Housing considerations for a battery in the bed of a topper-ed truck

[Bravo1782]

Hey Everyone,
I have a 2011 Ford F-150 XLT Crew Cab truck and there is no good way to add a second, large, deep cycle battery under the hood. To get around this, in the next few months, I'm going to install a CTEK 20A offroad battery system in the bed of my truck to serve as a DC-DC charger and MPPT solar charger for the main battery and a deep cycle "house" battery. I want to get a Deep Cycle AGM battery and mount it in the bed of my truck (which has a topper). Even though AGM are "sealed" it is my understanding that they still need to be able to be vented in the case of gas buildup. With this in mind, what is the best, safest way to mount the battery? Some ideas I've had:

1) Get a battery tray similar to this one and install it solidly in the bed of the truck. Install battery, cover terminals with appropriate terminal covers to prevent shorting, and call it a day. If just venting to the inside of the topper is "good enough" than this would work.

2) Install the battery is some sort of vented marine battery box like this one attach the box firmly (probably via good ratchet straps to facilitate easy removal).

3) Get a hardcore sealed and vented battery box like this or this , install securely, and vent to the outside of the topper (drill a hole and seal the hose up real good).

Opinions? Suggestions? I feel like an AGM should mitigate most of the issues I could run into with a standard flooded cell (certainly no spilling), but I want to make sure its vented appropriately. I've already got a Minkotta battery center, so that would certainly save some money.

Thanks!

 

[jgardiner]

Have you considered mounting it to the frame rails underneath?

 

[vtsoundman]

You're running the same setup I am...using a Ctek dual port 250S (Mppt + batt charger) in my jeep. Battery is mounted under my seat in rear. Look at the Universal Battery 121000 100ah battery from Amazon. I've used these in various industrial, ups, and comms applications and been pleased. Price is somewhat similar to Sam's Club AGM however. No venting necessary as it is a AGM VRLA battery. It cant handle large charging currents over 30A, so it's not suitable for alternator charging systems...it needs a DC charger. That being said, I have beat on them without noticeable
Iife issues but would not do it on a regular basis. This is the first time i will have be used it in a Jeep shake/ vibe environment (large trucks have been ok), so time will tell how it holds up.

I've added a transfer relay circuit to offload aux battery loads to the vehicle charging system...this will allow the CTEK to charge /dedicated all 20A to the battery. Recharge times while driving have dropped by 15% -25% this way. I have 1-2 fridges, a HAM radio, and 150w small pure sine inverter​ that charges my laptop and camera gear.

sent via the cone of silence

 

[john61ct]

offgassing from AGM is negligible

 

[southpier]

any room behind the behind seat in the crew cab? I would vent it wherever it ends up, but don't know why ...

 

[dwh]

I can't swear to this, but I'm pretty sure the 250s does *not* charge the main battery *at all* unless you add the SmartPass.

I.e., if you were thinking the 250s would keep your main battery topped up via solar...don't think so.

I've added a transfer relay circuit to offload aux battery loads to the vehicle charging system...this will allow the CTEK to charge /dedicated all 20A to the battery.

Oooh...that's a bloody good idea...

 

[Bravo1782]

You're totally right, you DO need the smartpass system if you want to charge BOTH batteries.

There's NO room at all behind the rear seat.

I've thought about a frame mount system, but I would be worried about 1) breaking it and 2) drowning it. Can you completely submerge an AGM? I feel like the battery would ultimately be safest in the bed, don't you think?

So you guys seem to think I'll be safe putting an AGM in the bed?

 

[vtsoundman]

I can't swear to this, but I'm pretty sure the 250s does *not* charge the main battery *at all* unless you add the SmartPass.

I.e., if you were thinking the 250s would keep your main battery topped up via solar...don't think so.

You are partially correct. The CTEK SmartPass is another box that will increase the charging & load current to 250A - total overkill for me...and drives up the cost quite a bit.
I am not aware of any CTEK chargers that will back feed power to the main battery automatically...I'd not want any system to automatically attempt the charge the main battery as aftermarket electrical is always more prone to fail than OEM systems. (I am chasing a parasitic drain now - think it is tied to the CIBA AutoDimming mirror I added).


I left space to add a relay to redirect charging energy into the main battery do just this - but so far, have not seen a reason.

Quote Originally Posted by vtsoundman View Post
I've added a transfer relay circuit to offload aux battery loads to the vehicle charging system...this will allow the CTEK to charge /dedicated all 20A to the battery.
Oooh...that's a bloody good idea...

