Batteries? Start and House

[FarmerFrederico]

Hey guys,

2010 E350 with a V10 and 155amp alternator. I've got the second battery on the frame rail installed by the factory for powering the trailer when the vehicle is off. It is isolated from the battery in the engine compartment.

Right now I have my ARB twin air compressor wired directly to the second battery but it has been drained - battery is 6 years old. My main battery was load tested recently and it was a bit low too. So, I'm going to replace them both.

I'm working on a house battery system too, which I think I'll separate from the factory system with a Blue Sea ACR. It will also get a charge from a 150w panel I'll install shortly. It will definitely run my ARB fridge, two fans, some DC outlets, lights, and maybe an Espar heater and a small inverter in the future.

Should I get some dual purpose deep-cycle/starter batteries to replace the two factory batteries? I was thinking about some Odyssey group 65 AGMs. I'm still in paralysis deciding on house batteries too. I'll likely have to get a custom built battery box for those because I need more than 130ah total storage which is what I think I could fit in two group 65 factory battery boxes.

Am I on the right track?

Thanks!

 

[Paddy]

Build your own lithium polymer battery! I built a 4cell 100aH bank and it's been great so far. Much longer cycle life, deeper discharge, smaller space and light weight. Win/win.

I built from surplus Chinese cells, and total cost was about 500$.

 

[luthj]

Dual purpose means not good at either. In general dedicated deep cycle will preform better and last longer. Some AGM deep cycle batteries can also be used as starter batteries. This is because their internal resistance is so low that they can readily supply starting current (even without the sponge-like plates that starter batteries use).

If the battery doesn't have a C/20 or C/100 AH rating, it for sure isn't a true deep cycle battery.

If you can find a single 12v battery that will fit and meet your AH needs, that is the way to go. A single battery is simpler to wire, and will not suffer from imbalance issues that can sometimes affect parallel battery setups. I am referring to the house battery of course. You will want/need a separate starting battery regardless. Another option is 2 6V batteries in series. Sometimes the 6V batteries will have thicker and more durable plates. This makes them more resistant to abuse.

As a note AGM batteries are generally more resistance to vibration than flooded batteries. The AGM mat provides physical support and separation for the plates. This helps prevent plate cracking or internal short circuits. This is really only important for vehicles that use crappy roads a decent amount. They can also be mounted on their sides if needed.

 

[FarmerFrederico]

I was considering these for the start/auxilliary factory battery locations: http://www.odysseybatteries.com/batteries/pc1750.htm Should I keep my compressor and a future winch connected to these as long as I use it while the engine is running?

luthj - two 6V batteries in series is what I was considering for the house set up, but I can't find a 6V battery (Crown or Trojan) that is lower than 235AH - for a total of 470AH that seems like too much battery for a permanently mounted 150W solar panel and the alternator, correct?

 

[luthj]

When batteries are in series, the voltage is additive (6+6=12), but the AH are not. So the bank would be 235AH, which is a very reasonable size. You could go larger if you want. Ideally you would have more solar for a larger bank, but the system will still work just fine.

What amp draw does your compressor and winch have? Just trying to get a feel for your system. Any other items on your house system, such as a fridge?

 

[IdaSHO]

but I can't find a 6V battery (Crown or Trojan) that is lower than 235AH - for a total of 470AH t

The AH rating is at 6V

When paired to make 12V, you will have 235AH @ 12V

 

[FarmerFrederico]

Ahh...see I knew I should ask a question or two!!! AH does not change. Cool! That's what I'll go for the house system then.

My compressor is an ARB twin which draws 56amps. A winch (I don't have one yet) draws around 400amps, correct? I figured those should stay on my start/factory auxiliary batteries.

On the house side I currently have and ARB 62qt (3ah) fridge which isn't wired yet, a MaxxFan (2ah), and standalone Fantastic fan (2ah), lights (1ah)...all of that should be below 150ah/day. I've got a 150W panel coming my way through a Bogart Charge Controller, and I'll tie it to the alternator for charging too. In the future I imagine adding an Espar heater to the loads and another 100W deployable panel so I can take advantage of the shade.

