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battery voltage reading

ercp98

Well-known member
Joined
Aug 5, 2003
Messages
1,340
Location
northlake in illinois
has anyone noticed their battery voltage reading drop from 14.5 to 11.1/10.9 after they switched on their electrics; headlight, fogs, radio and heater fan?
when i noticed this, i immediately rev-up the engine. this did not do anything. the voltage barely move to 11.4. i understand that with all the electrics on, the battery and alt is given an extra load. but i thought the alt and voltage regulator was suppose to keep the voltage up in the 13 volt range.
could all this mean that my alt is on its way out again? or my battery is not taking on extra charge because i moved it in the trunk? i have the battery grounded to the shock tower. will adding more grounding points for the battery improve this situation?
 

Hertz

Staff member
Joined
Jul 29, 2002
Messages
13,501
Location
Chicago, IL
Where are you reading this from?

Do a sanity voltage check right at the battery.

Do you really turn 14.5 with no load? That's pretty good.

Did you get a 75A or 90A alternator?
 

FlyingEagle

Staff member
Joined
Mar 5, 2005
Messages
1,635
Location
THE Ottawa
Check with a multimeter at the battery terminals. You have to get more than 12.6V at the battery, as that is standing battery voltage, in order to actually maintain charge in the battery, but obviously it should stay higher. The colder the regulator or sensing equipment believes it is, the more it will influence how much voltage the regulator will send to the battery through the alternator output. The FSM details all of this with temperature changes, and how it affects output voltages. 12.6 is still not enough, so any voltage below that, or on par with that is showing a system that has links that are not up to par, period.
 
Last edited:

gvr4ever

Well-known member
Joined
Aug 6, 2002
Messages
6,196
Location
central Indiana
I think you should check the alt too. That can be working fine, but the battery might not be holding a charge right.

My logger was reading 14.xx the other day.
 
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