A 3 month old battery loses its charge with 15 miles

Hi there folks.

i bought a new battery in April 2026 for my 1981 KZ440 LTD. The battery model is Yuasa AGM  Motorcycle Battery YTX7L-BS

it took around 5 hours to charge, after being left in the unused bike, charged after receiving it in April then installed. After an 8 mile trip into town the bike stalled on low revs. I got it home after hill starting a couple of times.

it appears that the battery is simple a dud, however I’d like to test it to confirm, as perhaps there is a wider electrical problem that might be draining the battery while it is unused.

id be grateful please for any advice about checking the integrity of the battery and/or checks I can make on the bike to see if the cause of the battery drainage lies elsewhere. 

very many thanks. James

Use a volt meter set to DC and jumper across the battery to read voltage.  Start up the bike and rev to 5000 rpm, to see what the charging system is doing.  A proper charging system will charge the battery at about 14 - 14.5 VDC at 5000 rpm.  Chances are high that you are not getting much if any charging.

Thanks Nessism.

I’ll recharge the battery and do that.

in the meantime, would a good battery 3 months old, without any charging, last more than 15 miles of typical riding? I would have thought so, making me think it’s a dud battery, but I may be wrong. 

thanks again. 

Jimbo68 wrote:

Thanks Nessism.

I’ll recharge the battery and do that.

in the meantime, would a good battery 3 months old, without any charging, last more than 15 miles of typical riding? I would have thought so, making me think it’s a dud battery, but I may be wrong. 

thanks again. 

Probably not to be fair

Battery charged. I won’t get a chance to start her up and measure the voltage until next week. 

I’ll be back in touch then. Cheers.