Rolls Surrette

[RainDog]

I was always under the impression Rolls where way more expensive than other batteries. I was surprised when I look that they are only about 25% more then Trojans at the 20 hour rate:

T-105 x 4 = $600 = 450 ah = $1.33/ah
Rolls Surrette S-530 x 2 = $680 = 400 ah = $1.7/ah

And about 13% more if drawing 5 amps continuously (which is more like my use case):

T-105 x 4 = $600 = ~100 hours = $6/hour
Rolls Surrette S-530 x 2 = $680 = ~100 hours = $6.8/hour

Am I missing something. If this is the case, based on what I have heard, it seems surprising so few people seem to use Rolls Surrette.

[DotDun]

Originally Posted by RainDog

I was always under the impression Rolls where way more expensive than other batteries. I was surprised when I look that they are only about 25% more then Trojans at the 20 hour rate:

T-105 x 4 = $600 = 450 ah = $1.33/ah
Rolls Surrette S-530 x 2 = $680 = 400 ah = $1.7/ah

And about 13% more if drawing 5 amps continuously (which is more like my use case):

T-105 x 4 = $600 = ~100 hours = $6/hour
Rolls Surrette S-530 x 2 = $680 = ~100 hours = $6.8/hour

Am I missing something. If this is the case, based on what I have heard, it seems surprising so few people seem to use Rolls Surrette.

I can buy T-105 for <$100 each.

[RainDog]

Originally Posted by DotDun

I can buy T-105 for <$100 each.

Where?

[mitiempo]

All Rolls batteries are good, but some are better. The 2 volt cells are amongst the best, but very expensive.

[DotDun]

Originally Posted by RainDog

Where?

Affordable Carts - Home

[twistedtree]

Originally Posted by mitiempo

All Rolls batteries are good, but some are better. The 2 volt cells are amongst the best, but very expensive.

"Best" is relative. I have an off-grid house that uses 1350AH 2V Rolls cells. I paid a small fortune for them thinking I was getting the best, but for the most part I regret the purchase. The problem is that they really aren't suitable for an environment where you can't give them a very long absorption cycle. That means they are not good for off-grid, solar powered homes, nor for boats where the charge source is your engine. If you don't give them a really long absorption time (4-6 hrs) they don't come back to full charge and you will build up a charge deficit, get sulfation, and generally have a bad experience. They really are much better for their traditional application in railroads, large commercial ships, fork lifts, and other applications where they can regularly get a good long recharge. The only situation where I'd consider them for a boat is one that returns to a marina on a regular basis and can sit with a shore powered charger.

[mitiempo]

I do not know of any battery that doesn't need to be fully charged as often as possible. This is even worse with AGM batteries than with flooded. That is why long term cruisers use solar and/or wind generators to top the batteries up. Engine charging won't get you past 80% to 85% SOC without many hours of engine time.

Good traction batteries like the Rolls/Surrette can be 15 year batteries if properly treated.

[twistedtree]

Originally Posted by mitiempo

I do not know of any battery that doesn't need to be fully charged as often as possible. This is even worse with AGM batteries than with flooded. That is why long term cruisers use solar and/or wind generators to top the batteries up. Engine charging won't get you past 80% to 85% SOC without many hours of engine time.

Good traction batteries like the Rolls/Surrette can be 15 year batteries if properly treated.

Sorry, I wasn't clear. I know all batteries need to be fully recharged, including running them through the full absorption cycle. The issue with the big Rolls is that it takes much longer the get them through the absorption phase than batteries like Trojans. Apparently it's a side effect of the heavier plates in the Rolls.

I've got mine where they can be recharged via a generator with 6KW charger in about 8 hours. It takes 3-4 hrs to get them through bulk, then 4-5 for absorption. But that's charging at 60V (it's a 48V bank) bulk/absorb. That's equivalent to charging a 24V bank at 30V. It's a really hot charge voltage and is the only way to get them through charge in a reasonable time. All this was arrived at after working with Rolls for about a year. Initially they wanted some ridiculous absorb time like 8-12 hrs - basically longer than the sun shines, and longer than anyone would be willing to run a generator or main engine. It works, but they consume a lot of water - about 8-10 gal every 6 months for the bank.

I had Trojan L16s before and they would go through the absorption phase in about 2hrs.

The "tail" of the charge cycle (absorption phase) is the Achilles heal of battery charging for cruisers, and Rolls batteries have a much longer tail than other batteries.