House battery not charging from chassie

Hi BJean,

There is a fuse. On a Ford it is a 60 amp in the engine compartment fuse box. After the 3rd fuse I replaced mine with an autoreset breaker.

There is a relay. The contacts may burn. Replace with one that is much larger sized. I went to a 200 amp rating.

Yep and to eliminate the mess entirely use what Mr. Pianotuna suggests in the form of a



Sure Power Battery Separator
Part #: 1315-200

The Sure Power Battery Separator is designed for use in multi-battery applications as a excessive loading while allowing auxiliary batteries to be charged. The Sure Power Battery Separator has two basic operational characteristics.

Bi-Directional Battery Separator :
Able to have two charge sources connected; one upon the Main Battery, and a second upon the Auxiliary Battery - This means that the charge current can go in two different directions, from the Main Battery to the Auxiliary Battery, or the Auxilary Battery to the Main Battery. Whichever battery is connected to the ACTIVE charging source will be considered the "Main Battery" as far as the functions of the Battery Separator are concerned.

Voltage: 12 Volts
Amperage: 200 Amps
Approx. Item Weight: 3 Pounds


https://www.allbatterysalesandservice.com/graphics/INSTRUCTION_1315-200.pdf

Eliminating wires, switches and junk grade relay/solenoid will eliminate about 99% of the chance you will have a charge interconnect problem for the next (many) years. Solenoids with switches are buggy whips. Vulnerable buggy whips. Yuck.

Yes, when the relay that MEX pictured in his post above energizes a few seconds after you start the engine, you should hear it click while switching the house batteries into the chassis charging system. No click, no work. But as previously mentioned, the contacts do get dirty and fail to work.

Make sure the house battery terminals are clean.

Chum lee

The beauty of a 200-amp rated relay. A White-Rogers not a scumbag no-brand. The Sure Power will work for years unless subjected to an intense seashore salt-air environment. From experience with dozens of these units.

Again - the secret is to choose the 200 ampere model.

Scumbag, metal case standard relays are pre-broken as they leave the assembly line. You couldn't PAY ME to use a scumbag relay. Been there done that. As foolish a choice as my choosing Wal-Mart's, Douglas Tires.