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The self contained units are overpriced, underperforming "power for dummies". I would not recommend, but the learning curve is plug and play. If you're willing to learn the basics, you can piece together a better system at significant savings - with the ability to customize and expand.

There's a ton of solid electrical advice here, as well as a few that swear by such things as the goal zero. Personally, I wouldn't use one if I found it 50+% off (although I might resell it at that price if you have a hook up $_$)
 

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Thanks. If it’s the AGM batteries themselves that limit charge rate to about 26 Ah in an hour of highway driving for 200 Ah battery bank, I’ll have to find an alternative. Something just doesn’t add up because AGMs are marketed as being able to charge up to 5 times faster than flooded. Maybe 13% or 0.13C isn’t that bad in that a battery down around 50% SOC could be topped off in under 4 hours of driving.

Lithium may be the only solution for large systems needing to charge 500 Ah in reasonable time.

Thanks again MsNomer.
 

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The self contained units are overpriced, underperforming "power for dummies". I would not recommend, but the learning curve is plug and play. If you're willing to learn the basics, you can piece together a better system at significant savings - with the ability to customize and expand.

There's a ton of solid electrical advice here, as well as a few that swear by such things as the goal zero. Personally, I wouldn't use one if I found it 50+% off (although I might resell it at that price if you have a hook up $_$)
thank you! I'm learning why they are not popular on this forum, and doing my homework. Up to my eyeballs on the "Electronics" forum and slowing getting up to speed. have inquiries on a couple of 2018-2019 Promasters and will purchase soon. so grateful to you all for sharing valuable expertise and educated thoughts and opinions.
 

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AGM charges faster than gel. That's where the up to 5x charging speed comes from, iirc. I think they prefer slower charges than flooded. Their real selling feature is maintenance. Flooded you can abuse more and replace fluid. If you cook an AGM, you need a new one. You don't need to (can't) water an AGM. All lead batteries will offgas if overcharged. Flooded is more noticeable because it is more open.

I think people (especially sales people) get confused about battery types, and you can't trust marketing - they're specifically trying to sell you stuff. As far as I know, the 50%(flooded) and 80%(AGM) DoD is also a myth and both should, optimally, be kept to a 50% discharge limit. Gelled is for true deep, slow discharge as well as high heat environments.
 

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That’s a lot lower than I would have expected. If I understand your system correctly, it charged 13% of 200 Ah, or about 26 Ah, in one hour of solar plus alternator?

Is that typical and in line with what you’ve experienced previously?

I’m curious if your 1-hour drive included a lot of idling along the way, or is it mostly highway? Also, at what time of day was it since it affects solar?

Thanks for data — it’s appreciated. (y)
Hi Chance

I have no solar, & mostly charge from my PM 180Amp alternator, 250Ahr Rolls AGMs, no B2B just “switches”.

It depends upon SOC, but a rule of thumb for me if @ 90% SOC is 1% recovery from my PM alternator every 6mins ( 25Ahrs per hour back into the batteries ). Mostly highway

If I take the batteries down to SOC @ 70% I, would assume about 60 Ahrs per hour

Im “tapped off” the “upfitters” 70Amp fuse
 

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Hi Chance

I have no solar, & mostly charge from my PM 180Amp alternator, 250Ahr Rolls AGMs, no B2B just “switches”.

It depends upon SOC, but a rule of thumb for me if @ 90% SOC is 1% recovery from my PM alternator every 6mins ( 25Ahrs per hour back into the batteries ). Mostly highway

If I take the batteries down to SOC @ 70% I, would assume about 60 Ahrs per hour

Im “tapped off” the “upfitters” 70Amp fuse
Thanks for the additional data. Your charge rate of about 0.10C at high SOC and about 0.25C at lower SOC seems consistent, and makes me question the value of a dedicated second alternator unless a van has a huge AGM battery bank, or faster-charging lithium, or can get the second alternator for a few hundred dollars.

As an example, with 700 Ah of AGM like some here have (and close to what I’d need to power A/C overnight), your charge rate would suggest up to 175 Amps, which is in 2nd alternator range. Like with MsNomer, it sounds like it would take about 4 hours of highway driving to get back near 100%. For me that would work fairly well, but nearly 400 pounds of AGM batteries is still a lot of weight and cost. Thanks again.
 

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Thanks for the additional data. Your charge rate of about 0.10C at high SOC and about 0.25C at lower SOC seems consistent, and makes me question the value of a dedicated second alternator unless a van has a huge AGM battery bank, or faster-charging lithium, or can get the second alternator for a few hundred dollars.

As an example, with 700 Ah of AGM like some here have (and close to what I’d need to power A/C overnight), your charge rate would suggest up to 175 Amps, which is in 2nd alternator range. Like with MsNomer, it sounds like it would take about 4 hours of highway driving to get back near 100%. For me that would work fairly well, but nearly 400 pounds of AGM batteries is still a lot of weight and cost. Thanks again.
The way I look at it Chance, is all of us DIYers are individual “test beds” for electrical & everything else DIY Camper Van. Data shared amongst us is very very valuable. The scientific understanding will vary amongst us DIYers as will the ability of data collection & variables.

