trickle charge Car battery charge

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Hi
I have a 12 volt trickle charger that when tested with the multi meters only puts 10 volts out
The man from the shop said this is normal and I tock my charger and meter down to his shop and did a few tests on his other chargers and they all put out about 10V

Dose this seam odd to you?
Thanks
FF
 
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Depends on the charger design. Some won't output correct voltage until they 'see' a serviceable battery is connected. The best way to check if it's working is to measure the current flowing into the battery when first connected.
 
Hi
I have a 12 volt trickle charger that when tested with the multi meters only puts 10 volts out
The man from the shop said this is normal and I tock my charger and meter down to his shop and did a few tests on his other chargers and they all put out about 10V

Dose this seam odd to you?
Thanks
FF
No the RMS voltage may be 10 volt but peak voltage with be 14.14 volt so it will charge the battery to that point in fullness of time.
 
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If your multimeter has a current option (usually a different hole for the + probe) then use it, set meter for amps, put meter in series with charger and battery
 
No the RMS voltage may be 10 volt but peak voltage with be 14.14 volt so it will charge the battery to that point in fullness of time.

Yep, they are often quite crude devices, just a transformer and a full-wave rectifier - no smoothing, no voltage or current regulation.
 
Yep, they are often quite crude devices, just a transformer and a full-wave rectifier - no smoothing, no voltage or current regulation.

Exactly, a standard DMM will not read the voltage correctly on a device like this.
 
Exactly, a standard DMM will not read the voltage correctly on a device like this.
With the sort of waveform you're talking about, it would be quite hard to decide what one would regard as "reading the voltage correctly" (with a digital or analogue meter).

Kind Regards, John
 
I went through this recently when SLA's only charged to a bit over 11V, I was convinced it was the charger at fault when I measured its voltage at 10.?V and even opened it to try to fix it, and reverse engineered it.
Basically it is a voltage regulator in the +VE line and a transistor switch in the -VE line. Between the lines is a 'voltage detector' which switches the transistor on when it sees >x.xV and off when it sees >13.8V.
The 10V I could see is via a fairly high value resistor, something like 10KΩ so not part of the charging circuit.

The promlem in my case was, of course, faulty batteries which I refused to consider initially.
 
I went through this recently when SLA's only charged to a bit over 11V, I was convinced it was the charger at fault when I measured its voltage at 10.?V and even opened it to try to fix it, and reverse engineered it.
Basically it is a voltage regulator in the +VE line and a transistor switch in the -VE line. Between the lines is a 'voltage detector' which switches the transistor on when it sees >x.xV and off when it sees >13.8V.
The 10V I could see is via a fairly high value resistor, something like 10KΩ so not part of the charging circuit.

The promlem in my case was, of course, faulty batteries which I refused to consider initially.
So you have been hear (discusion) before then:D

So you think it could be a high value resistor that keeps it at 10V then?

While we are on the subjuect of 10V, on another thread hear I asked a question about inverters and weather or not they cut off at 10V. If they do that then do you think they too have a high value resistor in circut to do the same
 
So you have been hear (discusion) before then:D

So you think it could be a high value resistor that keeps it at 10V then?

While we are on the subjuect of 10V, on another thread hear I asked a question about inverters and weather or not they cut off at 10V. If they do that then do you think they too have a high value resistor in circut to do the same
Perhaps I've not explained that very well.
The charge voltage is controlled by a voltage reguator in the +VE, the charge circuit is completed (switched on) with a transistor switch in the -VE and that gets switched on and off by the voltage detector circuit connected across the +VE & -VE leads. That consists of several components which don't draw much current but will have the effect of 'providing' an output voltage, as such they are unable to supply anything like the current required to charge the battery. So to confirm this is deffinitly not the charging voltage/current, this is just the way it senses if there is a battery connected and if it needs charging.

The other point about the inverter, it will have to stop at some time when the battery goes flat. At 10V a 12V lead acid battery is basically flat and 10V is chosen as a cut off poit rather than letting it go completely flat and potentially causing premature failure of the battery.
Don't get hung up on this 10V value, keep the wiring short and possibly somewhat thicker than needed to take the current (my inverter runs at about 8A and 1mm² wire is adequate - I have used 2.5mm² wire), keep any connectors in good condition and clean.

A little job today:
IMG_20191211_150111.jpg

Sorry about the poor quality.
This is possibly the mixer I ran on 2x18V batteries (12V and 6V each) that I mentioned on the other thread.
 
Perhaps I've not explained that very well.
well you do keep abbreviating things and if one dose not know the term then one has to guess

At 10V a 12V lead acid battery is basically flat and 10V is chosen as a cut off poit rather than letting it go completely flat and potentially causing premature failure of the battery.
Don't get hung up on this 10V value, keep the wiring short and possibly somewhat thicker than needed to take the current (my inverter runs at about 8A and 1mm² wire is adequate - I have used 2.5mm² wire), keep any connectors in good condition and clean.
I have noticed with several inverters that when they switch them selfs off due to lack of power, there is still plenty of life left in my batterys to run think like lights. But these are car cold cranking batteries and not deep cycle
 
well you do keep abbreviating things and if one dose not know the term then one has to guess
My apologies, it's easy to make assumptions of peoples understanding of some abreviations.
Does this help?
I went through this recently when SLA's (sealed lead acid batteries) only charged to a bit over 11V, I was convinced it was the charger at fault when I measured its voltage at 10.?V (a potential difference [voltage] between 10V and 11V but I don't recall the exact reading) and even opened it to try to fix it, and reverse engineered it.
Basically it is a voltage regulator in the +VE (positive) line and a transistor switch in the -VE (negative) line. Between the lines is a 'voltage detector' which switches the transistor on when it sees >x.xV ( a potential difference [voltage] over a preset value [typically between 6V and 10V dependant on manufacturer etc]) and off when it sees >(over)13.8V.
The 10V I could see is via a fairly high value resistor, something like 10KΩ so not part of the charging circuit.

The problem in my case was, of course, faulty batteries which I refused to consider initially.


I have noticed with several inverters that when they switch them selfs off due to lack of power, there is still plenty of life left in my batterys to run think like lights. But these are car cold cranking batteries and not deep cycle
This is correct but when a battery discharges, the internal resistance rises as the charge falls and his becomes fairly rapid towards the end of the useful life. This means the voltage may still be say 12.5V with no load and say12.2V with a 1A load (12W bulb) but only say 9.5V with a 10A load (all figures are off the top of my head but I'd like to think fairly reasonable). From that I agree with your comment that it may still seem to be servicable for lighter loads but realistically not for too long.
I expect my 200 Watt inverter to run for about 6 to 7 hours on an 80AH (Ampere/Hour) leisure battery when running at my typical load of around 100W. However my elderly 95AH car batteries (some purchased 2003 and used exclusively in leisure mode of charge/discharge cycles) will only run for about half of that time. When using the batteries to power 24V 120Watt amplifiers where the current varies considerably between about 0.5A and 8A I struggle to tell the difference between the performance of the 2 types and ages of battery.


 
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