 

[luthj]

Seems like you are on the right path. 200AH is the smallest I would go with a fridge. This allows you to park in the shade or a parking garage for a few days, and still have cold food (beer) when you are done. The same goes for cloudy days, or camping without solar.

It is possible to connect the winch to your AUX battery system. However you need to size the wiring accordingly, which can add some cost depending on where the AUX battery bank is located in relation to the winch.

As far as the compressor goes, you can connect it to either bank. 50A is not a large load for a 200AH+ battery bank.

I suggest getting a shunt based battery monitor. Xantrex, victron, etc. They are usually around 125-200$ and can make diagnosing and monitoring your house electrical system almost effortless. If you want some can even be used to disconnect loads when the AUX bank gets too low.

If you size your alternator charging circuit appropriately, you can expect 50A or more of charging current. Of course this will taper off as the batteries approach 85% charged. Larger wiring on this circuit can also allow you to boost or jump start your engine if the starting battery goes dead or fails. Voltage drop in this circuit will be the biggest factor in alternator charge rates. Often the alternator wiring and engine ground strap are undersized, or just weak due to corrosion. Upgrading them can have a noticeable impact on how much "free" charging you can get from the alternator. For example, on my sprinter the engine ground strap was dropping 0.1V during charging! It may not sound like a lot, but that can drop the charge rate by over 30% in some cases.

 

[FarmerFrederico]

Thanks, luthj. I do have a shunt (500A) based battery monitor - the Trimetric, from Bogart as well. Now that I know the AH is not additive I might consider something just a bit bigger. I was thinking having about 300-400Ah would be ideal.

 

[FarmerFrederico]

Anyone have any thoughts on the Odyssey's I mentioned? I've read around these parts to stay away from Optima but I guess I should take some of that with a grain of salt. I should be able to pick up some Optima's quickly - I'd have to have Batteries Plus here in town order in the Odyssey's. Can't find any Lifeline's yet.

Where to people order 6V Crown batteries? Our local Golf Cart store only deals in Trojan.

 

[IdaSHO]

Certainly nothing wrong with Trojan

For 6V deep cycle batteries, they are just as good as any other wet cell.

 

[Luinil Explorations]

Build your own lithium polymer battery! I built a 4cell 100aH bank and it's been great so far. Much longer cycle life, deeper discharge, smaller space and light weight. Win/win.

I built from surplus Chinese cells, and total cost was about 500$.

Is there a build thread?

 

[IdaSHO]

Not sure of a build thread, but there is quite a bit of info online about building your own cells.

Just be sure you know what you are getting into. They can be tricky (dangerous) to charge.

 

[Paddy]

I didn't do a build thread. Probably should. But I wasn't sure if it would work! I used an undersized BMS but I was trying to go on a budget and figured I'd try the cheapo first. Well it's been doing fine by my estimation. And 500$ for 100AH of lithium I think it's pretty much superior to any lead acid. I may do a top balance annually but maybe not. I'm Kindof curious how long it will last like this. As far as charging dangers the newer chemistries are much safer than a few years back.

 

[luthj]

No experience with the odyssey batteries. Trojan makes a good quality battery, as does Deka. In fact the flooded GC2 batteries sold by costco and sams club are made by deka. I had a pair in a previous van, and they were solid performers. Just remember that flooded batteries need to have water added on occasion. The AGM batteries take a charge more efficiently. This means it takes less AH to recharge them compared to a flooded battery. They also never need watering, so they can be mounted in more locations. However, just make sure your solar charger is properly configured for AGM batteries. The manufacturer's specs should be followed closely with regard to charging voltages. Also, you REALLY want temperature compensation for your solar charger. Ideally this means a temp probe attached to the batteries case. Trust me, temp compensation means faster charging, and longer battery life.

Most major battery stores can order lifeline batteries for you. They are expensive, and the shipping will add $100-200. They are very robust though, and charge very quickly, even from the alternator. Just make sure you can completely charge them on a regular basis. This means 14.4V (@ 77F) until charging current drops to 0.5% of the capacity rating.

FullRiver also makes good AGM batteries. They have a bit better availability than lifelines in some regions and are usually cheaper. They require different (higher) charging voltages than many AGM batteries.