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Old 05-02-2014, 11:24 AM   #84 (permalink)
paulgato
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Join Date: Sep 2013
Location: Oxford, UK
Posts: 126

Black Beast - '02 VW Goff Estate S
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Another conversation with Enersys UK tech support about Odyssey batteries. This time to find out why they require a minimum of 40% of the Ah rating as a charge current - in other words, a 100Ah battery will require at least a 40A charger. This I only found out AFTER buying the battery of course.

It turns out this is the case (so I will need to buy yet another charger!) and that charging at a lower than 40% rate will SIGNIFICANTLY reduce the number of cycles and the overall life of the battery. Conversely, there is no upper limit on the size of a charger provided the charge voltage is properly regulated. The battery itself will limit the amount of current going into it. Charging at a high current will have no adverse effect on the battery whatsoever. (The guy I spoke to had done some testing using an industrial charger capable of well over 1000A.) Another very useful conversation. It turns out the technology for these Odyssey batteries was developed in the UK by a company that was later acquired by the Enersys group.

So, I need to get another charger. Unfortunately powerful chargers will always have fan cooling, which means they cannot be waterproof, which means engine bay installation is not ideal. So I shall have to get another charger AND find another place in the vehicle to install it. (Maybe I should have a re-think. Maybe the Odyssey is not such a great choice after all and maybe I should return it. Maybe a supercapacitor array in the engine bay and two deep cycle 100Ah batteries in the rear is not such a crazy idea after all.)

...As to WHY the Odyssey batteries work so much better with a higher charge current, the guy I spoke to said there are different theories as to why that is but in truth no one really knows. They just know that IS the case in practice.
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