Your math doesn't work for me.
I thought that if they are in series it's still only 120 amp hours, but at 24V. If you put them parallel then it's 240 amp hours at 12V.
1 amp of 24V power is twice as many watts as 1 amp of 12V, or equal to 2 amps 12V as there is 1 amp 12V going to each of the batteries.
1 amp 24V = 24 watts power
2 amps 12V = 24 watts power.
The total available watts is the same either way you do it, but in one configuration it's higher voltage, the other configuration it's higher amperage.
To be correct the MEP’s alternators have about 1/10 of current output compared to an average Truck or V6/V8 Alternator and on top off that is that the starter is 300% bigger than an average starter on those trucks / cars
If an average starter in a car draws 40 to 60 Amps to crank the engine than the MEP starters will draw 120 Amps to 180 Amps on each crank you do - that’s why cranking is limited to 15 seconds max - otherwise you will see multi colored smoke coming out of your starter, which is really a spectacle to watch with double vision after a case of beer and a couple joints, might be even better after popping some LSD........
Last edited by peapvp; 10-07-2019 at 22:53.
Peter
INOVA HIGHTECH Ltd.
Cage Code 6ZJM5
Replacement Transformer T2 MEP004/5A Complete Kit NSN: 5950 00 600 0840
MEP 0xx and 8xx Auto / Remote Start Kits - THE ORIGINAL - since 2013!
Thank you for being a Customer!
Watt is Volt x Ampere
batterie capacity is Amperes x Hours
has nothing to to with VA or Watt
all charging is done by current and time alone - voltage of each cell gets to its max when fully charged
when in series both batteries are drained equally but at the same time each cell has to be recharged
you can get easily a 1000 Ampere per second out of those but you still need to charge 12 cells
Last edited by peapvp; 10-07-2019 at 22:51. Reason: added some missing info
Peter
INOVA HIGHTECH Ltd.
Cage Code 6ZJM5
Replacement Transformer T2 MEP004/5A Complete Kit NSN: 5950 00 600 0840
MEP 0xx and 8xx Auto / Remote Start Kits - THE ORIGINAL - since 2013!
Thank you for being a Customer!
Yes, I'm just saying if you run two 12V batteries in series it doesn't make 240 amp hours of power, it makes 120 amp hours of 24V power, so charging at 1 amp at 24V will only take 120 hours not 240.
If they were in parallel then it becomes 240 amp hours of 12V power, and charging at 1 amp of 12V would wake 240 hours as you previously stated.
Coug, this would be correct if your battery is a constant voltage source as you would need it to be in a inverter system.
However, when operating a starter with very high current need then the battery system becomes a constant current source
this is very very different from a constant voltage source, as voltage completely falls out of the picture and time enters the picture hence ampere hours becomes irrelevant as everything is shifted to Ampere seconds which is joules
if you take 1000 joules out for 10 seconds and you have only 10 joules per second available to charge then it would take 1000 seconds of charging
Last edited by peapvp; 10-07-2019 at 23:35. Reason: Typo
Peter
INOVA HIGHTECH Ltd.
Cage Code 6ZJM5
Replacement Transformer T2 MEP004/5A Complete Kit NSN: 5950 00 600 0840
MEP 0xx and 8xx Auto / Remote Start Kits - THE ORIGINAL - since 2013!
Thank you for being a Customer!
Yes, but that is different from saying that 2 12V 120 amp hour batteries in series is 240 amp hours of power, when it is no longer 12V input/output but now 24V, you can't double the amp hour rating when you double the voltage.
This seems like you're confusing the original math. Joules is energy use over time, typically watt-seconds. as previously stated, watts are amps x volts. The original math that I had an issue with was the 240 amp hours of power from 2 12V 120 amp hour batteries in series, and that charging at a rate of 1 amp hour would take 240 hours to charge. You don't charge 2 12V batteries wired in series at a rate of 1 amp hour at 12V, unless you are charging them one at a time individually, or you want your batteries to die a horrible death very quickly.
