Mixing battery types

[AndrewB]

My domestic bank consists of 3x100Ah 12v lead-acid 'Leisure' (deep cycle) batteries. The oldest one became tired and no longer held a decent charge, so has been ditched.

I've been offered for a totally give-away price, an unwanted almost new 100Ah lead-acid start battery, a Varta H3 'Silver Dynamic'. If I use it to replace the missing battery in my domestic bank, will it cause major problems?

 

[PaulRainbow]

My domestic bank consists of 3x100Ah 12v lead-acid 'Leisure' (deep cycle) batteries. The oldest one became tired and no longer held a decent charge, so has been ditched.

I've been offered for a totally give-away price, an unwanted almost new 100Ah lead-acid start battery, a Varta H3 'Silver Dynamic'. If I use it to replace the missing battery in my domestic bank, will it cause major problems?

Are the batteries genuine deep cycle ? Make/model ?

 

[ChromeDome]

Varta H3 'Silver Dynamic' is a dedicated, non stop-start feature, starting battery.

As such doesn't like the consumption lifestyle.

OTOH at the cost of give-away I'd be off to get my hands on it for other uses

 

[AndrewB]

Are the batteries genuine deep cycle ? Make/model ?

The other two are Halfords HLB700 12v 100Ah Leisure batteries

 

[ChromeDome]

Me thinks the Halford batteries are designed for 200 cycles of 50% discharge (down to 12.23 volts).

More than a start battery but not really Deep cycle.

 

[PaulRainbow]

The other two are Halfords HLB700 12v 100Ah Leisure batteries

Wouldn't be a great mix. The Varta needs charging at 14.8v, most EFB batteries won't be happy at that voltage, but there is no information on the Halfords site.

If the Halfords batteries are coming towards the end of their life and the Varta is super cheap, might be worth it......

 

[AndrewB]

Thanks guys, it doesn't sound as if mixing batteries is going to cause a major problem. Of course, the start battery will not stand up to repeated discharge and so will not last all that long. But in practice my batteries are generally kept well topped up and only occasionally get discharged. These days the number of overnighters on an anchorage is fairly limited!

I'm not sure about the significance of PaulRainbow's comment on charging voltage. The charging voltage for leisure batteries, according to the information with my charger, starts at 14.4v if the batteries are discharged, reducing to 13.6v when they reach a full state.

 

[VicS]

Thanks guys,

I'm not sure about the significance of PaulRainbow's comment on charging voltage. The charging voltage for leisure batteries, according to the information with my charger, starts at 14.4v if the batteries are discharged, reducing to 13.6v when they reach a full state.

I think what he is saying is that the recommended charging voltage for the Varta H3 Silver Dynamic is 14.8 but that this may be too high for the Halfords EFB leisure batteries, although there is no charging info on Halfords website.

Presumably your 14.4 v is OK for the EFBs but it will be a tad on the low side for the Varta H3 meaning that it won't be charging fully.

It would be interesting to know (they may be labelled) who the Halfords batteries were made by. In the past their top of the range batteries have been Yuasa batteries.

 

[AndrewB]

Presumably your 14.4 v is OK for the EFBs but it will be a tad on the low side for the Varta H3 meaning that it won't be charging fully.

I'm a bit ignorant on batteries, but I thought that any charging voltage above the 'natural' voltage of the battery - 12.6v - would charge it. Isn't it just a matter of how long it takes? The higher the charging voltage, the quicker the battery will be charged. However too high a voltage might charge the battery damagingly fast, so it overheats and disintegrates.
I can understand that start batteries may withstand a higher charging voltage than leisure batteries, and so can be charged faster; but even at a slightly lower voltage won't they both end up fully charged?

 

[geem]

I'm a bit ignorant on batteries, but I thought that any charging voltage above the 'natural' voltage of the battery - 12.6v - would charge it. Isn't it just a matter of how long it takes? The higher the charging voltage, the quicker the battery will be charged. However too high a voltage might charge the battery damagingly fast, so it overheats and disintegrates.
I can understand that start batteries may withstand a higher charging voltage than leisure batteries, and so can be charged faster; but even at a slightly lower voltage won't they both end up fully charged?

There are optimum charging voltages for different batteries. You can't have optimum for two different types. Yes, by all means connect them, but don't expect good life from them