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LiPo Q

Old 10-04-2010, 05:01 PM
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Tundrahog
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Default LiPo Q

Did a couple speed runs with my DF 16" hydro. 3695kv motor, 2200 11.1v 3s 25c LiPo, 90a esc, BEC, and Octura 435 prop. Motor and esc not that warm. Battery was warm to hot.

Battery was swollen/puffed up about 1/8 inch top and bottom. It still took a charge. Did not use it yet. Never had this problem with aircraft/heli LiPo's. Still new to boats.

Is it safe to use? I have two other batteries as backups.

Just got my radar gun today. Now I can see how fast she is.

Thanks!
Old 10-04-2010, 05:42 PM
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Default RE: LiPo Q

Unfortunately it's already damaged. I don't know your set-up, runtime, or current , but I think you may be ok with 2 of those packs in parallel. This would cut the load in half. The other possibility could be that the pack was ran down to "too low of voltage"
Old 10-04-2010, 10:37 PM
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Default RE: LiPo Q

Runtime 10+ seconds per run. Four runs flat out. Setup listed.?. Twin batts out of the question, hull too small. There has to be a basic formula for current even with different props.?.

I' ve been looking for that formula since I started electric boats.?? []
Old 10-05-2010, 08:24 AM
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Default RE: LiPo Q

Hi John,

Running lipo's in a 'hot' set-up requires pre-heating the lipo to 40°C prior to the run, failing to do so may result in bloating.
This is a 'normal' response of a Lipo that's been put 'cold' in the boat and 'tortured' with high ampdraw.

I didn't know that and have a few packs that are bloated, I still run them without any problems, other than some drop in capacity.

Pre-heating the packs makes the difference, specially is you're running budget Lipo's like I do.

Regards, Jan.
Old 10-05-2010, 11:41 AM
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Default RE: LiPo Q

P=U²*(1/R)

What that formula says is that you must increase your cell count, and reduce your motor KV, and then you get a reduction in amp draw and a increase in power.
Old 10-05-2010, 05:11 PM
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Default RE: LiPo Q

How much capacity did you use in 40 seconds?

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