Battery - Lead Acid vs. NiCad preferences.

[Avnx EO]

I'm trying to understand customer preferences::confused: ..... Most helos were originally certified with NiCad batteries. But Sealed Lead-Acid has now come to the point where for the same weight and significantly cheaper cost, you can have a lead-acid battery. In addition lead-acid batteries recharge faster (so they are great for short hop operation), and they are not susceptible to overheat and fire from overcharging (no overheat sensor required). Periodic maintenance is also cheaper for sealed lead-acid. So if a lead-acid battery is available and certified on a helo, why would someone specifically want to go back to using NiCad? .... Had a customer ask for that and was a bit surprised.

(The usual problem is in switching an existing NiCad cert to lead-acid. AC 29-2C specifies that in replacing battery technology, it is not sufficient to simply swap for equivalent amp-hours. The discharge characteristics of the technology have to be considered against the ELA data -which is why going to lead-acid typically requires an STC. But once you're there, why go back.)
Anone got any reason for preferring NiCad over Sealed Lead-Acid.

Avnx EO.

[robipilot]

My only guess would be that the customer has had an experience where SLA batteries don't accept as many charge cycles as a NiCd. I don't have any experience with SLA batteries in aviation, but in other uses they are known to be cheap but not acceptable if you have a lot of charge/discharge cycles.

[mini]

(SLA are available in deep cycle (discharge/charge) configuration.)

Blacksheep is your man to answer this one.

[wrench1]

Avnx,

In a nutshell, the big performance difference is in the discharge rate during a start. If you were to plot the discharge rates on a graph the Nicad would be more or less a flat line for a period (3rd start) then rapidly fall off to 0, whereas the lead acid starts a proportional decline the minute the start button is hit. Also if you "abuse" a lead acid it will never recover to its original strength. There are also some extreme temp issues but I have only heard of them. Bottom line is that batteries are cheaper than engines and a fresh NiCad will always win. However, from a support side, lead acid is the way to go as you check them every 600hrs or so and when they fail, they are basically a throw away item, plus you don't need the specialized equipment and training to maintain the NiCad every 60 or 90 days. Hope it helps.

W1

[SASless]

Lead Acid batteries by all means.

Any down side is negligible compared to NiCads.

After going to Lead Acid batteries malfunctions and slow starts ceased being a factor. Throw in the maintenance cost and the price difference for the NiCad and it is a very simple choice.

I have never heard of a thermal runaway on a Lead Acid battery either.

[Gomer Pylot]

Lead Acid, no question. I have no idea why anyone would want NiCd. They'll try to give you a hot start, have thermal runaway problems, and in general are my last choice.

[nigelh]

i have 2 nicads in my AS350 which means loads and loads of inspections/maintenance which is hugely expensive in time and money. I would love to go to lead acid also due to the ability to recharge the battery in the event that it gets low ( ie youve left something on for too long ) I have been told however that it would be very expensive to do this re certification and even changing the make of nicad ( from a $6,000 one to an identical $3,000 one ) would be prohibitive .:ugh: Is there an easy way around this ? Has anyone converted their 350 to Lead ? Is there a weight issue ?

[TREAD LIGHTLY]

Pappilon Helicopters in Vegas have converted to lead acid in the AS350.

There must be an STC somewhere.

[rotorbrent]

We have a lead acid STC and the batteries are only lasting around 8 months and cost more than a NiCad so we will be going back to NiCad in our aircraft.

We are on our third Concord lead acid in less than a year

You also have to have special tools for the Lead Acid batteries to do the Cap checks ect. Now the cost of the Lead Acid is now higher to use than the NiCad for us so we are switching back to Nicad.



Brent

[AB139engineer]

[quote=rotorbrent;3052811]We have a lead acid STC and the batteries are only lasting around 8 months and cost more than a NiCad so we will be going back to NiCad in our aircraft.

I agree with rotorbrent, having the same experiences with Lead Acid Batteries. There cheap, and they only last 2 years at the most if your lucky. Most shops will not buy a spare battery for there helicopter due to expense, but where it really hurts financially is when you lose one your regular customers because the battery in your helicopter is dead when he really needs you.:{

139 engineer

[Hughes500]

C'ant believe anyone wants to use a nicad battery. They are very expensive, will let you down at the drop of a hat. Every ac I have ever owned ( 8 now) that has had a nicad we have swapped to lead acid. Nicads often pass a capacity check but still do not perform. Take the lead acid out and charge it ! Without special gearif you have a real problem, ie leaving ac out overnight when very cold and no remote start pack.
Interestingly the reson nicad's dont last is the charging regieme. You are supposed to virtually flaten them then recharge them otherwise they have a memory effect. So what do we do in an ac, start it using about 1/3 of the bat power then charge. So who is the dumb person who thought of nicads ? Now if they were Nimh batteries or Lion Batteries that would be different

[nigelh]

I am confused now :confused: I can accept that nicad may be more reliable and last longer but surely there are real benefits to lead.....ie you get up on cold morning and find you have a low or marginal battery....with lead you can just chuck it on fast charge for 30 min and you will prob be ok ? Also surely you can get lead batteries for less than $2,000 each ? That is about half the price of nicad. Lets hear more views from operators regarding cost/reliability. I agree that if your battery fails just as you are winding up to take your customer to Heathrow it could cost you a lot more .....In the charter market i would guess reliability is the most important part.

