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Old 09-26-2019, 05:39 AM   #21
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Thanks for the quick reply! After months of thinking I actually purchased 2x 100ah AGM batteries tonight, I just went to get on the road already! Always room for change in the future.

Too much to concern myself with learning about float charging voltages and what this alternator puts out. I don't want to damage the expensive lithium battery, so I got this pair of trainer batteries.
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Old 09-26-2019, 06:04 PM   #22
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Thanks for the quick reply! After months of thinking I actually purchased 2x 100ah AGM batteries tonight, I just went to get on the road already! Always room for change in the future.

Too much to concern myself with learning about float charging voltages and what this alternator puts out. I don't want to damage the expensive lithium battery, so I got this pair of trainer batteries.
Good decision, and you'll probably be just fine. Use as many 12v appliances as you can (exception is fridge on propane) so you won't need the 110v inverter with it's inherent drain and inefficiency. So long as you charge daily by driving at least a few hours or plug in to a campsite you may find you never get the batteries below 75% discharge. That includes running a few hours of lights & tv, plus overnight vent fan or furnace (depending on the temperatures).

Hopefully you have a battery meter to monitor your voltage. There will be fluctuations and voltage drops as you are using your batteries, but test your batteries at rest and don't let them drop regularly below 50% of charge or significantly past that so as to not shorten their life cycles. This means you have 200 amp hours times 50%; or 100 amp hours to use on a typical basis.

Here's a link to a general state-of-charge voltage chart of various lead-acid battery types:

https://www.energymatters.com.au/com...age-discharge/
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Old 09-27-2019, 10:26 PM   #23
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I don't have a dedicated inverter planned at the moment, infact I havent thought of anything I'll need that a 12v plugin cheap inverter cant handle, a laptop I suppose

I need to get a battery monitor it seems, and also learn about shunts.

is there anything Id be missing out on by not having a 1000w+ dedicated inverter?
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Old 09-27-2019, 11:05 PM   #24
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Thanks for the quick reply! After months of thinking I actually purchased 2x 100ah AGM batteries tonight, I just went to get on the road already! Always room for change in the future.

Too much to concern myself with learning about float charging voltages and what this alternator puts out. I don't want to damage the expensive lithium battery, so I got this pair of trainer batteries.

What you learn with the AGM batteries may, or may not, be applicable to a future lithium setup as each type has their own set of advantages and disadvantages.


Lithiums charge faster, if you can supply enough current to do it, they will go all the way full at nearly full charge rate, and don't need to get full regularly since they are OK at any SOC over time. The can't be charged below freezing or stored below -4*F so heaters may be required. They may be more sensitive to high temps. They prefer not to be charged to totally full, so having a charger that will stop charging early is best. They don't like to be float charged, so a full cutoff/recharge control charger is best.


AGMs need to be taken to full regularly and getting the last 15% SOC takes as much as 6 hours of charge time at absorption. Don't believe the claims that AGMs can be brought to full in 2 hours of driving unless they are only 5-10% down on charge. Most AGM chargers don't do a good job of charging as they are timer or algorithm based and will either over or under charge depending on the system and DOD. Chargers that will do a good job are rare and expensive. Temperature at charging has no low limit, nor does storage if they are fully charged so no heaters required. They like to be float charged so charger can carry the van use while charging, which lithium can't do in most cases. IMO, don't believe the 50% discharge limit on AGM batteries. The actual loss of life, based on energy in and out is more like 15% than the 50% often quoted, even if you go to 20% on every cycle. The discharges average, so a few discharges to 20% SOC loses little life and allows you to have a much smaller battery bank.


We hear all the time about battery chargers that claim to be great for lithium, but don't leave headspace at full or do full cutoff, and about AGM chargers that claim to always charge to full but really don't in the real world. Top line equipment like is used on the very expensive integrated systems is very expensive but would do the best. The big question is risk vs reward on any of the systems. Will better equipment give you enough longer life to justify the cost? That is the decisions that have to be made for either AGM or lithium, or even wet cells which may actually work out the best economically in a lot of cases.


As was mentioned, don't believe the "drop in" sellers for lithium that claim to be able to seamlessly replace lead acid batteries, but also don't believe all the suppliers of "lithium" chargers, regulators, etc that really aren't all that great but just capitalizing on the lithium claim. Look very carefully at how they all work in detail. Also remember all three charging sources, shore, solar, engine alternator need to be suited to the battery type and size, which makes it all even harder to get just right.
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Old 09-27-2019, 11:46 PM   #25
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I don't have a dedicated inverter planned at the moment, infact I havent thought of anything I'll need that a 12v plugin cheap inverter cant handle, a laptop I suppose

I need to get a battery monitor it seems, and also learn about shunts.

is there anything Id be missing out on by not having a 1000w+ dedicated inverter?
You don't need anything expensive or complicated, just something that accurately displays battery voltage. I bought this that simply plugs into a 12v coach outlet. I like that the display swivels up and away to the lights don't bother us at night. I paid a lot less and don't know why the price has nearly doubled.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You can also splitters that show volts in the center display and leave you two outlets instead of blocking one. Shop around and test for accuracy when you plug it in. I've found most are accurate within .1 volts which is probably good enough.
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Old 09-27-2019, 11:58 PM   #26
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You don't need anything expensive or complicated, just something that accurately displays battery voltage. I bought this that simply plugs into a 12v coach outlet. I like that the display swivels up and away to the lights don't bother us at night. I paid a lot less and don't know why the price has nearly doubled.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You can also splitters that show volts in the center display and leave you two outlets instead of blocking one. Shop around and test for accuracy when you plug it in. I've found most are accurate within .1 volts which is probably good enough.

