Installing battery underneath

[mjalar51]

How feasible is it to install a couple 6 volt golf cart batteries underneath the body of a van. We have an extended E250 and I see some space in the back corner where they might fit. Access and maintenance would be a challenge but I am trying to imagine making a rack that could be raised or lowered to for inspection and keeping them filled. They are Costco GC2.

Would it be possible to cut an access from the van floor above? Just an idea.

 

[SternWake]

I made a battery box under the floor of my Dodge van. It resides under the floor behind my Drivers seat. From there it still requires ~11 feet of cable, one way, from the alternator(+) stud and about the same from the engine battery. I used 2awg cable to ensure good amp flow.

My underbody box however only accommodates flooded batteries a maximum of 9 3/4 inches tall to the top of the posts, and 6v GC-2 batteries are generally 11.5 inches tall. So I could not use these. It sticks down below my van body about 2 inches, and I would not want it to stick down the 4 inches required for GC batteries to reside here. I am Not willing to lose the ground clearance.

I also only made mine big enough to hold two group 27 batteries side by side at 12.5 inches wide each, instead of the bigger(wider) group31 12v batteries at 13 inches wide each( I was a fool!!).

But over the years I found I do not need the 230 or 260AH house battery capacity anyway.

I do have an access hatch( sealed) from above for checking water levels and specific gravity, but It is not so simple/convenient to get to them for watering, and I prematurely ended 2 sets of group 27 batteries lives by not checking water levels in time. (water usage increases as batteries age)

Right now I only have one group27 AGM battery in the underbody box. I used to have a 130AH group31 under my hood, but it lived out its cycle life in June and I have been able to get away with just the 90AH AGM for both house and engine starting duties.

6v flooded GC batteries are the best battery for house battery duty, but they have that height requirement of ~11.5 inches.

If you go ahead with them and want to utilize the alternator to recharge them( which I recommend), then keeping them closer to the engine compartment means you can use shorter lengths of thinner cable, compared to putting them all the way in the back, further away, which would necessitate thicker heavier $$$ier cable to pass the same amperage.

If you can accommodate GC battery height in your intended location, and make sure to protect them from rocks thrown from the back tire, and can make an access hatch from above, I'd say to use no less than 2awg cable and preferably much thicker to them from alternator. You can use lesser cable but charging amps will be reduced greatly and it will be much less efecitve.

Of course those with adequate solar wattage and enough sunlight can get away without using the alternator at all, but I personally would not be able to go without utilizing this very effective charging source.

 

[Spaceman Spiff]

One thing I didn't see Sternwake mention is that deep cycle batteries are heavy.  My GC-2's weigh 60 lbs each and a 12 volt deep cycle battery weighs 100+ lbs.  Your strength/physical capabilities/awkwardness of position of battery box needs to be factored in when thinking of where to place your batteries.

-- Spiff

 

[SternWake]

Yep the weight is a good point. My group27s were 52 to 57Lbs, and they were difficult to install and remove into that hatch as the hatch is also inside a cabinet.

Later I had the single 64Lb group31 flooded battery, and now I have the single group27 AGM battery at 74Lbs in there.

I am not looking forward to the day I have to remove that heavy beast, but that should be well in the future

 

[flying kurbmaster]

I have a box behind the rear axle below the floor on my Dodge caravan for one 12 volt battery. it is accessed from the inside it is a little awkward to remove the battery to check it but I can manage. Easy access is a good idea lifting them in and out as well as checking the water level or connecting a battery charger or wires or whatever you do with batteries. If you are worried about ground clearance you can always make the lid a bit higher inside if you have the room which would make them partially inside and mostly below this would also make them easier to access to service etc. mine is made with L shaped steel, I suggest you make or have it made so it fits in from above with a flange screwed to the floor. You can line it with plywood to protect it if you wanted or thin metal. good luck it is a good place to put a battery.the cut out floor piece was used as an access door

 

[Gideon33w]

Seeled agm batteries are pricey but they don't need added water and can be mounted in any orientation. Most are built dimensionally like lead acid batteries but the ability to lay them on their sides makes life load easier. Do keep in mind your weight distribution when choosing a mounting spot.

 

[SternWake]

AGMS Can be mounted in any position, Except upside down.

One also needs to keep in mind that AGMs require high amp recharges from their most depleted state every so often, and it is more important with AGM to achieve a true 100% charge regularly with them, compared to a flooded battery.