I have limited understanding of how batteries work (& I believe that is generally true for most members here). The real unknown issue for me is not the charging profile Of the batteries we may purchase as that is usually well defined by the battery manufacture’s specifications, but with the PM Alternator charging system which I believe is regulated by the PM computer. Nobody here has presented the RAM documents that tell us how the magic black box works - or in the very least I have been unsuccessful in my search.

I rarely take my batteries past 85% SOC, but that may happen with different use (We tend to be daily travelers). We carry onboard a Honda 2200 generator. If we parked more, I would add solar to our roof. Solar is not a given for us as it is for many (SW Canada).

The one advantage of a second alternator & if you can get one that can be controlled “old school” via an adjustable “regulator” is you can “dial in” your own voltage & also limit the amperage with the max output of the alternator. I have not looked @ how to add a 2nd alternator, but think that would be the difficult part of setting up that system. A 60amp Nippon Denso “Lester # 14684” could cost $80 to $120 usd I would think. If you wanted a “non-computer” regulator a Transpo IN256 regulator might work for specs $20 to $30 usd.


or you can do some Brain Surgery;



I have other ideas on this if you want, but I believe the big issue is fitting a 2nd alternator to the PM engine, the rest of it is knowledge & a bit of trial & error.

I don’t think I would go to the effort of a 2nd alternator, but it does take out the PM computer controlled alternator out of the equasion & can be dedicated towards the house battery bank and can be “old school” set. If it was “easy” I would opt for a 2nd alternator over a B2B black box as I mildly understand the alternator/regulator & do not at all understand the B2B.
 

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Thanks for the additional data. Your charge rate of about 0.10C at high SOC and about 0.25C at lower SOC seems consistent, and makes me question the value of a dedicated second alternator unless a van has a huge AGM battery bank, or faster-charging lithium, or can get the second alternator for a few hundred dollars.

As an example, with 700 Ah of AGM like some here have (and close to what I’d need to power A/C overnight), your charge rate would suggest up to 175 Amps, which is in 2nd alternator range. Like with MsNomer, it sounds like it would take about 4 hours of highway driving to get back near 100%. For me that would work fairly well, but nearly 400 pounds of AGM batteries is still a lot of weight and cost. Thanks again.
On another note;

Assumingely if you need A/C overnight, then you got sun during the day = no brainer for solar power 🤔

You also have a need for a rocking good inverter. I purchased a Victron 12/3000/120 (12v / 3000w inverter 6000 peak / 120 Amp charger). I never installed it. I think it is great quality, but have no real experience & I might install in in my cabin.


63019



63020





 

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This isn't going to be very scientific. But in the couple years I have had my agm golf cart batteries, I definitely notice how the solar system will bulk charge them much more quickly than the flooded batteries I ran at first. Voltage level climbs quicker in the morning than with the flooded batteries. I haven't watch them finish charge as I am usually driving at that point. They do seem to accept the initial recharge very quickly. I have 400 watts solar on a 40 amp mppt controller to charge them.
 
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This isn't going to be very scientific. But in the couple years I have had my agm golf cart batteries, I definitely notice how the solar system will bulk charge them much more quickly than the flooded batteries I ran at first.
Agreed.

Flooded charging typically runs C/10 to C/5 (10-20A per 100Ah capacity), and AGM typically C/5 to C/3 (20A-33A per 100Ah capacity).

I'd never heard the "5x as fast" marketing claim mentioned earlier in the thread.
 

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That Victron PCB has a lot of DIP components on it. It is amazing that those old packages are still available for that many components. Reminds me of a 1980s Atari video game :-(

Hopefully, it's tried-and-true if not state-of-the-art.

Measuring current is often difficult with the typical meters we have. I have one of these meters (bought in 2014), it's not too expensive and not too bad:


Just clamp it around the conductor to measure current. Bonus: it also has probes and a basic DMM.

Wow, there are some even cheaper ones now, and with better reviews:


Make sure you pick one that does DC current in the clamp. Some of the cheapest ones are AC current only in the clamp.

If you have a deep interest and unlimited budget and want to do it "right" you could get 2x Fluke 287 or Fluke 2x 289 with the "FVF" (FlukeView Forms -- contains an optical interface to USB for your PC) and 1x I410:


Then you could use a laptop to monitor & record current and voltage (and therefore power) over the entire charge or discharge cycle:

63021


I've purchased several Fluke meters off eBay (all but one in the above picture, typically from pawn shops, typically with blown current fuses in the DMMs) and they are much cheaper than new and still work fine.
 

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I purchased a 12v FLA “Rolls” for my Cabin 130Ahr & paid $240 Can plus taxes. This is a bit of an experiment for me, but I‘m already thinking I would have been better off spending a bit more on AGMs. Here is the “Rolls” doc on charging and maintenance (which FLA requires more diligence than AGM). The maintenance is my Achilles’ Heel when it comes to batteries that I do not stay on top of 😳.

