battery problem

[shimon340]

hi guys

tihs question doesnt relate exactly to the 340 but I need some help!!

Ive got a volvo 66 and on two occasions ( once on my car and once on a second volvo 66 ) we have connected a 40Ah battery from a 340 to the 66 whicj has resulted in the earth from the altenator SMOKING!!! ( we promptly disconnected the battry! ) we tried a 3rd car and it was fine... turned over etc and no smoking

does anyone know detailed information on how battery ratings work?

What could be the problem with the 66s??

Would a bad earth cause this? ( bad earth on a 340 causes a wobbly speedo and inaccurate fuel gauge with an EMPTY light that doesnt flash but never Smoking!!! )

any ideas guys?? how come a bad earth causes this type of prob on a 66?

AND......... the AH tells you how long the battery can deliver 25A for at 25 deg C... so the higher the Ah the longer the battery lasts....

if its a 12V battery do they have different amp ratings

im lost with this one and have two previously-smokinhg 66s to sort out

any ideas??

shame I missed the meet but I only got back to the uk on tuesday.... hope the meet went well

anyone got any pics???

im looking forward to the next meet

shimon

[340GLT]

Hi mate, i cant help on the battery front although don't batteries have a load rating? Maybe thats too high for your car? I dunno. Anyway you can see pics of the meet here

http://www.volvo300mania.com/forum-uk/v ... 0-f554.htm

Going to your post i read that you put a bad earth strap alters your speedo? Makes it wobbly? I thought the speedo on a 300 was purely mechanical?

Cheers Adam

[SteveP]

I have a vague memory of this smoking business happening to my Dads old 300, which I think may have been down to a bad earth. So that may well be the case!

[Chris_C]

Tis a strange one, the only thing I can think of atm is if there is a bad earth (i.e. a bad connection in the circuit) this will significantly increase the resistance of that path, as there is no other path to the battery, the current has to go via the route of increased resistance. The higher the resistance, the more current is drawn from the battery, and heat gets significant.

The bit I'm having trouble with is the fact that it only happens on this battery. Although it is a 40Ah battery, this indicates the power stored in the battery, not the power that can be drawn from it (Stored = Power drawn X time, i.e. how you get amphours). Definately look at the earths, and test the alternator if you can (although as both do it, tis very strange)

[shimon340]

hi guys

thanks for your replies..... much appreciated

to answers a few questions....

adam, the speedo on a 340 isnt purely mechanical. there is a pickup or sensor on the front left wheel but the system in a magnetic based induction system... the faster the wheel spins, the further the speedo moves. i dont know the exact design of the system at the moment but a poor earth does cause the speedo to go a bit jumpy at low speeds.

Steve P.... interesting that your dad had a similar problem with his 300... at least if another car does it it makes more sense... Ive had a 340 with a bad earth and the result is a jumpy speedo, dodgy fuel gauge, stiff choke and stiff heater heat controller.... maybe in the 66 a bad earth causes more dramatic results....

Chris_C im also puzzled by the 45Ah rating as what you say is exactly what I learnt from learning about batteries last night. the Ah is the ability of the battery to delivery a certain ampage ie this one could deliver 45A in one hour and then would be flat....

so as you say I think there are some other battery properties and values that I need to double check.....

thanks for all your help guys

volvo300mania is an excellent online resource

i look forward to chatting again soon

shimon

[Bilbo]

yeah a/h doesnt make a difference,you could have a battery the size of your house and it shouldnt do any damage as long as its the same voltage.an old mini i had did this,but it was because it was positive earth not negative and when changing the battery i wasnt paying much attention and just saw the strap going onto chassis and thought it was the negative!!??

[SteveP]

When my Dad had the problem, he called the AA and it was fixed easily.. though I can't remember what the guy did which doesn't really help! However, he did mention that it was a common problem with Minis/Metros!