Batteries

[SauseaFoX]

Have deep cycle hybrid and cranking battery. The DC is new. Last run, battery selector was on both batteries, but the cranking charged at a slower rate. After 30 minutes it was only reading 10.5
My mechanic told me he has seen the new 27 series kill the cranks (mine is one year old) and that I should put two 27 series in the boat.
Why are they charging at differentvrates and what is the solution?

 

[paulswagelock]

If both are wet cell batteries, they will charge at the same rate, but the larger capacity battery would just take longer.

A battery at 10.5v is toast. Likely that battery is bad. Should never have a wet cell battery below 11.5 volt or so, preferably never below 11.8 v.

 

[electricaldoctor]

Have deep cycle hybrid and cranking battery. The DC is new. Last run, battery selector was on both batteries, but the cranking charged at a slower rate. After 30 minutes it was only reading 10.5
My mechanic told me he has seen the new 27 series kill the cranks (mine is one year old) and that I should put two 27 series in the boat.
Why are they charging at differentvrates and what is the solution?

It sounds like your cranking battery might be bad. Disconnect it and load test it. While you are at it, you may as well load test the both of them. When you have the battery switch on "BOTH" the cranking battery will bring down your good deep cycle battery.

 

[Little Ducky]

If you have 2 batteries that can run in "both" mode I would recommend that both batteries be the same in every way to give your charging system a fighting chance.

 

[Stingrayaxe]

Wouldn't an ACR (Automatic Charging Relay) also work? It will charge your starting battery first. Then when it senses that the battery is fully charged it switches over and charges the house battery. Once you get the condition of your batteries sorted it might be a nice option.

 

[Lazy Daze]

Generally, I like to charge one battery at a time - using the battery selector switch to do so. A deep cycle battery will not kill a starting battery, in and of itself. However, if you deplete a DC battery, then put the switch on BOTH, the DC battery will draw power from the starting battery - and a starting battery isn't designed for power being drawn from it over a length of time and this could absolutely shorten it's life. So, it's not that the DC battery kills the starting battery - it's the way the way the operator uses the switch. In the case of a depleted DC battery, start the engine on the starting battery, then switch to the DC battery to charge it up. Just make sure you don't inadvertently switch to OFF - that could be bad for other reasons.

For now, like others have mentioned, charge the starting battery up fully (on a regular charger) and then get it load tested. Another possibility is that you just have a bum battery. Even a relatively new battery can all of sudden go bad.

 

[wayne0]

Generally, I like to charge one battery at a time - using the battery selector switch to do so. A deep cycle battery will not kill a starting battery, in and of itself. However, if you deplete a DC battery, then put the switch on BOTH, the DC battery will draw power from the starting battery - and a starting battery isn't designed for power being drawn from it over a length of time and this could absolutely shorten it's life. So, it's not that the DC battery kills the starting battery - it's the way the way the operator uses the switch. In the case of a depleted DC battery, start the engine on the starting battery, then switch to the DC battery to charge it up. Just make sure you don't inadvertently switch to OFF - that could be bad for other reasons.

For now, like others have mentioned, charge the starting battery up fully (on a regular charger) and then get it load tested. Another possibility is that you just have a bum battery. Even a relatively new battery can all of sudden go bad.

YUP!