Practicality of a NiCad winch battery

[Chris Wilcox]

I have a big 24v NiCad battery that was used to start airplane engines from a ground unit. It is made up of individual cells so you could run 12V. What are your thoughts on running this vs a standard second car battery. Immediate issues I think of are charging hassles/speed and voltage limited at ~12v not 13.4. I have an 8274 front winch and a warn tabor 9k rear winch.
Specs are
24VDC
84.7 lbs
43 AmpHr,

which would be 86 AmpHr at 12V if I use the cells in parallel. This is roughly 10 minutes of winching at a full 8,000lb on the 8274 or Tabor 9K. Problem is I'd have to charge at 86 amps for 1 hour to recharge the battery before the next pull if it was dead. What kind of performance are you seeing on you setups?
Chris

 

[e9999]

don't you have to make sure the battery is fully discharged regularly to avoid memory effects on NiCad?

and are you sure the 43Ahr figure would hold at very high Amp discharge?

 

[Chris Wilcox]

it will havle some memory effect and I'm not sure about the second point. I know they work good enought at really high discharge rates in RC cars.

 

[IBCRUSN]

IMHO there is too much work required to make it work let alone the periodic maintenance. Aviation NiCAD's require a lot of periodic maintenance with specialized chargers (constant current rather than constant voltage) & capacity testers and then you have to figure out how to reorient the battery cell bars so you have two 12V batteries. After all that work then you have to address the charging. I'd have to do a little research but I think the 43Ahr capacity would be halved by converting it to two separate 12V batteries. I'm not saying that it can't be done but I think it'll be far more work to make it happen than it's worth.

Now days R/C has even gotten away from NiMH batteries and quickly going to LiPo and LiPoly batteries because of the huge increase in capacity. I recall my R/C racing days when 4-8 minute races often were the limits of NiCads and NiMH packs. Now days they have 11,000+ mA packs which is more than double the NiMH packs I raced with. It would be cool to be able to have 12-15 minute races but I digress.

However, seal up the vent ports and the connector receptacle with RTV or other good quality sealant and you have a great weatherproof box to store recovery gear or other stuff in while on the trail.

 

[Chris Wilcox]

You are right on the mark with all your comments. I will have to consider this further before shelving it but it isn't looking likely.
Chris