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#1
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Lowest Battery voltage
Hi Guys.
I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. |
#2
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Lowest Battery voltage
On Sun, 7 Dec 2003 10:42:47 -0000, "John" wrote:
Hi Guys. I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. Too many variables to answer that question. The actual performance is concerned with total power supplied to the cranking motor not the voltage. You would have to do a plot of voltages under all environmental conditions, like temperature of the battery and engine being started, state of the battery charge, wear on bearings, brushes, mechanical factors etc.. As batteries age they build up sulfate deposits on the plates which insulate the plates from the electrolyte. Your load of 1/2 amp is added to the normal self-discharge of the battery. "A few days" four days with a 1/2 amp load and self discharge would eat into your 100 amp hour capacity. That type of service (discharging over a period of days with a low state of charge) is bound to increase the sulfate problem. Put a charger on it if at all possible - something that can replenish the half amp and goose the plates enough to prevent or reverse sulfation. Failing that solution - rig a means of turning on the engine periodically and running it for an hour without regard for the thermostat. That will help warm the battery and engine while charging the battery. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#3
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Lowest Battery voltage
Divide and conquer. Rig a deep cycle for the control and leave the regular
battery for starting. Everytime a regula r car battery is fully discharged it loses a significant portion of its life and after 10 or 20 of these it's worhtlessfor starting but a deep cycle is made to discharge totally hundreds of times. hank wd5jfr "John" wrote in message ... Hi Guys. I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. |
#4
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Lowest Battery voltage
Thanks guys.
I thought it may be a difficult one, the fridge is on a trailer (semi) so no external charging system permitted. Solar had thought of that, and am looking at a trial. The 500mA is drawn by the controller and management system, the facility to be able to have the controller start/stop the fridge from a remote position was not part of the original manufactures brief (added at the request of the customer) so no provision was made to power down unnecessary systems. The battery draws directly from the alternator so no current limitations. To further complicate the issue, the engine is also capable of start/stop depending on temperature. The controller does have a sleep option (restart the unit when battery drops to 12.2v or engine temp below ox), this would require changes to software. So in an ideal world, with a new 100Ah charged battery how long do we have before the battery power is so low that it will not turn the starter and power the controller. John. "John" wrote in message ... Hi Guys. I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. |
#5
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Lowest Battery voltage
On Sun, 7 Dec 2003 19:09:55 -0000, "John" wrote:
Thanks guys. I thought it may be a difficult one, the fridge is on a trailer (semi) so no external charging system permitted. Solar had thought of that, and am looking at a trial. The 500mA is drawn by the controller and management system, the facility to be able to have the controller start/stop the fridge from a remote position was not part of the original manufactures brief (added at the request of the customer) so no provision was made to power down unnecessary systems. The battery draws directly from the alternator so no current limitations. To further complicate the issue, the engine is also capable of start/stop depending on temperature. The controller does have a sleep option (restart the unit when battery drops to 12.2v or engine temp below ox), this would require changes to software. So in an ideal world, with a new 100Ah charged battery how long do we have before the battery power is so low that it will not turn the starter and power the controller. John. Minimum should be ~two days Maximum 5-6 days, given a battery in good shape with a 100 AH capacity, but that's only my guess. Your battery wouldn't last long in that type of service so the capacity would probably drop quickly with time. Solar cells and charge controller would be expensive. Not to mention that it only takes shade on one cell of an array to limit the entire panel's output. With a semi, tracking arrays are probably out so your panel(s) would have to be very large, to compensate for the amount of sunlight you'd miss. Have to watch where it is parked also. I think Henry has the best idea - controller battery and starter battery. Small propane, or gas powered genset that runs continuously, or runs when necessary to maintain the battery? Be nice if there was some chemical means of providing the jolt to start the diesel. Compressed air starting would be a natural also. Anything you can do to use less power at the controller? -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#6
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Lowest Battery voltage
"John" wrote in message ... Hi Guys. I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. something mechanical that does not need power to initiate the control system might work. You could probably go a couple of weeks with this type of system. Lane |
#7
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Lowest Battery voltage
Simplest fix's.
The simplest fix would be to have the engine restart when the battery drops to 12.2v, run for a while then go back into standby. Alternate would maybe be a PIC that monitors voltage, if sees 12.2v for x period time (overcome spikes etc) start the engine for y period of time, providing that the controller is switched on etc. Does anyone know of a stand alone voltage/current data logger kit that could log the battery for a few weeks (UK). John. "Lane Lewis" wrote in message ... "John" wrote in message ... Hi Guys. I have the following problem, could you please help provide a little insight into the calculation. A piece of refrigeration equipment has a 50hp engine with a 12v control system, an alternator for battery recharge and of course a 12v (100Ah) battery for starting. The control system has a remote temperature and standby/ready control. To use the remote standby function the main controller must be on. The problem is this. When in standby mode the current draw from the battery is about 500mA, if the system is left in this state for a few days then the battery does not have enough capacity left for the starter to crank the engine. Question. What is the lowest voltage/capacity that the battery can be allowed to drop to but still be able to start the engine (12.2v seems to be the industry standard voltage). Finally how does the result equate to time e.g. do we have 20 hours at 500mA or 50 hours at 500 mA before the battery capacity is to low to crank. Battery standard lead-acid deep cycle type 100Ah. With a good battery during crank the voltage drops to 9.5v and rises to 10.5v. Same battery, initial engine crank current (cold) is 135A dropping to 36A. The engine is a direct injection diesel so starts in around 2 seconds. Thanks. John. something mechanical that does not need power to initiate the control system might work. You could probably go a couple of weeks with this type of system. Lane |
#8
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Lowest Battery voltage
Henry Kolesnik wrote:
Divide and conquer. Rig a deep cycle for the control and leave the regular battery for starting. Everytime a regula r car battery is fully discharged it loses a significant portion of its life and after 10 or 20 of these it's worhtlessfor starting but a deep cycle is made to discharge totally hundreds of times. hank wd5jfr "John" wrote in message ... Even with deep cycle batteries, it is best never to fully discharge them. The only difference in these batteries is an extra large gap between the bottom of the plates and the casing bottom. This allows for more charge cycles before the inevitable 'crud' (I dont know the technical term) piles up on the bottom enough to short out the plates. -- Luhan Monat, "LuhanKnows" At 'Yahoo' dot 'Com' http://members.cox.net/berniekm "The future is not what it used to be." |
#9
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Lowest Battery voltage
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