[quote author=Rich link=board=2;threadid=10425;start=msg96572#msg96572 date=1075339089]
My comments are based research I have done in the past regarding installing parallel banks of batteries in boats (common and very comparable to an offroad truck with engine off loads such as a fridge) and also more recently regarding using large banks of parallel batteries to provide either backup or primary power in a residence when the power grid is not available. The recomendations have been universal that when charging and loading batteries in parallel it is best that they are same type, model, manufacturer, and age. Obviously in a large bank, say in a home backup, if a battery suffers early failure it would get replaced with a newer battery, but still should be the same manufacturer and model.
So, to get more info, do a search on dual battery marine installation and residential solar power for more background. Online marine stores offer books on 12 volt wiring, including dual battery installations, for marine use.
Rich
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as you suggested I did some reading about banks of batteries very interesting and you are very correct about banks used in solar homes RV and marine use where they are discharged together but I think in this app as long as they are not paralleled without charging current (engine off) I should be OK with mixed batteries,
seams if
mixed batteries are paralleled without a charging current pressent then the one with the higher charge (if they are not identical models and age one will always be better off than the other) will try to charge the lower, not only does this leave you with 2 lower level batteries but charging a battery is not 100% efficient so when they finally find their level you will have less total capacity between the two than when you killed the engine
my earlier post above I was thinking of the charging side did not think of what happens when they go to discharge
the way I want to use them is one deep cycle "Tank" battery for all accessories that can safely be used with the engine off isolated from the Starting battery without fear of not being able to restart, also want the tank batteyr to keep voltage up to the accesories (prevent reboot) during starting so I need then to stay isolated until the alternator kicks in, not sure how I am going to do that (still have more reading to do) since they are only parallel with the alternator turning the two batteries should not interact as long as the alt can keep up,
depending on how much $ I can swing into the dual batt project I may go with 2 Odyssey's making the above a mute point
I have read that mods need to be made to fit the a 1700 into the USDS tray, but in my searching no one specified exactly how extensive? I don't mind modifying/replacing the hold down and cabling but I do not want to loose the heat protection of the box/tray
could any one elaborate? And what about the USPS added tray? Will it fit the 1700MJ if not will the 1200MJ fit?
Also if anyone knows the Max group size for both trays that would be great to know
the preliminary specs for the new
2150 put it to have a very similar footprint to the 1700 just taller witch I assume is not where the fit problem is? So if you can modify for the 1700 the 2150 might fit also?