[rotorbrent]

When the Lead Acids first came out they were a lot cheaper than the NiCads. I never had any issues with the Nicads that were properly serviced. But at $2800 every 8 months now the lead acid's are more expensive than the Ni-Cads. per year to operate. So our lead Acid will be switched back to Ni-Cads.

[Buitenzorg]

All this talk of which is THE best battery is silly since both have different strong and weak points, and depending on your intended use one or the other will be superior.

NiCad strong points:
- accepts rapid repeated deep discharge/charge cycles without deterioration;
- can be replaced cell by cell rather than the complete battery at once;
- long service life.

NiCad weak points:
- high acquisition cost;
- maintenance requires special equipment and training;
- deteriorates if stored in charged state (this is what happens any time we shut down, especially if shut down for several days or longer);
- possibility of thermal runaway.

Lead-acid strong points:
- low acquisition cost;
- ease of maintenance;
- good service life but only if kept (near) fully charged.

Lead-acid weak points:
- deteriorates rapidly when subjected to deep/rapid discharges (this is what happens anytime we start the engines);
- cannot be “rejuvenated” by deep cycling.

One thing to note about the maintenance requirements for NiCads is that the overhead (battery shop, training etc.) will be pretty much the same for one or fifteen batteries – so for a large fleet the maintenance costs per battery decrease markedly.

From these points we can see under which conditions one or the other would prove superior. If an operator were to run a large fleet, each of which would start engines using the internal battery several times a day, then that operator would be wise to equip his fleet with NiCads and invest in a battery shop and associated technician training. On the other hand, a single-ship operator who could make most if not all his starts using external power (e.g. a set of Caterpillar batteries in series which are promptly recharged) would be daft not to install a lead-acid battery.

[carsickpuppy]

What is the best way to ensure the lead acid battery is fully charged upon shutdown? (no external power guaranteed on next start)

- or after, say a half hour flight, is the battery as charged as it will get and running the engine for a few minutes with all electrical off (generator on) gains little to nothing?

[widgeon]

Supplemental Type Certificate (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/6B01B6D9BBE13B89862571CC006B668E?OpenDocument&Highlight=lead%20acid)

Concord webs site also reference falcon crest STC STC# SR09186RC

Seems to be some approval in NZ Flight Manual Details (http://www.caa.govt.nz/script/Flight_Man.asp?Manual_ID=2316)

Also some German ( LBA) approvals come up in search.

I don't think either Falcon crest or Helilynx STC have been EASA approved .

[EN48]

B...zorg is probably closest to the answer - it depends. I am currently looking at this issue for a new B407 which came equipped with the standard 17 amp hour NICAD. I am considering whether to stay with this battery, change this one out for a 28 amp hour NICAD (optional on the B407) or switch to a SVRLA battery, the only one of which is STC'd currently for the B407 is the Concord RG407 27 amp hour battery.

In favor of the NICAD 28 amp hour is that it can produce the highest starting current (Ipp) of the three (by about 30%) which should mean faster acceleration on the start (provided the battery is properly maintained) with lower probability of a hot or hung start (especially important when the acft is cold soaked). The NICAD life also wins; I am aware of NICADs in B407s that are still going after 13 years with no cell replacements, but with by-the-book maintenance. Re NICAD maintenence, Marathon Norco has a line of NICADs they call "Micro Maintenence" or "M^3". The claim is substantially lower maintenence than standard NICADs, and greater energy density. See Micro Maintenance Batteries - MNAI (http://www.mptc.com/batteryprod.html) . Not many helicopters approved for this battery yet. Marathon also permits an extended maintenance interval for standard NICADs under some circumstamces - see link for details.

The typical SVRLA is junk (for turbine engine starting) after 2-3 years, but these also cost about one third of a new NICAD of equivalent capacity. It is my understanding that SVRLA batteries are also subject to thermal runaway but that this is less likely than in a NICAD.

Teledyne Gill is said to be working on a new type of SVRLA battery with longer life and higher starting power, but it is not yet available with an STC for the B407.

I have used both NICADs and SVRLA batteries in lightly used airplanes and helicopters for years and have never had a problem with either, however, I have arbitrarily replaced the SVRLA after two years no matter what (all have lasted at least this long - in fact, I sometimes transfer these batteries to less demanding use like starting the acft tug, and they sometimes last another five years even when neglected). I use a Power Products Activator 282 charger/maintainer which can be set for either type battery to keep the batteries fully charged. This is a professional grade aviation product that can be easily carried in the helicopter (weight less than 2 lbs). Sells for about $450 U.S. See Power Products, Inc. - Our Products (http://www.power-products.com/products.html) for more info. The only drawback with this product is that the max charging rate is about 2 amps, so if the battery is low and you are in a hurry, this wont solve the problem. It is really intended to be connected all the time to maintain the battery at full charge, however it will charge a flat battery in the fullness of time (overnight for example). For faster charging, I use a Power Vamp PS30M 30 amp power supply. See powervamp Group - Product Detail: PS30M (http://www.powervamp.com/product_detail.asp?ProdDivision=1&Subcat=28v+DC+Power+Supplies&prodID=89) . Also a professional grade product. However, this is not a set it and forget it unit. It is a power supply useful for charging batteries, or powering avionics in the hangar. It should be monitored when charging a battery. Not intended to be used for engine starting. The Power Vamp Cool Spool 29 is a great unit for starting. See powervamp Group - Product Detail: Coolspool 29 (http://www.powervamp.com/product_detail.asp?ProdDivision=1&Subcat=28v+Portable+Starter%2FGPU%27s&prodID=78) .
I use each of these products and find them to be of high quality and a good value for the money.