Thread: Slowing Charge Rate 2nd Battery

Hi All

Do any of the electrical guys know how I can slow the charge rate from the start battery to the deep cycle when linked.

My case study: When camping for 3-4 days the fridge runs down the deep cyle into the red.
When I start up the National Lunar system monitors start battery voltage and then kicks in the solenoid linking the two battries. I found that the rush of current is nearly 20 Amps to the rear flat battery and it now seems to have over some time damaged my start battery as I notice from the LED monitor that it doesn't hold charge well anymore.

Is it a good idea to fit an in line sort of regulator so that you only get a trickle charge to the deep cycle and protect the start battery?

Or can the main battery handle this sudden discharge?

Thanks - James

as a very rough rule of thumb for deep cycle batteries (not gel cells, they have a max charge rate on their stickers) the rated max discharge amps is the same charge amps you can use.

Theres a dead simple old school regulator that IVe knocked up thats just a fuse with a headlight with a self resetting circuit breaker in parrallel.

hook the fuse up to the back of the exisiting isolator relay from there splice in the headlight and the circuit breaker in parrallel then hook up to the battery you want to charge.

I use a 7.5 Amp circuit breaker and a 55w headlight with a 20 amp fuse.

It works by the excess amps tripping the circuit breaker so the headlight takes over the current handling which is acting like a resistor therefore limiting the charge rate. The circuit breaker will keep doing the make brake thing till the battery is about 1/2-3/4 charged and then it will stay closed sharing the load between the breaker and the bulb and as the volts on the second battery come up the light does less and less work.

The best place to hook up your load is between the fuse and the controlling solenoid that way it gets full access to the charging volts from the alternator and fuse protection from the second battery.