Under drivers seat AUX 50aH that fits

[HackAl]

Jason,

I'm about to buy the MightyMax you brought last year. Are you still happy with it?

I'd be using it with GoWesty's aux. kit, replacing two 22ah batteries I had in parallel that are now shot.

Mounting under driver's seat.

Thanks.

Al
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91 Westy.

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[davevickery]

I just came across this battery and it looks interesting. This may be more than some people are looking for, but the performance for its size is amazing.

VMAX 34-75. It has a small foot print and looks like it would fit on it's side under the driver seat. It is a deep cycle battery that claims an incredible 300 cycles at 100% D.O.D. and 900 cycles at 50%.

The marketing material says it does it with pure lead and other quality components. It only weighs 45 lbs and not that much bigger than these 50 Ah Universal batteries. https://www.vmaxtanks.com/FAQ_ep_42.html

If you buy it from the VMAX site, you get free shipping and 10% off your first order, making the total cost $205. That's not the cheapest battery around, but it is 75 Ah and you can use all of it. If it performs anything like it says, that is impressive.
https://www.vmaxtanks.com/XTR34-75-12Volts-75AH-Deep-Cycle-XTREME-AGM-Battery_p_164.html

The dimensions are listed as 10.2 x 6.6 x 7.2 total height. It is basically sized as a group 34 battery but it has the Amp Hours of a group 65 battery. But to even list that it can be cycled to 100% 300 times is amazing.
I stuffed a group 65 into my aux battery box with some mods, but this looks like it would fit a lot easier and is a better battery for about the same price I paid for my Diehard Gold AGM and I wouldn't cycle my diehard to 100%.

VMAX XTR34-75
12-Volt 75Ah AGM Deep Cycle SLA Battery
Capacity(Amp Hours, @20-Hr Rate): 75Ah
RC (min): 145
Terminals: 6mm Hex Screws (included)
Dimensions (inches): 10.2"w x 6.6"d x 7.2"h
Weight: 45 lbs

Number Of Cycles/Depth of Discharge
300 100%
600 75%
900 50%
1500 25%

Anyone know anything about VMAX, or thoughts about this battery. Is it just marketing lies? - it looks legit. It seems like it could be the new favorite Aux battery for people that want to fit it under the driver seat.

BTW, they do make a 50 Ah version too that also looks worth the premium price and would just slip right in. https://www.amazon.com/VMAX-MR86-50-Cycle-Sealed-Battery/dp/B00TPC2L9M

[HackAl]

I saw that on Amazon but the dimensions looked a little bit too close for comfort so I never drilled down on the specs.

I was afraid that the height might be an issue after I make the connections but I see now there is a gap after the flap under the driver seat which provides a little more clearance.

Are we sure this will drop right in? This might be perfect if that's the case.

(Edit: I'm talking about the 50. I'm assuming the cycle rates are comprable to the 75. Is that so?)
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[davevickery]

[RichBenn]

75aH would be great under the driver's seat.

I can attest to the fact that moving all the solar controller, battery, fuses blocks and wiring to under the back seat in a quality manner is quite a bit of work. The driver's seat is where it was supposed to go.
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Rich

[crazyvwvanman]

I'm going to try one of these soon in an under front seat application. The indicated 300 complete discharge cycles is a strong reason for me. I do wonder if that can be achieved with the charging methods that we use while traveling. They list charging needs of the battery that are somewhat specific so those may be the key to such useful discharge depths. Thanks for pointing these batteries out.

Mark

[Syncronoid]

I researched the driver seat battery installation extensively and ended up with this 50Ah battery. Nothing else seemed to fit w/o making some sort of modification to the space or lid.

https://www.4mdmedical.com/maintenance-free-rechar...at-3c.html

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'90 Syncro Westy w/GW2.5L

[crazyvwvanman]

That one specifies pretty narrow charging requirements as well.
Notice that it says: MAX Charging current 15A

People should think about that when setting up their charging relays and stop thinking some high current relay device and wiring is always needed. It may actually be damaging.


Charging Methods at 25C ( 77F )
Cycle Use : Charging Voltage 14.4 to 15.0V, Coefficient -5.Omv / C / cell, Maximum Charging Current : 15A
Standby Use : Float Charging Voltage 13.50 to 13.80V, Coefficient -3.Omv / C / cell

Mark

[Syncronoid]

Please elaborate, if you will.

[crazyvwvanman]

The manufacturers of these special purpose batteries often spell out specific voltages and amperages that their batteries need. Our alternator systems generally don't supply charging that falls entirely within these requirements. Then we wonder why our expensive batteries don't last as long as we expected.

In this case why would we make the aux charging wiring very large when the MOST amps we want it to supply is only 15 amps.
Depending on what else is connected to the aux battery that may be in use while the alternator is charging, the supplied amps may need to be more than just what the battery is supposed to get.

Mark

[davevickery]

To add to that, the Yandina ACR is popular partly because it limits the charge current by using long thin wiring. And anyone with a deep cycle battery should have a way to charge it up fully from time to time if their alternator can't provide high enough voltage. People with solar panels and good controllers seem to be able to get away with never topping up their batteries on a shore charger.

