Battery question

[twsmith]

Sorry, kind of a stupid question, but I don't have my multimeter handy.

Why would a cheap 8.4V 1100 mAh NiMH battery have a slower rate of fire in my P90 than an 8.4V 600mAh NiCad?

Do shitty manufacturers use substandard cells or is it more likely that one of the cells in my NiMH battery is screwed?

Thanks.

Wayne

[Scarecrow]

NiMH typically shoot lower ROF simply because of the chemistry of NiMH. NiCADs are better at burst power. When you get up into the higher MAHs this is less of an issue as NiMH begins to approach NiCAD performance, but at the lower MAHs the difference is noticable.

If it is significant it could also be that the battery is f*cked, however, a NiMH and NiMH comparison would better to make than to NiCAD.

[twsmith]

Thank you. That also explains a similar problem I experienced with 2 stick batteries in my Uzi. I assumed my NiMH was screwed as I was under the impression that higher mAh rating would give higher ROF. My dumb!

[Scarecrow]

Also, you should make sure you charge the NiMH batteries at a lower setting than the NiCAD ones of the same MAH or you WILL damage the batteries. NiMH bats don't take well to peak charging as anyone in RC car racing will attest to.

[twsmith]

I use a smart charger like the one that BB bastard has at:
http://www.bbbastard.com/chargerdetails.htm
I think mine may be an older model though as it doesn't have a switch to change the charging rate.

[Kos-Mos]

you know "smart" is a big word.

Since this charger do both Ni-Cd AND Ni-Mh, there is 2 possibilities:

1- It won't charge Ni-Cd fully, since Ni-Mh have a lower neg. delta peak voltage.

2- It will over charge your Ni-Mh pack because it is made to charge Ni-Cd full, and ....they have higher (or lower since it's negative) delta peak voltage.

Also, Ni-Mh packs usually fall in "sleep" when not used for a while (like when they are in the storage room of a shop for a year). It will take about 2-3 good cycles before giving good results.

Try to get a hobby peak detect charger, one that allow you to set the charge current. Ultimatly if you only use "mini" sized packs, you can look for a charger that discharge your cells. Usually they will discharge at 6-10 Amps. It will let you cycle your pack automaticaly. A good one is the Intellipeak Digital. Here is a link:

Last one at bottom is great!

If you use large packs, get a stand-alone discharger, since large or Sub-C cells should be discharged more "violently". Look for 20-25 Amp discharge rate.

*edit*

Oh and take a look at the battery FAQ at top of this section. (What? Can do a little promotion for my work heh)

[twsmith]

Thanks for the info. I did read your battery thread before, but it seemed to contradict what I was seeing with the 1100 mAh NiMH vs the 600 mAh NiCd. I expected the NiMH to outperform the NiCd but it has a noticeably lower ROF in my P90. I take it that while the chemistry restricts current delivering capability in a NiMH it also allows the battery to last longer?

I'll have to look at getting a better charger that can charge the NiMH properly.

Thanks again.

Wayne

[ringsted]

in my experince the high quality NiMh out perform sayos NiCd batteries by a large margin.

go to www.cheapbatterypacks.com and get som intellect 1400 mah or elite 1500 mah batteries.

then get a smart charger, Graupers ultramat 14 works very well for me. when you recive the battety the first time charge it for 10 hours at 200 mah.

this preps the new cells.

afterwards you can fast charge them up to 1-1,5 A. the delta peak cut off should be set at around 5-10.

i will then guarntee you that you will have a battery that is extremely superior to the Sanyo 600 mah nicd cells.

[HaZarD SFD]

I charge my NIMH at 4A and Discharge at 10A for best results. Mind you
its a 9.6V 3600Mah. I know that any lower on the Amps for charging will
cause problems and battery failure.

[LUTNIT]

Originally Posted by Scarecrow

NiMH typically shoot lower ROF simply because of the chemistry of NiMH. NiCADs are better at burst power. When you get up into the higher MAHs this is less of an issue as NiMH begins to approach NiCAD performance, but at the lower MAHs the difference is noticable.

