Return-Path: Sender: (Marvin Kaye) To: lml Date: Thu, 01 May 2003 14:03:27 -0400 Message-ID: X-Original-Return-Path: Received: from [148.78.247.24] (HELO hestia.email.starband.net) by logan.com (CommuniGate Pro SMTP 4.1b5) with ESMTP id 2160058 for lml@lancaironline.net; Thu, 01 May 2003 11:41:00 -0400 Received: from regandesigns.com (vsat-148-63-101-227.c002.t7.mrt.starband.net [148.63.101.227]) by hestia.email.starband.net (8.12.9/8.12.9) with ESMTP id h41FelDm009944 for ; Thu, 1 May 2003 11:40:55 -0400 X-Original-Message-ID: <3EB1406D.6050302@regandesigns.com> Disposition-Notification-To: Brent Regan X-Original-Date: Thu, 01 May 2003 08:42:37 -0700 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Subject: Re: Electrical System Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Rob asks: << how much amperage does one need to apply to keep a 27 ampere hour battery topped off. Or better yet what amperage and voltage ie watts is needed to top off a battery on a continuous cycle?>> Rob: The trickle charge power applied to a battery must be greater than the self discharge rate of that battery. The self discharge rate varies considerably with temperature. At 77 degrees F the battery will discharge to 50% capacity in 12 months, 8 months at 90 degrees F. So, if 27 Ah/ 2 =13.5 Ah and there are 5760 hours in 8 months then 13.5/5760 = 2.3 milliamps (not much). You need to add to this any parasitic loads in the system like clocks or other components that draw a small current even when off. The recommended trickle charge voltage is 13.6 to 13.8 volts and regulating the voltage is important to battery life. Too much voltage and the battery will tend to electrolyze it's water. Your 200 mA charger has plenty of power but it is the voltage that is critical. These types of chargers are poorly regulated so checking the voltage without a load will not give accurate results. Your, or any, trickle charger you use should be checked after a day or two of charging by measuring the terminal voltage at the battery with an accurate volt meter. Be sure it does not exceed 13.80 volts DC. More information on these types of batteries is available at: http://www.panasonic.com/industrial/battery/oem/chem/seal/index.html According to B&C, they do not sell the Panasonic batteries but the information provided at the Panasonic site is pretty much generic to this type of battery. Regards Brent Regan