At a glance: One code, one battery: Optima YTU-4.2, 55Ah 12V 765A, for boats and motorhomes. Before anything else, measure the space: the case comes to 254 × 175 × 200 mm.
12VVoltage
55AhAmp-hours at C20
765AStarting power (EN)
About the Optima YTU-4.2
If the logbook says Optima YTU-4.2, here are the numbers for the replacement. Ratings of 55Ah 12V 765A give a starting point for sizing a service bank. At baterias.online, leisure batteries sit under maker and reference, so you can match a bank exactly.
Small and light at 55Ah, ideal where space is short. With 765A, it punches above its size on frosty mornings.
Technical figures at a glance
MakeOptima
Part numberYTU-4.2
Product lineOPTIMA YELLOW TOP
Suitsboats and motorhomes
Voltage12V
Amp-hours at C2055Ah
Starting power (EN)765A
Battery technologySpiral-cell AGM
Size L × W × H254 × 175 × 200 mm
Weighs20.6 kg
Positive terminalpositive on the left-hand side
Terminal type1 & 21
Barcode4016987113530
Using it day to day: practical tips
A caravan with a motor mover asks for big bursts of current. Write the fitting date on each battery in the bank. Old and new batteries side by side make a weak team.
The spiral-cell AGM technology explained
Spiral batteries are sealed and do not need water. Rally cars use spiral batteries for strong current. Keep the terminals clean and tight.
Will the Optima YTU-4.2 fit?
- ✓ Make sure your clamps fit 1 & 21 posts or tabs.
- ✓ Built with spiral-cell AGM technology: if your vehicle or system was set up for another chemistry, check the charging settings first.
- ✓ Grab a tape measure: 254 × 175 × 200 mm is what this case needs.
Frequently asked questions
I cannot read the label on my old battery. What now?
Usually on the top label or the front of the case, near the logo. Search for brand plus that code.
Is the Optima YTU-4.2 a heavy battery to fit?
The weight is 20.6 kg. Heavier batteries generally contain more lead and active material.
How strong is this battery when starting?
Under the EN test it delivers 765A.
Does this battery match my current one physically?
Size is 254 × 175 × 200 mm and polarity positive on the left-hand side. Both must match your current battery.
Same case, same terminal side
If you prefer another make, these fit the same space with the same terminal side.
Optima BTDC-4.2Optima YTS-4.2Optima BTSLI-4.2
Explore more
Prefer to compare first? The links below lead to other options for boats and motorhomes on baterias.online. Checking the data first saves the hassle of a wrong order.