Thanks

If you are going to use a 'transfer' relay, be sure the NC/NO contacts are sufficiently rated to handle the load. Many relays have a 40/20 or 50/30 rating with the NO usually having the higher rating. In our circuit, the CTEK will only supply 20A - so I looked for a relay that had a 30A NC contact rating and a 50A NO rating. It is a so-called 50/30. Using the NC contact on the relay means no power is consumed by relays in the 'default state' - which is solar charging. When the Jeep is running, I energizes the load transfer relay & activate the CTEK relay - the energy for these relays comes from a circuit that is live only during RUN. (Power consumed by relays can be non-trivial in battery only systems - so I tend to use them only when the circuit is powered during vehicle operation. A +/- 30A Simpson Milspec ammeter is in series with negative terminal of my Aux battery so I can keep on eye on its charge state - I find this to be much more telling than voltage alone.

There are 2 Anderson 50A connectors - one is for the 150W of portable solar panels, the other for 40A connection directly to the battery. The 50A connector for solar is overkill, but makes it easy to handle with gloves on. The other 40A connector allows me to connect a 2nd 100A 121000 battery, a charger, or another load if necessary. I'll use a 2nd battery when I won't be able to deploy solar and/or need to run more electrical gear.

Sorry for the dog hair. This is under the 40 portion of the 60/40 seat in a jeep JKU. The slope of the platform matches the slop of the 60 portion when laid flat. The camera image makes it look worse than it actually is. The CTEK, Blue Sea 6 circuit panel, a 4 circuit fuse block and load transfer relay are all tucked away. The battery is bolted to the floor with some steel brackets I fabbed up. There is add'l insulation under the battery in the form of 80mil alum/rubber, 1/6" foam, 1#/sqft MLV and a layer of DEI heat sheilding. I think there is a cat just below this portion of the floor...it gets pretty warm during long slow pulls in the mountains. The underside of the battery stays cool... Coolers are hardwired via 12V disconnect to the Blue Sea Panel. I will later add a small switch panel so I can turn off the HAM radio and cooler -> I am NOT a fan of leaving wires live for no reason. There is a 4th 12V port in the rear cargo area. The inverter, not shown here, will be velcro'd to the front of the battery. It is a 120W Samslex pure sine inverter. It has one of the lowerst quiescient power draws and is one of the more efficient units I've used. I find step sine units are sometimes incompatible with laptop and other chargers. All wiring is GXL, TXL under the hood. 600V high temp welding cable for the big stuff. Marine grade Ancor in the passenger compartment or for shot runs under the hood. I'm slowly replacing all PVC **** wire I used when I first got the jeep for interior aux lights (and didn't realize it was PVC)

My main inverter is a 300W Samlex. It is left hanging loose on the passenger side floor zip tied to the seat for now. I will hard mount this in the rear - likely behind the tailight in a dust tight box that is vented to the cab of the Jeep. I think there is also room on the passenger floor under the seat.

 

[vtsoundman]

Can you completely submerge an AGM? I feel like the battery would ultimately be safest in the bed, don't you think?

So you guys seem to think I'll be safe putting an AGM in the bed?

YES you can drown an AGM, but if the liquid is conductive enough you may get some leakage current & corrosion. While not not all AGMs are the same, ALL batteries have a relief valve in them to prevent explosion. ALL lead acid based batteries will outgas if overcharged (too much voltage). Some are safer than others. I went with a VRLA AGM from Universal Battery - these are used in relatively 'sealed compartments' like comms boxes all the time. I have zero concern about out gassing.

 

[dwh]

I've thought about a frame mount system, but I would be worried about 1) breaking it and 2) drowning it. Can you completely submerge an AGM? I feel like the battery would ultimately be safest in the bed, don't you think?

So you guys seem to think I'll be safe putting an AGM in the bed?

Lots of factory frame mounts. If there's some protection from flying rocks there's usually no problem. In fact I can't recall anyone ever reporting frame mounted batteries being damaged.

Sure you can submerge sealed batteries. The popoff valves only open while the battery is charging and overheating and building up excess internal pressure. IF it ever happened (unlikely unless something goes wrong) pressure will be pushing out - you won't end up sucking stream water into your battery the way ujoints do when they get suddenly cooled off by dunking.



Most of this has been covered many times. Here's some "catching up" reading:

https://duckduckgo.com/?q=+agm++bed+site:forum.expeditionportal.com&ia=web

 

[southpier]

You're totally right, you DO need the smartpass system if you want to charge BOTH batteries.

There's NO room at all behind the rear seat.

I've thought about a frame mount system, but I would be worried about 1) breaking it and 2) drowning it. Can you completely submerge an AGM? I feel like the battery would ultimately be safest in the bed, don't you think?

