Can I charge lipos with a nimh charger?

[speed demon]

Ok here's the deal. I'm getting my new lipo and my MM back and my coworker wants to run my old 3S in his rustler. I only have one charger and it takes around 60 min to charge one battery but I only have about 1 1/2 hours(after they cool down abit) to charge them both up for our next race. Can I use his nimh charger to charge one of the lipos for say 1/2 an hour then balance charge the rest of the time like normal? Thanks.

[DRIFT_BUGGY]

I have never used one or heard feedback on them but this unit converts a Nimh charger to be able to charger lipo
http://www.losi.com/Products/Feature...rodId=LOSB9607

[jhautz]

NO!

Lipo requires a lipo specific charger. Doing what you sugest is a recipie for disaster.

[speed demon]

His charger charges at 4 amps and that's what I charge my bat at. I'm a little confused on why it won't work. Now I can see if I forgot about the bat charging and left it on for over an hour but that's all I can see as far as a problem. Does the lipo chargers put juice into the bat a different way? Is it a different type of juice(as you can see I'm very knowledgeable)?

[jhautz]

Theorectiaclly during the first stage of charging a Lipo it is not really different than a conventional charger, but whe the lipo reaches it 4.2v limit the lipo charger switches to a constant voltage mode. Constantly adjusting the amount of current the lipo gets to keep the voltage at the 4.2v/cell.

The reason you shouldnt use a conentional charger is if that ever got to the 4.2v/cell the charger would just keep pumping the current into the pack and you would have a BIG problem.

I know it seems like a good idea, but it really is not! Lipos are very dangerous if not treated properly and this is just the kind of thing that can accidentally get out of hand very quickly. They are very dense power sources and need to be treated with respect to avoid problems. If you havent ever seen a lipos catch fire I sugest you do a youtube search for lipo fire and watch some video so you can understand what happens when things go wrong.



I dont mean to sound like sombodys father here, but I will never sugest doing what you are asking about and I seroiusly doubt anybody else on this forum would either.

There are some fairly cheap lipo chargers out there now days. This would also be a possible solution. http://www.slkelectronics.com/lipodapter/index.htm

If not I wouldnt do it.

[speed demon]

OK just making sure. I figure since for that bat at 4amps it charges there for at least one hour if the bat is run down to the voltage cutoff. We run the same truck and everything so I just figured everything would be constant and 30mins would be no problem. Just for the record I understand the risk if I attempt it.

Be sure to have some marshmellows on hand to roast.

[Sammus]

Yeah if you dont want to fork out for a charger, then get the lipo dapter. That said, for a similar price you could probably get something decent from hobbycity, like this for instance.

[bl-is-future]

Originally Posted by jhautz

NO!

Lipo requires a lipo specific charger. Doing what you sugest is a recipie for disaster.

K well i will shed some light! Lipo chargers are only lipo specific because they monitor cell counts and are preprogrammed with what voltage each cell should be. The max a cell should be is 4.2v. ex if you have a 4s batt the charger will stop at 16.8v or if it is advanced and allows for capacity, it will stop when capacity is reached. The lowest a cell can go, according to most chargers is 3.0v. so if you plug in a lipo that is below 3.0v per cell it wont charge it. So with a trusty multi meter you can use any charger you like but never and i repeat NEVER skimp out on a balancer. This will keep your pack life good and the risk of explosions to a minimum.

Just follow this when charging:
Never charge to over 4.2v per cell (ex 4s = 16.8v max)
Never dis-charge to under 3.0v per cell (4s = 12.0v minimum)(i use 3.2v per cell to add some overhead)
Always Balance the pack.

If any body else disagrees with this so be it but a charger puts out volts no matter what. The lipo specific are just pre programmed to monitor this stuff

[Arct1k]

BL - You are wrong... Lipos should only be charged with the CC/CV method.

A nimh is NOT suitable unless an adapter is used to change the supply to CC/CV method.

[bl-is-future]

Originally Posted by Arct1k

BL - You are wrong... Lipos should only be charged with the CC/CV method.

A nimh is NOT suitable unless an adapter is used to change the supply to CC/CV method.

I have a lipo specific charger but have revived one using a standard ni-mh charge. (was below 3.0v)
Not saying the above way is the best to do but it is possible. And i thought good ni-mh chargers had the cc/cv feature. But yes i am corrected it has to be cc/cv.

[speed demon]

Originally Posted by Sammus

Yeah if you dont want to fork out for a charger, then get the lipo dapter. That said, for a similar price you could probably get something decent from hobbycity, like this for instance.

Not looking to buy a charger since I have one already, I just don't have enough time to charge both batteries. Talked to a guy at work and he has a 15min timer that he can wire into the input side to shut it down. So two cranks of the dial and that will give me enough time to charge both. Thanks for all the replies, much appreciated.

[Arct1k]

Personally i think you are asking for trouble that is far greater than the $35 for a 5amp Hyperion charger... One puffed/damaged lipo will cost you a lot more than $35...

I think we've all looked at the video's of lipo fires on youtube... So now imagine that in your house!

[speed demon]

Only charge at work on a 1/2 thick 4by8 metal table. Never charged anything at home. If I can get him to come off some money then I'll order him a charger but he is tighter then a new boot. I might just charge mine then whatever time I have left charge my other bat for him to use and just call it good enough.

[Arct1k]

Well if your friend is that tight what will he do / say when his lipo smokes...