Batteries

Martin, you should always aim to charge hawkers between each battle. The deeper they are discharged, the shorter they live.

Thanks that what I thought but just wanted to check

Would this be a suitable charger just to check these old SLAs Will and I have aquired !
http://www.argos.co.uk/static/Product/partNumber/7402137/c_1/2%7Ccategory_root%7CGarden%2C+DIY+and+leisure%7C95 54618/c_2/3%7Ccat_9554618%7CCar+equipment%7C9554675/c_3/4%7Ccat_9554675%7CCar+battery+chargers%7C9554688.h tm?Price+Cut=1http://www.argos.co.uk/static/Produc...ategory_root%7 CGarden%2C+DIY+and+leisure%7C9554618/c_2/3%7Ccat_9554618%7CCar+equipment%7C95546 75/c_3/4%7Ccat_9554675%7CCar+battery+chargers%7C9554688.h tm?Price+Cut=1

Ian, That would do very well.

Thanks Leo...as the spec says Suitable for use with car batteries - 6 volts/12 volts/ sealed/ lead acid/ gel cell batteries between 20-120Ah - Charging rates 5.3 amps RMS would it be advisable to charge 17ah in parallel ? Read somewhere optimum C is 25% of capacity for SLAs

Our current batteries are old but we might buy some new SLAs so want to make sure we use the chargers properly from the start. At £20 each cant be a bad buy if there upto the job !

I would only charge batts in parallel when they are new so they act as 1 battery. Old ones you might get more of a charge in one than in the other due to memory effects.

I wouldnt worry too much over the minimum Ah rating of the charger, its a pretty intelligent charger and it will slow down in time.

If they are Hawkers, then you really need to read the application manual:
http://www.commutercars.com/downloads/batteryCharging/HawkerGuide.pdfhttp://www.commutercars.com/download...awkerGuide.pdf

Hawkers are different from other lead-acid batteries. A lot of people do not realise their potential (and shorten their life) by not charging them correctly. In particular, you must charge them at 14.7 to 15V, no less.

I would NOT recommend using any lead-acid battery charger that does not specifically say it is designed for Hawker batteries.

Also, as it says in the manual - there are no restrictions on the current limit. One good way to charge them is just to use a big 12V power supply, like the 40A one that a lot of teams use -http://technobots.co.uk/acatalog/Online_Catalogue_Power_Supplies_29.htmlhttp://technobots.co.uk/acatalog/Onl...pplies_29.html -
set to 14.7 Volts and connect the battery/batteries directly to it and let them draw as much current as they want.

We use to charge ours with a power supply, and took them off when the current dropped to about 1amp.

Im NO expert on charging batteries but the charger I previously linked to on ebay ... new link provided here http://a1autowise.com/BatteryCharger.aspxhttp://a1autowise.com/BatteryCharger.aspx

Seems to meets the requirements stipulated by http://www.odysseybatteries.com/charging.htmhttp://www.odysseybatteries.com/charging.htm

(Message edited by woody on July 12, 2008)

Thanks all for your help. We tried the cheap option from argos and either the cells are duff or they are not upto the job...so they are going back ! One last question....the power supply linked from technobots....is this a variable current adjustable / limited one...do we need one (? / advisable) or just set the votage and go ! We aslo found another alternative...
http://stores.ebay.co.uk/TK-RADIO_POWER-SUPPLIES_W0QQcolZ2QQdirZQ2d1QQfsubZ9476935QQftidZ2 QQtZkmhttp://stores.ebay.co.uk/TK-RADIO_PO...d1QQfsubZ94769 35QQftidZ2QQtZkm
These prices for the lower amp ones look quite reasonable. Still undecided to but new SLAs or go NiMH ! If we go SLAs would even the cheaper non hawker SLAs be perfectly ok to charge like this ? (well need a couple of sets and £400+ is a lot of pocket money and bedroom tidying for Will !!)