So you guys seem to think I'll be safe putting an AGM in the bed?

wherever it goes the mounting needs to be solid. if venting would be the main concern, mounted in a solid (threaded rods w/ nylok nuts) lidded (non-combustible/ easily cleaned not plywood!) box with a tube headed out to daylight (maybe under the truck) shouldn't be any more of a concern than any of the other holes (for example: the cables) which get drilled/ punched. prime, paint, & seal the penetration. I honestly don't think a $60 battery box would rank you among the "hardcore" elite. I think it would be a safe investment.

 

[vtsoundman]

dwh and Bravo are correct - the smartpass will charge both the main battery & aux battery when solar is present. Charges house/ alternator input then changes to the aux battery/load. I misread the manual and may have to alter my installation and use a latching relay instead to cut power to the CTEK unit.

You are partially correct. The CTEK SmartPass is another box that will increase the charging & load current to 250A - total overkill for me...and drives up the cost quite a bit.
I am not aware of any CTEK chargers that will back feed power to the main battery automatically...I'd not want any system to automatically attempt the charge the main battery as aftermarket electrical is always more prone to fail than OEM systems. (I am chasing a parasitic drain now - think it is tied to the CIBA AutoDimming mirror I added).


I left space to add a relay to redirect charging energy into the main battery do just this - but so far, have not seen a reason.



Thanks

If you are going to use a 'transfer' relay, be sure the NC/NO contacts are sufficiently rated to handle the load. Many relays have a 40/20 or 50/30 rating with the NO usually having the higher rating. In our circuit, the CTEK will only supply 20A - so I looked for a relay that had a 30A NC contact rating and a 50A NO rating. It is a so-called 50/30. Using the NC contact on the relay means no power is consumed by relays in the 'default state' - which is solar charging. When the Jeep is running, I energizes the load transfer relay & activate the CTEK relay - the energy for these relays comes from a circuit that is live only during RUN. (Power consumed by relays can be non-trivial in battery only systems - so I tend to use them only when the circuit is powered during vehicle operation. A +/- 30A Simpson Milspec ammeter is in series with negative terminal of my Aux battery so I can keep on eye on its charge state - I find this to be much more telling than voltage alone.

There are 2 Anderson 50A connectors - one is for the 150W of portable solar panels, the other for 40A connection directly to the battery. The 50A connector for solar is overkill, but makes it easy to handle with gloves on. The other 40A connector allows me to connect a 2nd 100A 121000 battery, a charger, or another load if necessary. I'll use a 2nd battery when I won't be able to deploy solar and/or need to run more electrical gear.

Sorry for the dog hair. This is under the 40 portion of the 60/40 seat in a jeep JKU. The slope of the platform matches the slop of the 60 portion when laid flat. The camera image makes it look worse than it actually is. The CTEK, Blue Sea 6 circuit panel, a 4 circuit fuse block and load transfer relay are all tucked away. The battery is bolted to the floor with some steel brackets I fabbed up. There is add'l insulation under the battery in the form of 80mil alum/rubber, 1/6" foam, 1#/sqft MLV and a layer of DEI heat sheilding. I think there is a cat just below this portion of the floor...it gets pretty warm during long slow pulls in the mountains. The underside of the battery stays cool... Coolers are hardwired via 12V disconnect to the Blue Sea Panel. I will later add a small switch panel so I can turn off the HAM radio and cooler -> I am NOT a fan of leaving wires live for no reason. There is a 4th 12V port in the rear cargo area. The inverter, not shown here, will be velcro'd to the front of the battery. It is a 120W Samslex pure sine inverter. It has one of the lowerst quiescient power draws and is one of the more efficient units I've used. I find step sine units are sometimes incompatible with laptop and other chargers. All wiring is GXL, TXL under the hood. 600V high temp welding cable for the big stuff. Marine grade Ancor in the passenger compartment or for shot runs under the hood. I'm slowly replacing all PVC **** wire I used when I first got the jeep for interior aux lights (and didn't realize it was PVC)

My main inverter is a 300W Samlex. It is left hanging loose on the passenger side floor zip tied to the seat for now. I will hard mount this in the rear - likely behind the tailight in a dust tight box that is vented to the cab of the Jeep. I think there is also room on the passenger floor under the seat.

View attachment 403148

 

[rayra]

#1 will do fine, has for 60yrs+. Hydrogen concentration in the real world is an overinflated (pun not intended) bunch of BS. And that's not even factoring the SLA / AGM batteries, which are only going to discharge gases under the worst sort of overcharging mistakes.