I have a Northstar Group 27(90 amp hours). I can use either it, or my USbattery flooded group 31(130 amp hours) for engine or house duties and often cycle one one day, then the other the next. I bought both the same time, last November. I have an amp hour counting battery monitor.
In terms of voltage held for amp hours removed, the Northstar Wins.
In terms of how fast it can crank the engine fully charged, the Northstar easily wins
In terms of how fast it can crank the engine when depleted, the NorthStar absolutely spanks the USbattery.
In fact, despite the Flooded battery being rated at 40 more amp hours capacity, it has not "beaten" the Northstar in any of my observations. Perhaps if I were to drain both more than 70 amp hours from full the flooded would hold more voltage.
The Northstar did require one deep cycle and a 25 amp charger to "wake up". Off the shelf it decided not to accept any more charging amps and had an open circuit voltage of 12.84v. After a 50% discharge and a 25 amp recharge, it was reading 13.07v 3 days later resting unused.
Batteries Plus rebadges Northstars as X2 power or something and adds another year or 2 to the warranty.
I was going to get a DHP 31 but the Oddysey recommended spec of 40% current until 14.7v is reached, then held at 14.7 for 4 hours was not going to happen with 200 watts of solar.
The Northstar does not give as much recharging specifics as to minimum current, and has not noticeably decreased in performance being recharged solely by the solar. It will still hold 13.07 for days and days after all charging sources and loads are removed from it.
When the NS is fully charged, it is almost scary how fast my engine starts. It is as fast or faster than 3 marine 27's in parallel.
I don't know how long the NS will last, but so far I have found it to be an impressive battery, and wish I bought two rather than the g31 USbattery.
I spent about 275$ before tax for the Northstar, and ~$170 for the G31 USbattery.
The Usbattery requires equalization charges every 10 cycles or so with a 14.6v acceptance and a 14.7v float, otherwise the Specific gravity falls into the red and the battery behaves poorly.
Really wish I had bought 2 Northstars instead
