I'm new posting on the forum so I hope this is the correct area for this question. I have a Sunpak auto 120J flash. It has 4 AA cells internally and a external HV rechargeable battery pack. It works fine on the internal cells but not on the external. I found a replacement battery at B&H and a new recharger. Still no luck. I'm getting a reading of about 70 V on the battery output after a 24 hr. charge. I can use it on the internal cells but I sure miss the sub 1 sec. recycle time with the power pack. If anyone has a direction to try I'd like to hear from you. Thanks.