Yep! From: Af [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, September 02, 2015 11:47 AM To: [email protected] Subject: Re: [AFMUG] 48v charging systems
Cycling the batteries rather than floating them will cause them to have a shorter lifespan. You never know where the surge is coming from or going to. Cat 5, tower steel, ground, power etc. From: Paul McCall<mailto:[email protected]> Sent: Wednesday, September 2, 2015 9:43 AM To: [email protected]<mailto:[email protected]> Subject: Re: [AFMUG] 48v charging systems That seems similar to what we have now flow wise, with fuses etc. Somehow I was thinking that if the charging system could be isolated from the batteries themselves that a strong surge can’t blow past the charger and up to our gear. I see what you are saying… I could run the charger on a timer only, but the timer could still be a point of vulnerability. I know it sounds funny, but I have actually been thinking of an RF based (cellular or digital 2-way service) to remote power cycle or turn on/off AC to a tower, in the event of pending nasty storms. We watch the weather pretty close here and have had lots of incidences this season. From: Af [mailto:[email protected]] On Behalf Of [email protected]<mailto:[email protected]> Sent: Wednesday, September 02, 2015 11:00 AM To: [email protected]<mailto:[email protected]> Subject: Re: [AFMUG] 48v charging systems Well, normally the bus voltage is 55 volts. And the charger/rectifier is paralleled with the batts and the load. I like fuses on the charger and on the batts. You want a fuse on the charger that is equal or slightly larger than the maximum charger output current. Fuses on the load appropriate to the load and wiring. Charger/rectifiers that are designed for float duty like this do not present any load to the batts when the power is off. No need for steering diodes or anything like that. One way to get a high quality charger is a solar charge controller. Then you can feed them with a cheap and dirty source. Consider whether you have to tie the + side to ground. I would float everything if I can, but some radios tie one side to ground so you may as well try to do common point grounding if that is the case. The only way I know to get true and total isolation is with a motor – generator set and still an impulse could be conducted through the grounded chassis of the device. From: Paul McCall<mailto:[email protected]> Sent: Wednesday, September 2, 2015 7:00 AM To: [email protected]<mailto:[email protected]> Subject: [AFMUG] 48v charging systems We are new to 48v, but are considering running 48v and fiber up the tower. What are the best devices to charge the batteries? Right now, we are using a 24v system with a common bus bar that allows everything to run off either batteries or AC to DC charger output. Was thinking conceptually of somehow isolating that so that everything only ran off the batteries if that is possible, thinking that might protect us better from surges, but maybe that isn’t possible. Hmmmm… Paul McCall, Pres. PDMNet / Florida Broadband 658 Old Dixie Highway Vero Beach, FL 32962 772-564-6800 office 772-473-0352 cell www.pdmnet.com<http://www.pdmnet.com/> [email protected]<mailto:[email protected]>
