Sooo, when will we see a Cheap Controls Systems automatic charger ?
From: Frank Pittelli <[email protected]> To: [email protected] Sent: Saturday, November 26, 2011 12:19 PM Subject: Re: [TANKS] Battery do's and don'ts > 1: Does it harm a SLA battery to fully depleate it's charge? Yes. A normal 12V SLA battery should never drop below 11V. > 2: Dose it harm a SLA battery to only recieve a partialy charge? No. > 3: If over charging a SLA battery occurs, how long would it take > before damage occurs? Depends on how high the charging voltage is during the over-charge period and the specific type of SLA battery. Old-style refillable batteries start boiling off liquid and need to be refilled. Sealed SLAs also start boiling off liquid, but can't be refilled. Newer glass-mat (AGM) SLAs are less likely to be damaged. Back in our warship days, quite a few SLAs died an early death because of over-charging in the motel room when we forgot to turn down the charging current before going to bed. > 4: Is the life of a SLA battery measured in months/years or by charge > uses? Both. SLAs only last a certain number of full re-charge cycles (roughly 250 for inexpensive batteries) and they only last about 5 years, whether they are used or not. Basically, the plates used in the battery corrode to the point where the chemical reaction isn't efficient enough to provide current. Better chargers allow batteries to last longer (by counter-acting the corrosive process with reverse voltage cycling) and more expensive batteries last longer because of thicker/better plates, but all SLA batteries are still limited by age. Even a battery just sitting on the shelf will die over time because of internal resistance which discharges the battery. If you leave the SLA on a cold surface, like a cement floor, it will discharge even faster because of thermal convection inside the battery. > 5: How long is the life of a SLA battery? 4-5 years for normal SLAs. > 6: Is it common for 1 SLA battery in a pair to go bad before the other? Yes. Any difference in resistance between a pair of batteries will cause one to be used slightly more than the other. Over time, the difference widens because of the unbalanced use, so one battery dies before the other. Large battery banks, such as those used in electric vehicles, counter-act this problem by using simple electronic circuits that continuously monitor the resistance of each cell/battery used in the bank and electrically balance the resistance so that all cells/batteries share the load equally. Those circuits are now fairly inexpensive and can be used with a two cell/battery bank just as easily as a 10 cell/battery bank. Typically, the same circuit is also used during the charge cycle to ensure that all cells/batteries charge evenly as well. Frank P. -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat
