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Thread: Ready to update Olson 34 battery banks

  1. #1
    Contributing Member II
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    Ready to update Olson 34 battery banks

    The boat currently has a deep cycle and starting gel batteries combined with a smart charger. I notice there is a voltage regulator on portside of the engine compartment. This is where the questions begin. I plan on replacing with the batteries with either gel or agm.

    The smart charger selector is limited to gel or flooded. So I am not sure if agm is an option for the charger.
    An additional concern is charging while motoring. As mentioned, there is a voltage regulator but there is no information as to the voltage output.
    I can test the regulator with the motor running. How much voltage output would charge without damage to gel or agm?

    Lastly, do I need some sort of smart charger for the alternator? or is there a simple less expensive way to accomplish a safe charge while motoring with the M25XP.


    Appreciate any insight that will save me from new battery destruction.


    Mark

    San Pedro

    Olson 34 "Wing Ding" Hull #35 built 1990

  2. #2
    Principal Partner footrope's Avatar
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    I looked for a gel group 24 battery to replace my start battery recently and really didn't find many for sale. Flooded (wet cell) batteries and their chargers and regulators are generally cheaper than gel or AGM batteries. My experience is with AGM batteries.

    AGM batteries need to be investigated individually because recommended charge voltages vary by manufacturer and some vary the recommended charge voltage based on the temperatures/environment in which they are operated. If you get AGM batteries you should have a 3-stage smart charger for use at the dock, for the best results and longest battery life anyway. Smart chargers can usually be adjusted to meet any AGM or wet cell manufacturers voltage recommendations.

    Modern Smart chargers provide initial bulk charging at constant voltage. When the battery reaches the right conditions the charger switches to absorption mode to fully charge the battery, usually at a similar voltage to the bulk setting. Once the absorption parameters are achieved, the charger switches to float at a lower voltage, about one volt lower than the bulk voltage for example. This voltage is maintained for long periods of time. Check out Xantrex or Balmar (not a recommendation for either, but they are well-known) and other brands to see how the smart chargers work for AGM batteries, if you choose that type.

    Smart alternator regulator - I'm starting to look for a couple myself for AGM batteries. Currently I use an external regulator that allows me to set bulk charge voltage to the manufacturer's spec and then it charges for a length of time that I can set. When the time is up it switches to a float setting. Not an ideal situation if you motor for long periods of time.

    Good luck and get some info and advice from a marine battery dealer.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20, Universal Diesel 5432
    Gig Harbor, WA


    In Puget Sound there are only two directions to go - North and South. That applies to the boat and the wind.

  3. #3
    Contributing Member II
    Join Date
    Jan 2017
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    San Pedro, CA
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    Battery replacement Olson 34

    Thanks for your valuable feedback. After pulling the batteries out of the boxes, I found both to be West Marine SeaGel Deep Cycle Gel 73ah. Since the batteries have been in service since 2006, one dedicated to starting and one house. I decided to go with the same. They are rather expensive but 12 years of service is not bad.

    Quote Originally Posted by footrope View Post
    I looked for a gel group 24 battery to replace my start battery recently and really didn't find many for sale. Flooded (wet cell) batteries and their chargers and regulators are generally cheaper than gel or AGM batteries. My experience is with AGM batteries.

    AGM batteries need to be investigated individually because recommended charge voltages vary by manufacturer and some vary the recommended charge voltage based on the temperatures/environment in which they are operated. If you get AGM batteries you should have a 3-stage smart charger for use at the dock, for the best results and longest battery life anyway. Smart chargers can usually be adjusted to meet any AGM or wet cell manufacturers voltage recommendations.

    Modern Smart chargers provide initial bulk charging at constant voltage. When the battery reaches the right conditions the charger switches to absorption mode to fully charge the battery, usually at a similar voltage to the bulk setting. Once the absorption parameters are achieved, the charger switches to float at a lower voltage, about one volt lower than the bulk voltage for example. This voltage is maintained for long periods of time. Check out Xantrex or Balmar (not a recommendation for either, but they are well-known) and other brands to see how the smart chargers work for AGM batteries, if you choose that type.

    Smart alternator regulator - I'm starting to look for a couple myself for AGM batteries. Currently I use an external regulator that allows me to set bulk charge voltage to the manufacturer's spec and then it charges for a length of time that I can set. When the time is up it switches to a float setting. Not an ideal situation if you motor for long periods of time.

    Good luck and get some info and advice from a marine battery dealer.

  4. #4
    Senior Moderator Loren Beach's Avatar
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    Electircal

    I have not tried an alternator built for (or converted to) external regulation. I did get good charging out of the stock Moto 50 alternator on our M25XP engine up until I changed it out for a Beta 25 this year. The new engine has a 70 amp alternator with internal regulation, BTW.

    I did convert from the stock pair of group 24 (12 volts each) batteries under the step to using that area for a pair of flooded golf cart batteries and then adding a separate emergency 12 AGM battery under the aft berth. Pictures are here, in my blog. This was done back in the 90's.

    If you can live with the output of one group 24 battery, at a time, the factory location is ideal from the standpoint of weight placement. We wanted the larger amp-hour house bank for cruising with refrigeration in use all the time.

    We have also kept the stock 1-2-all switch. We also replaced the ancient-technology ferro resonant factory charger with a 'smart charger' in about '95 or so.
    Last edited by Loren Beach; 08-11-2018 at 05:04 PM.
    1988 Olson 34 #8
    Sail # 28400
    Betamarine 25 (new 2018)
    Fresh Air
    Portland, OR USA

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