1) Are you speaking of the charging units that maintain your batteries?
2) If so, there are MANY brands.
3) Most are called "battery tenders".
. . . they are programs to charge the battery when needed
. . . they shut off unit charging s needed again
. . . this operation stops the battery from being burned up from excessive charging
NOTE: I burned up a battery on my motorcycle by having a charge always
on. The tender works like a champ, even over the entire winter. Now, eve
my boat has a battery tender.
1) Yes, this is what is commonly known as a Battery Tender.
2) For batteries not in constant use, they are HIGHLY recommended.
3) An inexpensive tender is worth the cost of a new battery, or batteries.
4) From personal experience, I know.
5) And, so does my wallet.