Dual battery for Africa expedition

[zsuzsiestekergo]

One more thing. This would of course need an automatic battery disconnect to prevent both batteries to discharge beyond what is necessary for starting. For example: http://www.batterybrain.co.uk/productspage.php

Is there any product recommended to use with Dual AGMs?

 

[chromisdesigns]

You can use a **real** deep cycle battery, like Rolls, Lifeline, etc. for starting it's nothing compared to the workout they get during deep cycle discharge. The cheapie "all purpose" deep cycle batteries from Sears like you see the trolling motor folks using are another matter. Regular starting duty will kill them off.

All in how the battery is made, nice thick plates, good electrolyte penetration, etc. in the high end ones, but you pay for it, too.

 

[Ducky's Dad]

The highest capacity dual purpose batteries I have found that are readily available (in the U.S.) and that will fit most vehicles are Grp 31M from Odyssey and Northstar. Both are over 100ah with 1150 CCA and the Odyssey has 205 mins reserve capacity with the Northstar claiming 220 mins reserve. Both have substantially more capacity than the 31Ms from Deka or Optima. I have had a bunch of Odysseys and the problem with them is that they require 14.7V+ input from alternator or solar or shore power charger to achieve and maintain a full charge, and they like high amperage input. If you can figure out how to deliver high voltage and high amperage, the Odyssey is a fine battery. If you can't deliver that, the big Odyssey will have a relatively short life and operate at less than full capacity, and will lose a small amount of capacity with each charge cycle, unless you periodically condition and desulfate the batteries with a high voltage/high amperage (25 amp minimum) conditioning charger with an AGM setting. That means you probably have to carry the charger with you and find shore power about every eight weeks. I have been through this on my Dodge, and the only practical solution (for me) is a dedicated Odyssey or similar charger on a reconditioning cycle every couple of months. The Dodge now has a triple battery system with the new Odyssey 2150 Extreme 31M in the starting position and a pair of Optima Blue 34M dual purpose as the house batteries with a new 270 amp alternator and appropriate isolators and switches. I just bought a new battery for my Tundra daily driver and I got a Northstar 31M because I just don't want to screw around with the Odyssey's goofy charging and maintenance requirements. All of these batteries are claimed to be true dual purpose (I have spoken with Optima reps at SEMA, with Odyssey's founder and tech support staff, and with Northstar's rep for the western U.S.), and they say there is no reason not to use them for starting or house batteries interchangeably. I use the marine versions on all of these because the extra studs are so handy for connecting refrigerators, emergency lights, compressors, etc.

 

[jonnyquest]

Interesting discussion. Subscribed. Great information on your website, DiploStrat. Thank you.

 

[DiploStrat]

Key Points

One more thing. This would of course need an automatic battery disconnect to prevent both batteries to discharge beyond what is necessary for starting. For example: http://www.batterybrain.co.uk/productspage.php

Is there any product recommended to use with Dual AGMs?

I have no experience with a device like this. In my case, with massive discharges from a microwave and an induction cooktop, my voltages drop very, very low. I had to lower the factory setting on my inverter down to 11v or lower (can't remember exactly) to keep it from shutting down. Of course, the moment that I finish cooking, the voltage rises back to normal levels. A refrigerator won't cause the same drops.

But the key point is this; there is no "magic" in what I am proposing. You MUST have a large enough battery bank to never drop below 50% discharge and less than that is better. I don't have a emergency shut off device because I simply never discharge my batteries that much.

You could use so called "dual use" batteries, but you will get better performance and longer life with true deep cycle batteries. The advantage of what I am proposing is that you can get both batteries under the hood and you don't need to bother with relays, controllers, etc.

At the end of the day, you are always better off with a conventional system that uses an isolation system and a dedicated starter battery. But in this case, you probably won't be able to fit everything under the hood as you would need 200Ah of camper battery(s) and a starter battery.

 

[sg1]

Hi,
We have been traveling through Africa, Europe and now Latin America for 4 years, usually about 5 months per year. We have a compressor fridge (90 l), lights, computers and the usual chargers, hair dryer etc. We don't use shore power. All this is powered by a pair of standard car batteries as house batteries with 80Ah each and another stock 80 Ah starter battery. Starter battery and house batteries are separated by a separator if the motor is turned off. All these batteries are charged by the stock alternator (150 A) and 160 Wph solar. I will now add a 60 Wph mobile solarpanel. This very simple setup has performed without any problems so far. My battery computer shows that I never had to discharge my house batteries below 60% capacity. This is probably the reason why my standard car batteries are still fine. A stronger alternator would be useless because my batteries have never accepted more than 50 A and after a few minutes charging the charge goes down to perhaps 15 to 20A. The last say 10 to 15% to full charge would even trickle in at far less than that. I use conventional car batteries because they are cheap and easy to replace even in the 3rd world and they do the job, at least for me. After a few years on the road in the 3rd world I can only urge you to keep it simple if you really plan a long trip in these countries. All the best, Stefan

 

[DiploStrat]

Csaba,

I had the pleasure of hosting Stefan at my home. He is well informed and has the advantage of being much more familiar with what is available in Europe.

I lived in various African countries for fifteen years; it is an incredible continent to visit.

Have a great trip!

 

[zsuzsiestekergo]

Thanks for both of you. Stefan's stup is really interesting. My calculation gave me 40-60 Ah a day, but maybe my estimation is too conservative.
I now move to the proper section and re-post my questions based on what I learnt from your advices.

 

[DiploStrat]

I would certainly start out with proper deep cycle batteries; batteries won't die just because you take them to Africa. If they do die, then, depending on where you are, you may have to simply use what you can find. In this case it is worth it to have reserves of charging capacity and space for larger, less powerful batteries. But with a properly designed system you should have a battery life of five years or more. How long are you going to be en Afrique?

If you go to my website and look under the tab "Documents,"you will find several articles and diagrams that may be useful. (They are all in English, but your English is much better than my Magyar.)

 

[sg1]

By far the biggest consumer of power is the fridge if you use a compressor fridge. Use a chest type fridge. It uses less than half the power of the fridges with front doors because every time you open the front door the cold air falls out.
Stefan