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Choosing leisure batteries and their charging parameters


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Hi all! I am a new member to this forum. I have read innumerous threads and I really admire the generosity with which you all share your knowledge on the electrics of motorhomes, particularly the legendary Allan. I have been learning a lot and organizing my own knowledge out of reading this forum and I am very grateful for that.


I also have some questions for you.


I live in a Rapido motorhome in northern Portugal and I am redoing the basic electrical system in various aspects. The first thing I would like to ask is about choosing the battery.


1. After reading Allan’s articles in his website, like this one http://www.aandncaravanservices.co.uk/battery-technology.php , and explanations in this forum about leisure batteries, I found the advice against Gel and AGM batteries as they are not tolerant to high temperatures and high charge and discharge currents safely. I was initially prone to buying Gel batteries but I now understand they are not suited to this purpose. Please, correct me if I understood wrong. So, I believe the best options, even when comparing with batteries at much higher prices, would the Varta LFD/Bosch L5 or the Yuasa L36-EFB. Am I correct, or are there any other really good suggestions?


2. To choose between these two, I believe the main differences between them are that the Varta LFD/Bosch L5 are more tolerant to high temperatures than the Yuasa L36-EFB and this one charges faster than the first ones. Is this correct, or are there more differences between them to be considered for a decision? Or is the L36-EFB as tolerant to heat as the LFD/L5?


3. The motorhome will rarely experience outside temperatures above 30 but the house batteries are near the central heating, the Truma Combi. I am trying to close a wood wall between them and to thermally insulate them. I am not yet sure of how successful will this endeavor be to cool down the battery compartment. So, do you find it more advisable, for safety, to go with the LFD/L5 instead of the L36-EFB due to the heat tolerance feature? Or up to 30 degrees centigrade is fine for both?


4. I am also considering and designing a thermally controlled fan that would circulate air from outside through the batteries if the outside temp is, at least, 5 degrees lower than inside and if the batteries are above 30 degrees centigrade. (Or should I set the limit at 25 degrees to better protect the batteries?) If I succeed on this ventilation system (my main worry is making two holes on the outside walls of the motorhome!) can I say the best option is the Yuasa L36-EFB?


5. When we say that the L36-EFB charges faster, does it mean that it takes more current when charging, for the same charging voltage, than the LFD/L5? Or it only takes a higher current when subjected to a higher voltage?


6. If the second possibility is true, then, at a fixed alternator voltage of 14.4V, LFD/L5 and L36-EFB will charge at the same speed. And, in this case, I would need to raise the voltage of the alternator, to 14.7V, for example, to benefit from the faster charging feature of the L36-EFB. This scenario requires the starting battery to tolerate well this voltage, as well - probably I would choose another EFB for the starting battery - and that all the electronics of the Fiat engine tolerate well those 14.7V without risking the electronic management circuits. Do you know if this voltage is safe for the engine electronics of the Fiat 2.3 multijet from after 2006? And for the rest of the electrics like motors of the window, wipers, pumps, etc?


7. When bulk charging, in the constant current stage, Is the L36-EFB tolerant to more current than the LFD/L5? How much current would you recommend for the charger from the shore power, which I will be using rarely? C/10 for the LFD/L5 and C/5 for the L35-EFB? Or a bit more is advised? How exactly do you recommend the charging currents to be for either battery model?


8. Considering where I live and where I plan to drive the motorhome, the temperatures range from +5 to +30 degrees year-round, exceptionally up to 35 or 40, I guess that having a charger with temperature compensation must be important. I believe the old CBE CB516 have NO temperature compensation, and only charge on 14.1 or 14.3V, depending on the profile selection. So, I think it is a good investment to get a new version of those where we can hook up an external temperature sensor, and that can charge at 14.4 and 14.7V, particularly the CB522-3, that charges up to 22A. Is my line of though correct or would it not make much of a difference in the health of the battery?


Thank you so much for your patience in reading all this and generosity in answering. I am amazed that I have found this forum!


Warm regards for everybody!


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