JumbleDuck
Well-Known Member
Well said. The OP's battery does exactly what it is needed to do with no problems. Chillax, dude, chillax.
Voltage drop curve of lead acid batterry with increasing discharge
- Thread starter Chanquete
- Start date
Well said. The OP's battery does exactly what it is needed to do with no problems. Chillax, dude, chillax.
LadyInBed
Well-Known Member
Everyone is focusing on the battery of unstated AH and CCA.
Another thing to consider is the state of the glowplugs and their specification.
How much current should they draw?
How many on the engine?
What is their designed resistance?
What is their resistance now?
If you can't disconnect them all and measure their resistance to see if one has gone low resistance, you could try disconnecting one at a time and measuring the voltage drop as you have been doing.
Another thing to consider is the state of the glowplugs and their specification.
How much current should they draw?
How many on the engine?
What is their designed resistance?
What is their resistance now?
If you can't disconnect them all and measure their resistance to see if one has gone low resistance, you could try disconnecting one at a time and measuring the voltage drop as you have been doing.
Chanquete
Well-Known Member
I measured with a precision digital Voltmeter
Before operating the glow plugs 12.64 Volts
Whilst operating the glow plugs 10.3 Volts
After operating the glow plugs, with the running engine 14 Volts
The engine starts instantly in less than half second.
Therefore the battery seems OK and I am happy
What have I learned?
That in a good battery a 1.7 voltage drop during a consumption of 30 Amperes is normal.
Thanks again for all advices and suggestions!!.
Read more at http://www.ybw.com/forums/showthrea...ncreasing-discharge/page2#JmkG4GhCmUCkjfP0.99
JumbleDuck
Well-Known Member
My car - a scruffy old Berlingo - is very reluctant to turn over while the glow plugs are on.
PaulRainbow
Well-Known Member
Not as much as you should have.
You didn't learn that taking a battery voltage reading with the engine running cannot work, you're reading the output voltage of the alternator. Although you were told that in posts #2 and #4. I did tell you what to check for in post#4, but sadly that's never been done.
So, back of the class for you i'm afraid (must try harder)
Chanquete
Well-Known Member
Hello Rainbow
Here are the answers again:
Before operating the glow plugs 12.64V
Whilst operating the plugs 10.3V
10 minutes later without starting the engine 12.85V
Of course I am aware that qith running engine I am measurin the alternator output
Therefore a voltage drop of 1.7 V during glow plug operation with more than 30 Amp seems normal.
And thanks again for your kind advice.
Regards, and dont be so cruel
pvb
Well-Known Member
Err... you didn't post all of that information before.
cpedw
Well-Known Member
And the battery's internal resistance was about .05 Ohm under the test conditions. I don't know much about your battery but that seems not out of the ordinary to me.
Derek
lw395
Well-Known Member
Firstly, 12.64V minus 10.3V is a drop of 2.3V.
The question is what is the capacity of your battery supposed to be?
If it was a 90Ah battery, the 30A would be a 'three hour rate' or C/3 and I would not expect to see a voltage as low as 11V for a reasonably well charged battery.
So your readings could be an indication that the battery is old and losing capacity.
Or not fully charged.
Assuming there is no resistance between the battery terminals and the measurement points.
As it still starts the engine, it will probably see the season out.
Some useful graphs in this thread:
https://forum.solar-electric.com/discussion/15348/what-should-i-be-measuring
Bear in mind that temperature has an effect, as well as what the battery has been doing recently. Also different alloys of Lead in your lead-acid battey can vary the voltage a little!
If it was mine, I'd be making sure the house battery could be used to start the motor and thinking I might need a new one in the Spring.
But first off, give it a good overnight charge and repeat the test perhaps?
HTH?
Chanquete
Well-Known Member
Dear Rainbow. I thank you for your well-founded suggestions and recommendations!.
I agree speculating that our tired battery maybe lives another year.
