Car/battery inverters with computers and related parts.

[Smart_Guy]

I'll keep a fire extinguisher at hand

This whole idea started to worry me and bring other stuff into it. I tested the battery and charging with my some how traditional car battery tester and got a reading of 12V for the battery and a frequency of 13-13.25V at supposedly full load (turned on the aux fan to full, head lights, fog lights, full A/C, read defroster, music with sub-woofer, and cabinet light on).

Guess I'm gonna have to make sure the charging system is fully functional first.

 

[pete.i]

I'll keep a fire extinguisher at hand

This whole idea started to worry me and bring other stuff into it. I tested the battery and charging with my some how traditional car battery tester and got a reading of 12V for the battery and a frequency of 13-13.25V at supposedly full load (turned on the aux fan to full, head lights, fog lights, full A/C, read defroster, music with sub-woofer, and cabinet light on).

Guess I'm gonna have to make sure the charging system is fully functional first.

Yeah thats the problem with doing all this stuff. It's a bit like googling your symptoms. By the time you finish you been dead for two weeks LOL.

I'm not sure about the bit I have highlighted in red in your quote. That would be the voltage not the frequency. This is a DC voltage so no frequency. Also those voltages are low, in fact if I saw 12volts on my boat battery I would consider that to be a discharged battery. I would expect to a charging voltage, that is with the engine running, of 14.4 to 14.8 volts on a modern car. Much older cars had a charging voltage of 13.8 so even by older standards your charging voltage is well down. Those voltages I would measure directly across the battery terminals with everything switched off and the engine running at a fast idle. 12.8 volts across a battery not on load and not being charged is considered to be a half charged battery in the boating world. Ah just reread your OP and you had everything turned on. Turn everything off and run the engine at a fast idle and read the voltages again. If everything is okay then you should get readings close to what I have quoted.

 

[Smart_Guy]

Yeah thats the problem with doing all this stuff. It's a bit like googling your symptoms. By the time you finish you been dead for two weeks LOL.

I'm not sure about the bit I have highlighted in red in your quote. That would be the voltage not the frequency. This is a DC voltage so no frequency. Also those voltages are low, in fact if I saw 12volts on my boat battery I would consider that to be a discharged battery. I would expect to a charging voltage, that is with the engine running, of 14.4 to 14.8 volts on a modern car. Much older cars had a charging voltage of 13.8 so even by older standards your charging voltage is well down. Those voltages I would measure directly across the battery terminals with everything switched off and the engine running at a fast idle. 12.8 volts across a battery not on load and not being charged is considered to be a half charged battery in the boating world. Ah just reread your OP and you had everything turned on. Turn everything off and run the engine at a fast idle and read the voltages again. If everything is okay then you should get readings close to what I have quoted.

Ah, I mean frequency in the general sense. I meant fluctuation. English is not my mama tongue

Yeah, it was on heavy load. On fully warmed up no load idle it is 13.25V. My car is a 1992 that lacks the electronics of a modern car. It even has an over voltage relay!

I asked in my MB community and they said specifically for my car it should be 13.2V to 14.5V to keep the battery charging. Dunno why it is lower than other cars.

I wonder of something's up with the battery tester. I always wanted one of those fancy cig lighter digital volt readers.

 

[Technician1]

The only fans I have there are in the restroom and it's a DC fan. The inverter puts out pure sine wave AC. Most of the lights are also DC powered LEDs. I also power a (small) refrigerator and A/C unit and my TV and computer. Charging your computer up off the inverter and then running it on its battery will be a lot more efficient as in charge mode it will draw a lot less power.

 

[pete.i]

Ah, I mean frequency in the general sense. I meant fluctuation. English is not my mama tongue

Yeah, it was on heavy load. On fully warmed up no load idle it is 13.25V. My car is a 1992 that lacks the electronics of a modern car. It even has an over voltage relay!

I asked in my MB community and they said specifically for my car it should be 13.2V to 14.5V to keep the battery charging. Dunno why it is lower than other cars.

I wonder of something's up with the battery tester. I always wanted one of those fancy cig lighter digital volt readers.

13.2 sounds a bit low even for an older car. Older alternators were usually regulated at 13.8. Newer car's alternators are regulated at 14.5 to 14.8. You could change the alternator for a newer one or you could change the regulator for a 14.5/14.8 one. Changing to a higher output alternator would be okay as long as you are sure that your battery is a reasonably new one. Changing the regulator is by far the cheapest option but a lot more work involved as the alternator will probably have to be stripped down. If your lternator did pack up then you would, almost certainly, get one with a higher charging voltage.

Having said all that if you do have an overvoltage relay then the charging voltage would be regulated by that.

 

[Smart_Guy]

13.2 sounds a bit low even for an older car. Older alternators were usually regulated at 13.8. Newer car's alternators are regulated at 14.5 to 14.8. You could change the alternator for a newer one or you could change the regulator for a 14.5/14.8 one. Changing to a higher output alternator would be okay as long as you are sure that your battery is a reasonably new one. Changing the regulator is by far the cheapest option but a lot more work involved as the alternator will probably have to be stripped down. If your lternator did pack up then you would, almost certainly, get one with a higher charging voltage.

Having said all that if you do have an overvoltage relay then the charging voltage would be regulated by that.

Hmm, perhaps this hidden info make a difference: originally the stock alternator is 70amp that meets all needs of the car. This one is 115amp. Now that mention the over voltage relay, Is it possible it is lowering (balancing) the voltage because the rated current is higher to give an output similar to the original to avoid excessive output? If that's what you mean by your last line.

Original alternator: 70amp X 13.8V (standard reading) = 966W
This alternator: 115amp X 13.25V = 1,523W (my reading) (Covers the above, and even is much higher. My electrician warned my to never use a higher alternator)

Unless it does not work like that, of course. The battery is +1 year old now and on a turned off engine it reads a tick above 12V. Would the battery be dead now if my found 13.25V is lover than the standard?

I have an idea. The laptop seems to like my setup. I think I'll test it alone with a CPU power stress test and see the reading.