From the listed items needing juice, it doesn't sound like you need much if anything at all. Have you replaced your bulbs with LED's?
Electrically challenged....Help me design a house battery system
- Thread starter gtbensley
- Start date
From the listed items needing juice, it doesn't sound like you need much if anything at all. Have you replaced your bulbs with LED's?
Mwilliamshs
Explorer
A 100 watt panel produces an average of about 6 amps per peak sun hour, or about 30 amp-hours per day. You don't want to discharge your battery bank more deeply than 50% and most expedition people plan to recharge in a single day (use at night, charge during the day) so your battery capacity is around 60ah. Think powered-wheelchair batteries. A little more capacity would be good but if 100w is your maximum solar input you mustn't get a battery so large that you're incapable of charging it fully. A small battery charged 100% is way better than a big battery you can't ever get over 80% at a time.
As an example, 2 6V GC2 batteries in series have roughly 250ah total capacity. This needs about 200w of solar to replenish daily. Again, that's to replace 125ah. This may seem like overkill but efficiency losses and differing amounts of sunlight really impact it. Remember when sizing batteries and PVs the numbers on them come from people selling you something.
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_hein_
Observer
Two CG2 6V batteries will provide 250Ah at 12V. The Ah rating is at 6V so needs to be cut in half for a 12 V system.
@OP. Send me a PM and I'll reply with my contact info.
Then you can call and we can go over your system needs and requirements
A basic diagram would be a great way to start the conversation.
All the best,
Hein
Impact, Inc.
IdaSHO
IDACAMPER
As stated, your math is off.
Also, I maintain that exact battery bank with nothing more than 200 watts of 24V panels and an MPPT charge controller.
You do not need anywhere near the 800watts (really???) of panel you suggest.
Or even 400 watts.
If done right, 200 does it.
Mwilliamshs
Explorer
You guys got me. I was goofing off in here at work and spaced on 6v in series ah. I'll correct the original post to avoid further confusion.
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Not a huge draw by any means, I might use more so I would rather have a system in place. Evil, you are correct and that was my actual issue. I know how to wire a second battery with isolator in, however my power for the fuse box and relays are coming from the starting batteries and I want to change that. If I could on a simple discriotion just disconnect my starting batteries but still have everything work, I would be happy.
I'm pretty confused about what you are trying to do. I don't believe there is an easy way to separate out your starting batteries from your factory wiring harness. If I understand your question, the solution would be to disconnect your accessories from the fuse/relay box and route them over to a new one connected to a isolated house battery system. I know I am repeating my self here and bear with me, I'm just an internet dude trying to help.
Oh I appreciate the help! You are correct, that is what I would ideally like to do but I am thinking there is no easy way to do this. I could possibly just wire in parallel my house battery and use negative disconnects on the starting battery to disconnect them until I want to start the vehicle. Would need to open the hood but that might work.
Mwilliamshs
Explorer
Dunno bout a Chev but on a Ford there'd be a heavy cable from battery to a threaded lug in the under-hood fuse box (aka power distribution center) and that box would feed the under-dash fuse box. Disconnecting the start batteries from there would kill power to the chassis but leave start batteries connected to each other and the starter. You could then connect the house batteries to the under-hood fuse box to power the chassis from them. The start batteries should still be connected to the alternator so they'd charge but if not you'd need to do that and connect the house batteries to the start batteries with a manual switch, relay, etc. so they could charge from the alternator and the system could function as 1 if/when the need arises. Using a smart relay there could make the process automatic.
I think follow what you are saying. I will sketch out how they are attached and the system as best as I can figure it out and post a picture to see if that makes sense to you wizards.
Although now that I think about it, I have two batteries under the hood. One battery has a side post and top post. If I disconnect that side post I loose all power to the cab. I can probably pull that, feed a second battery with an isolater from that correct?
Maybe that only made sense in my head.
Maybe that only made sense in my head.
patoz
Expedition Leader
Agreed! I've always heard the rule of thumb is, one Watt of Solar for every Amp Hour of battery / battery bank capacity rating (AHr), to completely recharge it.
And Mwilliamshs, I did see where you edited your post so please don't misunderstand what I'm saying here.
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patoz
Expedition Leader
Is this a Type II Ambulance, which is basically just a van with a raised top?
Without seeing the actual wiring it's hard to say for sure, but I believe you may be able to add a second 'House' battery at that point. However, you would still need to provide an isolated charging system, such as the Blue Sea ACR in order to get charging current to the new battery. Even though you switch the load using the new 1/2/Both battery switch from the OEM Starting batteries to the House battery, it is disconnected it from the alternator. If you put it in the 'Both' position, you connect all batteries together in parallel, but this defeats the purpose of the ACR.
A House battery should be a true Deep Cycle battery of some type, which differs from Starting batteries. Starting batteries are designed for shallow discharge (no more than down to 10V) and quick recharge. Deep Cycle batteries are designed for deep discharge down to 50% and slow recharge.
The ACR will charge both types of batteries by combining, while keeping them separate when charging stops. It doesn't matter if the batteries (Starting vs. House) are different types, as long as your alternator has the ability to charge both types and there is not too much differences their sizes.
A dual-sensing ACR will sense an active charge source on one or both batteries and not solely on a designated battery. The ACR will operate if the measured voltage on either of the terminals is of a level to initiate a connection or disconnection. An ACR does not direct the charge to the battery that “needs it the most” or has the lowest terminal voltage. If there is a charge present on either battery, indicated by a high enough voltage, the ACR will combine the batteries.
See Blue Sea System's reference here: https://www.bluesea.com/support/articles/1366/Automatic_Charging_Relay_[ACR]_Explained
However, unless you separate the 'House loads' from the 'Vehicle loads', you will be running everything off of one or the other. You would never want to use the 'Both' position with the ACR in place. As a matter of fact, I would probably use a 1/2/OFF switch instead so that couldn't happen.
A disadvantage to using that type of switch is you have to remember to switch it appropriately when the time comes, and back when you're driving. Lots of room for human error here.
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