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Old 12-07-2016, 09:53 PM   #1
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Location: Minnesota
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Default Full auto, all manual, or in between charging system?

We have seen all of the different kinds on here, from totally integreated and monitored Silverleaf lithium system to manual systems where you plug in the charger or inverter when you need to use it. And lots in between. Of course the quality of how well they take care of the batteries is also very variable, with many factory systems and components not doing very well if left alone. Some manual setups can do a very good job with good user input, or not.

What would folks prefer within the realm of real world realities like space, cost, reliability? What do you have now and how do you use it in real life. Also how do you know, or not, just how well it is doing at taking care of your batteries.

We would love to have a fully automatic, reliable, reasonable cost, 3 system (shore, solar, alternator) that would do it all perfectly, but not in the cards for us for several the requirement reason.

That being out, we have a kind of Hybrid system of automatic and manual input, with the huge plus that they play well together without a lot of the compatibility stuff that can be very problematic (been there).

Solar is essentially on it's own, so no real intervention needed unless shutting off for storage times if not outside with no shore power. Only glitch is that it will rebulk charge once the batteries are full, if the voltage falls below float voltage. This can have it go back to absorption and stay there too long on full batteries, if solar output drops after it switches. Setting the float nearer battery resting voltage takes care of it, but isn't ideal due to low float voltage. Blue Sky will have a fix into their newer systems in the future. Charge quality is excellent and shunt controlled.

Shore charger is also shunt controlled so excellent charging, and requires only one input, only when first put on shore power, and only sometimes. It will not go into a full charge profile is the batteries have a surface charge on them or if solar is holding up the voltage a bit, so can go to float when a top off would be good. To remedy requires using a simple 3 button push (10 seconds) on the remote to start a cycle manually. Magnum knows of the issue and that it should be a settable option to always run a full cycle when a shunt is used to control charging, and they will implement that in future new stuff.

Our alternator charging does require more manual input, as there are no standalone systems that will reference a shunt to get the accurate charging. It isn't as much an issue as it would with watching the other solar or shore power, as all of it is right on the dash, and your are stuck there anyway unless you have self driving van. We can see amps to the coach batteries and can force the alternator to charge at absorption voltage until we switch it to float, so basically just like a shunt based system would do and very accurate charging. We also have two selectable charge rates, one set at 180 amps, which is about as much as the batteries want for a deep discharge recovery due to heat, and 280 amps for a quick charge for less than 30 minutes to recover a few days use if needed. We can also see the temp for each of the two alternators to watch for overheating (no automatic turn down in the regulator unfortunately), but we should really never have an issue at the charge levels we have set. The manual attention might be 2-3 times during an all day drive, so pretty simple.

Our requirements were accurate charging first and foremost, with no over or under charging. Second was there had to be no bad, or needed to addressed all the time, interactions, that were not known and very easy to handle. Third was off the shelf stuff with user friendly controls, and also minimal complexity for reliability. Fourth was to be sure it matched our us patterns and power requirements. Fifth was considered on all the other 4 requirement filling, and was reasonable cost (of course cost is always in the eye of the beholder). We are a bit higher than we thought we would be, but OK if everything works out well for us in practice.

Hopefully, we are getting close to having it all covered, with just the alternator charging needing a good long camping test in tougher conditions.

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Old 12-08-2016, 11:27 PM   #2
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I have an in between system, also Blue Sky for solar and Magnum for shore power. Both are shunt controlled.

Since I only have the Sprinter 220A alternator the engine changing takes a bit of manual control in daytime when there is sunshine because the Battery Isolator will not connect the batteries for alternator charging when there is solar charging. Its just a basic voltage controlled system from Precision Circuits Inc.

I modified the system Airstream installed so I can force alternator charging when needed. I do it without a meter reading at driver seat. When I need to give the coach batteries a boost I check how far down they are on the Blue Sky meter and then check how much the alternator will provide at idle. I then leave the batteries connected so I can get alternator charging to replace the missing Amp-Hours, but never more than an hour at a time. Its crude but seems to work. I have never done this yet with my 440AH Lifeline AGM battery pack down more than 20%. My weak link 4AWG wire Airstream installed between the Sprinter and my coach batteries in back. The newer Interstates have a 1/0AWG wire for the connection.

2013 Airstream Interstate Lounge EXT on 2012 Sprinter 3500 170Ext
Formerly: 1973 Dodge B300 DIY pop-top conversion
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Old 12-09-2016, 12:26 AM   #3
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The 4ga is rated for 80 amps in conduit or loom, but for a short time (20-30 minutes) probably double that. A factory alternator will drop near 1/3 in most cases when hot, plus it will be running the engine, so you would likely have under 150 amps. At idle you won't get that much, I would think, unless you have high idle. You may also have 80 amp breakers in the engine cable to the batteries, so that would be top end then.

All of this assumes the van electronics don't mess with the charging when it doesn't know where they are all the power is going.

The 440ah of Lifelines will accept over 300 amps when at 20% SOC, so you will be able to charge with whatever you can send them.
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