Voltage is not a very good indication of state of charge for lithium or AGM batteries. Lithiums have a very flat voltage vs SOC profile so very easy to be inaccurate because of that. AGM voltage needs to be a rested voltage so any loads mess it up, and is still approximate even when rested.

IMO, voltage indication is not even in the same ballpark as a shunt based monitor if you actually want to know what you SOC is at any given time, especially when checking for full on AGM batteries.


A monitor will also allow you to see how much power you are using, both in real time and compiled over time, so very useful in knowing how long you can be on batteries without charging.
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Old 09-27-2019, 11:58 PM   #27
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You don't need anything expensive or complicated, just something that accurately displays battery voltage. I bought this that simply plugs into a 12v coach outlet. I like that the display swivels up and away to the lights don't bother us at night. I paid a lot less and don't know why the price has nearly doubled.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You can also splitters that show volts in the center display and leave you two outlets instead of blocking one. Shop around and test for accuracy when you plug it in. I've found most are accurate within .1 volts which is probably good enough.
https://www.amazon.com/EPEVER-Contro...omotive&sr=1-6

This is the charge controller I bought, a 30a EPEVER MPPT. It displays voltage and would make a battery monitor unnecessary right?



Another question, most diagrams I've seen online show the load connections not being used on the charge controllers, why is this?

Also, my class b came with a 5w solar panel, and the "solar volt meter"(charge controller from 99) connect the panels straight to the 12v fusebox, which is connected to the battery. Should I do the same?
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Old 09-28-2019, 12:20 AM   #28
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https://www.amazon.com/EPEVER-Contro...omotive&sr=1-6

This is the charge controller I bought, a 30a EPEVER MPPT. It displays voltage and would make a battery monitor unnecessary right?



Another question, most diagrams I've seen online show the load connections not being used on the charge controllers, why is this?

Also, my class b came with a 5w solar panel, and the "solar volt meter"(charge controller from 99) connect the panels straight to the 12v fusebox, which is connected to the battery. Should I do the same?

I just looked at the manual for that controller and it is a basically timer unit in charging, with and algorithm for tracking power point. Very common configuration. With timer controls, you don't have any assurance that the batteries will not be over or under charged based on depth of discharge, loads from the van, etc. As mentioned earlier, voltage is really not any good indication of SOC, especially for solar, or any other charging method, when it is charging. IMO, it is not a substitute for a battery monitor.


In a small van, it is kind of a waste to use the load outputs as you need to have double wiring for stuff you want to run in case the solar is not producing or off. Everyone normally runs the solar output to the batteries directly. You really also don't even want a switch in the line to the batteries from the solar because is you shut it off when the panels are in the sun, you can spike the voltage and kill the controller. If you want to be able to turn off the solar controller, you have to shut off the panels first to be safe.
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Old 09-28-2019, 07:09 AM   #29
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I would strongly suggest to get a shunt-based battery monitor especially with 200 Ah capacity. I have 230 Ah AGMs and monitor SOC regularly. I also have good voltmeter and primarily use it to check if batteries are being charged, is voltage going up or down. To make a decision if I have enough to last a night or to make sure batteries are fullty charged I go to SOC Magnum battery monitor. The only good justification for not having a good battery monitor would be budget limits, but justification based on sufficiency of idiot lights or a voltmeter doesnít work for me.

Regarding the inverter decision. Early in the conversion process I decided to have 1000W Magnum inverter, my wife was against it. The only use for it is the 600W microwave which we practically donít use. So, we ended up with !000W unit for about 100-200W actual loads. To reduce battery drain I recently added a very efficient Morningstar 300W inverter ending up with 2 inverters. My point is to make inverter decision on predicted use, my wife knew that we will not use microwave often, I didnít want to buck the trend, she was right.
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Old 09-28-2019, 11:14 AM   #30
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Regarding the inverter decision. Early in the conversion process I decided to have 1000W Magnum inverter, my wife was against it. The only use for it is the 600W microwave which we practically donít use. So, we ended up with !000W unit for about 100-200W actual loads. To reduce battery drain I recently added a very efficient Morningstar 300W inverter ending up with 2 inverters. My point is to make inverter decision on predicted use, my wife knew that we will not use microwave often, I didnít want to buck the trend, she was right.

Sounds familiar, except we have a 2000 watt inverter to run the microwave! It is also big enough to run a hair dryer, but DW has not used it for that to this point.


Since the original power system update, I added two small 120 watt Samlex inverters, one in the audio cabinet to run the TV/DVD stuff and another to create a "charging station" for things that need charging. We are getting rid of the 12v power charging adapters as we replace items as I have found that they take just as much power as using the small inverter and factory 110v chargers.
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