Dodd preamp battery plays 40 minutes

Hi Audiomole,

>>"Gary says the batteries lose about 2% of their charge a day without use, and ideally should be played every day."

This is not correct with SLA batteries. Stored at room temperature, the self-discharge rate of SLA batteries is around 3% per month. SLAs degrade from deep cycling and they have a finite number of charge/recharge cycles. The deeper they are discharged, the shorter the overall lifespan of the batteries. This will all be clear when you look at the datasheet of an SLA battery. For example, the Power Sonic 12V, 5Ah SLA datasheet:
http://www.power-sonic.com/site/doc/prod/86.pdf

SLA batteries do NOT suffer from "memory effect." However, they DO suffer from being deep-cycled (especially if you do not fully recharge right after use). They ALWAYS like to be in the charged state, so they should be charged as soon as you are finished using them. Even if you play for a few minutes, you should turn off the unit and begin charging. If you are not using the unit for a while, just keep it plugged into the charger and this will "float-charge" the batteries and this will keep the batteries from self-discharging over time. Again, there is NO memory effect with SLAs.

>>"But there seems to be a need for some way to relieve the user of the battery maintenace issue. It should not require that much thought to use your preamp. I'm not sure if Vinnie's preamp works differently."

Hi Pubul57,

I cannot speak for the Dodd preamp - I can only speak for RWA products. They feature our Red Wine Audio SMART module (SLA Monitoring and Auto Recharge circuiT)that continuously monitors the battery voltage - and if it falls below 11.5V, we the unit will automatically shut off and being charging. This way, you cannot accidentally deep cycle the unit by leaving it ON and forgetting to turn off. Ealier RWA products (the original Signature 30 and 70s) did not feature this, but the current product range (Sig 30.2, 70.2, Isabella, Isabellina) all feature the SMART module and all our future battery-powered products will feature this. It is an important feature.

The Power Sonic and Enersys SLAs are very good, but we still use a battery analyzer to carefully test and match them for each unit. We learned how important this is because we were hearing from customers whose batteries were not lasting as long as they should. It turns out we were getting some batches of batteries that were inferior (from a different manufacturer) and proved this under load testing and are still trying to get refunded - uggh! So now we make sure they are top-quality before installation.

Best regards,

Vinnie Rossi
Red Wine Audio

Vinnie, a local retailer where I bought by last set of batteries suggested that these batteries will suffer reduced life if the batteries are not used and/or recharged while in the upright position, i.e. with terminals on top. I don't recall the exact technical explanation, but they suggested that using or recharging the battery positioned on its side was not optimal due to the way the liquid was contained in the battery. Do have an opinion on this and how do you position the battery in your products?

I'm not sure how the Smart Module works, but it does seem to me that battery powered gear does need built-in "intelligence" to take care of the battery for the customer. I really don't want to think about the battery, I just want to turn on the preamp when I want to listen to music and turn it off when I'm done, and not worry about it. I don't mind replacing the batteries every year or two, but in between, I want to forget all about them. The Smart Module seems to me essential to the design.

Hi Cruz123,

This would only be true if the battery was a "wet cell" or "flooded lead acid" type (i.e., most automotive batteries). If you pick up the battery and shake it and can hear liquid sloshing around inside, they you have such a battery.

However, SLA batteries do not fall into this category, as they are AGM (absorbent glass mat) or "gel cell," and they are also valve-regulated , so they do not need to be stored or charged in the upright position. Any position is fine and it makes no difference.

Hope this helps,

Vinnie Rossi
Red Wine Audio

Hi Pubul57,

Exactly - and this is what we designed it for :-)

- Vinnie