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Specialist DIR Kit OK this is the home of the Gavin - but questions and observations about other scooters, lights, video housing, RB80 etc. can find a home here.
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May 29th, 2006, 05:33 PM
| #1 (permalink) |
| New Member  Join Date: Dec 2005 Location: Finland
Posts: 88
 | X-scooter Li-ion batteries in cold Has anyone (Tobin?) any experience of how the new X-scooter Li-ion batterypacks perform in cold water, meaning 4 deg celsius or less? Cellphone li-ion or li-poly batteries freeze really easily in cold weather so this could affect the X as well. Maybe the head insulates the pack a little so it could work fine? I'd also appreciate comments from people with Salvo li-ion packs. The water especially in caves here up north is always cold, so this matter could limit my options. Aleksi |
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May 29th, 2006, 06:29 PM
| #2 (permalink) |
| New Member  Join Date: Nov 2005 Location: Southern California
Posts: 566
 | Quote: (Originally Posted by aleksi) Has anyone (Tobin?) any experience of how the new X-scooter Li-ion batterypacks perform in cold water, meaning 4 deg celsius or less? Aleksi,Cellphone li-ion or li-poly batteries freeze really easily in cold weather so this could affect the X as well. Maybe the head insulates the pack a little so it could work fine? I'd also appreciate comments from people with Salvo li-ion packs. The water especially in caves here up north is always cold, so this matter could limit my options. Aleksi I'll admit I stay out of the water when it's white and crunchy on top  NiMh batteries will loose significant capacity at -4C, maybe 25% of capacity, but you may not see these temps in the battery pack. Li-Ion should be ok. At ~ -20C you may have limited current delivery due to increase impedance of the solvent in the Li-Ion cell, but here too the pack may not see those temps. If you can keep either pack warm (room temps) until shortly before you start using it I would guess that you will see little degradation in capacity. A discharging battery pack will generate heat, the internal resistance of the pack assures that heat will be created. This heat should keep the battery from getting cold enough to affect performance. The X scooter offers little in terms of thermal protection, the hulls aluminum, but the pack is insulated by the plastic bulkheads, so direct thermal conduction is likely to be fairly slow. If on the other hand the battery is allowed to "cold soak" I would expect a significant reduction in the capacity of the NiMh packs and a somewhat less reduction in the performance of the Li-Ion packs. Increased impedance a low temps will be exhibited by a greater voltage depression at a given current load. If the resultant voltage is too low the motor controller of the X may not allow use. The combination of a much smaller capacity, 13 amphour for the NiMH vs 30 amphour for the Li-Ion pack, and the greater effects of low temperatures makes me suspect that a cold soaked NiMh pack may not work. A cold soaked Li-Ion pack might well be able still deliver sufficient current without excessive voltage depression that the "cold scooter" will have a chance to warm up the battery due to use. All of the above is nothing more than my speculation based on past experience with both NiMh batteries and Li-Ion batteries in other applications. I have not done any low temperature testing of either pack in an X Scooter. Regards, Tobin |
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May 29th, 2006, 08:25 PM
| #3 (permalink) |
| New Member Join Date: Mar 2006 Location: italy
Posts: 63
| Interesting but in the water we are talking about +4°C, not -4, therefore it should be sufficient to leave the scooter in the water while getting ready to dive and the pack should be just fine. Certainly if the scooter is left out of the water in -20°C for a while... |
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May 29th, 2006, 09:37 PM
| #4 (permalink) |
| New Member Join Date: Nov 2005 Location: Southern California
Posts: 566
| Quote: (Originally Posted by tanto) Interesting but in the water we are talking about +4°C, not -4, therefore it should be sufficient to leave the scooter in the water while getting ready to dive and the pack should be just fine. Yes, I would expect so.Quote: (Originally Posted by tanto) Certainly if the scooter is left out of the water in -20°C for a while... That fits my definition of cold soak :BIG:Tobin |
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May 30th, 2006, 01:30 PM
| #5 (permalink) |
| New Member Join Date: Dec 2005 Location: Finland
Posts: 88
| Thanks Tobin, this gives me an idea what might (not) happen in this case! Quote: (Originally Posted by tanto) Certainly if the scooter is left out of the water in -20°C for a while... Diving in Finland in the winter this is normal. Typically if I go diving in the evening the gear stays in the car the whole day during work and it deffinitely will get cold.The +4°c water probably helps but it might take a while to warm up, who knows? No-one in Finland has an X. It would be nice to hear it's not a problem from someone who has really tested. Aleksi |
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May 30th, 2006, 05:51 PM
| #7 (permalink) |
| We Go Down  Join Date: Nov 2005 Location: Ottawa Canada
Posts: 227
| Quote: (Originally Posted by aleksi) Thanks Tobin, this gives me an idea what might (not) happen in this case! I would at least bring your batteries in from your car when you are at workDiving in Finland in the winter this is normal. Typically if I go diving in the evening the gear stays in the car the whole day during work and it deffinitely will get cold. The +4°c water probably helps but it might take a while to warm up, who knows? No-one in Finland has an X. It would be nice to hear it's not a problem from someone who has really tested. Aleksi |
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