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I’ve begun outfitting my new (to me) Metris Cargo, and ready to fit a inverter in it. I have a Dimensions 12/1200 Pure Sine inverter. And a large Marine deep cell battery. On my last van, I ran the main battery cables from the inverter to the marine battery - then jumped off the marine battery to the car starting battery in parallel. Would there be any issues doing this on a Metris?
 

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You will likely have problems. You did not say what type of deep cell battery you're adding- lead acid, AGM, or lithium ion. They all have different charging profiles. An AGM identical to the start battery would be best- the same chemistry and the same size ( identical amp hour rating). If you go with a different battery chemistry or different amp hours you need to seriously consider something like a battery to battery charger. Sterling, CTEK, Renogy, Victron and other companies make them.

I installed a Sterling since it meet my needs better than other models that I looked at when I did my install. It has worked fine but that model is no longer sold in the US. You could probably get one sent over from the UK, which is where they are made. https://www.metrisforum.com/threads/sterling-battery-to-battery-charger-install.6650/#post-74250
 

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Thanks Ransom. The current battery being used as a auxiliary unit is a 29HM lead acid with approximately 115 AH @ 20 hour rate. It’s worked without issue. I’m wondering if I could use a stock sized battery instead? Those are rated at 100 AH if I’m not mistaken. If I were to go that route, and my van isn’t pre wired for the second battery. Could I just run 4gauge wire leads from the stock battery to the second battery?
 

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Is the 100 Ah battery an AGM? You'd want an AGM to match the charging profile that the Metris uses for the start battery. The AGM also has far less or no issue with releasing sulfur dioxide when its being charged, which is part of the reason not to go with a typical lead acid battery.

I think I've seen a thread where someone wired in another battery with cable from the start battery. There is very little space around the start battery to add any heavy cables. I saw one post that stated that Mercedez does not allow authorized upfitters to make changes with the start battery or its associated wiring.

You should pull out the start battery first to see how much of a challenge it will be. MB has good reasons for not wanting upfitters making changes in that very tight space. I think you'll be more inclined to go with a battery to battery charger when you see what you're faced with. Despite what the the name implies, you can wire a battery to battery charger without directly connecting to the battery posts.
 

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Thanks Ransom. The current battery being used as a auxiliary unit is a 29HM lead acid with approximately 115 AH @ 20 hour rate. It’s worked without issue. I’m wondering if I could use a stock sized battery instead? Those are rated at 100 AH if I’m not mistaken. If I were to go that route, and my van isn’t pre wired for the second battery. Could I just run 4gauge wire leads from the stock battery to the second battery?
A 1200 watt inverter will pull about 100 amps from the aux battery to operate at that level. That of course is more like 1/0 or 2/0 wire.

I am not sure how often or long you will be running at that level, but 50 amps per battery in the 27 - 31 size is a good target. This isn't always possible of course, so the balancing decion that only you can make is to either have 2 batteries or accept shorter battery life. The M in the 29M usually indicates a marine battery vs a starter battery or deep cycle battery. M batteries are a good choice for use with inverters if possible.

The battery to battery charger is pretty much a must have with the 4 cylinder sprinter and metris. Unlike vehicles of the past, one of the reasons that MB was able to pull off the performance / engine / efficiency / emissions balance was how highly engineered the alternator operation is. There is nothing brute force about it. You could almost say that it is designed in a way that your idea is certain to not work. The sterlings work pretty well - other than they cannot maintain their current rating under load for very long, so don't buy one that is too small. Maybe 60 amps size.
 

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Connecting the Aux battery directly to the Main battery is asking for trouble on many levels. Aren't you going to implement some kind of battery isolation when the vehicle is off? The Metris charging system just barely keeps the Main battery in good shape...it's not a multi-stage charging that all AGM battery manufacturers recommend. Like RR said, I'd avoid an old-school wet-cell (flooded) battery in this day and age. Your typical AC usage and current draw will play into which route to go also.
 

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The sterlings work pretty well - other than they cannot maintain their current rating under load for very long, so don't buy one that is too small. Maybe 60 amps size.
I have a Sterling BB1260 in my van and I'd advise not to run it while putting a heavy load to your AC inverter.
 
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I have a Sterling BB1260 in my van and I'd advise not to run it while putting a heavy load to your AC inverter.
You are right, the sterling only is not ideal for this application. I am going to change my suggestion.

Especially for MB 4 cylinder applications, a better path is to plan to use solar panels to charge the house battery pack and keep the house battery and starter battery isolated.

For a 1000 watt inverter, 2 each size 31 marine batteries will be enough for modest use. For heavy use, 4 are better. A Lifeline 8D is about the minimum size individual AGM battery designed to supply enough amps for a 1000 watt inverter.


