jfetter
Posts: 321
Joined: 11/25/2003
From: MIRAMAR, FL, USA
Status: online
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quote:
ORIGINAL: reincarnate
Hey Jfetter. If I can interject...with you being the battery guru, I have a question. I'm going to use a lipo for my ignition battery. Do I need to have a safe to charge the battery in? (Using Accucycle Elite) I definitely plan on removing from the fuse to charge, with it being a gas engine (I'm not that dumb... Yeah I am, but it's my story) but how do you mange your lipos, of master of the electrics? 
I have used LiPo's for the past 3 years exclusively and in that time I have puffed a few packs. In every case but one it was on discharge (too hot in flight) and in the other case, I strongly suspect I ran it up to the edge and just didn't notice the damage until I charged it. The most important thing to remember with LiPo's is never charge them unattended, in every case that I've personally had a LiPo puff up, it clearly showed signs it was puffing up and there was plenty of time to react because I was monitoring the charge. I'm not saying sit and stare at them but I charge in the kitchen, on a tile island, away from combustibles with a fire extinguisher in the cabinet. I don't anticipate a problem but I am prepared and try to limit my exposure to damage, the only thing I could do better is charge outside but my fear is that would be more unattended.
LiPo rules are pretty simple, charge using a LiPo charger only (the AstoFlight 109 LiPo is my favorite, up to 10 cells and 8 amps), verify the correct cell count is detected by the charger when you hook it up, set the charge rate to 1C (or 1 times the capacity of the pack, if a 2100 MAh pack, charge at 2.1 amps, if 3200, charge at 3.2 amps, etc), never let your battery packs get above 160 degrees F (I prefer 140 F but this shouldn't be an issue for you as you are using it for the ignition and not high-amp discharges like what you'd see if using it for powering a model), always charge your packs when they are at room temp, not right out of an electric plane without cooling off and use a balancer! The balancer is what will give you the maximum life as well as limit your chance of fire by making sure all of the packs are equal in voltage. This ensures a low voltage cell doesn't make it look like the pack is still under charged and the charger keeps trying to put more in, effectively over-charging the cells that don't have low voltage.
My rules for balancing are simple, balance right before you charge and again right after, this ensures the batteries in a pack are the same voltage before and after they are charged, this is the leading cause of LiPo issues so get a balancer and use it (it takes 1 minute to balance). Store your LiPo's charged and in a non-combustible box that latches, it's not like they will explode but you'll feel better having them in the house with this extra protection. Finally, respect them and understand if damaged or punctured, they should be discarded (they are recycleable), some people say puncture and soak in salt water, others say discharge completely using a flashlight bulb or something equivalent (key here is slowly). I don't lke the salt water idea nor puncturing, not because they might explode from a simple pucture but because you might short the battery with the nail you are using. Safest bet is discharge with a flashight battery, outside and when dead take to your local recycling center...
Jack
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RE: H9 Sundowner - 