Being a constant current source or constant voltage source when cranking the starter doesn't have anything to do with charging the batteries at 1 amp hour.
Joules per second is equal to watts. 1 watt is 1 amp at 1V.
So a charge rate of 1 amp on a 12V system would be 12 watts. 1 amp on a 24V system would be 24 watts power. Hence, for the same total amount of stored power, 24V will charge at a rate twice that of a 12V at the same amperage. And series versus parallel system. These generators and most military equipment is based on the 24V source, not 12V, so using 2 12V batteries makes it 24V, and if they are both 120 amp hour batteries at 12V, putting them in series is 120 amp hours of 24V.
I don't want to get into the current supply vs voltage supply, as that has nothing to do with the original math you posted that I disagreed with.
These gen sets are not designed for starting and stopping, or short term running. They are made to run for days and weeks at a time. Just one of the reasons we always ran a set 6-8 hours after a repair, at full load, was to fully charge the batteries. When a customer took one of our sets, it had to be right.
The 00X gen sets were not so affected by low batteries. The 80X gen sets do not act well with low battery's. It is very important to make sure they are in top condition. The whole time Kris has had this set, he has never had an opertunity for a long run.
Very good info about the batteries. I have been considering a solar cell trickle system so I don't have an extension cord or remember to plug it in.
I could mount it atop the gen. if the solar cells can take the vibration. I have solar cells on my property operating my security system and been in operation for years.
Update:
I finally ran Peters request to check hz and volts at L1 and L0.
I was witnessing on the control panel the hz and volts varying.
hz was varying from 59 to 60 hz. The volts varying about 2 volts at 208 setting.
So peter instructed me and patiently helped me set my DMM to hz.
Started the gen and compared the control panel gages to the DMM with no load on the gen
Panel switch was in the L1-L2 position
Results:
Panel was varying 59 to 60 hz entire time the gen was running
DMM was varying approx. -.5 hz starting at 59.5 hz then during 5 mins of running climbed to 60 hz varying only -.05 hz
The readings were the same with the breaker closed and open.
The gen doors were open and the slight breeze seemed the effect the hz. approx. .05 hz
After this test gen was shut down.
Next was to test the volts against the panel and DMM.
Set the DDM to VAC
Started gen and compared volts
Breaker open
Panel: 208 varying +2 volts
DMM : 15.9 volts
Breaker closed
Panel: 208 varying +2 volts
DMM: 119.7 solid no variance
Peter thinks the Frequency regulator in the control panel needs looked at. (Peter correct me if I misspoke)
So I told him I would un install it and have him test and repair.
Also because the volts was not varying he said the A11 was operating to spec
Kris
Murphy is my friend
Thanks Kris, only a formal correction - Frequency Transducer
Note: Kris's DMM in Hz Mode has a AC Voltage Range of 0.7VAC to 600VAC with an Impedance of 10MegOhm - hence the Hz / Voltages displayed with Open Contactor as a result of no load attached to the output terminals - we call this phenomenon cross talk / bleed through / Phantom Voltages - the output terminal wires to the contactor are running in parallel to the already powered wires from the Generator head and are picked up through stray inductance.
Peter
INOVA HIGHTECH Ltd.
Cage Code 6ZJM5
Replacement Transformer T2 MEP004/5A Complete Kit NSN: 5950 00 600 0840
MEP 0xx and 8xx Auto / Remote Start Kits - THE ORIGINAL - since 2013!
Thank you for being a Customer!
Got some bad news.
Tried to start the gen and would not crank the engine.
The Amp gage showed a lot of discharge.
Also the starter would not turn the engine over. It tried but no bueno.
I disconnected the batteries and put them on the charger.
One battery was at 90% and the other was at 95%.
Charged each to 100%
Also verified the battery terminals were clean and tight.
Still no crank. As if the starter was trying to draw more amps than the batteries could produce.
This is what I was reporting last night the last two times about slow crank.
What is yalls opinion
Kris
Murphy is my friend
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