NiCd battery for starting

[cranetruck]

Been working on this off and on for about a year, simply tired of the problems with lead acid batteries, poor cold weather performance, trickle charging, maintainers that fail not to mention poor contact burning battery studs etc.

Yesterday I started the truck on the LA's and charged the nicads at a rate of about 10-15 amps for two hours. Figured that would be about 60-70% of a full charge for the 30 AH NiCd cells (charging current drops and it would take several more hours to complete the charge).
Today I removed the LA's and cranked the 8x8 engine with the fuel solenoid "OFF", looking for current draw, cranking rpm and voltage before starting it.

So far, the Nicads are doing the job very well, voltage dropped to about 21 VDC and the current draw was about 295 amps. I have a current shunt permanently installed as part of the transition from cell to original cable connection. The copper links seen in the image will be replaced with nickel plated bars to keep from corroding.

Very happy with results and without the lead alloy terminals, the connections can be torqued to normal bolt spec, hopefully eliminating poor connection problems.

 

[BikerBi11]

hmmm... that is interesting. I have no idea what you just said!

 

[paulfarber]

Neat idea, but as you said the charging part is the kicker.. more parts to handle the NiCads charging profile.

Have you considered the AGM batts like Optimas?

 

[cranetruck]

Neat idea, but as you said the charging part is the kicker.. more parts to handle the NiCads charging profile......

Charging is only a bit time consuming the first time around since I have to put 30 or more AHs into them (the cells were completely discharged when installed). They will only be used for starting and will replenish quickly after each start..within minutes actually.

 

[Rustygears]

Why NiCad and not Nimh? I fear that with such heavy current and frequent, but shallow charge cycles, you'll have significant issues with NiCad memory, higher internal resistance and resulting lower current available for starting which then makes the problem get progressively worse.

NiCads don't like to be stored charged, unlike other battery types. They work best when each cycle they are fully discharged and they are not kept in a charged state for any appreciable length of time. For most commercial applications, NiCads have been replaced by newer chemistries that don't have these issues.

 

[motorolanut]

Neat idea, but as you said the charging part is the kicker.. more parts to handle the NiCads charging profile.

Have you considered the AGM batts like Optimas?

+1 for AGM's...I will never go back to conventional flooded cells again..

 

[cranetruck]

There are a number of reasons why I'm going with the nicads, here is a set of specifications. Note the "unlimited" storage time "regardless of state of charge". Note: -22°F is -30°C not 30.

Having to discharge the cells to zero ("flatten" them) now and then is a small price to pay. There is a reason why they are used in aircraft.
Hopefully these cells with stay with the truck for as long as I own it. The cells are over ten years old now and no limit for lifespan according to references...

But, I'm willing to learn, that's why I'm posting to learn from others with more experience.

Edit: The BB-693A/U is similar to my set-up, except mine was put together from scratch and I added one cell to reduce the charging current and pretty much eliminate overcharge consequences.

 

[tennmogger]

Cranetruck, I support your decision 100%. I have been using wet cell NiCads since the 60's. Some of mine must be 40 years old. All the ones I have had have been used, taken out of service, and obtained for free, but with a little TLC they are servicable for many more years.

I presently have a set of 36AH wet Nicads sitting at the entrance gate powering the gate opener, float charged with a solar panel. This has been the most trouble free setup in a series of 3 different batteries.

As you know, overcharging is bad for them. Reversal of cell voltage is worse. Don't discharge to under about a volt per cell, as a battery, or weaker cells will see reverse charge. If you hit the starter and cranking is slow, don't proceed. Charge them first.

Under charging will cause imbalance of the cells. Again, as you said, they need to be discharged (individually by cell) occasionally to equalize them. I have resistors on clip leads, and a busbar for each cell. Discharge to well under a volt then strap across the dead short and leave overnight. And of course you know to add distilled water to the cells (KOH - potassium hydroxide electrolyte) after the cells are charged so they don't overflow.

FYI, I use a constant current, regulated voltage charge after equalizing, and recharge at about 1/10 C. In the truck they get whatever current the alternator/generator will provide, and voltage regulation from the voltage regulator.

Remove and soak the pressure caps occasionally so they still vent when needed.

I wash the batteries off occasionally with a hose to get rid of the 'bloom' that will form on the terminals (wash out of the vehicles).

Is your battery in a stainless box? The box is important because it also acts to restrain the cells when they charge so they can't expand from pressure before venting takes place.

These batteries are extra work but well worth the effort, IMHO. They can certainly save you a lot of $$ over the years.

Bob

 

[JDToumanian]

Very interesting! What kind of NiCads are those? I've never heard the term "wet NiCads".... Before I enlarged the picture I expected to see the type of cells used in radio controlled cars.

Jon

 

[paulfarber]

Not knowing much I read up on NiCads and found this little blurb:

When not under load or charge, a NiCd battery will self-discharge approximately 10% per month at 20°C, ranging up to 20% per month at higher temperatures. It is possible to perform a trickle charge at current levels just high enough to offset this discharge rate; to keep a battery fully charged. However, if the battery is going to be stored unused for a long period of time, it should be discharged down to at most 40% of capacity (some manufacturers recommend fully discharging and even short-circuiting once fully discharged), and stored in a cool, dry environment.

