theoldwizard1 wrote:
Photomike wrote:
On that subject during the build of my vans electrical system I had the opportunity to talk to one of the suppliers of battery to battery charging systems. He gave me lots of information that I never knew but one point that he made is that many people operate on the wrong assumption that we are doing things outside of what a vehicle or a boat for that matter is designed to do with charging. In fact it is the opposite - a charging system is designed to charge and will do so as long as we do not do something stupid and it will do so with a number of batteries as all batteries will equalize in a system and charge from that point. The charging system does not know if you have 5 batteries at 12.5v or one, it will take longer to top up but it is doing the same thing as it was designed for.
I am sorry, but that person is living in the past ! And fairly DISTANT past !!
Smart charging systems are designed around the assumption that they only have to recharge the ONE (or possibly two) batteries installed by the OEM. The have knowledge on what the "capacity" is of that size battery back. They know (approximately) how much energy was used to start the vehicle. They know (approximately) how much power is being used by accessories and adjust for it. They even understand short, high load (electric power steering).
An auxiliary battery bank will look like a parasitic draw. The system will compensate for it (increase voltage slightly) but not enough to re-charge a house battery bank at 50% state-of-charge.
Old regulators worked on the principle of "the battery voltage is low, charge at max rate." The new one basically says (after replenishing the energy from starting), "the battery voltage is low, charge at a rate that will not let is discharge any more."
That needs a little in-the-field proof... ok it needs a lot of proof, because there are numerous examples that prove the opposite.
Ambulances, police cars, motorhomes... all doing just what we do with our campers.
The new vehicles charging system does not know if the starting battery is low or if there’s aux batteries connected in parallel to it that are low.
The newer vehicles have battery temperature sensors but that won’t prevent them from properly charging, in fact just the opposite because the starting battery isn’t getting hot.
