Herbie
Rendezvous Conspirator
So here's an odd question, with explanation to follow:
If I have two AGM house batteries of arbitrary capacity, but likely at different states-of-charge, voltage wise, would I need two (parallel) isolating/charging systems? Moreover, shouldn't they be isolated whenever not being charged?
Explanation:
I'm in the phase of my van build where I need to start worrying about the house-power system. "Version 1" of the plan was to just install either 1 or 2 Group 22NF AGMs into a convenient cubby that's in the rear quarter panel of the van, using the usual National Luna or similar battery isolator/charging system.
However I've been trying to think about life in Bear Country - specifically that with the wife and daughter along, there will be times when we'll end up in State or National park campgrounds where bears are well accustomed to humans and their goodies. (A different use case versus "wilderness" camping.) In these scenarios, it seems moving the fridge and a battery to the bear box would be a prudent step.
Fortunately, the location I've chosen for my batteries will be readily accessible, and I have a ready store of all the high-amperage connectors I would need to make the battery easily removable. "Version 2" was just that, a removable house battery with quick disconnects and the appropriate sockets so that I could put battery and fridge into a bear box.
However, while the fridge is my MAIN house-power consumer, I would really prefer to wire the reading lamps, other house lights, and any future accessories like on-board water pump, etc. to house power as well, lest I negate the whole value of a house a battery. My thinking there is that these demands are relatively light (compared to the fridge), so maybe I could have a smaller-capacity "auxiliary" battery to run things after the fridge was stored for the night or whatever.
When I started drafting up this "version 3", though, I started to worry about what happens in the morning when I reconnect the big battery - If everything is tied together, the main and aux house batteries would try to equalize, right? (assuming the alternator wasn't charging). If I started driving first thing in the morning, then at least everybody would be getting charged, but it still seems like I would need two charge controllers to keep everything happy and safe. Suddenly the cost of 2x NL smart relays, etc. starts looking very daunting.
Am I missing anything?
A thought that's just occurred to me (Version 3.1?) is that rather than run a permanent main/aux setup, I could just use one of those portable jump-packs as a SUBSTITUTE battery to run the lights, etc. whenever the main house battery was in the bear box. (I'm thinking a cig-lighter adapter to the fuse-panel input.) When the main battery was installed, the same cig-lighter connection to the house voltage would become an input to charge the jump-pack. The advantage here is lower cost, plus I could leave the jump-pack at home if I new I wasn't going anywhere with bear boxes. I assume these jump-packs have some (rudimentary) level of isolation? Or is this just the same problem?
If I have two AGM house batteries of arbitrary capacity, but likely at different states-of-charge, voltage wise, would I need two (parallel) isolating/charging systems? Moreover, shouldn't they be isolated whenever not being charged?
Explanation:
I'm in the phase of my van build where I need to start worrying about the house-power system. "Version 1" of the plan was to just install either 1 or 2 Group 22NF AGMs into a convenient cubby that's in the rear quarter panel of the van, using the usual National Luna or similar battery isolator/charging system.
However I've been trying to think about life in Bear Country - specifically that with the wife and daughter along, there will be times when we'll end up in State or National park campgrounds where bears are well accustomed to humans and their goodies. (A different use case versus "wilderness" camping.) In these scenarios, it seems moving the fridge and a battery to the bear box would be a prudent step.
Fortunately, the location I've chosen for my batteries will be readily accessible, and I have a ready store of all the high-amperage connectors I would need to make the battery easily removable. "Version 2" was just that, a removable house battery with quick disconnects and the appropriate sockets so that I could put battery and fridge into a bear box.
However, while the fridge is my MAIN house-power consumer, I would really prefer to wire the reading lamps, other house lights, and any future accessories like on-board water pump, etc. to house power as well, lest I negate the whole value of a house a battery. My thinking there is that these demands are relatively light (compared to the fridge), so maybe I could have a smaller-capacity "auxiliary" battery to run things after the fridge was stored for the night or whatever.
When I started drafting up this "version 3", though, I started to worry about what happens in the morning when I reconnect the big battery - If everything is tied together, the main and aux house batteries would try to equalize, right? (assuming the alternator wasn't charging). If I started driving first thing in the morning, then at least everybody would be getting charged, but it still seems like I would need two charge controllers to keep everything happy and safe. Suddenly the cost of 2x NL smart relays, etc. starts looking very daunting.
Am I missing anything?
A thought that's just occurred to me (Version 3.1?) is that rather than run a permanent main/aux setup, I could just use one of those portable jump-packs as a SUBSTITUTE battery to run the lights, etc. whenever the main house battery was in the bear box. (I'm thinking a cig-lighter adapter to the fuse-panel input.) When the main battery was installed, the same cig-lighter connection to the house voltage would become an input to charge the jump-pack. The advantage here is lower cost, plus I could leave the jump-pack at home if I new I wasn't going anywhere with bear boxes. I assume these jump-packs have some (rudimentary) level of isolation? Or is this just the same problem?