Charging convertor (starter battery in dual battery system)

[rasu]

Hi guys,

I have an original dual battery system and my own third board battery added.

Holding charging convertor in my hands which will be used for charging the third battery while motor runs.
BEMM says "do not connect anything to the starter battery".

Do you know why there is such restriction ?
Is it because Ford likes only have starter battery isolated from all consumers, or because of real problem with control unit etc. ?
(Starter batterey would keep more power for invertor I would say ).

I´m decided to follow Ford instruction and plan connect convertor to customer connection point (Ford auxiliary battere respectively), but I´m courius about .....

Thanks in andvance.

rasu

[rasu]

While installing the converter I had to try direct connection to the real starter battery.
The system has been running for about 30 minutes with no fault results.

Because such installation is not recommended by Ford, I went back to my original plan recommended by Ford and converter is connected to the Ford auxiliary battery.
I was afraid about enough storm for converter, but no problem, I´m very satisfied with charging ....

N.B. All wires for connection of the third battery (in the back on the driver´s side) were laid under the chassis and thanks to the original hole of proper diameter under Ford batteries container it was very easy make a link without drilling ....

[ake]

The whole point of the Ford surestart twin battery system is the the starter battery is isolated at key off.

All additional loads should be connected to the aux battery via the relevant connectors.