Partial state of charge cycling is harder on an AGM than it is a flooded Deep Cycle or Marine battery.

Some AGMS say no more than 30 amps per 100Ah of capacity, other higher$$ AGMS say no less than 20 amps or 40 amps when deeply cycled.

This higher amperage recharge requirements means they are not a good battery for low and slow Solar only recharges, especially when cycled to 50% or less. One needs to be able to approach the 30% maximums recharge rates of le$$er AGMs and exceed the 20 or 40% minimums listed by the higher$$ AGMS from Northstar/Odyssey/Lifeline AGMS when deeply cycled.

The sealed/no maintenance aspect of AGMS is great, as is their low self discharge and higher CCA figures, and for some of them, to accept HUGE recharging currents. But they require more attentive recharging requirements to remain healthy for an acceptable timespan/Accumulated # of cycles, otherwise they become paperweights prematurely, and cost significantly more to become that paperweight.

They also tend to weigh more than a flooded battery in the same size factor.

For example:
My 170$ 130AH flooded group31 13"x6.75"x9.25" weighs 64LBS

My 325$ 90Ah AGM group27 12.75"x6.5"x9" weighs 74 Lbs

I do not really believe the 130AH claim of that flooded group31 USbattery, I think it was closer to 120AH
I think the 90Ah claim of my NorthstarAGM is conservative, I think it is closer to 100AH

 

[Gideon33w]

All good points. I like the agm batteries but have the luxury of an oversized solar array and a quality charge controller. They aren't for everyone. No experience yet with gel batteries but they look promising.

 

[SternWake]

Gels are great for deep cycle service, but their recharge requirements are very specific. Feed them at too high a rate when depleted and the battery is instantly capacity compromised as large voids would appear in the gelled electrolyte.

They got a bad rap when they first came out because they were not recharged properly.

 

[MikeRuth]

How feasible is it to install a couple 6 volt golf cart batteries underneath the body of a van. We have an extended E250 and I see some space in the back corner where they might fit. Access and maintenance would be a challenge but I am trying to imagine making a rack that could be raised or lowered to for inspection and keeping them filled. They are Costco GC2.

Would it be possible to cut an access from the van floor above? Just an idea.

I installed two Trojan T-105 batteries behind the drivers seat under the body. It took some work and fabricating to do. They are not that easy to service in that location. But for me it was the ticket. I have some pictures on my photobucket account from the link in my signature. Currently today photobucket is down! check back later I guess. 

What I did, I bought two new T-105's and then out of 1/2"X 1/8" flat bar stock built a battery holder which has four mounting points to attach to the Chassis rail. I then drilled out the chassis rail and mounted the set using 1/2" Grade 8 hardware. 
the bottom of the battery tray is just slightly visible when standing back from the van about 10 feet. My wiring runs up and through the Gas shroud and I have two buss bars, one for + one for -. This keeps the run from the battery to the bars at about 3.5 feet and I used #4 wire. I also have a run of #2 wire going back up to the engine bay, neg goes straight to the neg post on the starting battery and the positive to a 300 amp continuous duty solenoid mounted to the firewall, and from that back to the alternator post. 

It need two floor jacks to either install or remove the batteries. One is to raise the drivers side just about 2 inches and the other goes under the tray. to install I set the tray on the jack, slide it under in position and then raise them up until I can slide the tray on to the mounting bolts, then install washers and nuts. Takes about 10 minuets. To remove I place the jack under the tray, loosen the bolts, slide off the studs and lower gently and then slide them out from under the van. 

I also use a hydro water system as there is no way to water the batteries once installed. I choose the Pro fill system and a hand pump to water them. I do this roughly once a month. 

so far I'm quite pleased with this setup. My batteries are now about 14 months old and I just pulled them to do a hydrometer check. Happy boy as all cells were at 1.280 per trojan.  I tell ya if I could figure out a way to mount two more I would. Just to have the reserve capacity. I know I could add two more panels on the roof. I use a Tristar TS-45 PWM solar controller for charging. 

this is meaning less to you if you are not the type and or have the equipment and experience to fab out a tray etc. I originally inquired about the battery box that ambulances use, turns out they want $600.00 just for the box and then you have to go about quite a bit of work to install it. Choose to build my own. 

The other option of course is to put your batteries inside, but of course there are hazards to this of which you can find a ton of info on this site. 

Mike R