If this just isn't enough power by itself, then it makes sense to add a small amount of draw from the vehicle. IIRC, MB recommends that this is pulled from the aux battery under the drivers seat via an active charger method.

I think that there is a sterling specifically for dealing with this smart alternator design. I usually use a different setup but I am not sure what the issue would be.

What are you observing on yours?

Do you have the version for the smart alternator?

Harry
 

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Is the 100 Ah battery an AGM? You'd want an AGM to match the charging profile that the Metris uses for the start battery. The AGM also has far less or no issue with releasing sulfur dioxide when its being charged, which is part of the reason not to go with a typical lead acid battery.

I think I've seen a thread where someone wired in another battery with cable from the start battery. There is very little space around the start battery to add any heavy cables. I saw one post that stated that Mercedez does not allow authorized upfitters to make changes with the start battery or its associated wiring.

You should pull out the start battery first to see how much of a challenge it will be. MB has good reasons for not wanting upfitters making changes in that very tight space. I think you'll be more inclined to go with a battery to battery charger when you see what you're faced with. Despite what the the name implies, you can wire a battery to battery charger without directly connecting to the battery posts.
And if my memory serves there is a pending incomplete recall on the passenger seat base cover due to the possibility of material dropping down and, I assume, shorting something.

I have the aux. batt under the driver's seat -- why not use that space for your house battery?
 

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You are right, the sterling only is not ideal for this application. I am going to change my suggestion.

Especially for MB 4 cylinder applications, a better path is to plan to use solar panels to charge the house battery pack and keep the house battery and starter battery isolated.

For a 1000 watt inverter, 2 each size 31 marine batteries will be enough for modest use. For heavy use, 4 are better. A Lifeline 8D is about the minimum size individual AGM battery designed to supply enough amps for a 1000 watt inverter.


If this just isn't enough power by itself, then it makes sense to add a small amount of draw from the vehicle. IIRC, MB recommends that this is pulled from the aux battery under the drivers seat via an active charger method.

I think that there is a sterling specifically for dealing with this smart alternator design. I usually use a different setup but I am not sure what the issue would be.

What are you observing on yours?

Do you have the version for the smart alternator?

Harry
But I don't want a 156# battery, although at 255Ah it's tempting
 

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But I don't want a 156# battery, although at 255Ah it's tempting
I have a friend who is a big fan of using the Lifeline 8D battery in his van - and highly recommend it. He also owns a small tractor that has a bucket on it. He put his in place (in his sprinter) with the front end loader attachment. I guess if I owned a tractor like that I might agree.

My personal opinion is that it is dangerous for most people to try to use a battery that heavy. The heaviest battery that I will lift is a Lifeline size 27, which weighs 60 lbs and is a great performing 100 amp-hr x 12 volt AGM battery.


Another very good AGM battery is this size 24 model that is 80 amp-hrs each, but an excellent performer for a minimalist system.


2 each of either one of those will power a 1 kW inverter very well.

In fact, 2 each of the smaller battery is what is used in this 1x1 unit that I install in small vans like the metris.

1x1 Drop in power system for conversion vans | WirlNet, Inc

If you want one, I can get you a really good deal on it.

__

If you van use will always be in areas that stay above ~ 40 F, then you can always use a LiFe battery and shave off about 40% of the weight for 2.5x the price.
 

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And if my memory serves there is a pending incomplete recall on the passenger seat base cover due to the possibility of material dropping down and, I assume, shorting something.

I have the aux. batt under the driver's seat -- why not use that space for your house battery?
According to MB, the factory aux battery under the drivers seat is required just to support the load of having any kind of "house battery bank". In other words, the van's electrical system is so anemic that without this additional factory battery under the drivers seat, all the van can do is drive around and power itself.

Unfortunately, our eco green friends have turned the screws too tightly on the auto industry. The results are vehicles with no margin of operation to support accessories in the way that a traditional van could previously support.

If you want to power things like you see in a traditional conversion van ( refrigerator, lights, fan, etc) - those largely need to be powered from solar panels on the roof. The metris electrical system is really just a supplemental / backup way to charge the end users house battery pack.
 

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What are you observing on yours?

Do you have the version for the smart alternator?

Harry
The Sterling has been great for my needs. It's intended to charge back up your battery bank, not provide 'more power' to support a long-duration heavy load. Doing so will not only inefficiently charge the battery but keep the DC-DC charge in a constant 'bulk charge' state. Size your battery bank to the load needed and then charge while driving. The BB1260 works with today's 'smart' regenerative alternators and the 'Green Label' version has improved by the longer regen braking mode time. I routinely pull 600 watts avg load for 3 hours on many jobs.
 
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