Skip to main content ↑ ↓
Topic: Start battery bank charging (Read 786 times) previous topic - next topic

Start battery bank charging

We have just completed installing a very interesting relay that automatically keeps our start battery bank charged when our engine is off. 

We used to use a diode device that can do the job, except when house batteries were very warm from being in an enclosed area or during a hot summer day.

Automatic relays charge start battery bank at a better voltage than diode devices.  Relay "combines' start and house banks similar to a boost solenoid, but it does it automatically and will keep start battery from discharging.

We used a Blue Sea Automatic Charging Relay (ACR) that starts to charge when higher voltage battery is above 13 volts and stops charging when voltage drops to 12.75 volts.  The ACR aslo has a cool feature, that we used to turn relay off when ignition is on, to prevent combining when engine is being started or when engine is running.  A LED inside our coach lets us know the status of the ACR.

Many of us have used Blue Sea high amperage relays for ignition or boost.  Information on the ACR can be found at SI-Series Automatic Charging Relay - Blue Sea Systems.  Relay cost about $75.

Let me know if there are any questions.
Barry & Cindy

Re: Start battery bank charging

Reply #1 –
Would you prefer your suggsted relay to the james triana suggested "voltage sensitive relay" made by a New Zealand marine electronics company. ???
r.schwab
2004 U270 36'

Re: Start battery bank charging

Reply #2 –
What I find so telling is that the marine industry appears to be much further advanced in matters concerning mobile electrical applications than the recreational vehicle industry is.  In fact, some of the SOB portion of the industry actually still appears to be in the dark ages.
1994 U225
build #4514
 

Re: Start battery bank charging

Reply #3 –
I would need to see installation notes on Foretravel's relay to better understand it.

There are other 'smart' voltage sensing relays in the market place, including other Blue Sea voltage relays, but the Blue Sea SI-ACR relay I installed has a special feature that I don't see in other relays.

The relay I am using has a "Start Isolation" (SI) feature that when powered, opens relay to stop combining, which stops charging start battery bank. To keep high current drains from house battery, I do not want to automatically combine when starting engine. Engine alternator charges start & house batteries, so I don't want to combine when engine is running. Using the "SI" feature, when the ignition key is on, the relay stops combining.