[Syncronoid]

I would suspect, and hope, that anyone using an auxiliary AGM, or 2 like me, would also have installed a smart charger, like an Iota DLS-45, which charges at the required voltages and intervals when the van is on shore power.

And regarding the wiring gauge, if anyone has a separator with an override switch for utilizing your auxiliary batteries to start the van in an emergency, you'll want the large gauge wiring.

[crazyvwvanman]

The issue is what happens when your alternator is charging the aux battery. Namely the whole time you are driving. What is limiting the current then? Once the battery is full what is reducing the alternator voltage to what the battery maker says is a suitable float range? Most people are just letting the electrons fly, and if anything trying to maximize them without thought that it may be the wrong thing for some batteries. Are you monitoring the amps going into each battery? Why chose a 45 amp charger unless your specific batteries want that much? Camped on shore power there is plenty of time for charging so a smaller unit may make more sense if it better matches the limit of the batteries.

For me a major point of having an aux is to not run down the starting battery so not much need for jumping a starting battery with almost no loads left on it. I've traveled and camped for weeks and months on end in North America and can't say I have ever camped with hookups more than a few times. Don't care to usually.

Mark

[Syncronoid]

Ya, I over did it on the Iota, but what's done is done. I've used my aux batteries to start the van once, in very cold weather, shortly before replacing the starter battery due to unknown origin a year after buying the van.

I have 200 watts of solar on the roof, too, but have never really tested out the entire system, off the grid, for more than a week or so straight camping. Maybe when I retire or Silicon Valley gives me a break. :/

[HackAl]

Having read these latest posts (with limited understanding) I'm hesitating on the Vmax 50.

I'm running Gowesty's simple auxiliary battery kit with their isolator. Does this need to be replaced? I also use a Battery Tender Jr. to keep it topped off at home.
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[davevickery]

Maybe Mark will come back and reassure you. He is an electrical guru. But if you look at the specs for all those 50Ah batteries including the one GW sells, they are all pretty similar.

For example this Mighty Max ML-50 says charge voltage 14.6-14.8 volts and standby volts of 13.6-13.8 and charge current less than 15A. The Universal Power group version of the 50 Ah says 14.5-14.9 volts and 15 Amps. Look at what is printed on the front of our 22Ah batteries, I bet it is somewhat similar.

Compare that to the Vmax which says charging from vehicle alternators with voltages from 14 to 15 volts is acceptable, and charging current 3-15 Amps. So the vanagon alternator will actually do better with the Vmax than the Mighty max because teh Vmax tolerates a larger range of voltages. Occassional home charging is necessary if the battery is not getting fully charged off the alternator and that was one of the points being made earlier as well as limiting charge current.

Smaller wire will help limit the charge current I think. So I think that the GW relay setup will probably work fine with these type batteries, which makes sense since they sell a similar battery. The Yandina combiner is maybe a better relay in terms of durability but I don't think it would work any differently than the one you have. But there are people that know way more about it than me so I will stop there.

[HackAl]

I ordered the Vmax 50 from Amazon. Guess I'll be the guinea pig for a change.

Thanks everyone.
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[HackAl]

It came today (90% charged) and I installed it. It fits fine standing up with room to spare and the lid closes even with the connections.

I had to install it with the terminals facing the rear of the van because I needed the + side on the inside for my positive connections to reach. I just had to lengthen my ground wire to reach the negative terminal on the outter side. I had originally envisioned the terminals in front with the lid gap providing the height for the connections. In the end, it didn't matter.

Time will tell if this was the right choice, but so far, so good. Thanks again, Dave.

(Where to I get the battery bracket to hold the battery down? I've seen it some pictures. Small, simple metal-finish bracket with one screw.)
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[HackAl]

No real issues to report yet with this battery or setup. So far, so good.

Wondering if I should get this: http://www.gowesty.com/product/power-supply/23410/trickle-charger-solar-panel-

Is there something comparable that might be better? Is it even worth it?

I don't camp enough to justify a more elaborate solar system but like the idea of replenishing my power use to extend battery life.

Thanks.
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[davevickery]

From what I read on that battery it can tolerate being partly depleted better than others and it can sit for months without loosing a charge (unless you have a parasitic drain). But it does specify a minimum and maximum charging amperage I thought. I think even the plug in trickle charger you have is below spec for that battery. And that solar trickle charger is much weaker. Either charger might be ok, but I think it would be better to occassionally put it on a real smart charger to make sure it gets fully topped up.

I bought this $65 high quality CTEK 4.3 amp charger https://www.amazon.com/CTEK-56-864-Automatic-Battery-Charger/dp/B006G14FK8 and mounted it in the van plugged into the electical outlet under the sink and permanently wired to my aux battery. I can't use it now for other cars, but it is easier to use on the van, I just attach an extension cord to the outside electrical hookup and it starts charging. It keeps it settings too, so it starts up in AGM mode whenever I plug it in. You might not have to go that fancy, but putting it on a decent charger once in a while might extend it's life. I would not bother with the solar charger at all. And if you just want to see how it goes, you could try it on your low amp trickle charger and see if it ever gets fully charged up after a trip. The reason I replaced my $14 black and decker trickle charger https://www.amazon.com/BLACK-DECKER-BM3B-Automatic...9W8EDBNGG1 is it never went into idle mode on my new AGM batteries even though it shut off fine for regular batteries.