Are you sure? I don't know much about the chemistry but I had a 1700mAh NiCd large pack and its ROF was noticeably lower than a 1400mAh NiMh mini pack in another stock TM gun. Also higher mAh NiMh begin to approach NiCd performance? I have a 7.2V 4200mAh NiMh that has provides an obviously higher rate of fire (don't need any fancy ROF calculator) than an 8.4V 2400mAh NiCd pack so it would seem that NiMh packs outperform NiCd easily.

I'm not bashing/flaming you or anything its just that what you states seems contradictory to practical results.

NiCd packs outperforming NiMh packs that are well used or not properly charged (what 90% of airsofters do) is possible as NiCd packs can take a lot more mistreatment and still work great where NiMh packs are more sensitive and easier to screw up. Don't know about NiCd charging but NiMh packs should be charged at at least 1C from what I understand. So my 4200mAh pack should be charged at 4.2A. MY room mate did competitive R/C car racing before he needed money for school and sold it all and he laughed when he hard of airsofters still using NiCd batteries (literally, broke out laughing) and I went to one of his events and asked around and no one charged their packs below 4A. I showed him some airsoft battery charging advice and charger prices and he almost shit himself, he couldn't believe that retailers where charging $65 for a "Smart Charger" that retailed in R/C stores for $15-20. When he read the advice to charge NiMh packs at the lowest possible amperage you have time for his response was "yeah, if you want to fuck up your pack." I've also talked to a lot of people out there (HAM radio operators, electricians, R/C car/boat/plane hobbyists, and many others) and its airsofters and airsofters alone that say to charge batteries at a low amperage (0.5-1.0A). That is completely contradictory to the most basic fundamentals of batteries according to everyone else I talk to.

[flack]

Originally Posted by vondnik

RC people use MIMH because their power needs are constant and that is somewhere MIMH batteries excel. Unfortunatly that is not the case with airsoft. MIMH do provide a more constant voltage and a more steady flow. BUT when your power demand is constantly cycling betwine on and off, from nothing to maximum power load your MIMH will burn out mutch faster. Also they don't handle the cold that well, but then again most batteries don't.

I never had satisfactory results with any MIMH batteries i tried so all my guns run on NICD, you can ask around what people think about my guns. I always had longer life, better rof or torque power out of a NICD. My comment comes from experience witch include airsoft, RC cars and planes and industrial use.

In the end I don't give a rats ass what you use but for the price of 1 MIMH i get3 NICD that in the end give me better results....you do the math

:-)

[LUTNIT]

Don't know what NiCd pack's hes using are but if anyone tells me the maximum potential ROF for a NiCd pack is higher than a NiMh I'll laugh at them.

NiMh packs have a higher surge amperage and a higher constant amperage. It is true that NiCd packs are more durable and can be mistreated (essentially what all AEG's do) more and handle it better than NiMh packs but for the performance I have as of yet to find any NiCd pack that can outperform a NiMh pack in anything but performance in the cold. There have been comments on this board from players in Asia that do the insane fps guns and even 10.8V NiCd packs can't turn over their guns, they need 3000+ mAh which is only available in NiMh packs. NiCd's are also very poisonous and bad for the environment compared to NiMh packs.

Lets all get LiPo's! Why worry about the difference between 20A and 30A surge amperage when we can get 100-150A surge amperage! Of course mistreating a NiMh means the cells will die, mistreating a LiPo means it will burst into flames and give off incredibly toxic gas, but just be careful.

As for the 1 NiMh pack = 3 NiCd packs cost wise, thats only if your getting ripped off. Base cost from any decent battery shop puts 3600mAh NiMh cells at ~1.5x the price of 2400mAH NiCd cells.

[Scarecrow]

Originally Posted by LUTNIT

Are you sure? I don't know much about the chemistry but I had a 1700mAh NiCd large pack and its ROF was noticeably lower than a 1400mAh NiMh mini pack in another stock TM gun. Also higher mAh NiMh begin to approach NiCd performance? I have a 7.2V 4200mAh NiMh that has provides an obviously higher rate of fire (don't need any fancy ROF calculator) than an 8.4V 2400mAh NiCd pack so it would seem that NiMh packs outperform NiCd easily.

Ah what? You're comparing a 4200mah battery pack to a 2400mah battery pack and claiming the 4200mah has a higher rate of fire?!?!... of course it does. You need to compare the same voltage and same amperage to make a proper comparison!