Regards
I agree speculating that our tired battery maybe lives another year.
Regards
halcyon
Well-Known Member
Couple of passing questions
10.3V ... at the start of running the heater, part way, or at the end ? what run time estimate.
12.85V ... was engine run after the heater operation ?
Brian
Chanquete
Well-Known Member
Constant 10.3 V during the 13 seconds of the heater operation
The engine was run one hour after the heater operation
KompetentKrew
Well-Known Member
It doesn't make sense to me that the engine voltage is higher 10 minutes after. Where has that come from?
lw395
Well-Known Member
Heating and agitating the battery. Seen this happen!
Chanquete
Well-Known Member
The voltage was lower because the plugs consumed more than 30 Amperes. As soon as the plugs were disconnected without startin the engine the voltage increases to values without current consumption. As the engine was running and charging the battery one hour before I performed this test the voltage without consumption increased from 12,64 when I just arrived at the boat to 12.85
KompetentKrew
Well-Known Member
Yes, the fall from 12.64v to 10.3v seemed obvious.
It's the rise from 12.64v to 12.85v for no apparent reason that I don't understand.
It's the rise from 12.64v to 12.85v for no apparent reason that I don't understand.
Chanquete
Well-Known Member
After a week of inactivity I went to the ship. At that time measured a battery voltage of 12.64V
Then I activated the glow plugs and measured 10.3V during warming.
I started the engine and let it running and battery charging for an hour.
Then I stopped the engine , disconnected everything and measured a battery voltage of 12.85V.
This increase seems obvious due to the recent charging.
Then I activated the glow plugs and measured 10.3V during warming.
I started the engine and let it running and battery charging for an hour.
Then I stopped the engine , disconnected everything and measured a battery voltage of 12.85V.
This increase seems obvious due to the recent charging.
PaulRainbow
Well-Known Member
You need to be very clear about the 12.85v reading.
You first said you took that reading without running the engine.12.64v is about 95% charged, 12.85v is fully charged.
Getting from 95% to 100% by just using the glow plugs is not possible, if it is i'll be energising my glow plugs for 13 minutes each hour and i'll never need to charge my batteries.
If, on the other hand, you ran the engine for an hour, stopped it and immediately too a voltage reading, that reading is meaningless. To take a reading after charging you need to leave the battery at rest, no load or charge, for quite some time.
Back in post #4 i suggested you take some readings and said exactly how they should be taken. They needed to be taken at the battery, with a reliable voltmeter (multi-meter is ok), not the boats panel meter, these are not generally accurate, as you found. They also needed to be taken at specific times, as i said. Taking them at different times, or running the engine makes the readings meaningless.
Taking the final reading after running the engine only tell you that the alternator is charging, you could have done that test without using the glow plugs. Taking it 10 minutes after using the glow plugs gives an indication of how much the battery was affected by using the glow plugs.
That said, i suspect your battery is OK, but would benefit from being on charge to get it to a genuine 100% SOC on a regular basis.
KompetentKrew
Well-Known Member
Right, but I thought the point was to measure the battery voltage before and after putting the load of the glow plugs on the battery, but WITHOUT running the engine.
Perhaps the post which asked you to do this was not explicit about the without-running-the-engine part, but running the engine charges the batteries again. As you say, this is obvious.
But you don't want to know the batteries' state of charge after being recharged again by the alternator - to learn the condition of the batteries you want to test them being loaded and discharged. You measure their voltage, put the load on, take the load off and see if the voltage returns to (nearly*) where it was before. If it does then they're good.
If loading the batteries for a short period lowers the battery voltage significantly* then that means that the load is flattening the battery and it may be knackered.
* I don't know the correct values for "nearly" and "significantly" here, but others on this thread do and can diagnose if you give them the measured values.
Chanquete
Well-Known Member
I checked the voltage of the battery , before and after putting the load on, and after taking the load off I found the same voltage as before.