[Repeater-Builder] Suggestions for Gel Cell Charging - Large Array
I have a site which seems to be at the bottom of Idaho Power's to-do list when it comes to outages. The last major service interruption for for 8 days. Previously, our repeater was piggybacked on a commercial user's battery back up which gave us working power for about 3 days (duty cycle on the commercial gear was much higher than our equipment). That company has since gone belly up and removed their equipment and back up power leaving us with nothing but AC to rely upon. I've inherited several dozen Gel Cell batteries previously in use for CATV line equipment power supplies. These are rated at 85-90 amp hour. Our plan in the spring is to put 10 of these up on the site for roughly an 800 amp hour array, with plans to go up from there. The vast majority of the Ham plans I've seen on the web are designed for 7-12 amp hour Gel Cell charging at a rate of less than 1 amp. Is there an a relatively inexpensive method of charging these batteries without completely breaking the bank? I know in a recent conversation here on RB, one of the users had a Solar Charge Controller inline between his 12 volt power supply (in our case a GE Mastr II 30 amp supply) and the actual repeater equipment. Any *useful* information is much appreciated HI HI :) 73s, AJ, K6LOR
Re: [Repeater-Builder] Suggestions for Gel Cell Charging - Large Array
AJ wrote: snip I know in a recent conversation here on RB, one of the users had a Solar Charge Controller inline between his 12 volt power supply (in our case a GE Mastr II 30 amp supply) and the actual repeater equipment. That was me askin' the questions, and Doug doin' all the answerin'. :-) Basically, what he (and others) advised was to make sure of the maximum charge rate on your batteries, and to not exceed that charge rate. Doing so causes heat buildup in the batteries and will over time boil them dry, causing failure. Google Xantrax (I think that is how it is spelled) solar charger and you should find what you want. Your application is exactly the same as ours, except we are probably only looking at 8 hours. After that, we can pull one of our trucks up to the site and use jumper cables if it is still out... Anything to add Doug? Mike KA4MKG
Re: [Repeater-Builder] Suggestions for Gel Cell Charging - Large Array
These units are very popular with RV boat folks. I have the 60 amp version in my truck camper, I am very happy with it. By what I can determine, it will give a full charge in about 8 hours. I have it feeding a 190 AH battery string. You will have to work the numbers to find out the charge time, I would buy the 80 amp version. It will take a while to bring a string that size back up. Make sure you add a low voltage disconnect to protect the batteries. If they go flat, they will never come back to their original capacity. If you use a charge controller, and a 13.6 supply, the job will get done eventually. Note the charge curves. http://www.progressivedyn.com/prod_details/charge_wizard.html Best Converter seems to have good pricing on them. http://www.bestconverter.com/80-Amp-RV-ConverterCharger_p_173.html If you want really snaz it up, use a battery monitor gauge. http://www.xantrex.com/web/id/274/p/1/pt/5/product.asp You can use the alarm relay to trip your controller, to tell you when the battery capacity has gone below the set threshold. I have read, repeated discharges below 50% are not recommended for long life. At 10:04 AM 2/16/2009, you wrote: I have a site which seems to be at the bottom of Idaho Power's to-do list when it comes to outages. The last major service interruption for for 8 days. Previously, our repeater was piggybacked on a commercial user's battery back up which gave us working power for about 3 days (duty cycle on the commercial gear was much higher than our equipment). That company has since gone belly up and removed their equipment and back up power leaving us with nothing but AC to rely upon. I've inherited several dozen Gel Cell batteries previously in use for CATV line equipment power supplies. These are rated at 85-90 amp hour. Our plan in the spring is to put 10 of these up on the site for roughly an 800 amp hour array, with plans to go up from there. The vast majority of the Ham plans I've seen on the web are designed for 7-12 amp hour Gel Cell charging at a rate of less than 1 amp. Is there an a relatively inexpensive method of charging these batteries without completely breaking the bank? I know in a recent conversation here on RB, one of the users had a Solar Charge Controller inline between his 12 volt power supply (in our case a GE Mastr II 30 amp supply) and the actual repeater equipment. Any *useful* information is much appreciated HI HI :) 73s, AJ, K6LOR
Re: [Repeater-Builder] Suggestions for Gel Cell Charging - Large Array
That was the general gist... The Charge controller will pass dc through from the charger or in this case the power supply to the load under normal operations, but be aware of the maximum current flow needed for the repeater as well as the batteries for charging.. a large stack of batteries has different charge rates and floats per battery... paralleling them makes for messy charging... Everything assumes each battery will charge/discharge at the same rate.. if the batts are matched this is true.. but 12v batts tend to be made up of several cells and those individual cells age differently in most batteries... assumptions will boil a cell and avalanche from thereOne larger battery is better than several smaller batteries... or put a separate charger on smaller groups... A big bank of say 8 90a/hr batts is going to take a lot of charge and that level could hurt the weakest cell in the lot under full bulk charge.. the deadest batt will take current first but 800 a/hr worth of batts will take a long time to recover if a discharge occurs...at 30 amps... sustained like 24hrs... if you double the charge current with a bigger charger.. you could be charging one battery at 60 amps.. and you should be real careful about that... Most serious battery stacks are series arrangements.. and higher voltage but flat current through the system... then run a UPS to get to 110v Many of Trace Engineering (Xantrex) and other makers of UPS type Inverters use 4 12v batts in series for 48v... the invert to 110v.. Series and higher voltage uses smaller wire gauges to accomplish backup... I would recommend talking to vendors before paralleling 10 batteries on a 12v charge controller...I would think some additional engineering would be suggested... Paralleling 200-300 amp batts is one thing.. paralleling 80-90 amp gel cells is another matter... especially 10 of them... Surplus is not necessarily a bargain Doug KD8B At 10:48 AM 2/16/2009, you wrote: AJ wrote: snip I know in a recent conversation here on RB, one of the users had a Solar Charge Controller inline between his 12 volt power supply (in our case a GE Mastr II 30 amp supply) and the actual repeater equipment. That was me askin' the questions, and Doug doin' all the answerin'. :-) Basically, what he (and others) advised was to make sure of the maximum charge rate on your batteries, and to not exceed that charge rate. Doing so causes heat buildup in the batteries and will over time boil them dry, causing failure. Google Xantrax (I think that is how it is spelled) solar charger and you should find what you want. Your application is exactly the same as ours, except we are probably only looking at 8 hours. After that, we can pull one of our trucks up to the site and use jumper cables if it is still out... Anything to add Doug? Mike KA4MKG
