, the battery tests OK. If the test voltage is below, then the battery failed and needs to be replaced.
You said, “and a 4-gauge cable running positive up to the fuse block under the hood.”, try this…
Run the 4ga directly to the starter motor and run an 8ga from the starter motor to the engine bay fuse box, [stock batt. terminal location] eliminate the fuse block and all it’s connection points.
Also, what kind of fuses are in the fuse block, [type and size]?
You also said, "Also I put a on positive cable right next to the battery ", what exactly is a “fatty marine fuse” what size, [amps] is it?
Do you have a 12V test light? 94
yea, I have a test light. also a cheap multi-meter. The 4ga cable from the positive on the battery I hooked up where the old battery cable used to go when the battery was under the hood. The “fuse box” is just the stock one with stock fuses, nothing special, sorry if that sounded like I had something else going. The starter works perfect when the battery is fully charged, it’s just that the battery dies slowly and alternator doesn’t seem to be charging enough. The “fatty marine fuse” is a “slow-blow” 150 amp (might be 200 amp?) that I added just in case that 4ga cable ever shorts to ground (chassis) because that would be like fully shorting the battery out and by the time that 4ga melts I worried it would catch fire or blow up or something hehe…
After fully charging batt and doing some tests I measured:
I noticed a lot of corrosion at the alternator output terminal (white cable). I’m gonna pull it and clean the contacts. Someone else suggested using an ammeter to look for parasitic drains when the car is off. Otherwise want to get batt and alt load-tested…
If you have the 4ga connected to the engine bay fuse box, how do you have the starter connected to power?
It is important to know what type of fuse and it’s amperage, especially if it is a “slow blow”.
Current capasity of 4ga cable is no more then 150A, if it is a 200A, [and slow blow] your not protected against a short.
By the readings you are getting it sounds to me like the alt. is working properly, the drop in voltaage between alt. and batt. will be due to lenght of cable.
Use your 12V test light to look for parasitic draw, connect test light to both sides of fuse on 4ga cable, ground clip to one side of fuse and the probe end to other side of fuse then remove fuse, the test light is now in series, [power must go through test light] if test light lights up at all you have a parasitic draw, if test light does not light up there is no draw. 94
thanks for the tip about the test light. I was going to try with an ammeter but was a little worried I would do it wrong and fry the meter (I fried one once with wall current hahaha - nothing like some smoke and the sound of popping caps to make your day).
Also good point about the 4ga current capacity I didn’t think of that. My starter is connected in the standard OE way, from the battery main positive (my 4ga) it splits in 2 - one thick cable goes straight to starter, a smaller one goes to the rest of the car through the main fuse which is 70 amps.
In any case – an upd8:
After noticing all the corrosion on the alternator main terminal I pulled it and cleaned it up real good sanded the contacts with 320 grit. The terminal screw was loose!! :dozing: And there was hell-of corrosion all over I almost think I should replace the main alt cable, it was all green and white where the crimp is. I haven’t replaced it but just cleaning the contacts and tightening the screw has made a huuge diff. As soon as I start the car it’s at 14+ volts, and before I start it the batt voltage is almost 13. The lights are brighter and the car seems to run better. I think the Oddysey batt is perfectly fine glad I didn’t replace it or pull the alt out woulda been a waste of time and PITA.
And now that I have the voltmeter gauge I can keep an eye on it
it probably wouldn’t hurt anything to replace it but as long as there is no corrosion at the connection point and all the fittings are tight you should be fine. The reason for corrosion was mostly likely caused by the looseness of the connector to the alternator.
Eliminate the connection at the split, [connections are a point of resistance and corrosion] run the 4ga directly to the starter motor and run a smaller gauge from starter motor to engine bay fuse box.
For the corroded alt. terminal, dip it into a glass of about 75%/25% baking soda and water, let sit for a few min. then dry off and reconnect, [do not reconnect wet terminals] the baking soda will “neutralize” the corrosion. 94
