by paulgato » 29 May 2014, 03:02
Aha! That's really useful information. (Just seen your second post too.) So Tech Guy B at Enersys was right then. That's good news.
Tech Guy B said that from a charging point of view the Odyssey batteries are identical to the industrial/telecom SBS battery range, on which the Odyssey batteries are based, and for which the Thin Plate Pure Lead technology was originally developed. I had discovered that the tech literature for the SBS batteries gives a minimum recommended charge rate of 0.1C, whereas the tech literature for the Odyssey Extreme batteries gives a minimum of 0.4C. Tech Guy B said the reason for the difference is that they reckon that managers of large battery banks in industrial settings are more knowledgeable, and more able to closely monitor and control the charging regime, whereas ordinary public people using them in devices where they are discharged and recharged daily usually don't appreciate the length of time it takes to get to a 100% charge, nor do they recognise the absolute importance of achieving that 100% charge.
I'm sure to you this is obvious, and now it all makes sense to me too, but to a non-expert like myself, who was getting different stories from supposed experts who were all equally sure of their opinions and who sounded equally plausible as far as I could tell, it has been very confusing, to the point where I was regretting ever getting involved with Odyssey batteries.
I think what I will do is use the CTEK 10A charger for the time being and make sure it is on charge whenever it is not being used, and then try to get hold of a decent charger of 20A-30A rating, which also has a 14.7v setting, once I have worked out where I'm going to put it. The CTEK MXS10 charger I already have has a 14.7v setting, but the CTEK 25A chargers (MXS25 and M300) only have a 14.4v setting, which is why I was looking at the Sterling Power PCU ones, which have a user-adjustable setting as well as loads of factory settings.
I should perhaps say what I'm using this battery for, as I'm not using it in a power chair. It's a project to try to get an average of 100mpg out of the Mk4 VW Golf TDi estate car I use for work. (It's a bet I have with a friend who recently bought a Prius Hybrid. So far I'm at about 82mpg overall average.) Right now I'm engaged in sorting out a permanent system for doing away with the alternator, or rather, only switching it on for very long journies where I can't plug the car in to recharge. I've already killed one cheap AGM 'leisure' battery in about 6 months of alternator-less driving, so I wanted to get the best deep-cycle-capable battery that would fit in the Golf engine bay without modification, and that, I was told, would be the Odyssey PC1220.
(I apologise if this is 'off-topic', but hopefully the parts about Odyssey battery charging will apply equally to power chairs.)
I also have a second battery which feeds power into the main car electrical system via a DC/DC step-up converter, which outputs 12A at a steady 14.0v. 12A covers daytime driving current requirements easily, but at night, or with wipers going, power is drawn from the main starter battery as well. (I can add a second 12A DC/DC converter in parallel if it seems necessary.) Currently I'm just using an old but decent car battery as the 'donor' battery, but once I've done all the taking-the-carpets-up-and-running-wiring and so on, I'll be using either one or two Yuasa YPC100-12 105Ah AGM deep cycle batteries, which will be mounted in the spare wheel well below the load area. One YPC100-12 is already installed there but not wired up yet. I was a bit concerned about the added weight of a second YPC100-12 but I'm leaning now to the view that a nicely comfortable over-supply of lead in the rear will result in a much better and more long-lived system, as then my daily short journies will barely make a dent in that 210Ah bank and the batteries will only be drawn down low on those very occasional longer journies.
I came across your site here, saw that you had been using Odyssey batteries for your daily personal transport, and realised that power chair users probably make roughly the same demands on batteries as I do by driving without an alternator, ...or probably even more. Oh. and yes, I am saving about 10% on fuel by not using an alternator. That's 10% of about £1500/year, so not negligible, although I don't expect to actually save any money with this project! I plug the car in to the mains via a discrete bumper plug whenever the car is on the driveway. I also have an engine pre-heater fed via the same bumper plug, which I switch on with a remote control key fob thing from inside the house an hour before driving off. That also saves about 5% on fuel overall, but more on shorter journies of course.
The reason I was reluctant to get a larger charger than the CTEK 10A one I already have installed in the engine bay is that larger chargers are too bulky to fit there, and/or they have cooling fans so are not waterproof. I would have had to put a larger charger inside the cabin somewhere, drill yet more holes through the firewall for the charger output cables, plus it's hard to find places where larger chargers would fit and get adequate ventilation. I found ONE place in the rear where a 25A CTEK charger for the rear batteries will fit, but nowhere in the front really. So it's good news that I don't absolutely NEED a high current charger for the starter battery and I really appreciate your advice.