Battery Charging Question

Automotive
#1

Can I charge my ‘84 F-150 battery at 2 amps while the cables are still connected?

I’ve always disconnected both cables, but this may be a nightly task until I find out why ibattery is not charging. I replaced solenoid, because truck wouldn’t even turn over with a freshly charged battery. Now it starts, but not charging. O’Reilly’s says alternator and battery both good. I checked fuses under hood per YouTube.

Second question is, Any ideas on not charging?

Edited for clarity.

#2

Can’t speak to O’Reilly’s methodology, but I once had Wal-Mart “load test” a thoroughly dead NeverEverstart using a “battery meter” featuring tiny cables that wouldn’t suffice for a $5 multimeter and proclaim it good; took it back a few days later and the clerk exchanged it without comment.

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#3

I routinely have used a Schumacher smart charger at 10 amps on a 2001 mercury grand marquis and a 2003 Mazda Tribute with the battery still connected and no issues. While it may run higher voltages and charge pulsing, So far, I’m less concerned about that, than the inrush current causing damage when connecting the battery back up. So far, zero issues with either car. But your experience may be different, and this is not to be construed as advise.

As for charging, does the charging system warning light come on with rest of the panel when you start the engine? For a long time, ford used the current through that bulb as the current to initially excite the alternator field. So bad bulb, no charge.

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#4

With the engine running measure the battery voltage. It should be about 13.7 V. If it isn’t the charging system has a problem.
If you disconnect the battery, charge it, and leave it disconnected it should hold the charge.
If you connect it back up and it loses charge you have a problem.
To answer your original question maybe.

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#5

Thanks for the responses.

#6

Here’s an easy to make speed charger. Gotta love Maker solutions.

image
image504×622 390 KB

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#7

Does the 60Hz regimen desulphate the plates?

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#8

Looks like a highly advanced version of your basic bench suicide cord. :grimacing: :astonished: :scream:

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#9

Something missing from this NecroThread;

Q: how do know when the battery successfully charged?
A: by the VoltsDC once you disconnect from the charger.

You have to disconnect the charger, then let it settle for a few minutes, then measure the Voltage. The reading should be steady, not dropping.

|Charge%|Lead Acid batt volts|Gel batt volts|AGM batt volts|

|100%|12.70+|12.85+|12.80+|
|75%|12.40|12.65|12.60|
|50%|12.20|12.35|12.30|
|25%|12.00|12.00|12.00|
|0%|11.80|11.80|11.80|

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