The up side is this; When I get a dead AGM & I blame myself I usually think I just purchased the battery & in actuality it isn’t the case. I recently replaced an AGM purchased in 2010 thinking I only got 5 years out of it.

The Rolls Battery Type & “Charging / Maintenance“ Specs;


 

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On another note;

Assumingely if you need A/C overnight, then you got sun during the day = no brainer for solar power 🤔

You also have a need for a rocking good inverter. I purchased a Victron 12/3000/120 (12v / 3000w inverter 6000 peak / 120 Amp charger). I never installed it. I think it is great quality, but have no real experience & I might install in in my cabin.


View attachment 63019


View attachment 63020




To keep costs down, I’m presently planning on 2,000-Watt inverter/charger if I keep using small A/C, and bump it to 3,000-Watt inverter/charger if using a 11,000 BTU/hr roof-top Power Saver. However, that can change if direct-current A/C like the ProAir used by Coachmen and others becomes more affordable.

To your point, if the van will have an inverter/charger anyway (for microwave, coffee, etc.), an option that works (although not as energy efficient) is adding a simple inverter off the engine/battery/alternator that can power the main house’s inverter/charger. Orton from Transit forum uses this approach. Again, not as energy efficient as a DC-DC converter, but it allows the multi-stage battery charger to adjust voltages as needed. It also has advantage that it’s not as dependent on alternator voltage, and that house battery bank can be at any reasonable voltage (48V comes to mind).

As I recall, the charger must be programmable or small enough so peak charging rate can be limited within alternator and/or first inverter capacity. More food for thought.
 

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I'm really intrigued by these real world feelings that AGM charges faster. Were the chargers and bank sizes the same? Can someone point me to documentation on the AGM charging faster or at a higher ratio? Everything I see, outside of sales pitches by resellers, says flooded can be fed more voltage.

I'm not advocating flooded over anything, but I'm nearly certain that they have the highest charge rate of lead acid. There are plenty of other reasons for the variety of lead acid styles, but I don't think efficiency is one of them. Safety and convenience generally distract from efficiency rather than add to it.

On the maintenance side, look into watering kits. They can be had for pretty cheap (or super expensive).
 

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Whether flooded or AGM, not all are comparable. As I recall (please correct if wrong), starting batteries should charge fastest, Marine/RV Dual-Purpose next fastest, and true Deep-Cycle slowest.

At Tampa RV Show in January I saw a few vans with dual-purpose AGM batteries. I’d assume they charge faster than golf cart and other true deep-cycle batteries. Thoughts?
 

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You are correct. I was only talking about deep cycle, however. These are the type wanted for any sort of solar starage/rv usage. Starting batteries do indeed charge and discharge very quickly, but cannot efficiently handle low, continuous draws. My understanding (I haven't used one) is that the dual purpose batteries are subpar in both categories. I would not recommend. In a rare case, ie. 1 battery small boat or van without dedicated "coach" and "house" banks, maybe. Big maybe. I'd mostly suggest avoiding dual purpose.
 

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As the owner of the 99th post on this topic, I'd like to take the opportunity to make a few points...

1) the OP hasn't been back since posting the original question. Maybe because there are very few replies that address his question.

(then again, see post #9)

Which was, "How long to run engine with van stationary at idle without trouble?"

Maybe that's because he wasn't asking about charging curves, solar setups, SOC's, %'s, dual alternators, AGMs, FLAs, or anything else!

As always, I find our threads entertaining, insightful, informative and thought provoking! And sometimes I just step back and look at the big picture 😁 And then I laugh....

Hope we can all join in a group laugh every now and then, especially under current circumstances.

If not... please disregard this post (#99) no offense intended... and feel free to carry on! 😈
 

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I agree we diverged awhile back, and apologize for my role in that. New topics probably should have been new posts. I, for one, am absolutely terrible at staying on track. Not an excuse, but I just get emails and then respond. I think about stuff after the fact (which has absolutely never-ever steered me wrong :rolleyes:).
 

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As the owner of the 99th post on this topic, I'd like to take the opportunity to make a few points...

1) the OP hasn't been back since posting the original question. Maybe because there are very few replies that address his question.

(then again, see post #9)

Which was, "How long to run engine with van stationary at idle without trouble?"

Maybe that's because he wasn't asking about charging curves, solar setups, SOC's, %'s, dual alternators, AGMs, FLAs, or anything else!

As always, I find our threads entertaining, insightful, informative and thought provoking! And sometimes I just step back and look at the big picture 😁 And then I laugh....

Hope we can all join in a group laugh every now and then, especially under current circumstances.

If not... please disregard this post (#99) no offense intended... and feel free to carry on! 😈
In fairness, if so many people don’t know exactly what was being asked, it’s because the question was not clear. He could have taken an extra minute or two to be more specific. Or as you stated, come back to explain more about what he wanted or needed.
 
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