i allways thought it was best to avoid running batteries in parralel if at all possible as no two batterys are the same, on a lot of plan that used to run twin batterys in parralell i've duffed 1 singel bigger battery on it where possible it seems better for it.
there are meany meany ways of doing split charge and i think it massivly depends on what your fitting it to and what it's been used for. on really really simple crude split charge systems that basicly just use a relay that connects the batterys together when the engine is running but battery life is massivly inproved for a shunt, as when you connect a flat battery to a fully charged one a fair whack of current can flow, a very small resitance ( shunt ) can help tame that current down to 20-30 amps.
all the way through to the much newer stuff where the only real option for a heavly used system in an onverter based battry charger they are a good mind as they'll charge the battery quick and safely without cooking it. and an added kicker is you have to take power from the veichels distrobution pannel by the batterty, there is usally a provision for this in the way of an unocupied link fuse , they get uspet if you connect straight to the battery, they monitor current n/out the battery ( pair of small wires from ether side of a shunt going from the dist pannel to the battery is the give away if it dose that )
there are meany meany ways of doing split charge and i think it massivly depends on what your fitting it to and what it's been used for. on really really simple crude split charge systems that basicly just use a relay that connects the batterys together when the engine is running but battery life is massivly inproved for a shunt, as when you connect a flat battery to a fully charged one a fair whack of current can flow, a very small resitance ( shunt ) can help tame that current down to 20-30 amps.
all the way through to the much newer stuff where the only real option for a heavly used system in an onverter based battry charger they are a good mind as they'll charge the battery quick and safely without cooking it. and an added kicker is you have to take power from the veichels distrobution pannel by the batterty, there is usally a provision for this in the way of an unocupied link fuse , they get uspet if you connect straight to the battery, they monitor current n/out the battery ( pair of small wires from ether side of a shunt going from the dist pannel to the battery is the give away if it dose that )