Mixing Optima YellowTop and BlueTop batteries?

[filhere]

I have a 2007 Beneteau Cyclades 43, ex SunSail. Just bought two months ago. It came with a house bank of 4 Optima YellowTop batteries, which we have just realized are the source of our power problems. It looks like all 4 are running in parallel, and two of them are shot. (We used a proper load tester and drew that conclusion.)

My question is this. I am considering replacing the two bad batteries with Optima BlueTop's in the same size amp hour rating. If money wasn't an issue I'd replace all 4 with BlueTop's. Otherwise, it's a 8 hour push from here in Hvar to get to Split just to source a pair of YellowTops.

More details on the setup:
All charge comes from either when the diesel is running, or when we are on shore power. No solar, wind power. Fridge is on most of the time, stereo and minimal lights as needed, water pump.

We kept all 4 batteries connected for the first 3 weeks but found that the main panel would start to beep within less than a days time, and that was when we were being as frugal on power as we could. Now we disconnected the two bad batteries and we still run out of juice in about the same amount of time.

The batteries are: Optima D34 YellowTop, 55 Ah, 750 CCA, 870 MCA

Thanks.

[Zil]

Mixing old with new is not a good idea. Maybe you could wire two separate banks and do some switching as needed. more work for you but saving money is never that easy.

[barnakiel]

Do not mix. The old ones will drag the new ones down and you gain nothing. Remove the faulty ones and go. If this is a no-no option, replace the whole bank in one go with something more economical. Optimas are expensive batteries.

b.

[dockbumdan]

according to optimum they are identical except for the posts.
see note from the web page.
Note: The difference between BLUETOP® and YELLOWTOP® deep-cycle batteries is that BLUETOP® batteries have both automotive (SAE) posts and threaded studs, while YELLOWTOP®S (other than D31T) only have SAE terminals.
that being said, it always better to replace all batteries in the bank at the same time. best of luck.

[dockbumdan]

Note: The difference between BLUETOP® and YELLOWTOP® deep-cycle batteries is that BLUETOP® batteries have both automotive (SAE) posts and threaded studs, while YELLOWTOP®S (other than D31T) only have SAE terminals.
the above is from the optimum web page.
technically they are identical except for the posts.
that being said, it's always preferred to replace all batteries in a bank at the same time.

[NewMoon]

Those Optimas don't really make a very good house bank. I'd consider selling the two that are still OK, and replacing all four with two group 31 AGM's, for a total of about 140 lb and 210 AH. More AH/pound, more AH/dollar. Less cranking power, but you said this was your house bank.

Good brands include Deka, Odyssey, and Lifeline. Don't really know about Full River, but some say they're good too.

[hellosailor]

Phil, "do not mix" applies, because if you mix them, the old ones pull down the new ones, and you wind up wasting money as the new ones are just abused by the old ones.

The bluetops and yellowtops are supposed different, with the yellowtops having a thinner plate designed for dual-purpose use (starting plus cycling) while the blues are designed with thicker plates for deep cycling. Which doesn't stop you form using themas starting batteries, as long as they have sufficient power, as that bank would.

But you might want to reconsider using Optimas at all. Usually you can buy flat-plate AGM batteries for 1/3 less, with more capacity because there are "square" cells using flat plates in the rectangular box, while Optimas are cylindrical cells that waste empty space in the battery case. Typically a 10% loss, same-size.

Flat plate AGM batteries are available from many vendors, just ask around. And of course, that's ignoring the entire "Do I want AGM?" question.

But mixing new and old Optimas? That's an expensive way to go. Pointless waste, I'd say.

[goboatingnow]

Given where you are Id mix them, the sage advice is a bit misplaced yiu can mix batteries and anyway , these are very similar .


Do it ,go sailing

Dave