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ContinuousWave: Small Boat Electrical
Improving Re-Charge on Accessory Battery
|Author||Topic: Improving Re-Charge on Accessory Battery|
posted 05-07-2009 06:01 PM ET (US)
My current battery set-up consists of two cranking batteries (for twin motors) and a separate accessory battery. The accessory battery does not retain a charge as the two cranking batteries do. It is fed by a single isolator feed from one of the two motors and grounded to one of the cranking battery's in accordance with Yamaha's rigging guide. The guide also suggests both motors isolator leads can be fed to the accessory battery positive terminal. Will this second isolator lead improve the recharge of the accessory battery? I should add that the accessory battery is not over-taxed; it is usually only powering a GPS and a radio and other low usage items such as a 12V receptacle and fishfinder.
posted 05-07-2009 08:10 PM ET (US)
Charging system are effective charging two batteries when they are putting out 15- to 20-amps. Electrical requirements for a GPS, fishfinder and VHF radio are quite small. Your starting batteries should be able to handle this load. Mine do. You can eliminate your accessory battery and go with dual-purpose batteries when your current batteries expire. These batteries would be more forgiving to deeper discharges.
posted 05-07-2009 08:30 PM ET (US)
More specifically, the typical scenario I am having trouble with would be when I am beached for the day. I would typically have the radio playing for several hours, need to blow up a floating island with an electric pump, etc. I installed the accessory battery so as to not draw down my starting batteries (which are dual purpose). And presumably when I pull up anchor and motor off for a cruise, the accessory battery would/should re-charge. This is the part that is not happening. A couple weekends of this type of activity and my accessory battery is toast. So, specifically, what function do the isolator leads preform, and how can I better maintain charge on the accessory battery?
posted 05-07-2009 08:33 PM ET (US)
P.S. radio refers to stereo/CD player. My head unit is rated at 21 watts RMS.
posted 05-08-2009 05:07 PM ET (US)
What do you have for twin motors? Do you have a BEP battery distribution cluster with VSR?
posted 05-08-2009 06:30 PM ET (US)
Im going to buy this lash up. Been researching and it seem to solve the problem for me for one engine, two batteries. Is smaller foot print the the BEP switches. Blue Seas has similar system to, this is a hybrid using their switch and the BEP VRS to keep both batteries charged.
posted 05-08-2009 08:07 PM ET (US)
Motors are 1999 Yamaha 250 EFI. My current set-up is reflective of the Whaler Factory Installation for dual engine, dual battery set-up as seen in the reference section http://continuouswave.com/whaler/reference/dualBattery.html only with a 3rd battery. This 3rd battery is grounded to the Starboard dual purpose/cranking battery and fed by the isolator lead from the Starboard motor in accordance with Yamaha rigging guide. The guide also suggests the isolator lead from the port engine can be fed to the 3rd battery as well.
posted 05-09-2009 05:31 PM ET (US)
TransAm, from here it looks like you might be discharging the accessory battery more than the isolated charging circuit can recharge in the amount of running time you give it. Or, there is a problem with the isolated charging circuit. And, if the accessory battery has been left in a discharged state it is probably sulfated and will not hold as much charge as when new.
Put the accessory battery on a charger and fully recharge, check voltage after letting set 12-hours, it should be +/- 12.7 volts to be fully charged. Go for a cruise and check voltage when running, it should be +/- 14.? volts. Use as normal for radio, inflation duties, etc. Check voltage again before starting engine, this will tell you well the battery capacity is suited for your use; if it is less than 12.5 volts you need a new or bigger battery. Crank engine and run for a few minutes and check voltage, it should be coming back up towards 14.? volts. At the end of your run, check voltage again before shutting engine off, this will tell you how well it is recharging. Check again a few minutes after shutting engine off, this will tell you how well you have recharged it. If voltage is not 12.7 range, you have not recharged it back to full capacity; you will need to hook up to charger to fully recharge.
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