house/chassis, isolation and charging systems

[bodaver32]

Hello all.

I need to design/purchase the components for the 12v system of the bus. My intentions are to have a 12v DC/120AC distribution center, a chassis battery (wet cell) and a house battery(AGM). When on shore power the distribution center has a three-stage Wizard charger that will recharge the house batteries.

When traveling I would like to use the alternator to help charge both but am in need of determining the best way to isolate them. I have looked at all options. I am curious what others are doing. The Cole Hersee Smart Battery Isolator intrigues me, but don't believe you can mix wet cell and AGM batteries with the system.

[bodaver32]

pjespers,

I take it you don't have any issues/problems with the voltage drop across the isolator or it working your alternator more. I do have an externally regulated alternator so the use of an isolator would be easier to wire into the regulator to compensate for the voltage drop.

[bodaver32]

check this out.....
http://www.colehersee.com/pdf/hot_fe...BatteryIso.pdf

I emailed their tech services with some questions and got this response......

The smart battery isolator does not have any internal regulation to prevent the AGM from overcharging. However, with most AGMs if your alternator is regulated to not put out more than 14.4V (as is typical) you should have no problem with the AGMs. Check with your AGM manufacturer to get their recommended max charge voltage from an alternator. The problems with over charging AGMs mostly come from using cheap 120V chargers that do not do three stage charging. Those chargers can put out close to 16V to achieve rapid charging and this is when you can get damage to AGMs. With the voltage regulated off of your alternator at the recommended level for your batteries, the battery will cease taking a charge when the reach that level and they will not overcharge. I would have the output of the alternator checked to make sure that it is not putting out over the recommended value and also measure the voltage that is reaching the auxiliary bank with the isolator in place. The other issues that have been mentioned with mixed banks (AGMs stealing charge during charging, and starting batteries stealing charge during engine off operation) are mitigated by the smart isolator with its start battery charge priority.