Spice Cat Posted August 9, 2016 Share Posted August 9, 2016 Good afternoon all, I recall reading an article about starting a car with a LiPo, but can't remember if it was a spoof or not. The reason this has become top priority is that I have recently inherited a ride on mower with electric start and the battery is a little flaky. Being tight fisted, I don't want to lash out the £50 for a new one so as an emergency back up, can it be started from a 40C 11.1v LiPo?? Cheers. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 9, 2016 Share Posted August 9, 2016 What capacity? 40C is a bit meaningless without that info... The answer is quite probably but get it disconnected very smartly - you don't want the charging system to put any meaningful charge into it once it's running! Quote Link to comment Share on other sites More sharing options...
Spice Cat Posted August 9, 2016 Author Share Posted August 9, 2016 3s 2650mah. I stress for emergencies only. Quote Link to comment Share on other sites More sharing options...
bert baker Posted August 9, 2016 Share Posted August 9, 2016 Jump started my mates automatic rover with a Lipo,, I don't think it needed that much of a top up to start the car. but did work. Bert Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 9, 2016 Share Posted August 9, 2016 That should supply @ 106 A in theory - but you can probably exceed this for short periods without too much stress on the battery. Any idea what current the starter motor pulls? Edited By Martin Harris on 09/08/2016 15:02:50 Quote Link to comment Share on other sites More sharing options...
onetenor Posted August 9, 2016 Share Posted August 9, 2016 Re £50 for a battery ! Get thee to a scrap-yard or breakers. Any number of decent batteries about. Get one from a recent wreck Or maybe an MOT failure £10 or £20 should see you with a half decent battery Look out for any damage to it that's all Quote Link to comment Share on other sites More sharing options...
onetenor Posted August 9, 2016 Share Posted August 9, 2016 Oh Yes if it;s no good take it back and swap it .Most yards will do that but they put a mark on the one you take in case you try taking a duff one back of your own. also they will sometimes take your old one in part ex Quote Link to comment Share on other sites More sharing options...
Spice Cat Posted August 9, 2016 Author Share Posted August 9, 2016 No idea what the starter pulls but I can check.As for the breakers it's one of those small ones not a wheelchair battery though. Quote Link to comment Share on other sites More sharing options...
MattyB Posted August 9, 2016 Share Posted August 9, 2016 There are people in the US who have started massive 4x4s with relatively small 3S lipos, so what you are trying to do should work fine. Whether it is recommended I can't say - that depends on the amp pull. However from memory my old diesel Civic required about 50-60A to turn over (found that out one time courtesy of the AA man when I let me down on the drive), so I would think a lawnmower should be 20-30A max. Edited By MattyB on 09/08/2016 17:07:45 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 9, 2016 Share Posted August 9, 2016 Very surprised at that, Matty - I've always been under the impression that 150 - 200A was typical... Quote Link to comment Share on other sites More sharing options...
Pete B Posted August 9, 2016 Share Posted August 9, 2016 I have started my ride-on with a Lipo - just as a stop-gap measure - and it worked very well but if you do, make sure you've got a meaty cable to extend the Lipo lead to the terminals - I had a short adaptor with croc clips, about 18-20AWG and the wires got very warm and melty very quickly.... Pete Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted August 9, 2016 Share Posted August 9, 2016 I have tiny Sakura starter pack. That has started a 7.5 litre 4Cyl bus engine! Spun my 2.0 Diesel GTI engined car over so fast I thought it might over-rev it!! (It has EC5 connectors!!) Quote Link to comment Share on other sites More sharing options...
Spice Cat Posted August 9, 2016 Author Share Posted August 9, 2016 I'll give it a go. Cheers Quote Link to comment Share on other sites More sharing options...
MattyB Posted August 9, 2016 Share Posted August 9, 2016 Posted by Martin Harris on 09/08/2016 17:11:59: Very surprised at that, Matty - I've always been under the impression that 150 - 200A was typical... Nope, you are right, looks like I was remembering the pure capacity in Ah rather than the cranking amps. Just looked up the battery from that car, they are rated at 500-600 CCA. I don't think it takes that much to turn the engine over though, otherwise a lipo would never be able to do it. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 9, 2016 Share Posted August 9, 2016 I use a 3S 2200mAh LiPo on my model engine starter & it works brilliantly...no trailing lead & bags of power...I put the watt meter into the circuit & tested it with my usual 7Ah SLA starter battery...it always struggled to turn a 90 2 stroke over & the voltage dropped to around 7V or so. With the LiPo the 90 spun over really quickly & from cold pulled about 45A out of the LiPo Will it start your mower? I would say almost definitely... Quote Link to comment Share on other sites More sharing options...
cymaz Posted August 9, 2016 Share Posted August 9, 2016 So, you have a Flymo with a Li po Quote Link to comment Share on other sites More sharing options...
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