All batteries charging on shore power?

[N147JK]

Originally Posted by Scalf77

connects the House & Start battery systems together. Then the shore power charger just see it as one battery bank.

I have always wondered about this. 2 batteries, 2 different states of charge, on 1 battery charger. One battery needs charging, the other doesn't. Both on the same charging circuit.

What does the charger do in this case?
What happens to the fully charged battery in this scenario as the the lower charged battery receives a charge?

[boywonder]

....and since the inverter/charger is typically connected to the house batteries, the separator/isolator etc needs to be bi-directional to connect when the house battery voltage bumps up from the charger to connect the starting battery(s).


The Blue Sea ACRs are Bi-directional, as well as the Surepower 1315 (which may be what the OP has based on the age of the van). The Surepower 1314 is starting battery/alternator only (front to back only).

[Scalf77]

Originally Posted by N147JK

I have always wondered about this. 2 batteries, 2 different states of charge, on 1 battery charger. One battery needs charging, the other doesn't. Both on the same charging circuit.

What does the charger do in this case?
What happens to the fully charged battery in this scenario as the the lower charged battery receives a charge?

So the charger see it as 1 bank, and the charging parameters are what you have the charge set (presumably for the house battery). In some ways the difference in capacity and depth of discharge get handled via the internal resistance of the batteries. Typically you would have the bulk charge rate set for the size of your house battery, adding the starter won't make it push out more current. The current will generally go to the battery that needs it. It is not going to be perfect but not necessarily the end of the world.

While I favored the Blue Sea ACR, and really recommend to add their switch to add control over the unit. My general practice was to bring my house battery up to a full charge with the ACR disconnected. When the house was fully charge I would engage the ACR, and keep the batteries charged in float.

I don't think it is a necessity to do that, I do think it is better. I even went as far developing a circuit where the ACR was in Auto mode when the van is running, when the engine is off, it is under control of the switch.

I would generally just monitor the starting batteries and engage the ACR if the voltage was down. I generally had more monitoring capabilities than most, so it didn't seem like a big deal to me.

Are any of these things going to improve overall lifespan? Probably, but it would measured in day/months not years.

-greg

[boywonder]

Originally Posted by Scalf77

My general practice was to bring my house battery up to a full charge with the ACR disconnected. When the house was fully charge I would engage the ACR, and keep the batteries charged in float.

I don't think it is a necessity to do that, I do think it is better. I even went as far developing a circuit where the ACR was in Auto mode when the van is running, when the engine is off, it is under control of the switch.

I would generally just monitor the starting batteries and engage the ACR if the voltage was down. I generally had more monitoring capabilities than most, so it didn't seem like a big deal to me.

Are any of these things going to improve overall lifespan? Probably, but it would measured in day/months not years.

-greg

I've been playing with that idea with my Lithium House battery and AGM starting battery when the van is sitting in the driveway. Solar is only connected to the house batteries.

I have a Blue sea giant battery combiner switch in parallel with the Orion DC-DC. I disable the Orion in bluetooth (other wise combining batteries with the switch shorts the Orion) and combine the banks and let the voltages even out over a little time......and let them float.

[N147JK]

Originally Posted by Scalf77

While I favored the Blue Sea ACR, and really recommend to add their switch to add control over the unit.

Thank you for the explanation. As for adding a switch as you describe here, wouldn't an old-school solenoid battery isolator setup work for this? If I want to top off the engine battery while on shore charger, I switch ACC power ON and that brings the engine battery onto the charge circuit. ACC ON will consume a small amount of power, but the charger should be able to more than make up for that and charge the battery. Seems like a simple way to do this without adding additional equipment such as an electronic ACR. Does this make sense, or am I missing something?

[boywonder]

Yes that certainly works.....there are a couple of drawbacks:

As you pointed out the solenoid consumes some battery power.....if you forget it's on it can certainly drain the batteries over time. Wiring it to the ACC circuit consumes additional power because other stuff will be powered on as well.

The above applies more to solar power than to shore power..yes with shore power you can burn excess power without any issues. With solar if you forget and the sun goes down now you are consuming power from both battery banks.

..and if you are dry camping using lots of power and forget to turn it off you run the risk of depleting both battery banks and not being able to start the van.

The automatic switches/relays etc eliminate the "forgot to turn off the switch/solenoid issue"

[Scalf77]

Originally Posted by N147JK

Thank you for the explanation. As for adding a switch as you describe here, wouldn't an old-school solenoid battery isolator setup work for this? If I want to top off the engine battery while on shore charger, I switch ACC power ON and that brings the engine battery onto the charge circuit. ACC ON will consume a small amount of power, but the charger should be able to more than make up for that and charge the battery. Seems like a simple way to do this without adding additional equipment such as an electronic ACR. Does this make sense, or am I missing something?

Sure, you could. The assumption being that your powering the solenoid off of a line that is hot in both "Accessory" and "Run". This would give the ability to control charging while the engine is not running.

There are some good reasons that the voltage controlled relay can be better. I ran a straight solenoid to the "run" circuit for about a year. In the end you have to be comfortable with your solution and understand the pro's and con's of how you will use it.

-greg

[dogsandcats]

Looks like two batteries behind back axle in blue case. If I interpret correctly, these are the van batteries.

[boywonder]

Originally Posted by dogsandcats

Looks like two batteries behind back axle in blue case. If I interpret correctly, these are the van batteries.

Very likely, yes. Unless of course you find batteries under the gaucho or the dinette.....

[dogsandcats]

Tried to load 3 photos but at least this one shows my solenoid. I assume this is the original solenoid. Recommendations for need for replacement and what does it do in terms of the van and house batteries? Many thanks for your expertise and patience.