Is this true? Would seem to be a distinct disadvantage if Wiki is correct.

 

[rlwm211]

I have several of these batteries I use for deep cycle applications for my radio work and also to power the shelter on my deuce. I got mine surplus from the aviation industry as they were too old to be used and were replaced by newer products.

They were originally 28 volt nominal voltage, but I changed the buss bars so they are 14 volts Nominal. I agree with Bjorn about the durability of these batteries. I have been using them for 3 years without issue.

I use Optima yellow tops in my deuce and agree that they are the best thing going in terms of a commonly available type of battery.


Just my two cents

RL
.

 

[cranetruck]

Not knowing much I read up on NiCads and found this little blurb:

When not under load or charge, a NiCd battery will self-discharge approximately 10% per month at 20°C, ranging up to 20% per month at higher temperatures. It is possible to perform a trickle charge at current levels just high enough to offset this discharge rate; to keep a battery fully charged. However, if the battery is going to be stored unused for a long period of time, it should be discharged down to at most 40% of capacity (some manufacturers recommend fully discharging and even short-circuiting once fully discharged), and stored in a cool, dry environment.

Is this true? Would seem to be a distinct disadvantage if Wiki is correct.

The self discharge rate reads about right based on my references also, but so what?
Quoting:
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif] All batteries, regardless of their chemistry, will self-discharge. The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. a lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will loose 80 amps of its 125-amp capacity. It will also have severe sulfation, which causes additional loss of capacity. Keep your batteries charged while not in use![/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif] Do lead acid batteries develop a memory?[/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif] Lead acid batteries do not develop any type of memory.[/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif] Do I need to completely discharge my lead acid battery before recharging it?[/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif] [/FONT][FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif] No, in fact you should never discharge your lead acid battery below 80% of its rated capacity. Discharging it below this point or 10.5 volts can damage it.[/FONT][/FONT]

Manufactured ten years ago, my cells arrived with a shorting spring attached, so that is also true, again, so what?

These are very rugged cells and can handle hundreds of amps during the charging process. I charge my other set of Nicads from a 100-amp alternator and can have them fully charged in 45 minutes after their 60 amp-hour capacity has been used up. They can handle over 1,000 cycles of complete discharge/recharge.
The design of these cells have not changed since the 60's except for some improvements in material perhaps.

 

[cranetruck]

There are many references in PS magazine concerning nicad batteries, here are a couple. Note, KOH (potassium hydroxide, also used in biodiesel making) is not explosive, but corrosive, Hydrogen plus oxygen will explode under the right conditions, just like the gassing from a lead acid battery. Because of that, my battery box is vented by force from the engine compartment fan.

The PS mag articles may answer some of your questions Jon...

 

[tennmogger]

It's actually rather convenient to have batteries that when you want to take them out of service, you just take them out of service. Set then out of the way somewhere and not have to worry about topping them up occasionally. My stash of extra cells has been stored for about 7 years now and when I need one it will usually charge right up. Have to monitor electrolyte level and keep charge rate down on the first recharge.

These cells do grow whiskers internally and short sometimes. It takes a good jolt to clear that whisker. I use a big charged up capacitor with heavy leads to accomplish that.

I think wet/flooded Nicads fell out of favor because of two things, need for more TLC than most people are willing to give them, and the emphasis on recycling that has risen at exponential rate in the last few years. They are also 'wet', and all replacement aircraft batteries today (that I know of) are sealed. That's a serious improvement in convenience.

 

[cranetruck]

A lead-acid battery is perfect for one application only, to start a good running vehicle that is driven daily or almost daily. Very little of its capacity is used, a few amp-hours only and it's put right back when the car is driven off.
Just about any other situation is a compromise for the LA battery, car doesn't start right away and the battery is drained. It is recharged at a relatively slow rate from a charger and sulfates. A few of these cycles and the battery will not regain its original capacity or even become useless.
A lead-acid battery that isn't used, self-discharges and sulfates and looses capacity again.
So there are trickle chargers, computerized maintainers, Solargizer de-sulaftors etc for applications where the battery isn't used exactly as described in the opening sentence above.
Yes, there are new technology (AGM) lead acids, but they are still compromises.

In contrast, the Nickel Cadmium cells are almost indestructible. Much more expensive for general civi car use, but we have access to military surplus, so why not use them.

Cadmium is a hazardous material and disposal may be a problem..I believe that the batteries are banned in parts of Europe for this reason, but the nicads are so good we shouldn't have to worry about disposal, ever.

 

[cranetruck]

An observation.
Using 24VDC (or 12) to 120VAC inverters, powered from lead acid batteries is so common that apparently the inverter manufacturers limit the low voltage input to exactly 10.5 or 21 VDC, since harm will come the LA battery if discharged further.
A NiCd battery can run down beyond that and can not fully expend its energy with this limitation.
Anybody know of any inverters with an adjustable low voltage threshold? I'd like to see 9 or 18VDC...