Battery voltages - is mine dead?

[landspeed]

In true gassavers fashion, I remembered I had a battery in my 200SX that isn't being used just now (the car needs work for the MOT, the yearly roadworthiness test). The best thing is the battery is the wrong shape anyway so would be better placed in my car!. It is a 'Calcium' battery (normal lead acid but has very slightly different chemistry or something). This means I don't have to buy a new one. I will keep the old battery charged up so I can use it in the 200SX for now

The individual cells testing technique didn't work very well - it was 10 volts from cell to cell, but 12.5 volts across the whole battery. I have put the battery on charge now so it will be ready in the morning.

The reason the individual cells technique didn't work, I think, is that there was very little electrolyte for the electrodes to touch - when I put them in deeper the voltage went up. The electrolyte is quite well 'hidden' due to the shape of the battery.

An interesting note for Project Forkenswift etc - this battery of mine has a reserve capacity of 110 minutes at 25Amps - which is 300 watts. This will be good for engine-off coasting, but, 10 of these batteries would give 3000 watts for nearly 2 hours - this could be enough to maintain a low-speed cruise in a light EV (or, in my case, when I get my electric motor installed, would give 2 hours of 3kw engine-off-coast prolongation

Edit : read '1 hour' rather than 2 hours above if you want to drain the battery to 50% max capacity, obviously

[GasSavers_Bruce]

IMO, for EOC'ing with the headlights on, this should be the hot ticket:

http://www.optimabatteries.com/publi...eep_cycle.html

Unfortunately, I just bought a new battery in October.

[GasSavers_Ryland]

sulfer compounds build up over time on the plates, and lower the effectivness of lead acid batteries, I've used a battery charger with a de-sulfater and had "dead" batteries come back to life about half the time, best of luck is with batteries like you have that are just a little weak, worst luck was with one that had sat dea for 3 years... it's still mostly dead, the de-sulfating battery charger pulsates the current, acting kind of like an electric toothbrush on the plates to brake up the deposits, even tho there isn't any accual mecanical puslating.

[basjoos]

Originally Posted by landspeed

If I drive fast through a very deep flood across the road, it might slip for 2-3 seconds, and the lights go very dim. After engine-off coasting, it very often slips for quite a while, suggesting that the battery is putting quite a load on the alternator.

With the above said, I will again note that it doesn't normally slip, the lights remain bright, etc

You may want to increase the tension on your belt. Slipage of the belt will cause premature failure of the belt.

[landspeed]

When it stops raining, I will look into tightening the belt (not sure which belt it is, as there are two belts between the crank and the alternator). I will also look into a desulfating charger if I can find one - would be especially useful for an EV with lead-acid batteries

The new battery seems to be doing well though - I have got 242 miles out of half a tank - usually on commuting I would get 180min - 210 max on half a tank. Given the current fuel scare in the UK, I don't think I will fill up for a week or two yet, so will have to wait to see what the economy has been!