Recommendations on Small Battery for a Minivan Build-Out?

[dl777]

I plan on converting a minivan into a small Class-B RV and am trying to figure out the best type of battery assuming this use type:

- travelling cross country and visiting parks and cities (not staying longer than a few days at each place and driving a lot between stops

- trips of a few weeks to a month at a time

- Two laptops and two phones
- small water pump
- small portable refrigerator (possibly the Dometic CFX3 25: YouTube video
(

https://www.youtube.com/watch?v=EA6JLgY7DZQ

) showed it drew 4.4amps)
- 5v fans and lighting

I would like to house the battery in the Stow and Go area available on the Grand Caravans that would be covered but somewhat accessible (not too directly available).

Any tips appreciated. Space consumption is a huge factor though. I read a lot of the threads about batteries and it is still not clear to me what type to use.

Or should I consider using a Jackery or a Goal Zero type unit that has the electronics and conversions built in and just put a larger alternator in and get a cable and isolator to be able to charge it off the van motor?

Thanks!

[wny-pat]

I have been running a Dometic CFX28 in my Honda Odyssey van for several years now. Runs on the rear 12 cigarette outlet with no problems. Doesn't run down the battery at all. When the grand kids are with us, they both use their phones on usb plugins.

[booster]

The critical part is the comment of staying as much as 2-3 days and a compressor frig. My guess is if you didn't drive during those 2-3 days you would probably need upwards of 150-200ah of battery capacity

[dl777]

Originally Posted by booster

The critical part is the comment of staying as much as 2-3 days and a compressor frig. My guess is if you didn't drive during those 2-3 days you would probably need upwards of 150-200ah of battery capacity

Thanks for the replys. I probably should have said we would do some local sightseeing type driving every day probably so hopefully we would keep it charged sufficiently through that. Any recommendation on a small form factor battery type that can provide 12V output? I read about using two 6V batteries and am not sure why people consider those versus one 12 V battery.

[booster]

Originally Posted by dl777

Thanks for the replys. I probably should have said we would do some local sightseeing type driving every day probably so hopefully we would keep it charged sufficiently through that. Any recommendation on a small form factor battery type that can provide 12V output? I read about using two 6V batteries and am not sure why people consider those versus one 12 V battery.

Daily driving will certainly reduce your need for capacity, but be sure to remember it takes a long time for lead acid (both wet cells and AGM) to get totally full, in the range of 6+ hours of charging in many cases. They get to about 80% full at a much higher rate and in a small battery may get there in less than an hour. So count on only 80% of the rated capacity in your battery search, unless you are really going to be driving a lot.


The 6v vs 12v thing is a throwback to the past in some ways, I think. Traditionally, the best lead acid batteries for camping and RVs have been the 6v golf cart batteries which are made for the deep discharge use. With many of the AGM batteries these days there really is no difference in construction so very little or no benefit in going either way. Size and fitting probably are the most important to you. AGM is the way to go, I think, as no maintenance, leaks, or gassing and can be placed in any position except upside down.


AGMs come in lots of sizes and some way of getting to 100ah capacity with either a single or multiple should be enough for you.


You might also even consider putting a small solar panel on the roof. Flexible stick down ones are quite easy to do, and for small battery systems like you are proposing they can pretty much cover your power use except in horrible sun conditions. It would also take care of topping up the charge on battery for a bit of extra capacity and longer life. Costs of solar have come way down so you could probably do the solar for a modest cost. A 100 watt panel and a 100ah battery capacity is a quite capable and well matched small system.

[dl777]

Originally Posted by booster

Costs of solar have come way down so you could probably do the solar for a modest cost. A 100 watt panel and a 100ah battery capacity is a quite capable and well matched small system.

Great info. Thanks so much for the history.

[Rockwood27]

I think Booster has it right. 100 AH should be enough for your needs. A single 12V AGM battery can be installed almost anywhere and forgotten about. Don't forget about a fuse block to keep everything safe!

Since you're planning on recharging the house battery from the alternator, you should install a battery separator under the hood to keep from running the van's battery down.

