Charging question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72gmcshorty · 10-15-2003, 07:12 PM

What would cause the charging system to OVERCHARGE the battery? My prelude is charging my battery at around 14.9 shouldn't it be around 14.2? I just had to relpace my battery because it died. Can overcharging kill it? I can see an alternator undercharging as the brushes wear out and the alternator wears out but overcharging? Should I hook up a big car stereo to drain some of the amps?

*67Fleetsidedream* · 10-15-2003, 07:25 PM

The voltage regulator may have went south in your alternator. And yes overcharging a battery will kill it.

Andy4639 · 10-15-2003, 07:43 PM

If you have the factory voltage regulator on the radator support on the drivers side of the truck it may have gone bad. These old ones were bad about it. I bought 3 of them once before I got a good one. Then I swaped it out when I bought the late model alternator with it in it. That was one of the best things I ever did.

JimKshortstep4x4 · 10-15-2003, 08:41 PM

I believe that you are not talking about a truck, since you called it a prelude. Anyway 14.9 volts is not that much voltage. It is not unusual to see over 15 volts on the newer charging systems and there is always a question as to the gauge calibration.

Usually when you have an overcharge situation the battery will boil and smell. At 14.9 volts, I would not suspect the charging system. If you are in doubt, though I would suggest getting a gauge known to calibrated to check the output before condemning the system.

Jim

Hooter · 10-15-2003, 10:57 PM

14.9 is just a bit high, but Honda's like to sit around 14- 14.5 volts when running, try get another voltage regulator, plug it in and see if it makes a difference.

Longhorn Man · 10-15-2003, 11:46 PM

I agree on hitting it with a volt meter before spending a penny on it. (Asuming you are going by the stock guage and have not already done so)

72gmcshorty · 10-15-2003, 11:51 PM

It's reading 14.9 with an actual meter not off the dash gauge. I'll check into the regulator (if it has a seperate one).

Longhorn Man · 10-16-2003, 12:36 AM

I think it is internal, although, it has been a while since messing with the charging on a honda.

Mechanic · 10-16-2003, 12:56 AM

If you have 14.9 at the battery and its a lead-acid battery you'll dry it out quickly. That's a bit hot.

71GMC_3/4T · 10-16-2003, 10:21 AM

You may be missing a wire that ties the (-) terminal to chassis ground. A lot of people cut off and chuck these when they install a new battery with the posts reversed and the wire won't reach. At the time, they think "Ha it still runs fine without it!" Unfortunately, the battery doesn't last long w/o it there.

Since you obviously have a voltmeter, measure from the battery (-) terminal to the alternator case when it is running. ANY voltage you see will be added to what the alt puts out. Also, measure from the alt output terminal to the alt case when it's running. If it's more than 14 V, you likely have a bad internal regulator.

10-15-2003, 07:12 PM	#1
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	Charging question What would cause the charging system to OVERCHARGE the battery? My prelude is charging my battery at around 14.9 shouldn't it be around 14.2? I just had to relpace my battery because it died. Can overcharging kill it? I can see an alternator undercharging as the brushes wear out and the alternator wears out but overcharging? Should I hook up a big car stereo to drain some of the amps? __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

10-15-2003, 07:43 PM	#3
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Voltage Regulator If you have the factory voltage regulator on the radator support on the drivers side of the truck it may have gone bad. These old ones were bad about it. I bought 3 of them once before I got a good one. Then I swaped it out when I bought the late model alternator with it in it. That was one of the best things I ever did. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

10-15-2003, 10:57 PM	#5
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	14.9 is just a bit high, but Honda's like to sit around 14- 14.5 volts when running, try get another voltage regulator, plug it in and see if it makes a difference. __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

10-15-2003, 11:51 PM	#7
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	It's reading 14.9 with an actual meter not off the dash gauge. I'll check into the regulator (if it has a seperate one). __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

10-16-2003, 12:56 AM	#9
Mechanic Registered User Join Date: Jun 2003 Location: Seattle Posts: 77	If you have 14.9 at the battery and its a lead-acid battery you'll dry it out quickly. That's a bit hot. __________________ Shop Labor $75, if you watch $100, if you help $125, Wisecracks-$25, Boxjobs-don't even think about it. Yes,Cash.

10-15-2003, 07:25 PM	#2
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	The voltage regulator may have went south in your alternator. And yes overcharging a battery will kill it.

10-15-2003, 08:41 PM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	I believe that you are not talking about a truck, since you called it a prelude. Anyway 14.9 volts is not that much voltage. It is not unusual to see over 15 volts on the newer charging systems and there is always a question as to the gauge calibration. Usually when you have an overcharge situation the battery will boil and smell. At 14.9 volts, I would not suspect the charging system. If you are in doubt, though I would suggest getting a gauge known to calibrated to check the output before condemning the system. Jim

10-15-2003, 11:46 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I agree on hitting it with a volt meter before spending a penny on it. (Asuming you are going by the stock guage and have not already done so)

10-16-2003, 12:36 AM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I think it is internal, although, it has been a while since messing with the charging on a honda.

10-16-2003, 10:21 AM	#10
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	You may be missing a wire that ties the (-) terminal to chassis ground. A lot of people cut off and chuck these when they install a new battery with the posts reversed and the wire won't reach. At the time, they think "Ha it still runs fine without it!" Unfortunately, the battery doesn't last long w/o it there. Since you obviously have a voltmeter, measure from the battery (-) terminal to the alternator case when it is running. ANY voltage you see will be added to what the alt puts out. Also, measure from the alt output terminal to the alt case when it's running. If it's more than 14 V, you likely have a bad internal regulator. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

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