lipo and ni-mh in series?

[broken_civic]

Anyone ever ran them together in a series?

I put together a e-maxx with a 1800kv 1/8scale motor and 1/10 esc. I'm pushing 22.2 volts through it rite now. A buddy of mine has a summit he put a the mamba 2200 kv 1/8 scale setup on. He's pushing about 9,000kv's less than I am. I'm only pushing 40,000 kv's through my motor and he's pushing 30,000+ (don't feel like doing the exact math) on his summit on 4 cell lipo. He's faster than I am on 6s. Mostly because his tires are much larger and they balloon working as a centrifugal force making for a higher top speed. Regardless, i wanna try putting 2 9.6 volt 8 cell ni-mh packs along with the 2 3s packs just to see what it would do. I'm still debating. I might just throw another 2 cell lipo in series and see if that gives me the extra power I need. This isn't going to be ran like this but for 2-3 high speed passes.

I have a spare esc in case I burn this one up, obviously that's why i'm pushing 22.2 when it only calls for 11.1.

 

[Lessen]

No, No, No, No! You should NEVER mix battery types... ESPECIALLY LIPO. That's just a.recipe for disaster and probably quite dangerous.

 

[beason]

your going to do more then burn up the esc, your gonna burn down the whole rig. have you seen lipos gone bad?

 

[broken_civic]

Yea, I've seen lipo's go bad. I understand what can happen. however, current is current, I just wanted to know if anyone tried it. I do have one cheap 3 cell lipo I may mix with a ni-mh battery pack at a distance and see if anything gets hot or explodes. Might create a servo to complete the connection so i'm not near it when it does.



Since nobodies tried it, I guess i'll be the first to take this adventure. want videos? LoL

 

[frickenjoey]

No, battery current in not just battery current...but whatever, it is your rig...We are just saying bad idea but if you wanna do it have a nut.

 

[beason]

you can't fix it joe.. just can't..


civic, you do realize that if you run a mix, the lipos can output more then the nimh, and the voltage cutoff may not work right. but hey its your stuff, just dont come whining on here when it goes up in smoke..


who was that guy that plasti dipped his esc then wanted to know why it burned up?

 

[broken_civic]

Ok, first of all, I would not come on here crying. I experiment to see what works with what, if it doesn't work, oh well, try something different. Do not degrade me or my ability for trying something you guys haven't. If any of you are in chemistry and can break down exactly why the material the packs are made with will conflict with eachother then tell me. Rite now you guys are basing your facts on assumptions. The lipo cutoff? I don't run one, I haven't ran one since I started running lipos. When my truck slows down I take the packs off and charge them, I've yet to burn one up and i've been running lipos for about 2 years now.


I guess everyone missed the part where I said I'd create a servo/ platform/ radio switch to test it out and asked if you guys wanted a video? I have 3 spare brushless 1/10esc's rite now to use that are not on anything if I do burn it up.


Now, would you guys like a video of the test experiment?


I'd bet money if I told you guys I was going to run 2 3s lipo's on a mamba max esc rated for 1 3s lipo, you would have told me I would burn it up too, rite? Well, i've been doing it for about 6 months or longer now. It does get warm and shut off after about 30+ minutes of runtime, I need to put a fan on the esc.

 

[slowngreen]

Legitimate question for sure. Nothing I've ever thought about but yeah, best not do it unless you just want to try on some spare able electronics.

 

[broken_civic]

Legitimate question for sure. Nothing I've ever thought about but yeah, best not do it unless you just want to try on some spare able electronics.

Thanks. I'm going to try on a spare made up contraption with some spare parts before i try it on my truck.

 

[hamz9561]

Let us know how your experiment turns out.

 

[broken_civic]

I think i'm going to videotape it

 

[Lessen]

I have a feeling the low voltage cutoff won't work properly so you'll have to be quite careful about that if your aim is to experiment AND keep everything if at all possible. Also, I would be concerned about the temp. of those Nimh cells. I have a feeling they are going to get hot from higher than normal discharge rates.

 

[robmob]

Can you do it? Yes

Will it work? Yes

Will it burn up the electronics? No, unless you exceed the voltage limit for too long on the esc.

What will happen? Initially nothing, everything will work normally when batts are fully charged. The problem arises when the different batt types discharging at different rates. If LiPo discharges first, you will damage the pack and it will become garbage. If you're lucky, it won't puff up and go boom. Same goes if the NiMh discharges first. NiMh cells have been known to blow an end off. A LVC will help, but since voltage will take the path of least resistance, you could drain all the juice out of one of the pack types before the LVC shuts everything down.

Not recommended since you will run the risk of burning up your rig if either pack type explodes. Do it outside on dirt or concrete so if it does go boom, you don't catch anything else on fire. Have a fire extinguisher on hand just in case. I don't think bench testing this setup will tell you anything since the amp draw is nothing like actually running the rig.

Good luck with your experiment and keep in mind that doing this is not safe. It may work once, twice or even a dozen times, but it only takes one time for it all to go to poof.

 

[Lessen]

Great response there!

Sent from my DROIDX

 

[broken_civic]

Can you do it? Yes

Will it work? Yes

Will it burn up the electronics? No, unless you exceed the voltage limit for too long on the esc.

What will happen? Initially nothing, everything will work normally when batts are fully charged. The problem arises when the different batt types discharging at different rates. If LiPo discharges first, you will damage the pack and it will become garbage. If you're lucky, it won't puff up and go boom. Same goes if the NiMh discharges first. NiMh cells have been known to blow an end off. A LVC will help, but since voltage will take the path of least resistance, you could drain all the juice out of one of the pack types before the LVC shuts everything down.

Not recommended since you will run the risk of burning up your rig if either pack type explodes. Do it outside on dirt or concrete so if it does go boom, you don't catch anything else on fire. Have a fire extinguisher on hand just in case. I don't think bench testing this setup will tell you anything since the amp draw is nothing like actually running the rig.

Good luck with your experiment and keep in mind that doing this is not safe. It may work once, twice or even a dozen times, but it only takes one time for it all to go to poof.

Ty for this!

---------- Post added at 9:51 AM ---------- Previous post was at 9:47 AM ----------

anyone ever ran lipo's of different capacities in series?