[dl777]

Any input regarding how to allow for three types of charging (car engine, wall/110V and possibly solar)? I can probably forgo solar now but it would nice to be able to add later. Thanks.

[mkguitar]

a charging lead/acid battery will produce hydrogen gas.


make sure that your battery is in a vented location- hydrogen rises, you don't want it trapped in your well and catch a spark


mike

[dl777]

Originally Posted by mkguitar

a charging lead/acid battery will produce hydrogen gas.


make sure that your battery is in a vented location- hydrogen rises, you don't want it trapped in your well and catch a spark


mike

Thanks Mike. I am only considering an AGM or a Lithium so I don't have to worry about positioning and things like this.

[ks@yvr]

KISS - keep it simple. You don’t need much for 110v power over a good extension cord from shore power to van and just run a couple of duplex plugs inside the van for 110V shore power outlets. I would recommend outlet #1 being a gfci outlet and outlet #2 slave off the gfci that way both outlets are protected. Run a small 110V battery charger to your house AGM battery to keep it charged up when on shore power (medium sized trickle charger) more than what your fridge draws. Run a small 110v inverter 300-500 watt for power items that don’t charge off 12V and you should be set to go for minimal cost.

[ks@yvr]

A mixed lithium/starter battery setup brings extra costs for charging etc., unless you go the Jackery or Goal Zero route so I would suggest staying AGM as it will be the most economical to setup for a simple system you want.

[dl777]

Originally Posted by ks@yvr

A mixed lithium/starter battery setup brings extra costs for charging etc., unless you go the Jackery or Goal Zero route so I would suggest staying AGM as it will be the most economical to setup for a simple system you want.

Thank you for the advice Ken! I just purchased a Jackery 1000 as it seems like a very simple solution (big dollars though). It can do all three charging types.

I am not sure if the 46ah Lithium battery will be enough though. Maybe once we get back from the three week trip I will sell the Jackery and put in two 100watt panels, poke a hole through the roof, add a 100ah AGM battery and upgrade to a 200 amp output alternator and then figure out all the fuses and inverter/chargers I need (that is a mouthful).

[ks@yvr]

A 100 ah AGM in reality is only 50 ah as you cannot run a AGM to zero like you can a lithium power pack/battery. So if 46 ah doesn’t do it the 100 ah won’t either. Anyway you will see from your trip. I think you’ll be pleasantly surprised that it works out just fine since you will have an opportunity to charge it up almost daily. Lithium also charges much quicker than AGM’s so you should be at full charge with less driving time.

My Pleasure Way only had a 100 watt solar panel on the roof (no room for more) and I found that was enough to keep a 200 ah AGM fully charged up running all the day to day electronics. The fridge was 12/110v and propane and we always ran it on propane if we were not on shore power (almost never). We had a generator but only used it to power the microwave and AC on 2 occasions (15-20 mins for AC each time) (30 hours total on generator when we sold vehicle). The AC and generator are not on the current build

[booster]

Originally Posted by ks@yvr

A 100 ah AGM in reality is only 50 ah as you cannot run a AGM to zero like you can a lithium power pack/battery. So if 46 ah doesn’t do it the 100 ah won’t either. Anyway you will see from your trip. I think you’ll be pleasantly surprised that it works out just fine since you will have an opportunity to charge it up almost daily. Lithium also charges much quicker than AGM’s so you should be at full charge with less driving time.

My Pleasure Way only had a 100 watt solar panel on the roof (no room for more) and I found that was enough to keep a 200 ah AGM fully charged up running all the day to day electronics. The fridge was 12/110v and propane and we always ran it on propane if we were not on shore power (almost never). We had a generator but only used it to power the microwave and AC on 2 occasions (15-20 mins for AC each time) (30 hours total on generator when we sold vehicle). The AC and generator are not on the current build

A 100ah AGM can easily be used as 80 usable with minor penalty in life, there is lot of information a calculations on this forum about that.


