P38A Hot start problems or stuffed battery????

New thermostat fitted to my 98P38 2.5 dse, temp gauge needle sitting in the middle as it should. However, leaving Argos this evening the engine spun over but would not fire up. Hot start issue I thought, so decided to let the engine cool down a bit. Turned on the ignition the glow plug light showing on the dash, start the engine then the battery started to flatten. The engine started almost immediately after a jump start from a taxi driver. I tested the battery with my battery tester which showed OK after a 10 second discharge and no bubbling from the cells. I must say that the battery looks a bit old and needs put on the charger every few days. Should I change the battery first to see if that cures the hot start problem?
Thanks

Well if it needs charging every few days either your alternator is knackered or the battery is.

Thanks Wammers, the alternator is reading 14.5 volts @ 2k revs. I'm sure the battery is tired, so just going to get a new one this weekend. Got a price of £70 for a Varta-96 Amps with 570 CC. I don't think this one is suitable for a P38 2.5 diesel engine. Any suggestions?
Thanks

Musicmaker said:

Thanks Wammers, the alternator is reading 14.5 volts @ 2k revs. I'm sure the battery is tired, so just going to get a new one this weekend. Got a price of £70 for a Varta-96 Amps with 570 CC. I don't think this one is suitable for a P38 2.5 diesel engine. Any suggestions?
Thanks

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If you have 14.5 volts on a diesel somebody has changed the controller. Should be 14.2 max. But with that you can afford a full calcium battery. 14.5 will fry a lead acid battery PDQ. Fit the largest one that fits minimum 107 amp, 115 amp better, 130 amp as good as it gets. 96 amps 570 CCA is not good enough for a diesel.

Thanks wammers. Interesting, you say that 14.5 will fry a lead acid battery. Makes sense, the battery was almost dry when I got the car two years ago and I have had to top up the battery a few times since. What I don't understand is that the alternator on my petrol engine Volvo reads 14.5 volts and the battery is ok.
EDIT: Sorry, senior moment. I don't know where I got 14.5 volts from LOL. Just checked the Volvo just now, it's reading 13.8 at tick over with side lights on. The P38 is reading 14.3 at tick over.

Musicmaker said:

Thanks wammers. Interesting, you say that 14.5 will fry a lead acid battery. Makes sense, the battery was almost dry when I got the car two years ago and I have had to top up the battery a few times since. What I don't understand is that the alternator on my petrol engine Volvo reads 14.5 volts and the battery is ok.
EDIT: Sorry, senior moment. I don't know where I got 14.5 volts from LOL. Just checked the Volvo just now, it's reading 13.8 at tick over with side lights on. The P38 is reading 14.3 at tick over.

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There are generally several types of battery about. Lead/antimony on both negative and positive plates. (Old type batteries) Lead/calcium/antimony which uses calcium on one plate and antimony on the other. (Early nineties). And lead/calcium which uses calcium on both plates which last longer in storage and produce less gas whilst charging. (Present standard). All need different charging rates. Full calcium batteries need an higher charge rate than the others to start the chemical reaction to charge. And are less prone to gassing. If you use the higher charge rate on lead antimony batteries they gas profusely and boil off the electrolyte. They should be topped up with a solution of acid and water in the correct ratio, not just water or they become weak as time goes by. If for instance your car has the older type and a charge rate of 13.8 volts, which was pretty standard in the nineties on a lot of cars. If you fit a full calcium battery to it, the battery will never reach full charge and the low charge rate will cause it to sulphate the plates ultimately causing it to fail. Sulphated batteries can sometimes be recovered using a high charge rate for a given period subject to unit temp, but not always. Charge rates for the three types of batteries mentioned are in general terms. Max 13.8 volts, Max 14.2 volts and 14.5 to 14.8 for full calcium.

Thanks for that info, much appreciated. Like they say, every day is a school day.