Aside from owning both types of packs (and selling...) I can assure you there is a SIGNIFICANT difference. NiMH is also more temperature sensitive so what works in your basement at 20 degrees isn't whats going to work in a Canadian february. Its also generally acknowledged that the chemistry differences between the two types of cells give them different electrical load and burst characteristics.

Also point of fact, people use NiMH at the lower MAH levels to go into smaller spaces in airsoft gun configurations that are space-challenged. When you get into the sub-1000mah range, you WILL notice considerable differences in life and performance that favors NiCAD over NiMH.

Originally Posted by LUTNIT

Lets all get LiPo's! Why worry about the difference between 20A and 30A surge amperage when we can get 100-150A surge amperage! Of course mistreating a NiMh means the cells will die, mistreating a LiPo means it will burst into flames and give off incredibly toxic gas, but just be careful.

I looked into carrying Lipos and what stood out to me was the cost of the pack would be considerably higher because of the electronics that would allow you to safely use a lipo in an airsoft application. It was cost prohibitive.

[ringsted]

Originally Posted by Scarecrow

Ah what? You're comparing a 4200mah battery pack to a 2400mah battery pack and claiming the 4200mah has a higher rate of fire?!?!... of course it does. You need to compare the same voltage and same amperage to make a proper comparison!

Aside from owning both types of packs (and selling...) I can assure you there is a SIGNIFICANT difference. NiMH is also more temperature sensitive so what works in your basement at 20 degrees isn't whats going to work in a Canadian february. Its also generally acknowledged that the chemistry differences between the two types of cells give them different electrical load and burst characteristics.

Also point of fact, people use NiMH at the lower MAH levels to go into smaller spaces in airsoft gun configurations that are space-challenged. When you get into the sub-1000mah range, you WILL notice considerable differences in life and performance that favors NiCAD over NiMH.



I looked into carrying Lipos and what stood out to me was the cost of the pack would be considerably higher because of the electronics that would allow you to safely use a lipo in an airsoft application. It was cost prohibitive.

so you should not compare a NiMh SC cell with a NiCd SC cell because it would be unfair on the nicad battery, thats funny, compare the small NiMh with the big nicad thens its fair on the nicad. OMG thats just obscene.

evene the most cramped battery space still allows for a 1500 mah elite NiMh so i dont see whats the problem.

and the man compared a 7,2 volt 4200 to a 8,4 2400. and it still beats it thats saying something.

[Scarecrow]

Originally Posted by ringsted

so you should not compare a NiMh SC cell with a NiCd SC cell because it would be unfair on the nicad battery, thats funny, compare the small NiMh with the big nicad thens its fair on the nicad. OMG thats just obscene.

evene the most cramped battery space still allows for a 1500 mah elite NiMh so i dont see whats the problem.

and the man compared a 7,2 volt 4200 to a 8,4 2400. and it still beats it thats saying something.

Obscene? Eh?

Read up on the chemistry differences and what MAH is and how it affects your gun. What I've said here is not only what people's experience is based on, but its also electrically true.

There is a significant difference between those two batteries, voltage being one, MAH being another. Both values affect the gun and the battery time differently as stated. Because of that you are comparing apples to oranges. To see the differences between the two TYPES of bats, you need to compare them at the same voltage and MAH and then judge performance. Scientific method bud, try it, it works. Go back to his original question, thats the question I am answering, I am not having an ontological argument on the perceived benefits of NiMH or NiCAD as a religious experience.

Yes, the primary advantage to NiMH is battery space - you can get more power and MAH into a smaller space. Disadvantages of NiMH are that at lower power and MAH levels the battery simply doesn't have the same torque that a NiCAD does - ask an RC hobbiest, they'll tell you that as well. That will directly affect your on station time with that battery before you need to swap it out.

That being said a certain level in airsoft may be 'good enough' depending on your motor (EG700 motor vs EG1000 motor) and upgrades (spring, gears, piston, bushings) in your box. I've got a 'perfect storm' gun that runs great on a large 8.4v NiMH but it can't push the box in my other gun nearly as long. There are a lot of factors that affect what you see in performance on your gun, battery power is an important one, but, its a marriage of parts as well.