The 1000 watt power supply you got is really closer to 80ah as they have it rated at 21 volts. Note that you can only get 10 amp rate out and charge at only about 12 amps, so no big discharge or recharge and absolutely no need for a big alternator. The bad side is that it will take nearly 7 hours to charge, which is a lot of driving, so you probably will need solar to keep charged.


Always be sure to read the tech specs carefully, as the selling descriptions are often not all the great and knowing what you will really get.

[dl777]

I am now thinking about mainly running the portable refrigerator off of the van starter battery as opposed to the Jackery1000 and have two questions:

1. Should I replace the stock Dodge Grand Caravan alternator with a high output one? I think the standard is 140 or 160 amps. They make 200 and 250 amp alternators for it.

2. The van battery is four+ years old so I am thinking of replacing it from a preventative maintenance point of view and am wondering what type I should use for the van starter battery (flooded or AGM)? Can I go bigger or does form factor come into play (H7 currently)? Any brand recommendations?

Thanks.

[booster]

Originally Posted by dl777

I am now thinking about mainly running the portable refrigerator off of the van starter battery as opposed to the Jackery1000 and have two questions:

1. Should I replace the stock Dodge Grand Caravan alternator with a high output one? I think the standard is 140 or 160 amps. They make 200 and 250 amp alternators for it.

2. The van battery is four+ years old so I am thinking of replacing it from a preventative maintenance point of view and am wondering what type I should use for the van starter battery (flooded or AGM)? Can I go bigger or does form factor come into play (H7 currently)? Any brand recommendations?

Thanks.

It is definitely an option, but I would worry more about the battery size than the alternator size. I don't know what size battery you could squeeze into the minivan, but I would guess you would be lucky to get to a gp24 or equivalent, so maybe 75-80 amp hours of battery. You have to be very careful as this is also your starting battery so you don't dare pull it down very far, maybe 50% max and most vehicle batteries are rarely fully charged when you start discharging. You might be able to get one day of use on a small cooler safely, but it would take a long drive to recharge to full, getting to 80% full happens fairly quickly, though.


Why don't you want to use the portable power pack at this point? It seems like the most practical and convenient way to go.

[dl777]

Originally Posted by booster

It is definitely an option, but I would worry more about the battery size than the alternator size. I don't know what size battery you could squeeze into the minivan, but I would guess you would be lucky to get to a gp24 or equivalent, so maybe 75-80 amp hours of battery. You have to be very careful as this is also your starting battery so you don't dare pull it down very far, maybe 50% max and most vehicle batteries are rarely fully charged when you start discharging. You might be able to get one day of use on a small cooler safely, but it would take a long drive to recharge to full, getting to 80% full happens fairly quickly, though.


Why don't you want to use the portable power pack at this point? It seems like the most practical and convenient way to go.

Maybe I will start using the Jackery for everything (two laptops, two phones, USB light and refrigerator) and see how it goes. I can always plug the fridge into the van starter battery if I need to. It comes with an always-on 12V plug. I will be sure to bring jumper cables just in case.

Do you think I should replace the 4+ year old battery preventatively?

Thanks.

[booster]

Originally Posted by dl777

Maybe I will start using the Jackery for everything (two laptops, two phones, USB light and refrigerator) and see how it goes. I can always plug the fridge into the van starter battery if I need to. It comes with an always-on 12V plug. I will be sure to bring jumper cables just in case.

Do you think I should replace the 4+ year old battery preventatively?

Thanks.

I would just get the battery load tested, which is a good idea every year anyway. At 4 years some batteries are good as new and some show their age, so could be either.


I think you are right on with the rest of it, and just see how it goes.

[dl777]

I left the doors open to the van and the key in the on position for about an hour and the battery was dead on my close to 5 year old battery so I am going to proactively replace the van starter battery. I was planning on purchasing a Sam's Club battery (Duracell AGM Automotive Battery - Group Size 94R (H7)). Is an AGM a good way to go for the starter battery if it turns out I will use it for running the fridge if the Jackery can't handle it all (or recharge quick enough)? I wasn't sure if a flooded would be better. Thanks.